A Guide
for the
Study of Animals

By a Committee from the
Biology Round Table of the Chicago
High Schools

• Worrallo Whitney, Chairman
  
  Bowen High School
• Frederic C. Lucas
  
  Englewood High School
• Harold B. Shinn
  
  Schurz High School
• Mabel E. Smallwood
  
  Lane Technical High School

D. C. Heath & Co., Publishers
Boston — New York — Chicago

Copyright, 1911,
By D. C. Heath & Co.
1 E 3

PREFACE

The following guide to the study of animals is intended
for pupils in secondary schools. It was prepared by the
authors at the request of the Biology Round Table, an
association composed of the teachers of Biology in the
Chicago High Schools, to whom the authors wish to take
this opportunity of expressing their appreciation of the
many helpful suggestions and criticisms of the manuscript.

The time has passed when a high school course in
zoölogy consists simply of a somewhat simplified edition
of a similar course in college. All teachers now recognize
that the motivization of any course should be its
adaptability to the needs of the student, and that zoölogy
must be taught from the standpoint of the student rather
than that of the subject. In preparing this guide, the
authors have tried to keep these points in mind.

The matter of presentation, the order of topics, and the
choice of material has been much discussed, but the trend
of opinion has finally set in toward an ecological rather
than a type study of animals; that there should be in the
case of young students a brief study of rather a large
number of animals to bring out some general biological
law, rather than an exhaustive study of a very few types.
It is further recognized that the use of a reference library
is absolutely essential in connection with and to supplement
the laboratory work, as there are some topics beyond
the ability of the young student for original investigation
as well as impossible in the amount of time usually allotted
to the subject in our crowded curricula. Of great importance
is the economic side of zoölogy, especially its bearing
upon the applied sciences of medicine, sanitation, household
science, and agriculture, and this phase has received
special attention in this guide.

The desirability of field work has always been recognized,
but the special conditions under which schools must
work are so variable as to make any set directions for
field work of little value, and so they have in most cases
been omitted in this work. Each teacher can easily give
such special direction for collecting material and study
in the field as the locality of the school and the time available
for it shall determine.

Since zoölogy will probably be the pupil’s first laboratory
science, the authors have preceded the more formal portion
of the manual with a series of short exercises on
familiar and easily obtained animals in order to introduce
the pupil to the laboratory method and to stimulate his
interest, training him at the outset to be constantly on the
outlook for specimens and to show him how much may
be learned from common things right around him, if he
will only use his eyes. We have also begun the more
formal portion of the guide with insects, since in the fall
they are easily collected and may be studied alive. They
illustrate, moreover, the principles of classification and
method of using keys and other means of finding out the
names of animals. This would seem to be pedagogically
sound, for some recent experiments with pupils show that
the first question that comes into a child’s mind upon
seeing a new or strange specimen is “What is it?”

A larger portion of the guide is given to the chordates
than is usually the case. The authors also believe that
this is correct and in accord with the natural interest of
the pupil. It will serve to connect his zoölogy more
closely with his daily experiences.

There is material enough provided to allow the teacher
a chance to select that best adapted to his purposes or
conditions as well as to provide for those schools that
give more than one year to zoölogy.

CONTENTS

A Guide for the Study of Animals

CHAPTER I
INTRODUCTORY STUDIES OF LIVING ANIMALS

In the following brief exercises the primary purpose is
to arouse an active, attentive interest on the part of the
pupil in various forms of animal life which may be at
hand, reminding him of what and how various creatures
eat, how they breathe, how they get ideas of the world,
how they get about, and perhaps how they succeed where
others fail. Of secondary importance is the introduction
of laboratory methods by easy stages. The pupil should
feel that his natural curiosity is only being directed to
definite ends and that he is free to investigate in his own
way.

The types here given are only a few of the many to be
found in the early fall, and these exercises in several cases
may be used for other forms than those definitely mentioned.
There should be a great deal of promiscuous collecting
by the class, and in the mass of material gathered
the following types will probably be fairly abundant.

THE LIVING FLY

Materials.

Living flies in cages and individual specimens in small
wide-mouth vials with cotton stoppers for the admission of
air. Sugar crystals may be used for feeding. Simple
lenses.

Observations.

Notice the division of the body into three regions:
head, thorax, and abdomen. The six legs, the large
wings, and the small feelers may be easily found, as are
the large eyes, the extensible mouth, and beneath the
larger wings the small undeveloped ones looking like
tiny knobs.

1. State the general color of your specimen and give
   any special markings on its body.
2. Is the body smooth or has it a covering of any kind?
   Do you regard the fly as a cleanly animal? Why?
3. Under what conditions does the fly use its legs? its
   wings? What enables it to walk upside down? What
   use can you assign to the small wings?
4. Judging by the relative size of the feelers and the
   eyes, do you think the fly relies more upon its sight or its
   feeling? Since the eyes can probably see you any place
   where you see them, determine through how much of a
   circle the fly can see.
5. How does the fly eat? Does it eat solid or liquid
   food?
6. Where is the extensible mouth (proboscis) kept when
   not in use? What is the fly doing when “washing its
   face”?
7. From your own observation in the barn and the alley what do
   you know about the fly’s cleanliness in choosing its food? How
   would it affect articles in the pantry?
8. From the foregoing statements show how flies may be a serious
   factor in dealing with disease.
9. What means may be employed as protection against adult flies?
   against their breeding places and “maggots”?

Suggested drawing.

1. The entire fly, seen from above, × 4.

THE LIVING MAGGOT

Materials.

Living specimens in pans or cotton-stoppered bottles,
with some food material and moist cloth or paper; lenses.

Observations.

Notice the general worm-like form of the maggot, or
grub, the plain and uniform color, and the absence of all
elaborate structures, as wings and feelers.

1. Since this creature is destined to become a flying or
   walking insect, what organs will have to appear? Is
   there any indication of these structures at present?
2. Give the color of the specimen, and explain how the
   presence or absence of strong light seems to have affected
   the color. Is this effect usual in animals or plants that
   you know?
3. Tell how the animal gets from place to place, describing
   any special structures you find which aid in this work.
4. How can you tell the head end? Tell how the
   amount of work that the mouth and mouth parts do affects
   their size and indirectly that of the region where they are.
5. What senses and sense organs has the maggot?
   Test any of these senses or organs gently, by any means
   at your disposal, or recall any experience you have had
   along this line. Which senses or organs seem to be best
   developed?
6. Explain briefly how the active or sluggish habits either determine
   or are determined by the condition of the senses or sense organs.
7. Since “Mother Nature” seems to want maggots to develop rapidly,
   tell how she economizes in energy and material when forming
   them.
8. Show how the development of maggots in refuse matter is
   actually beneficial.
9. From the standpoint of flies and human welfare, show why maggots
   should not be allowed to live,—stating how they may be prevented.
10. 
    Look up the story of the pupa of the house fly; the development
    and work of the botfly; of the ox-warble; of the tsetse fly.

Suggested drawing.

1. The maggot or grub, side view, × 4.

THE LIVING COCKROACH

Materials.

Individual specimens in cages, jars, or wide-mouth vials
with cotton stoppers to admit air. Several roaches in large
cages with material for food and concealment.

Observations.

1. What is the general color and the average size of
   cockroaches?
2. During what time of the day are roaches most active?
   Where do they hide at other times? How do their shape
   and color aid concealment? Note any odd or striking
   colors or marks which might make them distinguishable to
   their mates.
3. Is the roach a quick or a slow moving animal? How
   does it get about,—by running, jumping, walking, crawling,
   swimming, or flying? Turn your specimen on its back
   and see how it recovers its proper position. Notice the
   relative size and development of the wings and their use in
   flying.
4. If uninjured, your specimen has six legs. Why don’t
   they step on each other? Notice the stiff hairs on the legs
   and the white pads under the feet. How would these
   structures be useful to the animal?
5. The large, black, shiny eyes are on the front and
   sides of the head; the long “horns,” or feelers, are attached
   just below the eyes. Upon which sense, sight or
   feeling, do you think the roach depends more? Explain
   your statement.
6. 
   Beside the mouth are a long and a short pair of
   “feelers”; perhaps these are for tasting or smelling.
   What do roaches like to eat? Do they choose their food?
   What damage do they do?
7. How can a house be rid of cockroaches?

Suggested drawing.

1. a. A cockroach, seen from above.

THE LIVING SPIDER

Materials.

Living spiders, preferably large ones, in cages; individual
specimens in battery jars or wide-mouth bottles.
Cocoons. Simple lenses.

Observations.

Each pupil may feel sure that if treated fairly any of the
common spiders may be handled without fear of bite or
injury.

1. Note that the spider’s body is of two regions, the
   head-thorax and the abdomen, and that it is supported by
   eight legs. To what part of the body are the legs attached?
2. Find the feelers; if they are club-shaped, your specimen
   is a male. State their number and tell where they
   are attached. What is the sex of your spider?
3. Usually there are eight tiny near-sighted eyes on the
   front of the head. State the color of the eyes and by a
   diagram indicate their arrangement.
4. With what kind of material is the body covered (use
   the lens)?
5. What is the color of your specimen? What special
   markings has it?
6. 
   Holding the spider aloft in your fingers, allow it to
   drop upon the thread it will spin, and watch it climb and
   spin. Record the number of the spinners, their situation,
   and how they act. Are the threads sticky? If so, why
   doesn’t the spider stick to its web? Is the web used for
   a home or for a snare?
7. Try to discover how the feet are enabled to cling to
   the thread.
8. Examine a cocoon, noting its outer form and structure,
   and look for an opening at the top. If you can open
   a cocoon carefully with scissors, look for its two coats and
   inspect its contents.
9. State three uses for the spider’s silk.
10. What is the work of spiders amongst the animal population of
    the earth, or of what use are they?
11. Out of doors find webs of various kinds: wheel web, tent web,
    triangle web, etc.
12. How do the jumping spiders differ from others in their spinning
    and feeding habits?
13. Look up what is meant by ballooning spiders. Find out when
    ballooning occurs and what is accomplished by it.

Find out the name of your kind of spider.

Suggested drawings.

1. The entire spider, seen from above.
2. A cocoon.

THE LIVING CRICKET

Materials.

Living crickets in cages, with materials for food and concealment,
and individual specimens in wide-mouth bottles
or vials with cotton stoppers.

Observations.

1. What is the average size and the general color of
   crickets?
2. 
   Just what do they do when you try to catch them?
   What structures enable them to do these things?
3. Of the three pairs of legs, which extend sidewise for
   running or grasping, and which backward for jumping or
   climbing? What structures have the legs to enable them
   to do their work properly?
4. Notice how well developed the cricket’s wings are,
   and state how much they are used or how they influence
   the habits of the animal.
5. How many projecting spines are there on the hinder
   end of the body? Are they ornamental or useful? how?
   The female crickets have a special spear-shaped spine for
   depositing eggs.
6. In a column make a list of the senses (sight, feeling,
   etc.), and opposite each state what kind of an organ is used
   and where it is located. The ears are oblong white spots
   on the second long piece of the front legs.
7. Find out whether the cricket chews solid food or
   sucks liquid food, and whether it has biting jaws or protrusible
   lips. See whether it will attack a toothpick or your
   finger, and if the crickets have been confined long, whether
   there has been any attempt at cannabalism. Is its natural
   food animal or vegetable matter?
8. How do crickets chirp?
9. What work do they do in nature?
10. How does a baby cricket develop?

THE LIVING GRASSHOPPER OR LOCUST

Materials.

Individual specimens in wide-mouth bottles or jars, and
other specimens in cages, with turf or foliage for food and
concealment. Simple lenses.

Observations.

Notice the form and size of your specimen, its color,
the number of its legs and of its feelers. Find the eyes;
the two large eyes, a tiny one between the two feelers,
and near the inner edge of each large eye, another tiny
one. With a lens notice the markings on the large eyes.
Find the mouth, and note its lips and finger-like feelers.
Draw out an outer wing, and then carefully draw out the
delicate under wing, allowing them both to fold into place
again. Under the wings find the circular or crescent-shaped
membranes, the eardrums. Watch the grasshopper’s
body expand and contract in breathing, and find
the small breathing holes along each side the body. Compare
its rate of breathing with your own.

Questions.

1. In what surroundings and how does the grasshopper’s
   color protect it? What color markings has it
   which might serve for other grasshoppers to see as
   signals? Explain how this signaling is done.
2. Explain how the legs are placed so as to act as
   springs in jumping and alighting.
3. What advantages in having the wings attached on
   the upper side and the legs on the under side of the body?
4. Explain how the small wings are protective, and how
   the large ones are protected.
5. Why is it better for the grasshopper to have its
   mouth on the under side of its head instead of in front?
6. The large eyes are supposed to be far-sighted, the
   small ones near-sighted. State how the large eyes have
   the more advantageous position, and around how much of
   a circle they can see.
7. Describe how the grasshopper breathes.

THE LIVING BUTTERFLY OR MOTH

Materials.

Individual specimens in large jars or cages, and other
specimens in cages with foliage; simple lenses and a
needle or pin.

Observations.

Butterflies may generally be distinguished from moths
by their habit of holding their wings together above them
when at rest, by the feelers which are knobbed at the
end, and by the rather slender abdomen. Moths generally
either fold their wings or hold them outstretched, their
feelers are not knobbed, and their bodies are rather
bulky.

Observe these points in your specimen and the colors
of the upper and under sides of the wings. Find the
large eyes and examine them with a lens. With the needle
or pin carefully uncoil the sucking tube which you may
find under the head between two shields. Note the
fuzziness of the body and the “dust” which covers the
wings. Examine some of this dust under a lens.

Questions.

1. Is your specimen a butterfly or a moth? Prove your
   statement. If possible, give the name of your specimen.
2. Write a description of your specimen—its size,
   general color, and special color pattern.
3. Describe the sucking tube, or “proboscis,” and
   name some flowers from which it might obtain nectar.
   Try to find out how the tube is operated.
4. Why is it that moths and butterflies never bite? Do
   they sting? How do you think they protect themselves
   from enemies?
5. 
   State how the fuzz and dust on your specimen might
   influence a bird’s liking for it.
6. Contrast the size and usefulness of the wings of the
   butterfly with those of some other insect you know about;
   contrast their legs; state how development of one set of
   structures may cause another set to be simple or feeble.
7. Most moths are active by night. What explanation
   can you give for their large eyes and expanded feelers?
   Feelers of insects may be for any or all of the following:
   touch, taste, smell, and hearing.

Suggested drawings.

1. The butterfly or moth.
2. An antenna (feeler).

THE LIVING CATERPILLAR

Materials.

Living caterpillars in cages or covered jars for individual
study, and other specimens in cages with foliage for food
or concealment.

Observations.

The pupil should observe the general form and external
construction of the caterpillar, watching it feeding, in
action, and at rest.

Notice how the creature moves. Find its head, its
segments (similar divisions of the body), and its breathing
holes along the sides of the body. Try to find its eyes,
any feelers, wings or paddles. Try to loosen it from its
support; find the tiny hooks on the feet for clinging fast.

Questions.

1. Give the general color of your specimen and explain
   how this color may make it conspicuous or may aid its
   concealment.
2. 
   Describe the outer surface or covering of the caterpillar.
   What structures, if any, are there, which might
   make the animal distasteful or inedible?
3. How many pairs of legs are there? How are they
   distributed along the body? Counting the segments, state
   which ones bear no legs.
4. To what extent do the legs act in locomotion? Are
   they mere organs for attachment while the body swings
   forward and backward, or do the legs do this, as in a
   horse? Make a complete statement.
5. Notice the openings of the internal breathing tubes.
   How are they protected against dust and other foreign
   matter?
6. Does the caterpillar seem to be a warm-blooded
   animal? State how the free access of air along the body
   would influence internal temperature.
7. What do you know about a caterpillar’s appetite?
   How might caterpillars be beneficial or harmful? What
   means has nature of holding their numbers in check?
8. Recalling that caterpillars finally “sleep” for several
   days or weeks and awaken as winged creatures, how can you
   account for their appetites?

THE TUSSOCK MOTH

Materials.

Directions for the study of the caterpillar stage will be
found in the exercise “The Living Caterpillar,” and
directions for the study of the adult male form will be
found in the exercise “The Living Butterfly or Moth.”
The female tussock moth is a wingless, thick-bodied
creature, gray in color, very downy, and about three
fourths of an inch long. The following directions apply
more particularly to the study of the cocoons and the
general harmfulness of the tussock moth.

This exercise may be done best outside of the classroom,
the pupil answering the questions on scrap paper and
rewriting these notes in the laboratory. Living caterpillars,
cocoons, some of them bearing their frothy masses of
wax and eggs, pupæ, and adult moths of both sexes may be
used in the laboratory.

Observations and Questions.

1. On what kinds of trees are the cocoons and the
   caterpillars generally found? What effect have the caterpillars
   on the trees, and what may possibly be the final
   effect upon the trees of the locality or the entire district?
2. Upon what part of the tree are the cocoons made,
   and why? Where on the bark are they, and why?
3. Is the opening of the cocoon at the upper or the
   lower end? What reason can you assign for this?
4. Count the number of cocoons upon the entire tree
   or estimate it by counting those upon a part of the tree.
   Now count the number of eggs on a cocoon. Assuming
   that one half of the cocoons bear eggs, calculate the
   number of caterpillars on a tree next year.
5. How is the waxy covering of the eggs a particularly
   good protection against winter weather?
6. Investigate the interiors of several cocoons and state
   what you find.
7. On the pupa find the jointed and tapering hinder
   end, abdomen, and at the head region and lying along the
   under side, the marks of the legs and the feelers, and possibly
   the wings, all pressed close against the body. Find
   also the breathing pores along the sides of the abdomen.
8. Unlikeness between male and female is called
   “sexual dimorphism.” Explain how the tussock moth
   shows this. For what work does each form seem particularly
   adapted?
9. What methods would you use that the tussock moth
   might be destroyed or kept out of a community?

The numerous small worm-like creatures often found are the caterpillar
stages of another insect, an ichneumon fly, which laid its eggs
under the skin of the tussock caterpillar. How has their development
affected that of the tussock moth? What great result does nature
accomplish by this arrangement?

Suggested drawings.

1. A caterpillar, × 2.
2. A cocoon with its egg mass.
3. A pupa as seen from the under side.
4. An adult moth, either male or female.

THE LIVING BEETLE

Materials.

Living beetles in cages, together with portions of the
plant upon which they are found; or if water beetles are
used, they should be kept in aquaria. Individual specimens
in battery jars or wide-mouth bottles, and preserved
beetles in pans or vials for reference.

Observations.

1. Upon what plant or in what surroundings is your
   kind of beetle generally found? If you can, give its common
   name.
2. What is the length, breadth, and thickness of your
   beetle? Would you describe it as a “small” insect or a
   “large” one?
3. Of what general color is it? Describe any color
   markings you see.
4. If any of the legs differ from the others or are of
   peculiar shape or length, describe them and tell what you
   think they may be fitted to do.
5. As a rule, beetles have harder “shells” than other
   insects. Does this shell completely inclose the body, or
   can you find any soft parts exposed? How are the head,
   thorax, and abdomen joined so as to carry out the apparent
   purpose of protection? What is the outline of the body—a
   continuous line or one with many irregularities?
6. If possible, try to lift up one side of the “shell” from
   the hinder end of the body. You will discover that this
   portion of the shell is a pair of hard sheath wings, and beneath
   them is another pair. How are the under ones
   unlike the upper in size and texture? in use? in arrangement
   when not in use?
7. Does a beetle spend most of its life on the wing, like
   bees and flies? How might the body covering and the
   structure of the outer wings affect or determine the beetle’s
   habits, even against its will?
8. Are the feelers or are the eyes of your specimen
   more easily distinguished? Upon which of the special
   senses does it seem to place most dependence?
9. Is your kind of beetle good for anything, either in nature or in
   human affairs? Make a statement regarding what good or what harm
   it may do.

THE DAMSEL FLY LARVA

Materials.

Living larvæ of the damsel fly in shallow watch glasses
of water for individual use, and others in large pans or
aquaria. Simple lenses or dissecting microscopes.

Observations.

1. What is the color and the shape of the larva? how
   long is it? Notice in what surroundings in the water the
   larva lives, and answer to yourself how its form and color
   would protect it in those surroundings.
2. Since the larva is an insect, though immature, its
   body is composed of three regions: head, thorax, and
   abdomen. How do these regions differ from each other?
3. What structures has your specimen to enable it to
   move from place to place? If fully developed wings are
   not present, what indication is there of their being
   formed?
4. What sense organs has the larva? Which ones
   seem to be the largest and most useful?
5. Although the aquatic larva is preparing for adult
   life in the air, there should be some arrangement for
   securing air in the water. Where do you find outgrowths
   of the skin which might increase the air-absorbing surface?
   How many of these structures are there? Look within
   them for the air tubes,—fine branching black lines.
6. If possible, without injury to the specimen, examine
   the larva’s mouth. Try to discover how it is used and
   how it is protected when not in use.

Suggested drawings.

1. The entire larva, × 4.
2. A gill, as seen through the microscope.
3. The feeding apparatus, × 10.

PLANT LICE AND SCALE BUGS

Plant Lice (Aphids)

Materials.

Plant lice on various kinds of plants, such as house
plants, golden glow, and other plants from the garden or
field. Garden asters with root lice (the asters should be
transplanted into pots).

Observations.

1. Describe the size, appearance, and colors of the plant
   lice in your collection and their relation to the host plant.
2. Are the lice active or sluggish? (Compare with a
   house fly, for instance.) What proportion of them have
   wings? What is the usual method of locomotion?
3. Examining a single winged specimen, how many
   wings do you find? How do they fold? What is the
   character of the wings?
4. What is the food of the plant lice? How is the
   food obtained? (With a hand lens identify the piercing
   organ.) On what parts of the plants are they found?
   Does the plant show any indication of being harmed by
   the lice? If so, how?
5. Make a count of the plant lice upon a portion of
   a plant and estimate the whole number upon a plant.
   Why are plant lice a very serious pest?
6. If any plant lice have ants associated with them,
   study the behavior of the ants in this curious relationship.
   What advantages result from this relationship of ant
   and aphis to either or both insects?

Scale Bugs

Materials.

Twigs of trees, leaves, fruit, ferns, etc., infested with
these bugs. If possible, have samples of San José scales,
maple scales, and oyster scales.

Observations.

1. What is the general size and appearance of the
   various scale bugs in your collection? How do they
   differ in form and size and color?
2. Remove a scale and study it carefully with a lens.
   What is under the scale? Of what is the scale composed?
   What do you discover about these bugs to indicate that
   they are really insects?
3. What can be said about the number of scale bugs?
   Why are they difficult to exterminate? How can they
   be distributed from one place to another, as from orchard
   to orchard, since only the males have wings?

Drawings suggested.

1. A single aphis as seen with hand lens.
2. Various scale bugs as seen with a hand lens.
3. Twigs showing the distribution and numbers of
   scale bugs.

WATER BUGS AND BEETLES

Water Bugs

Materials.

Water bugs and beetles of several species in small
aquaria covered with a wire net.

Observations.

1. With what legs does the bug swim? Describe their
   appearance and tell how used and how fitted for this use.
   Which legs are not used in swimming?
2. Remove the bug from the water for a moment to test
   other methods of locomotion, as jumping, crawling, flying.
   What do you discover?
3. Watch the bug as it gets a fresh supply of air, and
   describe the process. Where is the air stored for use when
   under water? Does the bug sink or rise when it stops
   swimming? Why?
4. Identify the bug’s mouth parts. What is their appearance
   and probable manner of use? How are the forelegs
   fitted for grasping food?
5. What is the shape of the body? What is the position
   of the wings? Do the two cover (fore) wings meet in a
   straight line or do they cross at their tips? Are they
   smooth throughout and sheath-like, or are they thick at the
   base and thin at the tips?

Summary.

Summarize your study of the bug by enumerating the
various ways the bug is adapted for life in the water.

Water Beetles

Use the same questions for the study of water beetles as
for water bugs. In addition answer the following:—

1. Identify the eyes of the whirligig beetle and note their
   peculiar construction. How can you explain this peculiar
   form of the eyes on the basis of use? Why are the antennæ
   of both water bugs and beetles so small?

Suggested drawings.

1. The dorsal view of both bug and beetle.
2. Ventral view of the bug’s head to show the beak and
   first pair of legs.

GETTING ACQUAINTED WITH THE LIBRARY

Directions.

The books in a zoölogical library may be roughly divided
into three groups:—

1. Reference books.
   1. Advanced textbooks.
   2. Elementary textbooks.
   3. Natural histories.
   4. Books for classifying or naming animals.
2. Descriptive books.
   1. Life histories and habits of animals.
   2. 
      Adventures with animals—popular accounts of animals seen on walks and travels.
3. Economic zoölogy.
   1. Books on harmful animals and methods of destroying them.
   2. Books on useful nondomesticated animals and their products.
   3. Books on domestic animals.
   4. Books of a general nature not included in the above.

Examine as many of the books in your library as you
can and record for each one in your notebook:—

1. Title of the book; author’s name; publisher; date
   of publication.
2. The kind of book as classified above.
3. What it includes or what animals or topics are covered
   by the book.
4. Whether the style is popular or technical, i.e. whether
   it is easy for you to read.
5. The general character of its illustrations and whether
   they appear to be especially helpful.
6. Comments on the value or interest of the book as it
   appears to you.
7. Select a book which interests you, for future reading.

CHAPTER II
STUDIES OF INSECTS

The effect of great numbers upon the structure and habits
of animals. The use of keys in finding the names of
animals.

1. FIELD STUDIES

Materials.

1. Boxes for carrying insects. 2. A net. This may be
homemade, using mosquito netting or fish net and a stout
wire. If it is to be used for a dragnet for water insects,
the wire must be stout and the netting strong. Make the
net twice as long as wide. 3. A cyanide jar for killing insects.
4. A few paper triangles for carrying butterflies.
5. A notebook.

Note.—Your instructor will give directions for obtaining the material
called for in 3, 4, and 5.

Directions.

Look carefully and quietly in the various situations noted
below. Do not be in a hurry. Weedy meadows or vacant
lots and neglected roadsides are good places for your first
trips. Note concerning each insect found: (a) its name or
something by which to identify it, (b) where you found it,
(c) what it was doing, (d) its probable food. Record these
observations in your notebook. Make a special study of
such insects as your instructor may designate.

Where to look for Various Insects

Grasshoppers, locusts, katydids.

Look along roadsides,
waste places, gardens, especially weedy ones, weedy lots,
and grassy meadows and pastures.

Crickets.

Under old boards, along the edges of board
or stone walks, along fences.

Beetles.

Same locations as for crickets, and also on
flowering plants, under loose bark of trees and stumps, in
rotten logs, etc. For water beetles drag edges of ponds
and streams.

Dragon flies.

Along water-courses, ponds, and swamps.
Drag ponds and ditches for larvæ.

Bees.

On flowering plants, especially on large patches
of wild asters, golden-rods, and thistles.

Wasps.

Sandy stretches,—especially along the water,—among
flowering plants, under the eaves and roofs of outbuildings.
Nests may be found in these latter places.

Butterflies and moths.

In fields where there are many
flowering plants; look carefully on the leaves of plants for
caterpillars, and for eggs. Also look very carefully on the
under side of leaves, on twigs, and on the bark of trees for
chrysalids of butterflies and cocoons of moths.

Bugs.

In same locations as for bees and grasshoppers
and water beetles. Also on fruit.

Aphids.

On the fresh growing tops of plants.

Tree hoppers.

On trees and shrubs. Hold your net on the
under side of branches and shake the branch vigorously.

Flies.

Around decaying substances, as garbage, fruit,
etc.; on flowering plants.

Ants.

Sandy waste places, decayed logs, along walks,
often in kitchens.

Note.—At night many kinds of insects fly around electric lights or
into open windows, attracted by the light and may easily be collected.

Form for Field Trip Report

The notes taken on a field trip may be conveniently
tabulated for permanent record in the form indicated below:—

In case the name of the insect is not known to you, use a
number and some designation as to color or other mark by
which it may be known until you have leisure to look up
its name by means of keys or books on insects.

Special Field Studies

The questions below may be used for a more careful
field study of any insect.

1. Just where was the insect found?
2. Note carefully what the insects are doing before they
   are disturbed by your presence. What did the insects do
   when you disturbed them? If you think this related to
   securing safety, explain what leads you to think so.
3. What senses do you conclude are well developed?
   Reason for your conclusion.
4. Has the insect a home? If so, what is its character?
5. What is the color? What is the relation between the
   color of the insect and its surroundings?
6. Is the insect solitary in its habits or associated with
   others of the same species? If in association with others,
   note the numbers, and what they are doing.
7. 
   What modes of locomotion do you observe in this
   insect? Which is the most common? If it flies or jumps,
   note the distance.
8. If you find the young, note whether they differ from
   the adult in general appearance, and if so, in what ways
   they differ. Do they differ in food?
9. What other insects do you find in the same habitat?

2. A STUDY OF GRASSHOPPERS (LOCUSTS)

Insects adapted to Life in Grassy Meadows and Fields

Materials.

Both living and dead specimens of grasshoppers. Various
stages of young grasshoppers either dead or living.
Some mounted specimens with wings spread. The wings
of grasshoppers mounted in pairs between two glass slides
for use with microscope or hand lens. Mounted preparations
of mouth parts and tracheæ.

Definitions.

Orthoptera,

straight-winged insects, order to which belong
grasshoppers, locusts, katydids, crickets, cockroaches, etc.

Vivarium,

a cage in which living animals are kept.

Anterior,

toward the head of an animal.

Posterior,

opposite to anterior.

Dorsal,

the upper surface of an animal.

Ventral,

opposite to dorsal.

Regions,

principal divisions of the body of an animal.

Head, thorax, and abdomen,

the three distinct regions
into which the body of a grasshopper is divided.

Somite,

a ring-like division of the body of an animal.

Prothorax, mesothorax, and metathorax,

the three divisions
or somites into which the thorax of any insect is divided.
A pair of legs is borne on each division.

Exoskeleton,

an external skeleton.

Femur, tibia, and tarsus,

the three principal divisions of
the leg corresponding to thigh, shank, and foot.

Veins,

thread-like thickenings of the wings.

Ocelli,

the single or simple eyes of an insect, composed
of a single eye element.

Compound eyes,

made up of many eye elements.

Auditory sacs,

organs for hearing in many animals.

Antennæ,

the feelers borne on the head.

Labrum,

the upper lip.

Labium,

the lower lip, formed by the growing together
of the second maxillæ.

Mandibles,

primary jaws situated under the labrum.

Maxillæ,

secondary jaws just in front of the labium,
each composed of three parts, a palp, a spoon, and a
tooth.

Palps,

the jointed finger-like structures used to handle
food, one pair on the labium and one pair on the maxillæ.

Spiracles,

openings into the trachea found along the
sides of the abdomen and thorax.

Tracheæ,

slender tubes used for breathing organs among
insects. They carry the air direct to the tissues in all
parts of the body.

Ovipositors,

structures on the posterior end of the abdomen
of a female, used to deposit eggs.

Metamorphosis,

refers to the development of the young
of animals when striking changes in structure occur in the
course of their growth. Metamorphosis is called complete
when the young have no resemblance to the adults,
and incomplete when there is a resemblance to the adult.
In complete metamorphosis the stages are larva, pupa, and
adult. In incomplete metamorphosis the stages are
nymph and adult.

Observations.

The Body.

1. Show how the shape of the grasshopper’s
   body is well adapted to its needs.
2. Which region of the body is the thickest? What
   seems to be the reason for this? Which regions are
   capable of movement?

Locomotion.

1. What are the various kinds of locomotion
   a grasshopper can use? Which are used in the vivarium
   and which when free in the laboratory?
2. Which legs are used in jumping? How are these
   legs especially adapted to this, in length, structure and
   direction? Could a grasshopper jump if the third pair of
   legs were arranged like the other two pairs? Why?
3. How is the animal able to cling to grass stems and
   not slip down? What is the direction of the body in
   relation to the stem or grass blade?
4. What is the position of the wings when at rest?
   when in use? How do the hind wings fold? How are
   the principal veins of the wings arranged to permit or
   facilitate this folding?
5. Contrast the fore and hind wings with respect to
   thickness, size, and use.
6. To which somites of the thorax are the wings attached?
   Nearer which surface, the dorsal or ventral? Why?

Sense Organs.

1. Discover all you can about the uses
   of the antennæ by carefully observing grasshoppers at
   rest, feeding, jumping and crawling, approaching an object
   or another grasshopper, etc.
2. How many compound eyes has the grasshopper?
   How many simple eyes? Where are they located?

   Examine a preparation of the compound eye with the low power or
   as demonstrated with the stereopticon. What is the shape of an eye
   element of the compound eye? About how many eye elements are
   there in a compound eye?

Feeding.

1. Do grasshoppers eat and drink while in
   captivity? Put a fresh bunch of grass which has been
   sprinkled with water in a vivarium with grasshoppers that
   have had no food or drink for twenty-four hours and watch
   results.
2. What is the position of the grasshoppers in feeding?
   In what direction do the jaws move in feeding? Compare
   this with the direction of movement of your own
   jaws. What is the use of the palps? What do you think
   is the use of the “molasses” or saliva that flows from the
   mouth?

Respiration.

1. Describe the breathing movements of
   a grasshopper and explain the relation of the movements
   to inhalation and exhalation of air.
2. Find the exact location and number of spiracles on
   the abdomen. There are two pairs of spiracles on the
   thorax. Find them. How do the spiracles prevent the
   entrance of dust?

   Describe a trachea as seen in a mounted preparation with the aid of
   a microscope or stereopticon.

Protection.

1. Explain how the colors of the grasshopper
   may be protective or useful when at rest in its
   natural habitat and when in flight.
2. Does the shell cover the entire body? What are
   the advantages of such a covering? A shell is likely to
   hinder activity, sensitiveness, and growth. How are such
   disadvantages overcome in this case?
3. What senses are probably most relied upon to
   detect approaching danger? Give evidence to support
   your answer.
4. What is the position of the hind legs when at rest?
   What relation has this to safety?

Reproduction and Development.

1. Describe the ovipositors
   and the probable method of their use. Describe
   the egg packets of grasshoppers, if discovered. About
   how many eggs in one? (They are sometimes seen
   against the glass sides of the vivaria.)
2. If you have young grasshoppers of various ages,
   arrange a set of them in what seems to you to be the order
   of their development. How do young grasshoppers differ
   from adults? What changes take place as they develop?
   What kind of metamorphosis is this?

Summary of Important Points in the Study of the Grasshopper

1. How many and what distinct regions of the body
   are there?
2. How many antennæ? Compare their length with that
   of the body. What other sense organs did you discover?
3. How many legs? For what specially adapted? How?
4. How many wings? What is their resting position?
   How do the fore wings differ from the hind wings? How
   do the hind wings fold?
5. To what kind of feeding are they adapted, biting or
   sucking the food? How many and what sets of mouth
   parts are there?
6. How is air necessary for respiration obtained?
7. In what various ways are grasshoppers fitted for life
   in meadows and weed plots?
8. How do they meet winter conditions?
9. What kind of metamorphosis has the grasshopper?

Drawings suggested.

1. Side view with the legs and wings removed. Label
   all parts shown in this drawing. (See Definitions on pages
   23 and 24 for names of parts.)
2. Face view of the head, showing the simple and compound
   eyes, the antennæ, labrum, and palps.
3. One of the third pair of legs. Label parts.
4. A fore and a hind wing arranged in natural position.
5. A young grasshopper.

3. COMPARATIVE STUDY OF ORTHOPTERA

Materials.

Mounted specimens of various common species of orthoptera.

Observations.

1. Where does the insect live? What is its color?
2. What is the size and shape as compared with the
   grasshopper?
3. What is the length of the antennæ as compared with
   the length of the body?
4. To what kind of locomotion are the legs adapted?
   How? Are the forelegs specially adapted for grasping?
5. What is the position of the wings when at rest?
   Are they large or small as compared with the size of the
   body?
6. Are the ovipositors long or short? (Compare with
   those of the grasshopper.)
7. Find the group to which the insect belongs and its
   name by the key in the following section.

4. KEY TO SOME COMMON ORTHOPTERA

A. Groups

B. Species or Genera

5. THE DRAGON FLY

An Insect adapted to Aerial Life

Materials.

Mounted specimens of dragon flies, some moist preserved
specimens, living specimens if practicable, simple lenses.

Observations.

1. Identify the three regions of the body and note the
   presence of a distinct neck. What is the length of the insect?
   What is its general form? If you have living specimens,
   discover what movements the head and abdomen
   are capable of making.
2. What is the position and general character of the
   wings? Explain how these wings are made very efficient
   for flying. Why should they not fold?
3. For what do the legs seem best adapted? Why?
4. Note the size of the eyes and of the antennæ?
   How do you account for the great size of the eyes and
   the relatively small antennæ?
5. What is the type of mouth parts, biting or sucking?
   If you have living dragon flies, try feeding them flies or
   mosquitoes and note how they are seized.
6. The food of dragon flies is mosquitoes and flies caught
   while on the wing. In what various ways is the dragon fly
   specialized for getting food in this manner?

Summary.

How is the dragon fly fitted for its aerial life
with respect to its body, means and method of locomotion,
sense organs, kind of food and manner of obtaining
it?

Suggested drawing.

1. Dorsal view, showing veining of one wing.

6. THE HONEYBEE

A Study of Adaptations for Community Life

Materials.

Preserved specimens of workers in small vials and in
watch glasses, and some mounted specimens. A demonstration
case showing the three kinds of members of the
community, stages in the development of the workers and
queens and the cells in which they are reared, specimens
of the comb. Small pieces of beeswax, a box of honey,
and specimens of comb free for examination. Mounted
preparations of mouth parts and stings. Simple lenses and
compound microscopes.

Observations.

The Worker Bee.

1. Observe and describe the form, size,
   regions, and covering of the bee. What are its colors?
2. Observe and describe the texture, veining, relative
   size, and position of the wings. Discover how the fore
   and hind wings are hooked together. What advantage in
   having them hooked together?
3. For what kind of locomotion are the legs best
   adapted?
4. Find the pollen basket on the tarsus of a hind leg.
   How is it fitted for carrying pollen? What are the wax
   shears?
   1. Examine and describe the structure at the posterior end of the
      body used for stinging. (Use a mounted preparation for this with
      low-power of microscope.)
   2. The mouth parts are fitted for both biting and sucking. Find what
      makes this possible. (Use mounted preparation.)
5. Describe the antennæ and the number, position, and
   shape of the eyes. Are the eyes fitted for keen sight?
   Give reason for answer.
6. 
   The worker bee gathers honey and pollen and defends
   the entire community from enemies. What various adaptations
   fit it for this work?

The Community of Bees.

1. How do the workers, drones,
   and queen differ in general appearance?
2. Describe the appearance of the comb and the arrangement
   and shape of the cells. Why this shape? How are
   the cells closed when full of honey?
3. How do the cells used for rearing worker bees differ
   from those used for rearing queens? What is the appearance
   of the larvæ? Of the pupa?
4. Examine and test in various ways a small piece of
   beeswax. What are the qualities possessed by this wax
   which make it suitable for making comb and protecting
   the home from storms?

Supplementary Studies of Bees

Materials.

For this study an observation hive of bees or opportunity
to visit an apiary will be helpful. If neither are practicable,
then look up the answers in books. There are government
bulletins on bee-keeping and much helpful information can
be obtained from large dealers in bees and bee supplies.

Observations.

1. How do bees protect their hives from rain and storm
   and light?
2. What are honey boxes? Where are they placed in
   the hive? Can the honey be removed late in the fall?
3. How is it safe to approach and handle bees in removing
   honey and caring for them?
4. What are their habits in entering and leaving the
   hive? What is the appearance of a returning loaded
   worker bee?
5. 
   How do bees survive the winter? Why are the
   drones driven away or killed?
6. Watch bees gathering nectar and pollen from flowers
   and describe the process. Try following a bee on its journeys.
7. When the bees are in the hive, how may you know
   the queen and drones from the workers?
8. What is swarming? When does it take place? How
   is the swarm hived?
9. What is the home of wild honeybees? How found?

Summary of the Study of Honeybees

How is the work of the community of bees divided
among the bees? How is each fitted for the work? What
do you think of the success of this kind of life? Give reasons
for your answer.

7. GENERAL STUDY OF INSECTS[1]

Materials.

Both living and preserved specimens of the insects studied
should be at hand, if practicable. There also should be
specimens of the young.

Observations.

The Body.

1. What is the shape and size of the insect
   and the number of regions in its body? Does the shape
   seem to be in any way adapted to the mode of life of the
   insect? If so, how?

Locomotion.

1. What methods of locomotion has the
   insect? Which is the most used?
2. 
   What is the position of the wings when at rest?
   What is the texture (e.g. thick, smooth, leathery, shell-like,
   membranous) of the fore and hind wings?
3. For what kind of locomotion are the legs fitted?
   How?

Sense Organs.

1. How many antennæ has the insect?
   What is their character as to shape and length? How
   many simple and compound eyes?

Feeding.

1. What is the food of the insect? How are
   the mouth parts specially adapted to obtaining this food?

   Note.—The mouth parts of insects may be jaws for biting, or may
   form a tube for sucking, or a beak for piercing and sucking.

Respiration.

1. Look for movements of the body indicating
   breathing, and describe what you find. Discover
   the location of the spiracles.

Protection.

1. What are the enemies of this insect?
   (Among the most important enemies of insects are birds,
   certain other insects, and various small vertebrates such as
   frogs, snakes, lizards, turtles, etc.) How does the insect
   protect itself from these enemies?
2. Describe the shell with respect to thickness and flexibility.
   What is the character of the surface as to roughness
   or smoothness or covering of hairs or scales?

Reproduction and Development.

Note.—It may be necessary to get
answers to these questions from books.

1. Where are the eggs deposited? What is the number of the
   eggs? How soon do they hatch?
2. What is the food of the larva or nymph? Are the food habits
   of the insects harmful to man? If so, how?
3. Describe the larva as to form, color, and appendages. Is it capable
   of locomotion?
4. Is the metamorphosis complete or incomplete? If complete,
   describe the pupa and tell where it may be found.

Drawings.

There should be one drawing of the insect to show its
general characteristics; usually a dorsal view is best. For
other drawings ask your instructor.

8. A REVIEW OF INSECTS

Directions.

The answers to questions in this study may be conveniently
written in the form of a table. Construct this table
by placing the topics at the left and the names of insects
at the top. Allow ample space, about one half inch for
the horizontal spaces and one and one half inches in width
for the vertical columns. Use one or two insects from
each of the principal orders, letting the table extend across
two opposite pages.

Topics.

1. What is the habitat?
2. What regions has the body?
3. How many antennæ? What is their form?
4. What kinds of eyes has the insect? How many of
   each kind?
5. How many legs?
6. For what kind of locomotion are the legs adapted?
   Which legs are thus used?
7. How many wings? Membranous or thickened?
8. What is the position of the wings when at rest?
9. If the fore wings are thickened, what is their texture,—leathery,
   smooth and sheath-like, partly membranous,
   covered with scales?
10. What kind of mouth parts,—jaws for biting, a beak
    for piercing, a tube for sucking, adapted for both sucking
    and biting?
11. By what means is respiration accomplished?

Summary of Important Points from the Table

1. What characters are common to all the insects described
   in the table?
2. What are the various types of wings? Why do they
   vary?
3. What are the various types of legs? How are they
   characterized?
4. What are the various types of mouth parts?
5. Show how the variations in insects are related to the
   habitat and mode of life of the insect.

9. KEY TO THE PRINCIPAL ORDERS OF INSECTS

Note 1.—When wings are folded, it will be helpful to remember that
thickened fore or cover wings always have membranous wings folded beneath
them.

10. SUMMARY OF THE STUDIES OF INSECTS

The Effect of Great Numbers

1. Take some insect for illustration, as the house fly,
   mosquito, tussock moth, or aphis, and show how insects
   increase in numbers with great rapidity.
2. 
   What can be said about the number of species of
   insects?
3. There is said to be great competition among insects.
   Why? For what?
4. How is the great increase of insects held in check by
   natural means?
5. What are the various habitats of insects? Give as
   many as you can with examples of insects that use the
   habitat.
6. Give examples to show how greatly the food of
   insects and the method of obtaining it varies.
7. Give some illustrations of the great muscular development
   of insects. Why is this needed?
8. In what various ways are insects protected against
   their enemies? Give examples to illustrate your statement.
9. Show how and why the great numbers of insects have
   affected the structure and mode of life of the insects.

Classification

1. By means of illustrations from your studies of
   insects show how classification is based upon likeness of
   structure.
2. In the same manner show how differences in structure
   affect classification.
3. Show how variation in the wings and mouth parts is
   used to separate insects into orders.
4. What are the principles of classification?

11. REVIEW AND LIBRARY EXERCISE ON INSECTS

General Topics

1. General characteristics of insects.
2. Principal orders of insects with characteristics and
   examples of each order.
3. 
   Respiration and air sacs of insects. Use of air sacs
   in flight.
4. The heart and blood of insects. How the function
   of the blood differs from that of other animals, as man.
5. Special senses of insects: their character, location,
   and efficiency.
6. Sound-making organs of insects.
7. Power of communication among insects, as among
   ants, for example.
8. Organs for depositing eggs, ovipositors. How they
   vary.
9. Homes of insects. Evidences of architecture in
   some of the homes.
10. How some plants make homes for insects. Galls
    and gall insects.
11. In what various ways do insects survive the winter?
    Illustrate with examples.
12. Community life among insects. Types of communities.
13. Pollination of flowers by insects. Why insects do
    this work and how the flowers compel them to do it in the
    right manner. Value to the plants. Types of insects
    useful for this purpose.
14. Adaptations for protection against enemies. Classify
    these adaptations and illustrate with examples.
15. The principal insect pests of the orchard and their
    work.
16. The principal insect pests of the garden and the
    work of each.
17. The principal insect pests of shade trees and their
    characteristics.
18. The principal insect pests of the household and
    methods of extermination.
19. 
    The work of birds in helping to keep the number of
    harmful insects down.
20. A spraying table showing what poisons are used,
    when and for what plants and insects.
21. The principal beneficial insects and the ways in
    which they are beneficial.

Special Topics

Much of the information called for by the topics below
may be obtained from United States and state government
bulletins. Most of these may be obtained free from the
Department of Agriculture and from various state agricultural
colleges, while others may be obtained by purchase
at a nominal price.

Orthoptera.

1. Locust migrations and their cause.
2. The locust plagues of the “great plains.”
3. Crickets and their “songs.”

Hemiptera.

1. The fight against the orange scale of
   California.
2. History of the introduction and spread of the San
   José scale bug and the efforts to find a natural enemy.
   How people fight the pest.
3. Aphids.
4. Relations of ants and aphids.
5. Phylloxera and its work.
6. The methods of fighting the chinch bug.
7. Scale bugs.
8. Cochineal bug and the lacs.

Coleoptera.

1. The carrion beetle and its peculiar
   habits.
2. Fireflies.
3. Egyptian scarabs.
4. 
   The curculio and methods of fighting it.
5. The weevils and their work.
6. History of the Colorado potato beetle.
7. Lady-bird beetles, their habits and use in exterminating
   harmful pests.

Diptera.

1. The investigations in Cuba of the cause
   of yellow fever.
2. The fight against yellow fever in New Orleans.
3. Methods of preventing plagues of mosquitoes.
4. How flies are carriers of disease. Methods of preventing
   plagues of flies.
5. The tsetse fly.
6. Sleeping sickness.
7. The house fly and typhoid.
8. Parasitic larvæ of flies.

Lepidoptera.

1. The silkworm and the silk industry.
2. Story of the gypsy moth.
3. Life history of the clothes moth.
4. Harmful butterflies.
5. The tussock moth and its history.
6. Blastophaga and fig culture.
7. The codling moth and its work.
8. Cutworms.
9. The brown-tail moth.

Hymenoptera.

1. The honeybee and honey making.
2. Gall and gall insects.
3. The habits of the digger wasp.
4. The homes of ants. Habits of ants.
5. Slavery among ants.
6. Agricultural ants.
7. Homes of bees.
8. Ichneumon flies and their beneficial habit.
9. Evidences of intelligence among ants.

SOME COMMON BUTTERFLIES—A Reference Table and Key

CHAPTER III
THE CONNECTION BETWEEN STRUCTURE AND FUNCTION

1. A STUDY OF THE CELL AND OF PROTOZOA

To show what Single Cells can Do

Materials.

Some single cells of plant or animal tissue, stained to
show structure. Slides of a one-celled animal, stained.
Living one-celled animals.

Definitions.

Cell,

the smallest living unit.

Protoplasm,

the living material composing the cell.

Nucleus,

a dense bit of protoplasm, usually near the center
of the cell, often staining dark.

Cytoplasm,

the less dense protoplasm outside of the nucleus,
usually taking a lighter stain.

Nucleolus, paranucleus or micronucleus,

a very small,
dense, dark-staining body, either within the nucleus (nucleolus)
or near it (paranucleus or micronucleus)

Cell wall,

the lifeless membrane surrounding many cells,
secreted by the protoplasm.

Food balls,

bits of food inside the cells of many one-celled
animals, usually showing through the walls.

Food vacuole,

a small drop of water containing digestive
material and a food ball.

Contracting or pulsating vacuoles,

small, clear spots in
the cell, filled with water. In the living cell these disappear
at intervals and then appear again.

Oral groove,

a funnel-shaped groove in one side of some
one-celled animals, conducting food to the mouth. In
paramecium it often shows as an oblique line when the
animal rolls.

Gullet,

the inner end of the oral groove.

Cilia,

numerous minute, vibrating, protoplasmic hairs on
the surface of many cells.

Respiration,

the passage of oxygen into the tissues of a
living organism and of carbon dioxide out of them. These
gases can pass through any thin, moist, organic membrane.
When such a membrane separates two fluids which differ
in the amount of oxygen they contain, oxygen passes to
the fluid containing the smaller amount.[2] The same is true
of carbon dioxide. Respiration is believed to occur in all
living organisms.

Digestion,

the process of making food materials soluble,
so that they can pass through membranes and be used to
build up protoplasm. A few forms of cells are able to
take in solid food and digest it in their protoplasm, but
most cells can admit only fluid food.

Fission,

a method of reproduction used in all cells, by
which a cell divides itself into two, usually through the center.
In some one-celled animals this may be preceded by
conjugation, when two animals unite temporarily and exchange
nuclear substance; or in some forms two cells may
fuse and the resulting cell may divide. Budding is a form
of fission in which a small projection is formed on the
parent cell and then cut off, making a new individual.

Protozoa (first animals),

animals of one cell, existing alone
or in loose colonies.

Observations.

1. Examine a single cell, stained to show structure.
   Identify the nucleus, cytoplasm, and, if present, the
   nucleolus or the micronucleus, and the cell wall. Draw to
   show the form of the cell and the details of its structure.
   Label all details.
2. Examine some stained paramecia. Select a typical
   one and identify in it nucleus, micronucleus, cytoplasm,
   and cell wall or cell membrane. You may also be able to
   see vacuoles, looking like holes in the stained protoplasm.
   Give reasons for considering this animal to be a single cell.
   Draw one, to show its cellular structure. Label all details.
3. Clean a slide and cover glass, place a drop of water
   containing living paramecia on the slide, cover it, and
   examine. What structures do you see which you saw in
   the stained paramecia? What structures do not show?
   Identify any new structures you may observe. Identify also
   the leading end and the side containing the oral groove.
4. Describe the shape of the animal.

   What is the actual length of the animal?

5. After watching the animal for some time, describe
   the path followed by a given specimen as it crosses the
   field of the microscope. What reason can you see, if any,
   why this paramecium is moving? What external factors,
   if any, seem to determine the path it follows?
6. How rapidly do paramecia really move? What
   structures do they use in locomotion?

   How do they manage to move in one direction, instead of alternately
   backward and forward? How do they manage to move in a straight
   line, though their bodies are not symmetrical?

7. 
   What is the food of the paramecia? How do they
   find it? Find a specimen at rest and watch the oral
   groove. Suggest a method by which food may be collected
   into it. If possible, note the process of swallowing,
   and the resulting food ball.

   Note.—If powdered carmine be placed in the water with some paramecia,
   it can be seen in the food balls a half hour or so later.

8. Where are the food balls located? Watch them
   in an individual until you notice their motion. Where
   are the larger food balls? the smaller ones? Assuming
   them to have been of approximately equal sizes when
   they were taken in, how can you account for differences
   now?
9. Where are the contracting vacuoles? How many
   are there? How often does one contract?

   What is their function?

10. As you have been studying paramecia, to what
    external influences (as contact, heat, light, etc.) have you
    seen them respond? How do they show it when they do
    respond? Is such a response an advantage to them or
    not? What would be the result if they were not able to
    detect changes in their surroundings?
11. Where does respiration occur in paramecia?
    Where do they obtain their supply of oxygen?
12. Among the paramecia you are studying you
    usually find at least one in the process of fission. Watch
    it until the halves separate, if you can. Compare the
    halves. Do they rank as parent and offspring? If so,
    which is which? If not, which are they, parent or offspring?
13. If you happen to find a pair conjugating, notice the
    process, as far as you can, in the living animals.

Suggested drawings.

1. A drawing to show all the details seen in the living
   paramecium.
2. A diagram to show the path followed by a paramecium
   to get around some obstacle.
3. Drawings to show that paramecia are constant in
   shape and yet flexible.
4. A drawing to show at least one stage in fission.
   This may be from a permanent preparation.
5. A drawing to show paramecia conjugating. This
   also may be from a permanent preparation.
6. Instead of all these separate drawings they may be
   combined into one. Represent the field of the microscope,
   and in it draw all necessary figures, to show the facts
   called for in the first five drawings and any other facts you
   have observed about living protozoa. Make the whole
   drawing to scale.

Summary of Important Points in the Study of Paramecia

1. Look back over your study of paramecia and list the
   different kinds of work you saw paramecia doing; also the
   kinds of work you infer they can do. What organs have
   they to use? When there is no organ to do a given thing,
   e.g. to digest food, how is the work done?
2. What conditions are favorable to paramecia? Why
   are they so numerous under favorable conditions?
3. What would you call a successful animal? Are
   paramecia successful? Give reasons why they are or are
   not.

Comparative Study of Protozoa

To enlarge your idea of what a cell can do, spend as
much more time on the one-celled animals as your course
will permit. Any stagnant water may furnish several
kinds. By means of reference books, identify as many as
you can. In each case notice:—

1. Its size, shape and general appearance, comparing
   and contrasting it with paramecium.
2. Its usual surroundings, i.e. the conditions it has to
   meet.
3. The means it has of finding out facts about its
   surroundings.
4. The means it has of adjusting itself to its surroundings.
   For example, is it stationary? If so, what does it
   do when conditions change? Is it locomotory? If so,
   how effective is its locomotion?
5. What is its food? How does it find food?
6. Can it do as many kinds of work as paramecium
   can? Can it do any that paramecium cannot do? If so,
   what?

Review and Library Questions on Protozoa

1. What are the characteristics which distinguish protozoa
   from other animals?
2. What are the classes of protozoa? Characteristics of
   each class?
3. What is digestion? Where does it take place in the
   protozoa?
4. What results from the fact that the amœba has no
   cell wall? (Give at least two points.)
5. In what ways are paramecia more specialized than
   amœba are? How does their greater specialization show
   in their work?
6. What different methods of locomotion are shown
   among protozoa? By what means is locomotion accomplished
   in each case?
7. 
   What is encysting? Name some protozoa which encyst.
   How long may an encysted animal live? When do
   they encyst? Why?
8. Give methods of reproduction among protozoa. Which
   method is fitted for rapid multiplication, for withstanding
   drouth; for renewing vitality?
9. Many scientists speak of protozoa as immortal. What
   argument is there to support such a statement?
10. Why are no protozoa large animals? Give at least
    two reasons.
11. Why are protozoa so numerous? Why more numerous
    in stagnant water?
12. Where are protozoa found?
13. Why are protozoa so widely distributed?
14. Write the probable history of a piece of chalk.
15. What connection is there between protozoa and some
    polishing powders?
16. Where in the human body are malarial protozoa
    found? How are they transferred from one human being
    to another? Why is there likely to be more malaria in
    newly settled regions than in older ones? If you were
    obliged to spend some time in a region where malaria existed,
    what precautions would you take?
17. Name other diseases caused by protozoa. How are
    they fought?
18. What beneficial effect have some protozoa upon the
    water of stagnant ponds and ditches? How may some
    forms injure water for household purposes?
19. Give at least three reasons for thinking that protozoa
    are the most ancient animals.
20. Why are protozoa of great importance to the
    world?

2. A STUDY OF SPONGES

To show how cells loosely associated may work together.

Materials.

The simplest of the many-celled animals are the sponges,
which, with one exception, are salt-water forms. That
one, the spongilla, is not easily found and is very difficult
to maintain in the laboratory. For these reasons the material
for this study is very meager, except at the seashore,
and much of the work must be done from diagrams and
reference books. Small simple preserved sponges and
complex toilet sponge skeletons will also be used.

Definitions.

Body wall,

the outer wall in bodies of the many-celled
animals.

Central cavity,

the cavity surrounded by the body wall
in the simpler many-celled animals, as in the sponges.

Canals,

channels through the body walls of sponges.

Inhalent pores,

the outer ends of the canals.

Ostia,

the inner ends of the canals.

Osculum,

the large opening of the central cavity, at the
distal end of the sponge.

Spicules,

tiny needles of mineral substance found in the
walls of many sponges.

Fibers,

flexible threads of horny material found in the
walls of many sponges.

Endoderm cells,

cells lining the canals. They have cilia
or flagella (projections larger than cilia).

Ectoderm cells,

cells covering the outside of sponges and
some other animals. In sponges it is believed that endoderm
and ectoderm cells are able to exchange positions and
functions.

Mesoglea,

a jelly-like layer between the endoderm and
ectoderm layers. In the sponges this contains many wandering
cells, probably from the other layers.

Porifera (pore bearers),

animals with many more or less
independent cells, supported by solid skeletal parts and
penetrated by a system of canals which open on the surface
as pores.

Directions.

Study a simple sponge to see the shape, size, and point
of attachment. Identify the osculum. In a diagram of a
long section of a simple sponge identify the central cavity,
body walls, canals, inhalent pores, ostia, and osculum. In
a simple sponge cut like the diagram identify the same
structures. Do the same for the toilet sponge.

Study a diagram of a portion of the body wall, considerably
enlarged. Identify the endoderm and ectoderm cells,
the spicules or fibers, and, among the spicules or fibers,
irregular amœboid cells, sometimes called mesoderm cells.

Examine a fragment or section of each kind of sponge
under the microscope. Notice the arrangement, shape,
and length of the spicules and of the fibers.

Test both kinds of sponges by dropping a bit of each
into weak acid, and noting the results. Also burn a bit of
each and notice the odor.

Questions.

1. What is the shape of a simple sponge? What enables
   a mass of cells to retain such a definite shape?
2. What seems to be the composition of the skeletons?
   Why is one type of skeleton rigid and the other elastic?
3. Since sponges are attached for most of their lives to
   stationary objects, suggest means for obtaining food and
   oxygen, and for getting rid of waste matter.
4. 
   Although individual cells are sensitive, a sponge as a
   whole is not. What connection has this fact with the fact
   that sponges are stationary?
5. Compare simple and complex sponges.

Suggested drawings.

1. A view of a simple sponge. Label everything shown.
2. A diagram of a simple sponge split in halves. Show
   by arrows the path followed by the water as it passes
   through the sponge.
3. A few spicules.
4. A few fibers.

Summary of Important Points in the Study of Sponges

1. What are two functions of the spicules or fibers?
2. What are at least two of the functions of the endoderm
   cells?
3. What can you suggest as functions for the ectoderm
   cells?
4. In what cases do cells show “team work” in accomplishing
   an object?
5. What degree of specialization is indicated by the fact
   that the cells may exchange positions and functions?
6. What work can any single cell of a sponge do?
   Compare the work done by such a cell with that done by a
   paramecium.
7. What work can a whole sponge do? Compare that
   with the work done by a paramecium.

Review and Library Exercise on Sponges

1. What are the distinguishing characteristics of Porifera?
2. Sponges were once supposed to be plants. In what
   respect are they plant-like? What made students finally
   class them as animals?
3. How do sponges reproduce? How are they distributed
   to new locations?
4. Where, as to depth of water, do most sponges grow?
   Where, as to oceans? Where, as to latitude?
5. What are some of the difficulties which confront a
   stationary animal? How are they overcome?
6. To what class of sponges do the “toilet” sponges
   belong? Why?
7. What conditions are necessary for toilet sponges to
   thrive? Where are the best ones found? Where are they
   most numerous? How are they collected? How are they
   prepared for market?
8. What is man able to do toward raising good sponges
   for market?
9. Using reference books and museum specimens, describe
   some especially odd sponges.

3. A STUDY OF CŒLENTERATES

To show cells working together more definitely than in
Sponges

A Study of Hydra

Materials.

Living hydras in permanent aquaria, undisturbed. Living
hydras in small aquaria, i.e. tumblers, test tubes, watch
glasses, etc., with pieces of water weed and if possible some
of the microscopic animals found in water where hydras
are abundant. If kept cool, hydras may live several days
in such aquaria. Permanent slides of hydras; some whole,
some in sections, and some showing the organs of reproduction.

Definitions.

Proximal end,

the end by which an animal is attached to
an object.

Distal end,

the end opposite the proximal end.

Tentacles,

slender projections around the distal end.

Mouth,

the opening through the distal end, into the central
cavity.

Bud,

a small hydra or other cœlenterate growing out
from the wall of the parent.

Mesoglea,

a thin, gluey partition, without wandering cells,
between the ectoderm and the endoderm.

Nettle cells,

very small cells, chiefly in the tentacles,
easily identified in permanent preparations as clear cells
with small hairs projecting from them. See text-books
for details of their structure.

Spermary,

the region or organ where the sperm cells are
formed.

Ovary,

the region or organ where the egg cells are formed.

Cœlenterates (hollow bowels),

sac-shaped animals, the
digestive tract having only one opening; the body wall is
of two layers.

Directions.

Take a small aquarium to your table, set it down carefully
and leave it undisturbed. Identify a hydra and
watch it for some time.

Observations on the living animals.

1. Describe the size and shape of a hydra when expanded.
   Disturb it slightly by shaking the aquarium a little, and describe
   its shape when contracted. Notice also the flexibility
   of the body. What do you infer concerning the
   hydra’s possession of a skeleton? What advantage can it
   be to have a body so flexible?
2. 
   How many tentacles has the hydra that you are studying?
   What does the hydra do with these tentacles when
   it is expanded? What is the probable object of such
   actions?
3. How does a hydra respond to contact? What seems
   to be the object of such a response?
4. Notice the location of the hydras in the large, undisturbed
   aquaria. Where are they placed as regards the
   light side of the aquarium? Of what value is such a response
   to light in their case?
5. How can a hydra locate the small animals which are
   its food?

   How can it capture them?

6. What motions may a hydra perform, while remaining
   attached by its base? What are the results of these movements?
7. If you have happened to see a hydra move from one
   place to another, describe the process. If not, give the facts
   which lead you to believe that it is able to do so. Suggest
   all the methods you think it may be able to use. What is
   your opinion of the hydra’s power of locomotion? Of what
   use is it in getting food; in escaping enemies; in following
   the fluctuations of the water supply? If you had to class
   the hydra as either one, would you call it a stationary or a
   locomotory animal?
8. Study budding hydras. Compare the bud with the
   parent hydra as to size, form and number and size of tentacles.
   Notice whether the bud moves independently or
   only with the parent. When does it separate from the
   parent?
9. In hydras collected late in the fall you may see another method
   of reproduction. If such material is at hand, notice small swellings
   near the proximal end and others near the tentacles. Eggs are produced
   in the lower one, the ovary, and sperm cells in the upper one,
   the spermary. Refer to your text-book for further details.

Details of structure.

1. Using an entire mounted specimen and a section of
   hydra, identify the body wall and the central cavity. What
   is the extent of the central cavity? (Examine both the
   body and the tentacles.) Where does it open to the outside?
   What do you think is its use?
2. In the body wall, identify the endodermal and ectodermal
   layers of cells, separated by the mesoglea, which is
   usually stained more deeply. Study these cell layers carefully.
   What work ought each to do? What can you discover
   in its structure which would fit each layer to do its
   work?
3. In the tentacles, identify the nettle cells. Where are
   they? How are they arranged? About how many of
   them would be discharged if a small animal were to bump
   into a tentacle?

Summary of Important Points in the Study of Hydra

1. Name the different kinds of cells in a hydra. Which
   kind differs most from such a cell as the starfish egg?
   What work does this specialized cell do?
2. How much of a hydra’s body may be set in action by
   touching a tentacle? Contrast this with the sponge.
   What do you infer concerning the nervous power of these
   two animals?
3. Look back over your notes and list the different kinds
   of work a hydra can do.
4. Can it do any more kinds of work than a paramecium
   or a sponge can? If so, give further details.
5. Can it do any of its work in any better way? Would
   you expect it to be able to? Why, or why not?

Suggested drawings.

1. Hydra undisturbed, and hydra after being touched
   or shaken.
2. A hydra in successive poses to show its flexibility.
3. A hydra taking food.
4. Hydras to show reproduction in one or both ways.
5. A section of hydra, showing details.

Comparative Study of Cœlenterates

Materials.

Various cœlenterates, such as hydroids, hydro-medusæ,
jellyfishes, sea anemones, corals, sea fans, etc. Since
nearly all the cœlenterates except hydras are marine forms,
these will usually have to be dead specimens, preserved in
formalin or alcohol, or put up as permanent preparations
for the microscope.

Definitions.

Colony,

as used in this group, a number of individuals
descended by budding from an original one, and remaining
connected.

Polyp,

an individual cœlenterate; one of the individuals
in a colony.

Observations.

1. How large is an individual specimen in the form you
   are studying? If the form is colonial, how large is the
   colony or portion of a colony you are studying? Estimate
   the number of individuals in it. Is the colony free-swimming
   or attached? If attached, to what is it usually fastened?
2. Compare the individual you are studying with a
   hydra, as to size and shape of the body, the location of the
   mouth, and the size, number, and arrangement of the tentacles.
3. 
   Is there a skeleton? If so, describe it. What appears
   to be its use? In corals, notice the radiating partitions.
4. Has the specimen any nettle cells? If so, where are
   they located?
5. Are all the polyps of the colony alike? If not, how
   many kinds are there? How do they differ?

   What is each kind best fitted to do? What is the probable result of
   this differentiation?

6. What kinds of reproduction, if any, does the specimen
   you are studying show?

   Find out from books what other forms of reproduction are sometimes
   used by this animal.

Suggested drawings.

1. At least one drawing of each cœlenterate you study.

Summary of the Comparative Study of Cœlenterates

1. How may polyps in colonial forms differ from polyps
   which live singly?
2. What variations in methods of reproduction are shown
   in this group?
3. Which of the polyps you have studied shows the
   greatest differentiation? In what ways?
4. What characteristic do you find common to all the
   cœlenterates you have studied?

Review and Library Exercise on Cœlenterates

1. What are the characteristics which distinguish
   cœlenterates?
2. Give the classes of cœlenterates, with the characteristics
   and an example of each.
3. 
   What enables a hydra to stick to a support by its
   foot?
4. What are the processes in a hydra by which food
   is captured, swallowed, and digested?
5. What is the chief fact of interest about Hydra
   viridis?
6. Why do hydras reproduce all summer by budding
   and in the late fall by eggs?
7. What change would have developed a hydra and its
   offspring into a plant-like colony instead of into a group of
   individuals?
8. Why are ctenophores more easily seen in the night
   than other cœlenterates are?
9. What relations may exist between hydroids and
   hydro-medusæ?
10. What are the advantages of a sedentary life? Of
    a locomotory one?
11. What is meant by the expression “alternation of
    generations”? Which animals are likely to develop alternation
    of generations, sedentary ones or locomotory ones?
    Why?
12. Give at least two differences between hydro-medusæ
    and true jellyfishes.
13. In the association between a hydractinia colony and
    a hermit crab, what advantages are derived by the hydractinia?
    by the crab? Define symbiosis. Give another
    illustration of it.
14. How are new coral colonies started? How are
    large colonies formed?
15. What are the conditions of life under which corals
    can grow vigorously?
16. Where are corals most abundant?

    Note.—Show by coloring the regions on a blank map of the world.

17. 
    How may corals form a reef? Why do they, as a
    rule, form a reef instead of adding directly to the mainland?
18. Give Darwin’s theory regarding the way a coral
    atoll may have been formed.
19. Where are fossil corals found in abundance? What
    does their presence prove?
20. What is polymorphism? Give an illustration. What
    may be a disadvantage of polymorphism? What may be
    an advantage?
21. In what ways is this group of economic importance?

4. A STUDY OF WORMS

To show cells associated even more closely than in
cœlenterates, forming tissues and systems of organs.

A Study of Earthworms

The Living Earthworm

Materials.

Living earthworms, some of which are left undisturbed
from day to day, in damp earth with leaves of various
plants scattered upon it.

Definitions.

Anterior end,

the head end, usually the leading end.

Posterior end,

the end opposite the anterior end.

Ventral surface,

the lower surface, usually the one which
contains the mouth.

Dorsal surface,

the one opposite the ventral surface.

Somites,

the rings or segments of which some animal
bodies are composed.

Bilateral symmetry,

the symmetry usually shown by animals
which have differentiated dorsal and ventral surfaces,
and right and left sides. Animals which do not have such
differentiated surfaces are usually radially symmetrical,
but sometimes asymmetrical (without symmetry).

Girdle,

the somewhat transparent band frequently found
near the anterior end of an earthworm.

Anal opening,

the posterior opening of the food canal.

Setæ (singular form, seta),

small bristles or stiff hairs.
In the earthworm these are set in the body wall at definite
intervals, and aid in locomotion.

Cuticle,

in the earthworm a delicate, shining cover over
the body.

Egg capsules,

small, light-colored, spindle-shaped sacks,
about the size and somewhat the shape of a grain of wheat,
containing the eggs or young of earthworms.

Directions.

Take a living earthworm to your table and keep it damp
by placing it in a wet tray or upon moist paper. Identify
the anterior and posterior ends, the dorsal and ventral surfaces,
and the right and left sides. Identify also the somites
and the girdle, the mouth with its projecting lip, and the
anal opening.

Observations.

1. Watch a living worm for some time. Does it seem to
   have a definite object in its moving? If so, what is it?
   Upon what sense or senses does it seem to depend for
   guidance? Which end usually leads? Why?
2. Over what sort of surface does it move most easily?
   Why? Watch it closely for some time and discover how it
   is able to move from place to place. (Suggestion. What
   is the function of the setæ in this process? How can you
   explain the alternate contraction and expansion of parts?)
3. From time to time, for perhaps a week, examine the
   leaves which were scattered where the worms could reach
   them. Have the worms moved them about at all? If so,
   where are the leaves left? Have any been eaten, in part
   or entirely? If so, is there any evidence of selection, either
   as to the kind of leaf or the portion of leaf eaten? If earthworms
   select food, what senses would be useful for the purpose?
   Have you any evidence that earthworms possess
   such senses?
4. Looking through the dorsal wall, notice the meandering
   red line, seen more easily in some regions than in others.
   This is the dorsal blood vessel. How long is it? Where
   is it wider? Where narrower? Notice its pulsations.
   How many times per minute does it pulsate? In which
   direction is the blood forced? Is there a corresponding ventral
   blood vessel? Place a small worm between two pieces
   of glass, so that you may see through it more easily, and
   identify the blood vessels encircling the digestive canal,
   near the anterior end. These are the so-called “hearts”
   of the earthworm. If possible, decide in which direction
   the blood flows through them.
5. The food canal, or alimentary canal, lies underneath
   the dorsal blood vessel, and is usually easily seen, especially
   if it is full of food. Notice it when the worm is fully
   stretched and again when it is contracted. How long is
   the canal? Why does it wrinkle when the worm contracts?
   Where does it open to the outside? Why does it need to?
6. Where do you infer respiration must take place in this
   animal? Why do you think so? What fits this surface for
   such a purpose? Why does an earthworm seem so uncomfortable
   when it is too dry?
7. Where do earthworms live? What conditions are necessary in
   their habitat?
8. When do earthworms usually leave their burrows? Why at that
   particular time rather than at another? Why does “the early bird
   catch the worm”?
9. What enemies do earthworms have? How are they protected
   against these enemies?
10. If you have found egg capsules when collecting worms, describe
    them.

External Morphology of Earthworms

Materials.

Preserved earthworms, the larger the better.

Observations.

1. In what respects are the dorsal and ventral surfaces
   alike? In what respects different? Why?
2. Why are the right and left sides alike?
3. In what respects are the two ends alike? In what
   different? Why?
4. How many somites are there from the anterior end to
   the girdle? How many under the girdle? How many
   from the girdle to the posterior end?
5. Where are the setæ located in a somite? How are
   they distributed over the body?

Suggested drawings.

1. An earthworm, dorsal aspect.
2. An earthworm, ventral aspect.
3. An outline diagram of a cross section, to show the location
   of the setæ, the blood vessels and the alimentary
   canal.

Internal Morphology or Anatomy

Materials.

(1) Preserved earthworms, as large as you can obtain.
(2) Cross sections of earthworms. (3) Longitudinal sections
of earthworms.

Definitions.

Body cavity,

the space between the body wall and the
alimentary canal.

Septa (singular, septum),

the thin walls between somites,
seen when the worm is opened.

Pharynx,

the hard-walled, rather bulbous, anterior portion
of the alimentary canal.

Esophagus,

the portion of the alimentary canal extending
back from the pharynx with thinner walls and smaller
diameter.

Crop,

the short, wide portion of the canal back of the
esophagus.

Gizzard,

the hard-walled, short region, just back of the
crop.

Stomach-intestine,

the portion of the canal reaching from
the gizzard to the anus.

Ventral nerve cord,

a light-colored thread lying against
the inner surface of the ventral body wall.

Nerve ganglia (singular, ganglion),

slight swellings on
the ventral nerve cord.

Nerve ring or collar,

a pair of nerves extending from the
ventral nerve cord around the pharynx to a pair of ganglia
(often called the “brain”) in the dorsal region of the
anterior end.

Kidney tubes or nephridia,

the excretory organs of the
earthworm, occurring as slender, paired tubes in nearly
every somite.

Directions.

Select a large worm and cut carefully through the body
wall along one side, midway between the dorsal and ventral
surfaces, from the anterior end to the posterior. Lay the
worm on any convenient fairly soft surface (a piece of
pine, cork, peat, paraffin), preferably under water, and pin
out the walls so that you can see into the interior.

Identify the structures defined above, as well as the
dorsal and ventral blood vessels and the “hearts.”

The nephridia are not easily distinguished, though they
are very numerous. They are long, slender, coiled tubes,
two in each somite, lying in the body cavity, one on each
side of the alimentary canal. If possible, identify them.

Notice that most of the internal organs are free from
the body wall, lying free in the body cavity.

Questions.

1. What is the extent of the body cavity, anteriorly and
   posteriorly? What is its shape?
2. What, in general, is the shape of the food canal?
   How many external openings has it?
3. Into what regions is the food canal differentiated?
   Suggest one advantage of having these specialized regions.
4. How is the alimentary canal of the worm kept away
   from the body walls? Why have it thus supported?
5. What is a septum? How many septa are there?
   What vessels and tubes pass through a septum?
6. Locate the nerve cord. How long is it? How frequently
   do the ganglia occur on it? Which end of the
   living worm is the more sensitive. Suggest the connection
   between this fact and the location of ganglia.

Suggested drawings.

1. Earthworm, showing structures mentioned in this
   study.

Details of Structure—Microscopic Anatomy

Materials.

Sections of earthworms, preferably both cross sections
and dorso-ventral, longitudinal ones.

Directions.

In a section under a simple lens, identify the dorsal
and ventral surfaces, the body wall, the body cavity, the
alimentary canal, and, if possible, the dorsal and ventral
blood vessels and the ventral nerve cord.

Under a microscope identify the same structures.
Notice that the body wall consists of three layers of cells:
an outer single layer, the epidermis; a middle layer, the
circular muscles; and an inner one, the longitudinal
muscles.

The nephridia show as loosely scattered fragments in
the body cavity, at the right and left of the alimentary
canal.

If you happen to have a section which shows one or
more setæ, identify the muscles which operate it, and the
group of glandular cells at its inner end, which are known
as setigerous (from seta) cells.

Questions.

1. Describe the epidermal cells. What is their probable
   function? Among them notice larger cells, clear and
   rounded. These are the mucous (slime) cells.

   What is the use of mucus to the worm?

2. Describe the muscle cells. In which direction do the
   muscle fibers extend? What is their function? Which
   layer of muscle cells is thicker, the circular or the longitudinal?
   Why should it be?
3. Notice the cells in the walls of the alimentary canal.
   What layers do you find? How are they arranged?
4. If the section you are studying is a cross section from
   the region back of the gizzard, the alimentary canal will
   look horseshoe shaped, indented from the dorsal surface.
   What is the effect of this indentation upon the amount of
   surface in the alimentary canal?
5. Study the cells of the nerve cord. How do they
   compare in size and shape with the muscle cells?

Suggested drawings.

1. A diagram of a cross section, showing the relation of
   the organs.
2. A diagram of a longitudinal section, at least
   through the body wall, to show the arrangement of muscle
   fibers.
3. A drawing of a portion of the body wall, to show
   details.

Summary of Important Points in Study of the Earthworm

1. Compared with a hydra, how many cells has an earthworm?
2. Compared with a hydra, how much are the cells of an
   earthworm differentiated?
3. How are these differentiated cells usually arranged
   with respect to one another? What advantage is there in
   this arrangement?
4. Recall the kinds of work done by paramecium,
   sponge, hydra, and worm, and at the same time consider
   also the efficiency of each. Can earthworms do any more
   kinds of work than any of the others? Can they do any
   more work? Can they do any of it better? Give the
   probable reasons for this?

Comparative Study of Worms

Materials.

As many different kinds of worms as you can get, living
or dead.

Directions.

Identify your specimens. Then study as many as your
time will allow, using these general questions for each:—

Questions.

1. How large is the specimen and what is its shape?
2. Can you distinguish a head or a head end? If so,
   by what peculiarities?
3. State whether the body is segmented or not, and, if it
   is, whether the segments are alike in form and appearance,
   i.e. whether the segments are uniform.
4. State whether the animal is bilaterally symmetrical,
   radially symmetrical, or without symmetry.
5. Compare this worm with the earthworm as to sense
   organs.
6. What organs for respiration has it?
7. What special protective devices has it?
8. If possible, find out and state where this worm lives.
   What can you see in the structure of this worm which
   enables it to live where it does?

Summary of the Comparative Study of Worms

1. Name the different worms you have studied. What
   characteristics have they in common?
2. What different methods of obtaining food do they
   show?
3. What variations do they show in senses? in sense
   organs?
4. Which one seems to you best adapted to its habitat?
   In what ways?

Suggested drawings.

1. One drawing of each worm studied.

Review and Library Work on Worms

1. What are the distinguishing characteristics of
   worms?
2. Give the classes of worms, and the authority for this
   classification.
3. What kind of soil do earthworms seem to prefer?
   Why should they? How do they form their burrows?
   What are the castings around the mouth of a burrow?
   How are they placed there?
4. In what ways do earthworms benefit the soil? How
   great is their effect estimated to be?
5. Give a brief sketch of the life of Charles Darwin,
   noting especially the work he did with earthworms.

   Why is Darwin’s work on earthworms noteworthy: because it is
   such a large proportion of the work he did, or because it is so much of
   the work which has been done on earthworms?

6. How are earthworms protected against the cold of
   our winters? What limits the northern range of earthworms?
7. Where are earthworms found geographically? Why
   are they so widely distributed? By what means are they
   extended from one locality to another?
8. How do earthworms reproduce? What care do
   they take of their young?
9. What tissues or organs of earthworms correspond in
   function with the ectoderm of hydra; with the endoderm?
   Why does an earthworm need a system of blood
   circulation more than a hydra does?
10. Contrast the number of openings in an earthworm’s
    alimentary canal with the number in a hydra’s digestive
    cavity. Which plan seems a better one? In what
    respects?
11. 
    Contrast a cross section of hydra with one of earthworm
    as to the number of cavities. Which seems to you
    the better plan? Why?
12. Why does a nereis need more respiratory surface
    than an earthworm does?
13. Comparing earthworm and nereis, in what respects
    is the earthworm degenerate? How does it manage to
    succeed so well with such a degenerate body?
14. What is a parasite? How many hosts does a
    typical parasite require for its development? Which
    host is known as the intermediate one?
15. Trace the history of a tapeworm from the egg to
    the adult. At what stage are they most likely to be
    destroyed? What provision is there for this? What
    advantages are there to the host in the fact that a tapeworm’s
    egg cannot develop in the original host? What
    advantages to the parasite?
16. What organs has a parasite lost, if it ever had
    them? How does it succeed without them? What connection
    is there between parasitism and degeneration?
    Can you decide which is cause and which is effect? If so,
    which is?
17. Why do worms so easily become parasitic? What
    advantages are there in becoming a parasite? What
    disadvantages?
18. What is radial symmetry? Name two animals
    which show it. What is bilateral symmetry? Name two
    animals which show it. What is the relation between
    locomotion and symmetry?
19. What is meant in biology by the term “regeneration?”
    To what extent have we this power? To what
    extent have hydra and earthworm? What are the results
    of this power?
20. 
    Name various methods of locomotion among worms.
    Give examples. Name a fixed or sedentary worm.
21. What is the economic importance of worms? Consider
    here not only earthworms and tapeworms, but also
    the stomach worms of sheep, liver flukes, trichinæ, hookworms,
    vinegar eels, and as many others as you have
    time and books to look up.

5. THE CONNECTION BETWEEN STRUCTURE AND FUNCTION

A Review of the Work done on the First Four Groups of
Animals

Review all your studies on the protozoa, sponges,
cœlenterates, and worms. Write the results in the following
summary:—

1. What work, i.e. labor, must an animal do to live?
2. How many cells are necessary to do this work?
3. When this work is divided among a number of cells,
   what is the effect upon the quantity and quality of work
   accomplished?
4. When this work is divided among a number of cells,
   how does the structure of the cells show it? How does
   the arrangement of the cells also show it? Give examples.
5. The technical expression for this specialization of
   cells, giving them different functions, is “division of
   labor.” Formulate a clear definition for this expression,
   giving an example to illustrate it.
6. Is division of labor a good thing for an animal body,
   or is it not? Give reasons for your opinion, with examples
   for illustration.

CHAPTER IV
ADAPTATION TO SURROUNDINGS

A Study of Crustacea

To Show the General Adaptation of an Invertebrate to its
Surroundings

1. A STUDY OF CRAYFISHES

Materials.

Crayfishes, living and preserved. Some of the living
crayfishes should be established in conditions as natural
as possible i.e. in an inch or so of fresh water, with rocks,
weeds, etc., and left undisturbed. Small crayfishes are
desirable to show locomotion in water.

Living Crayfishes

Directions and observations.

1. Observe living crayfishes in their usual habitat or
   in a large aquarium, without disturbing them, and see
   where they stay when they are free to choose. Notice
   their position. What senses are on guard? What is
   the color of the head and claws? How may this color
   aid the animal in getting food or in escaping enemies?
   Why is the color of the posterior region less important
   than the color of the anterior?
2. Offer them bits of meat. If one takes food, notice
   the appendages it uses. How does it discover the food?
   With what appendages does it grasp the food? How is
   the food conveyed to the mouth? With what senses, if
   any, does the animal test the food as it eats it?
3. If the crayfishes are in plenty of water and you
   startle them in any way, some of them may swim. Watch
   for such an occurrence and notice it carefully. How is
   swimming accomplished? Which end leads in swimming?
   How far does the animal swim at a stroke? How long
   does it continue to swim? Where does it go? Does it
   see where it is going? For what purpose would this
   method of locomotion be useful?
4. Place a living crayfish in a tray with water to cover
   it, and take it to your table. Watch the crayfish as it
   walks about in the water, then take it out and let it walk
   out of water. Compare the two processes. What causes
   the differences?
5. How many appendages are used in walking? What
   order, if any, is there in moving the legs? Which method,
   walking or swimming, does it use in going to some particular
   spot, e.g. in going to find food or cover? Why?
6. Gently turn the animal on its back and watch the
   movements of its appendages as it rights itself. Which
   appendages does it use and how does it use them? How
   can it manage to use so many appendages in harmony,
   for one result?
7. For what different purposes have you seen the crayfishes
   use their large claws? For which does the claw
   seem best fitted? Can you think of any change which
   would make it more efficient for its main purpose? If
   so, describe the change and tell how it would work.
8. Test the distribution of the sense of feeling. Is it
   anywhere especially acute? If so, where? Why have
   two pairs of feelers? Where is each pair carried when
   the animal is at rest; when it is in motion? How much
   territory can the two pairs guard?
9. Touch the eyes. Compare their sensitiveness with
   that of your own eyes. What movements can the eyes
   perform? How are they protected? What range of territory
   can they guard?
10. What other senses, if any, do you think a crayfish
    has? Why do you think so?
11. Early in the spring crayfishes may be found carrying
    eggs or young. If such a specimen is at hand, notice
    where and how the eggs or young are attached. How
    many are there? How are they cared for? Can the
    young crayfish let go? If removed, can they attach themselves
    again? How much care does the mother give
    them when they are removed?

Morphology of a Crayfish

Definitions.

Cephalo-thorax,

the anterior half of the body, divided into
the head and the thorax.

Cervical groove,

the groove dividing the head from the
thorax.

Abdomen,

the posterior half of the body, consisting of a
number of somites.

Note.—The central part of the tail fin is usually included as a
somite.

Carapace,

the continuous shell-like portion of the exoskeleton
covering the cephalo-thorax.

Rostrum,

the sharp projection of the carapace at the
anterior end.

Gill chamber,

a pocket on each side of the thorax, covered
by a flap of the carapace.

Appendages,

paired structures attached to the body.
They are named as follows:—

Eyestalks.

(These are not classed as appendages
by all students.)

Antennules,

the small feelers.

Antennæ,

the large feelers.

Mandibles,

the jaws, one on each side of the mouth.

Maxillæ,

the two pairs of small mouth parts just
back of the mandibles.

Maxillipeds,

the three pairs of appendages between
the maxillæ and the large claws.

Chelipeds,

the large claws or pinchers.

Walking legs,

the four pairs of appendages back of
the chelipeds.

Swimmerets,

the appendages on the abdomen.

Openings,

five on the ventral surface, as follows:—

• The openings from the excretory organs, through
  small white cones on the bases of the antennæ.
• The mouth, farther back, between the maxillipeds.
• The anal opening, in the last segment of the abdomen.
• The opening from the reproductive gland, toward
  the posterior part of the thorax.

Observations.

1. How large is your specimen? How does it compare
   in size with other crayfishes in the laboratory?
2. Describe the shape of the body, contrasting the anterior
   end with the posterior, and the dorsal surface with the
   ventral.
3. Study the amount of motion permitted in different
   parts of the body. What prevents motion? What permits
   it? Where is the body most flexible? Why?
   Where is it most rigid? Why?
4. How much of the surface is covered with exoskeleton?
   What arrangement is there to permit the animal to
   feel contact?

   How can the animal grow with such an exoskeleton?

5. Place a dead crayfish in dilute acid for a few hours.
   What is the result? What has the acid done? Explain
   the fact that crayfishes are often found alive and well with
   a soft shell?
6. Compare the cephalo-thorax with the abdomen as to
   size, shape, and flexibility.
7. How many somites are there in the abdomen?
   Which way does it bend? Study the somite shells on
   every side and then state what there is in their construction
   which determines the direction and amount of their
   motion. How are the somite shells arranged to protect
   the body during bending? How is the ventral surface of
   the abdomen protected?
8. Where are the appendages attached? Study a walking
   leg and describe its general construction, the number
   and kind of joints, the direction of motion in each joint,
   and the range of motion for the whole leg. Study an
   antenna in the same way. What methods are used in the
   crayfish to secure a wide range of motion? To secure
   flexibility?
9. Carefully split a crayfish into right and left halves.
   To do this, first cut through the ventral exoskeleton from
   end to end with scissors, then with a sharp knife or razor
   cut through to the dorsal exoskeleton and cut that with the
   scissors. Study one half, to get a better idea of the
   attachment of the appendages. These may then be removed
   and placed in order on a piece of paper upon which
   a list of the appendages has been written.
10. How many pairs of appendages are there? How
    may they be grouped according to location; how grouped
    according to function? How many pairs are there in each
    group?
11. What similarities of structure do you find in nearly
    all of the appendages? Assuming a swimmeret of the
    third, fourth, or fifth somite to be the least changed from
    the primitive type, what changes were necessary to make
    the sixth swimmeret; the third maxilliped; the walking
    legs; the antennæ; the antennules?
12. Remove the part of the carapace which covers a
    gill chamber. What are the boundaries of the chamber?
    Where does it open to the water?
13. Describe the appearance and the texture of a gill.
    How are the gills kept moist when the crayfish is in
    water; when it is on land? Why should they be kept
    moist?
14. Would you class the gills as external structures or
    as internal? Why do you think so? To what are they
    attached? How are the gills affected by the motion of
    the legs?
15. What work goes on in the gills? How is the supply of oxygen
    renewed? In this connection, try a live crayfish, kept quiet in water
    just about deep enough to cover it. Float bits of paper near it or
    carefully place a drop of ink in the water near it. By some such method
    currents of water may usually be shown, and their direction determined.
    Consider also the habitual motions of mouth parts and swimmerets, the
    bubbles sometimes seen when a crayfish is dropped into water and the
    habit crayfishes have of lying on one side, close to the surface of the
    water.

Summary of the Study of Crayfishes

To summarize your study, write a connected account of
the relations of crayfishes to their environments, under
the following topics:—

1. What are the varying conditions in their surroundings
   which crayfishes must meet? Which are most important?
2. What conditions must be maintained in order that
   crayfishes may succeed, i.e. may live and reproduce?
3. How does a crayfish know what are the conditions
   around it?
4. How is it fitted to meet these conditions? (Answer
   in the following details):—
   1. How wide a food range has it, i.e. how many kinds
      of food does it eat? How does it find its food? How
      does it reach it? How does it take its food? How does
      it make food small enough to be eaten?
   2. What are the organs for taking in oxygen? Where
      are they? How are they attached? How is the supply
      of oxygen kept up? How are the organs kept from drying,
      from clogging, and from mechanical injury?
   3. What ranges of temperature can crayfishes endure?
      What temperature is best? How do they avoid fatal extremes?
   4. What are the enemies of crayfishes? What protection
      against these have they?
   5. How often do crayfishes reproduce? About how
      many times during a normal lifetime? About how many
      eggs are there and how many of them hatch? What care
      is given to the eggs and to the young? About how many
      of the young reach maturity? (Suggestion. Do the crayfishes
      of a region vary noticeably in numbers from year to
      year?)
5. 
   What limits the range of crayfishes, north and south?
   What limits it on land? What in water?
6. When the crayfishes of a given locality are not well
   adapted to it, what can they do?

Suggested drawings.

1. The whole animal, dorsal surface, preferably without
   appendages.
2. One of each pair of appendages, except where they
   duplicate.
3. The tail-fin. Label the sixth swimmerets, the sixth
   and seventh somites.
4. The gill chamber, with gills in position. Show circulation
   of water by arrows.
5. A gill, to show construction.

2. COMPARATIVE STUDY OF CRUSTACEA

Materials.

Get together all the different specimens of crustacea you
can collect, and identify the material. Then study each
specimen as follows:—

Questions.

1. Briefly describe the exoskeleton, if there is one.
2. What region or regions are clearly segmented?
3. How much of the body is covered by a carapace?
4. Has it segmented appendages? Classify the appendages
   as to their use.
5. Are the cephalo-thorax and abdomen equally developed?
   If not, which is more developed?
6. How many antennæ has it? Are the eyes stalked,
   or are they sessile?
7. What organs of respiration has it? Where are they
   attached?
8. 
   How many thoracic appendages has it, if any?
9. What methods of locomotion does it use?

Summary.

1. Does this animal seem to be adapted to life on land
   or in water, or both? Give your reasons for your opinion.
2. What characteristics are common to all the crustacea
   you have studied?

3. REVIEW AND LIBRARY WORK ON CRUSTACEA

1. What are arthropods?
2. Give the classes of arthropods with an example of
   each.
3. What are the distinguishing characteristics of the
   class crustacea?
4. In what respects are most of the appendages of the
   crayfish homologous, i.e. alike in the plan of structure?
   Which do you consider the simplest, and why do you?
   Which do you consider the most specialized, and why?
5. Which somite of the crayfish is without appendages?
   How many somites are there in a crayfish’s body, if each
   somite bears only one pair of appendages, as many scientists
   believe? How many of these are in the head; thorax;
   abdomen?
6. Compare the nervous system of the crayfish with that
   of the earthworm as regards efficiency. Upon what do you
   base your answer?
7. Name two points in which earthworms and crayfishes
   are alike. Name three in which they differ.
8. How are crayfishes caught for market? Where do
   those sold in Chicago usually come from? How are they
   shipped?
9. Compare the young forms of a crayfish and a crab.
10. 
    Describe any five different crustacea.
11. Describe the work done by the United States government
    and by the state governments to protect and to
    perpetuate the lobster. Why is it thought necessary to
    do this?
12. Discuss the process and the advantages and disadvantages
    of molting, as seen in the crustacea.
13. Name two advantages in having such a shell as
    crustacea have. Name two disadvantages. On the whole,
    is such a shell favorable to an animal’s chances of success
    or is it not?
14. Give the curious myth about goose barnacles.
15. What crustacea are parasitic? Give an account of
    one.
16. Why are barnacles classed among crustacea? Where
    were they once classed? Why may they be considered degenerate,
    even though not parasitic? How do they manage
    to succeed? What is their economic importance? How
    are their effects checked or prevented?
17. Describe some of the odd means of self-protection
    shown among crustacea.
18. Describe a compound eye. Give two theories as to
    what can be seen with a compound eye. Why do we not
    know, instead of theorizing?
19. What is the economic value of the very small crustacea?
20. Discuss the value to man of the various forms of
    crustacea.

CHAPTER V
ADAPTATIONS FOR PROTECTION FROM ENEMIES

A. The Exoskeleton

1. THE CLAM—A TYPE OF MOLLUSCA

To Show the Effect of a Heavy Exoskeleton

Materials.

Living clams in aquaria, with enough moist sand to
cover the clams, preserved clams, sets of matched clamshells,
a few shells with the hinge unbroken, evaporating
dishes, hydrochloric acid.

Definitions.

Mollusca,

a branch of the animal kingdom including
those animals with soft, unsegmented bodies, inclosed in
two folds of skin known as the mantle. They are often
called shellfish as most of the forms have a shell.

Lamellibranchiata or Pelecypoda,

names given to the class
of Mollusca to which the clam belongs. The former term
refers to the broad, flap-like gills and the latter to the
hatchet-like foot.

Valve,

one of two parts of the clamshell.

Hinge ligament,

the elastic structure which fastens the
valves together at the dorsal margin.

Umbones,

a pair of elevations near the anterior end of
the shell.

Lines of growth,

concentric lines around the umbones.

Siphons,

two openings at the posterior end of the clam,
the upper opening is the excurrent opening and the lower
the incurrent. In the salt water clam the siphons form a
long tube, usually called the “neck.”

Hinge teeth,

projections near the dorsal margin on the
inner surface of the shell. The anterior irregular structure
is the cardinal and the more posterior blade-like structure
is the lateral tooth.

Muscle scars,

scar-like markings on the inner surface of
the shell indicating the point where muscles were attached.
The large scar just in front of the cardinal tooth is the
anterior adductor muscle scar, and the one just back of the
lateral tooth is the posterior adductor muscle scar.

Pallial line,

a line connecting the two muscle scars.

Mantle,

folds of skin covering the body of the clam and
lying close to the inner surface of the valves.

Foot,

a hatchet-shaped structure extending from the ventral
edge of the body.

Gills,

broad flap-like structures for respiration, situated
each side of the body in the mantle cavity. They consist
of a double fold of membrane through which run many
perforations lined with cilia. The waving of these cilia
cause the current of water needed for respiration.

Palps,

small flap-like structures near the anterior end of
the clam. They surround the mouth. On their surface
are cilia which cause currents of water toward the mouth.

Adductor muscles,

large muscles extending from valve to
valve.

Observations.

Identify anterior and posterior ends, dorsal and ventral
surfaces, right and left sides.

1. 
   Why may a clam be called a bivalve?
2. What is the position of the clam in the mud? What
   is the position of the foot if the clam is undisturbed?
   Are the two valves tightly closed or slightly open at this
   time?
3. What changes take place in the shell as the clam
   grows? What markings on the surface of the shell indicate
   this?
4. Where is the clam sensitive to touch or tactile stimulus?
   Why has the clam no eyes? Zoölogists have found
   a structure in clams which they have supposed to be an
   ear. Where do you think the structure is located? Why
   is the clam successful without eyes? (There are many
   bivalves which have them.)
5. Examine several clams until you find some with enlargements
   in the gills. Break off a small part of an
   enlargement with your forceps and examine under the compound
   microscope. Describe what you see.
6. Drop some powdered chalk or carmine in the water
   just above the siphon, watch the siphons for several minutes,
   and note what happens. What do you conclude to be
   the use of the siphons? Recalling what took place in
   sponges, what would you suggest as the probable cause of
   these currents? What does the clam thus probably obtain?
   How do the two siphons differ? Why?
7. Place a clam in water sufficient to cover it and heat
   slowly to about 40 degrees Centigrade, until the valves
   open slightly. Remove and proceed as follows: Raise one
   valve, separate the mantle from it, and then cut through the
   two large firm structures (adductor muscles) found at each
   end. What does the valve do when the muscles are cut?
   What is the cause of this? State your theory as to how a
   clam opens and closes its shell.
8. 
   Note the texture of the mantle. How many lobes
   has it? What is their extent? How are the lobes related
   to the valves?
9. Remove or lift up one mantle lobe. Identify the soft
   body, the foot, the gills, the palps, and the mouth. Which
   of these structures are arranged in pairs?
10. Determine the structure and composition of the shell
    as follows:—
    1. Break a thick clamshell and examine the broken
       edge. Identify the inner or pearly layer and the outer or
       chalky layers. What gives color to the shell in the living
       clam?
    2. Burn a small piece of shell in an evaporating dish
       over a bunsen burner. What is the appearance of the
       shell after burning? What has been burned, animal or
       mineral matter? What then is the residue?
    3. Place a small piece of shell in acid. What results?
       Is there a large amount of residue? What constitutes the
       greater part of the shell, animal or mineral matter?
    4. (Optional) Devise some method and determine the
       approximate per cent of mineral and of animal matter in
       the clamshell.

Summary.

1. Why did we study the clam? (See title of exercise.)
2. How has the heavy shell of the clam affected:—
   1. The character of the clam’s body,
   2. the locomotion,
   3. the development of sense organs.
3. What special problems has the clam as regards getting
   food and oxygen? How are these problems solved?
4. How does the clam protect the young clam during
   development?

Suggested drawings.

1. Dorsal margin of the clam.
2. Side view of the clam.
3. The clam with one valve removed or lifted back.
4. The clam with one valve and one mantle lobe removed.
5. The edge of a broken shell.
6. Diagram of cross sections.

2. THE SNAIL—A TYPE OF MOLLUSCA

To show Another Type of Exoskeleton

Materials.

Specimens of pond snails, edible snails, and “slugs,” and
other land snails, and a collection of shells of various
types.

Definitions.

Gasteropoda,

the name of the class to which the snail
belongs.

Spire,

the coiled portion of the snail shell.

Aperture,

the opening of the shell.

Lip,

the edge of the shell forming the margin of the
aperture.

Whorl,

a single coil of the spire.

Suture,

the depression between the whorls.

Foot,

the flat disk-like structure on which a snail creeps.

Breathing pore,

an opening in the mantle used in respiration.

Lingual ribbon,

the rasp or file like tongue of the snail.

Observations.

1. Why is a snail called a univalve?
2. Identify the head and mouth of the snail. Watch
   the snail feeding and examine the mouth of the snail with
   a lens. What do you notice? If your aquarium in which
   the pond snail is living has a green coating (algæ) on the
   side, describe its appearance after the snail has been crawling
   up and down over it. Explain.
3. How many tentacles has a pond snail? a land
   snail? Where are the eyes located in each case? What
   movements of the tentacles do you notice? What is their
   purpose?
4. How does the rate of locomotion of the snail compare
   with that of the clam? Find out if the snail can creep
   backwards or on the surface of the water. Does there
   seem to be any tendency for the snail to go up and down
   the sides of the aquaria vertically rather than to the right
   or left?
5. What does a snail do when disturbed? What is
   gained by this action?
6. Search for pond snail’s eggs on the side of the aquaria.
   Lift up the bits of cabbage on which the slugs are feeding
   and search for eggs. Describe what you find in each case,
   noting the size, appearance, and whether the eggs are laid
   singly or in masses.
7. Find the breathing pore. Describe its position and
   appearance.
8. Contrast the various types of shells, and note with
   care in what respects they differ. Holding the shell with
   the aperture toward you and the spire pointing up, determine
   whether each shell has the aperture on the right
   (right-handed shell) or on the left (left-handed shell).
   Is the right-handed or the left-handed shell more common?
9. (Optional) By means of some book in the laboratory,
   determine the scientific name of each of the snails found
   in the various aquaria in the laboratory.

Suggested drawings.

1. Drawings to show the pond snail in various positions
   in the aquarium.
2. A drawing of the slug.
3. At least three different types of snail shell.

Summary.

1. In what respects does a snail show resemblance to a
   clam?
2. What are the chief points of difference?
3. What reasons can you suggest for the better development
   of the sense organs?
4. What advantage has a snail over a clam in the matter
   of getting food?
5. How does the shell of the snail compare with that of
   the clam as an organ for protection?

3. THE SQUID—A TYPE OF MOLLUSCA

To show the Effect of a Much Reduced or Rudimentary
Skeleton

Materials.

Small squids, and a few large specimens for comparison
and dissection.

Definitions.

Cephalopoda,

the name of the class to which the squid
belongs.

Caudal fin,

a horizontal structure at the posterior end of
the squid.

Chromatophores,

irregular cells in the mantle which give
color to the squid.

Exhalent siphon,

a funnel or tube opening on the ventral
side just below the base of the arms or tentacles.

Pen,

a remnant of an exoskeleton imbedded in the mantle
along the dorsal side.

Ink sac,

a sac containing a dark, sticky liquid which may
be thrown out through the funnel into the water. The
opening is near the inner opening of the funnel.

Observations.

1. What is the shape of the squid? To what is this
   shape adapted?
2. Identify the head and the well-developed eyes.
3. How many arms or tentacles are there? How are
   they arranged with reference to the mouth? What do you
   find on the distal ends of the arms? How do the arms
   vary as to size? What does the position and arrangement
   of the arms suggest as to their function?
4. Identify the exhalent siphon. Where may water
   enter the mantle cavity? Recalling the action of the
   siphons in the clam, suggest a method by which a squid
   is propelled through the water. In what direction must it
   swim?
5. Split the mantle along the ventral surface and spread
   apart. Identify the long plume-like gills, the ink sac, and
   the inner opening of the exhalent siphon. How many gills
   do you find?

Suggested drawings.

1. The squid side view.
2. The squid from the ventral side with the mantle split
   open, arrows to show direction of water.

Summary.

1. In what ways does a squid show relationship to the
   clam and the snail?
2. What has a squid gained through the reduction of its
   exoskeleton? What has it lost? What changes were
   necessary in its structure to offset the loss of an exoskeleton?

4. A COMPARATIVE STUDY OF MOLLUSCA

Materials.

Specimens of as many different kinds of mollusks as
possible, charts, books.

Observations.

1. What is the symmetry?[3]
2. Is the body segmented or unsegmented?
3. Are lateral appendages present or wanting?
4. Is an exoskeleton present or wanting? If present,
   is it univalve or bivalve; if absent, what other means of
   protection has been developed to take its place?
5. Is the animal fixed, or is it free to move? If fixed,
   in what way? If it moves, what is the method and organ
   of locomotion?
6. What are the organs of respiration? What is their
   character?
7. How is food obtained?
8. What senses are probably present? What sense
   organs are present?
9. What is the habitat?
10. In what ways if any does the animal show degeneration?

Summary.

1. What characters are common to all mollusks?
2. What is the principal means of protection among
   mollusks?
3. Name three causes of degeneration among mollusks.

5. MOLLUSCA: REVIEW AND LIBRARY EXERCISE

Characteristics.

1. What are the general characteristics of mollusks?
2. Name the principal classes and give the characteristics
   of each.

Morphology.

1. What is peculiar about the structure of a clam’s
   heart? What is its position? Contrast with the heart of
   a crayfish.
2. Make cross-sectional diagrams to show the arrangement
   of parts in a clam: (a) in the region of the umbone;
   (b) in the region just in front of the posterior muscle;
   (c) in the region of the anterior muscle.
3. Describe the various types of eyes found in mollusks,
   and their location.
4. Describe the tongue or lingual ribbon of the snail,
   and its use.
5. What is the operculum of snails? its use?

Physiology.

1. Describe the circulation of water through the siphons
   and mantle cavity of a clam. How is it caused? What
   three uses has it?
2. What are the principal facts about the development
   of fresh-water clams?
3. Describe the circulation of blood in a clam.
4. What various methods of locomotion are found
   among mollusca?

Economics.

Write a short account of the following:—

1. Oyster culture.
2. Typhoid-fever and oysters.
3. 
   Clams, scallops, and other edible shellfish.
4. Pearls and pearl fisheries.
5. Fresh-water clams and the button industry.
6. Sepia, Tyrian dye, etc.
7. Harmful and useful mollusks.
8. The work of U. S. Fish Commission in propagating
   clams.

Natural history.

1. Give the class, habitat, and some important fact
   about each of the following: Pectens; wing shells; Tridacna
   gigas; abalones; limpets; oyster drill; periwinkle;
   mussel; cuttle fish; octopus; nautilus; argonaut.

6. A COMPARATIVE STUDY OF EXOSKELETONS

Materials.

Charts, specimens, etc. Since this is partly a review exercise,
your notes and drawings of invertebrates should be
at hand.

Definitions.

Exoskeleton,

a protective covering developed on the outside
of an animal.

Questions.

1. What are foraminifera; radiolaria? How do they
   differ from other protozoans? Of what two substances
   are the shells of protozoans composed?
2. How are the spicules formed in a simple sponge?
   What are glass sponges? Give reasons why the skeletons
   of sponges may or may not be considered exoskeletons?
3. What are stone corals? What is the relation of the
   coral polyp to the skeleton? What is the appearance of
   the coral when expanded as compared with its appearance
   when contracted? Of what substance is the coral composed?
4. Describe the exoskeleton of a starfish. Contrast the
   exoskeleton of the sea urchin and the starfish. Why does
   a sea cucumber need no well-developed exoskeleton?
5. What structure in an earthworm may be considered
   an exoskeleton? What other types of exoskeletons are
   found in segmented worms?
6. Of what substance is the exoskeleton of arthropods
   composed? What additional substance is found deposited
   in the shell in the case of crustaceans? What advantage
   in the arthropod type of exoskeleton?
7. Why are mollusks so commonly called “shellfish”?
   What advantage in the mollusk type of skeleton? What
   disadvantages?

Summary.

1. What type of exoskeleton is common among invertebrates?
2. What are the general purposes of exoskeletons?
3. What is the explanation of the various forms of exoskeletons
   found?
4. Of what substances are exoskeletons composed?

B. Protective Coloration

To show how Color may be Protective

Materials.

Specimens such as the Kny-Scheerer mimicry collections,
diagrams, etc.

Definitions.

General protective resemblance,

the general resemblance
between the color of an animal and its surroundings.

Variable protective resemblance,

the changing of the color
of an animal to correspond to the change in its background.

Special protective resemblance,

the resemblance of an
animal to some object found in its background in color
and form.

Mimicry,

the resemblance of an unprotected animal to
a well-protected one.

Warning colors,

bright colors which protect animals by
causing other animals to avoid it.

Questions.

1. Show how the transparent color of a paramecium,
   the green color of a cabbage worm, or the green color of a
   certain species of hydra may result in protecting an animal
   from its enemies. Mention as many other examples as
   you can.
2. What is gained by the ability of a squid to change
   its color? How is this change brought about?
3. Explain the protective coloration of the following:
   Dead-leaf butterfly, walking stick, geometrid larva. Hunt
   up other examples.
4. Explain the protective coloration in the following:
   Hover flies, clear-winged moths, viceroy butterflies.
5. Make a list of several invertebrates that are protected
   by their bright color. Explain the reason for the bright
   color.
6. How may the difference between the color of the
   upper and lower surfaces of animals be explained on the
   basis of use to the animal?
7. (Optional) Find out some other uses of color to an
   animal aside from protection.

Summary.

1. Name four uses of color.
2. Name four ways an animal is protected by being like
   its background.
3. Name one way it is protected by being unlike its
   background.
4. What disadvantages in this method of protection?

C. Animal Associations

To show Another Method of Protection from Enemies

Materials.

Specimens, charts, etc., illustrating animal associations.

Definitions.

Animal communities,

associations of many animals of
the same species in communities in which there is a greater
or less division of labor.

Gregarious,

associations where there is but little division
of labor.

Parasitism,

an association where one animal lives at the
expense of the other. The animal on which the parasite
lives is called the host. If there are two hosts during the
life cycle of the parasite, the second host is called an intermediate
host.

Symbiosis,

an association where two animals live together
in mutually helpful relations.

Commensalism,

an association where two animals live
together in relations not mutually helpful but without injury
to either.

Observations and questions.

Note.—To find answers to many of these questions it will be necessary
to refer to the reference books in the laboratory.

1. 
   Examine a specimen of Volvox. Why may this be
   considered a colonial protozoan and not a many-celled animal?
   What is gained by the colonial habit?
2. Is the colonial habit common or rare in sponges and
   cœlenterates? What is chiefly gained?
3. Describe the community life in one of the insects in
   each of the following groups:—
   1. ant, honeybee, termite.
   2. bumblebee, paper wasp, hornet.
   3. mining bee.
   4. carpenter bee, mud wasp, digger wasp.
4. Name the host or hosts in the following cases:
   trichina, liver fluke, malarial parasite, tapeworm, hook
   worm. Give the life history of one or more of the parasites
   just enumerated. What is the effect of parasitism
   on the structure of the parasite?
5. What is the relation between ants and plant lice?
   Show how this relation is mutually helpful. Mention other
   cases of symbiosis that you have come across.
6. With what animal are barnacles often associated?
   What is the habit of the pea or oyster crab? What are
   “guest bees”? What structure is lacking that is found in
   other bees? What are often found in the cavities of
   sponges? Why are these associations called commensalism
   rather than symbiosis?

Summary.

1. Into what groups can animal associations be divided
   based upon the number of species concerned?
2. From the standpoint of protection, is this a good or a
   bad method of protection?
3. What disadvantages can you see in this method of
   protection.

D. Protective Habits and Powers

Materials.

Specimens, charts, and books, showing habits of
invertebrates.

Definitions.

Regeneration,

the power to grow new parts of the body
when parts have been lost or injured.

Masking,

the covering of an animal by some object or
organism so as to hide its identity.

Nocturnal habits,

the habit of hiding in the daytime and
coming out at night to feed.

Terrifying attitudes,

the protective attitudes assumed at
times by animals in order to ward off attack.

Observations and questions.

1. How are Sabella and Serpula protected? What advantages
   and disadvantages in this habit? What changes
   in structure are associated with this tube-dwelling habit?
2. What two protective habits has the earthworm?
   Name some other animals that have similar habits.
3. Describe the protective habits of the caddis-fly larva;
   of the leaf-roller moth. What benefit to the hermit crab is
   the colony of hydractinia growing on the snail shell which
   it inhabits? Give other similar cases.
4. Name as many cases of regeneration as you can.
5. What peculiar habits has a puss-moth larva? a
   dragon fly? Give other examples.

Summary.

1. Name the various protective habits.
2. State any advantages or disadvantages you can with
   reference to these protective habits.

E. Defensive Structures

Another Method of Protection from Enemies

Materials.

Specimens, charts, books, etc., to illustrate the various
defensive organs found among invertebrates.

Observations and questions.

1. Describe the stinging hairs of the paramecium.
2. Describe the action and structure of nettle cells.
   Where are they located in the case of hydra; of jellyfish?
3. What defensive organs are found among the
   arthropods?
4. What are stinkbugs? What peculiar organs of defense
   have the caterpillars of the swallowtail butterflies?
5. Where is the sting of a hornet located? To what in
   a grasshopper does it correspond? Why does a hornet or
   bee inflict so painful a wound?
6. What peculiar organ of defense has a squid?
7. Find other examples of defensive structures.

Summary.

1. What advantages have organs of defense as a method
   of protection?
2. What disadvantages?

F. Thesis

To sum up the Important Points in the Study of Adaptations
for Protection

Directions.

Write a connected account of what you have found out
about protection of animals from their enemies, using the
following outline:—

1. 
   The struggle for existence—
   1. its cause,
   2. its threefold nature,
   3. the various kinds of adaptations.
2. The various methods of protection from enemies.
   1. The exoskeleton.
   2. Protective coloration.
   3. Animal associations.
   4. Protective habits.
   5. Defensive structures.

CHAPTER VI
VERTEBRATES

A. Studies of Fishes

THE LIVING FISH

Vertebrates adapted to Water Life

Materials.

Living goldfishes or other fishes in small aquaria for individual
study and a few fishes in a large aquarium where
they have considerable freedom of motion.

Definitions.

Trunk,

the portion of the body between the head and
the tail.

Compressed,

a term used to describe the shape of the
body when it is narrower from side to side than from dorsal
to ventral surface. When the opposite is true, the body is
said to be flattened.

Median fins,

the unpaired fins situated on the median
line, dorsal and ventral, including the tail or caudal fin, the
dorsal fin, and the anal fin.

Paired fins,

fins occurring in pairs of which the more anterior
are the pectoral fins and the posterior are the pelvic
fins.

Fin rays,

the framework or skeleton of the fins over
which membrane is stretched to form the fins. Fin rays
are of two kinds: those composed of bone and those composed
of cartilage.

Lateral line,

a sense organ extending along each side of
the fish in a line indicated by tubes or perforations in the
scales.

Gills,

respiratory organs adapted for taking oxygen from
the water.

Operculum,

the flaps covering the gills on each side of
the head.

Pigment,

a substance which gives color to an object.

Observations.

Locomotion.

1. Watch the fishes in the large aquarium
   and determine which fins are most used and how they are
   used (a) in swimming forward, (b) in swimming upward
   and downward, (c) in maintaining balance, (d) in remaining
   at rest, and (e) in guiding the movements of the fish.
2. What advantages are there to the fish (a) in the power
   to open and close the dorsal and anal fins, (b) in having no
   neck, and (c) in having a compressed form?
3. Enumerate the various ways by which the body of
   the fish is adapted to rapid movement through the water.

Feeding.

1. What is the food of the fishes you are
   studying? Feed them and watch them eat. Why is the
   upper jaw often called a “lip”? What is the shape and
   size of the mouth when opened in feeding? Does the fish
   chew its food? Describe in detail the fishes’ method of
   feeding.

Respiration.

1. Identify the opercula and the gill openings.
   Watch the movements of the opercula and mouth,
   and determine what movements are concerned in breathing
   and their order. Describe in detail the circulation of water
   used in breathing and how it is caused.

Sense Organs.

1. Identify the eyes, nostrils, and lateral
   line. How many nostrils are there and where located?
   What is the position and extent of the lateral line?
2. Describe the location of the eyes. What is the shape
   of the outer surface of the eyes? Why this shape? Can
   the eyes be moved, i.e. can they be rotated, rolled, or retracted?
   From what direction might an enemy approach
   without being seen? How would such an enemy be detected?

Protection.

1. With what protective structures is the
   body covered? Do they hinder the movements of the fish?
   What are the advantages of the scale covering of fishes
   over the shell covering of grasshoppers or crayfishes?
2. In what other ways are the fishes you are studying
   protected against enemies? Since you cannot account
   for the red color of goldfishes on the basis of use to the
   fish, then how do you account for this bright color?

The Body.

1. What is the symmetry of the fish? Into
   what regions is the body divided?

Summary of the study of the living fish.

Enumerate in one column the different adaptations
which fit the fish for life in water and in a second column
state the special purpose of each adaption.

The External Structure of the Fish

Materials.

Freshly killed or preserved fish in dishes or shallow
pans with enough water to prevent drying. Simple or
compound microscopes, forceps, and a bristle.

Directions.

Examine the fins and identify the membrane and the
supporting rods, or rays, of bone or cartilage. Notice
how the ends of the cartilaginous rays keep the membrane
from tearing.

Investigate the scales as to their arrangement, number,
and size. Remove a small patch of scales along the
lateral line to find how they are attached, where the fish’s
color is situated, and how access to the sensory organs of
the line is permitted. Examine a scale under the microscope.

Observe the eyes and identify the parts similar to those
of the human eye: lid, lash, tear-duct, cornea, iris, and
pupil.

In front of and between the eyes, find the nostrils. By
means of a bristle determine whether these are connected
and whether they do or do not open into the mouth or
the throat.

Questions.

1. Make a list of the fins, classifying them according to
   their structure.
2. Bearing in mind the differences in structure and
   consequent action,—what can you say regarding the
   adaptation of the several fins for protection? for rigidity
   or flexibility in locomotion?
3. State how much of the body is covered with scales,
   and where the largest and the smallest ones are found.
4. How are the scales arranged with reference to each
   other? What benefit is derived from this in protection?
   in locomotion? If you have noticed any mucus or slime
   upon the body, state its use.
5. Do the scales or the skin bear the pigment? Give
   the color pattern of the kind of fish used in class. How
   would this be useful to the fish in its natural home?
6. Describe the structure of a scale and state how it is
   attached to the skin. In what way is the lateral-line scale
   specialized?
7. State how, when the fish is swimming, the nostrils
   catch odors. By means of a diagram, with arrows show
   the probable direction of the water current through the
   nose.
8. State which of the structures of your eye are present
   in the fish’s eye, and which are missing. Could a fish
   weep? wink? How would a fish sleep?
9. Inasmuch as light penetrates water but a little way, so that
   objects can be distinguished only within about thirty feet, would the
   fish be nearsighted or farsighted?

Suggested drawings.

1. A side view of the entire fish, fully labeled.
2. A bony rayed and a cartilaginous rayed fin.
3. A scale, showing its minute structure.
4. A dorsal or a lateral view of the head, showing the
   sense organs.

The Mouth and the Gills of the Fish

Materials.

The same materials as those used in the preceding
exercise may be used here.

Directions.

The mouth, its structure and its action, can be seen by
pulling the upper jaw upward and forward until the mouth
and the gill chambers open fully. Examine the structure
and action of the jaws, the tongue, the throat, and the
teeth on each jaw and on the roof of the mouth.

Investigate the breathing apparatus from the throat side
and from the exterior, noting the number, form, and structure
of the gills, their attachment and their protection.

The mouth may be kept open by a short splinter or a
ball of paper.

The pupil should identify the following structures:—

1. Gill,

an organ for breathing the air dissolved in
water.

2. Gill arch,

an arch of bone or cartilage supporting the
gills.

3. Gill filaments,

fringe-like structures attached to the
gill arches, forming the gills.

4. Gill raker,

lateral projections from the gill arches.

5. Gill-slits,

openings between the gill arches for the
passage of water.

6. Operculum,

the flap-like covering of the gills on
each side of the head.

Questions.

1. Compared with the size of its body, how wide can
   the fish open its mouth? What do you infer as to the
   size of its “bite”?
2. Are the jaws rigidly affixed to the skull? Why
   should they be so attached, or why not?
3. Of how many pieces is the upper jaw composed? the
   under jaw?
4. Where are the teeth? Judging from their form,
   size, and situation, what do you think must be their use?
5. Do you think the tongue is used to assist in mastication?
   in tasting? in speech? in swallowing?
6. How many gills are there, and where are they
   situated? How are they attached? Which one is not free
   from the body throughout its length?
7. What probably causes the color of the gill filaments?
   What is there in their number and texture which fits them
   for their function?
8. 
   What is the direction of the water current through
   the gill chamber? Of what use are the gill rakers?
9. How are the gills protected?

Summary.

Write a complete account of how the fish eats and how
it breathes.

Suggested drawings.

1. A front view of the fish’s face, with the mouth fully
   open.
2. A side view, as above.
3. A ventral view of the head, with both gill-chambers
   wide open and the gills separated from each other. Indicate
   currents by arrows.
4. A single gill.

The Alimentary Canal and the Circulatory System of the Fish

Materials.

Small fresh fish, shallow pans or dishes of water, forceps,
and scissors.

Directions.

If the instructor has not opened the fish previously, this
is to be done by the student as follows: On the ventral
side, insert the scissors in the vent (in front of the anal fin)
and cut straight forward to a point between the opercula.
Care must be exercised in opening the chamber about the
heart; this lies between the gill chambers.

The various organs, so far as possible, should be carefully
drawn out and separated, in order that their structure may
be distinguished.

The pupil should identify the following parts:—

1. Body cavity, the entire internal space, divided by a
   membrane, false diaphragm, into a large abdominal cavity
   and a small chamber, pericardial chamber, between the
   gill chambers.
2. Liver, a large red or pink mass lying at the front
   end of the abdominal cavity, and divided into two unequal
   lobes. The gall-bladder, thin-walled and green, may be
   seen between these lobes.
3. Alimentary canal.
   1. Mouth.
   2. Esophagus, in the fish a very short tube.
   3. Stomach, white and muscular, beginning with
      a very short esophagus and ending as a blind sac.
      If it is much distended, open it to see what the fish
      may have eaten.
   4. Small intestine, thin-walled, tubular, and somewhat
      coiled.
   5. Large intestine, a short, thin-walled expansion
      at the posterior end of the small intestine; usually
      less than half an inch long.
   6. Cœca, from two to several small pouches
      attached where the small intestine leaves the
      stomach.
4. Spleen, a reddish brown globule between the folds of
   the intestine.
5. Swim bladder, an elongated chamber lying against
   the backbone, partitioned off from the cavity below by a
   delicate membrane.
6. Peritoneum, the delicate, silvery membrane which
   lines the abdominal cavity and enfolds the viscera. Note
   its spots of pigment.
7. Pericardial chamber, the chamber around the heart;
   see § 1 above.
8. Heart. As the fish is placed belly upward in the pan
   the ventricle faces you, pink, conical, and muscular.
   Posterior to it, on the dorsal side, is the auricle, a membranous
   sac.
9. Ventral aorta, arising on the anterior surface of the
   ventricle as a white muscular “cord” (really a tube) which
   is enlarged close to the heart into a bulb, the arterial bulb.
   You should follow up this aorta until you see it divide
   right and left to send its branches outward into the gills,
   the branches being called gill arteries.

Questions.

1. The fish frequently swallows its food alive. Why
   should the stomach be muscular? Why is it better that
   the intestine does not leave the stomach at the end opposite
   the esophagus?
2. Of what use can the cœca be? What structure of
   the human intestine do you recall that is at all like them
   in form or use?
3. How many times the length of the body is the length
   of the alimentary canal? Does this indicate that the fish
   is compelled to eat a great deal of poor food or that its
   food is highly nutritious, so that little need be taken?
4. Near which end of the fish’s body is the heart? Is
   this the usual or the unusual condition among animals you
   know about? What advantages can you think of in this
   arrangement?
5. What advantages are there in having the heart in a
   chamber separated from the other vital organs?
6. Of how many chambers does the heart consist? Why
   should at least one of them be muscular?
7. How many times does the blood pass through the
   heart in making a complete circuit of the body? Would
   you call this a single or a double circulation?
8. Does the heart force the blood onward or does it
   draw blood into itself, i.e. is the heart a force pump or is
   it a suction pump?
9. How is circulation made complete? If the heart is a
   force pump, is its power sufficient to drive blood through
   artery, capillary, vein, and into auricle, if the capillaries
   can stand the pressure, or is another action concerned? If
   it is a suction pump, why does the blood leave the heart?

Suggested drawings.

1. The body cavity, with viscera undisturbed.
2. The alimentary canal extended.
3. The anterior end of the fish with the sinus held open,
   to show the general situation of the parts.
4. The heart in its chamber, with the outgoing vessels
   as far as dissected. Use arrows to show direction of
   circulation.
5. A copy of some good diagram or chart which illustrates
   the heart of the fish with the connecting veins and
   arteries.

Fishes: A General Review and Library Exercise

1. Food and the feeding habits of young and of adult
   fishes.
2. The diet and habits of cod; lantern-fish; swordfish;
   ramora; hagfish; angler; gar-pike; sturgeon; shark;
   sawfish; paddle-fish.
3. The variations, real or apparent, in the breathing
   habits of the porcupine-fish; the climbing-fish; the lung-fish.
4. Peculiarities in swimming as seen in the flying-fish;
   the flounder; the sea-horse.
5. Intensity of sound under water, and the corresponding
   structure of the fish’s ear.
6. 
   Light and sight under water (as in 5).
7. Protection of fishes: sting-ray; torpedo; coral-fish;
   sturgeon; lava-fish; swordfish; sawfish; pipefish.
8. The social instinct of fishes, and “schools.”
9. The breeding habits of salmon; eel; stickle-back;
   sturgeon; whitefish; shark; sea-horse; sunfish.
10. The fishing industries of the Great Lakes or of the
    cold oceans, with a list of the fishes caught and their
    values.
11. Fish nets and traps: seine; gill-net; pound-net;
    trawl, French or English; fish-wheel; fish-weir; spear;
    dip-net; set-line; spoon; fly.
12. The U.S. Bureau of Fisheries: its locations, its
    problems, and its methods.
13. The State Fish Commission, as above.
14. Game and fish laws; their purpose and their enforcement.
15. Game fish of the fresh waters; trout, bass, pickerel,
    and muskellunge.
16. Game fish of the ocean: tarpon, tuna, sea-bass,
    swordfish, and bluefish.
17. Fish as food.
18. Fish diet and leprosy.
19. Fish diet and parasitic worms.
20. Fish nuisances: carp, catfish, and dogfish.
21. Commercial products of fishes, their preparation
    and their uses: caviar, shagreen, cod liver oil, isinglass, and
    glue.
22. The geographic distribution of fishes, with means of
    dispersal and restriction.
23. The faunal regions of the lake (or ocean), with
    characteristic forms.
24. Fishes of ancient times; of the Devonian period.
25. 
    The story of the early life of Louis Agassiz; of
    D. S. Jordan; of C. H. Eigenmann; of Bashford Dean.
26. Goldfish: their origin; how to care for them.
27. Fashions in fish tails, old and new.
28. Development and variation in scales; fashions in
    scales.
29. The common orders of fishes, with examples.

Primitive Chordates

Materials.

An acorn-tongued worm, a lancelet, a lamprey, a shark,
and a perch. If individual specimens are not available,
the pupil’s text-book and charts are to be used.

Observations.

Acorn-tongued worm:

Notice the very simple form and
structure of the symmetrical body, the “proboscis,” the
collar surrounding the neck with its simple rod of cartilage,
the marks of internal gills and gill slits extending some
distance along the body, and the presence or absence of
sense organs. The acorn-tongued worm (Balanoglossus)
lives in the sand of the seashore and in shallow water in
temperate and tropical regions.

Lancelet:

Observe the form of the body, of the fin, and
of the mouth; note the presence or absence of sense
organs, and find out the number of gills or gill slits. The
lancelet (Amphioxus) is similar in habit to the acorn-tongued
worm. By day it lies buried with only the
mouth exposed, but at night it swims actively about. It
is somewhat more confined to the tropics.

Lamprey:

Observe here also the primitive or unspecialized
form of the body, of the fin, of the jawless mouth,
the number of gill slits, and the sense organs.

Shark:

Examine the body, noting its form and differentiation
into regions, its covering, its fins, mouth, gill
slits, and sense organs.

Perch:

If you have not already studied the bony fish,
the points suggested for the shark will be sufficient for
this exercise.

In each case, find out the condition of the skeleton.

Questions.

1. Which of these animals seem most simple in form,
   and which most complex? Give a reason for your answer.
2. Give the stages which show how the fold of skin
   develops into separate fins.
3. How does the number of gills and gill slits change
   in the series? (Give definite numbers.) How may the
   reduction in the number of gills be compensated for in the
   amount of surface exposed for the exchange of gases in
   breathing?
4. How is protection afforded the delicate structure of
   the gills in the final form?
5. Give the stages in the formation of a definite, symmetrical
   mouth with jaws of equal size.
6. The presence of sense organs may be taken to indicate
   that there is an organ of control, or brain. How is
   the development of this organ like or unlike that of the
   other structures in the series?
7. For the developing brain and nervous system what
   protection and support is afforded in each case?

The foregoing questions may be answered in tabular
form by arranging the names of the animals in a line and
the questions in a column.

Suggested drawings.

1. Acorn-tongued worm, × 1.
2. Lancelet, × 1.
3. 
   Lamprey, × ½.
4. Shark: 1, head as far as the pectoral fins; 2, the tail.
5. Perch, as directed for shark.

B. Studies of Amphibia

Progress from Water-living Animals to Land-living
Animals

The Living Frog or Toad

To show how an Animal may be adapted to both Land and
Water Life

Materials.

Living frogs in small cages or aquaria; living toads;
some pungent liquid, as ammonia.

Observations.

The Body.

1. Contrast the body of the frog with that
   of the fish as to regions, shape, and compactness. How
   do you account for the differences?

Locomotion.

1. What kinds of locomotion can a frog
   use? Why is it difficult for a frog to crawl or walk?
   How far can a frog jump? How are swimming and
   jumping accomplished? What do you think is the use
   of the “hump” on the back?
2. Identify in the legs the thigh, shank, ankle, foot,
   toes, and web, and in the arm, the upper arm, forearm,
   wrist, hand, and fingers. State in detail the differences in
   structure and in position between the fore and hind limbs.
   How do you account for these differences?

Feeding.

1. Induce a frog or toad to eat by dangling
   food, such as a piece of raw meat or meal worms, small
   earthworms, etc., before it. How does it seize the food?
   What will it eat? How is the mouth adapted to this
   manner of feeding?

Respiration.

1. The frog has no diaphragm, and therefore
   no chest cavity; watch very carefully the movements
   of the mouth, the nostrils, the throat, and the sides of the
   body to determine how the problem of breathing (how
   the air is gotten into and out of the lungs) without a
   diaphragm is solved. Write a detailed account of the
   frog’s method of breathing which shall explain just how
   the air is forced into the lungs.
2. What would be the effect of propping open the
   mouth of the frog? Why? Does the frog breathe in
   the usual manner while under the water? If not, how
   do you explain its ability to remain under water for a
   long period of time?

Sense Organs.

1. Investigate the efficiency of the five
   special senses in the frog by devising experiments to test
   each sense; as, for example, giving a frog its liberty on
   the floor and trying to catch it again, to test the sense
   of sight. Write an account of your experiments and their
   results. Which of the senses is best developed? Give
   reasons for your answer.
2. Compare the eye of the frog with respect to its
   shape, movements, parts, and protective structures with
   that of the fish. In what respects are they similar? in
   what respects different? Why should they differ?
3. Where are the frogs’ ears located? What do you
   think of the efficiency of an eardrum situated on the
   surface of the body? Why?
4. The frog has certain other responses. Try turning
   the jar or cage containing a frog around to face the
   frog in another direction. What happens? How do you
   explain this response on the basis of use? What other
   responses have you noticed?

Protection.

1. Has the frog an exoskeleton? Describe
   the color scheme of the frog and explain how it may be
   protective. Why are frogs brighter in spring than in fall?
2. Why do frogs usually live near water? Do they
   ever leave the vicinity of streams? If so, when?

Summary.

In what ways is the frog adapted to water life? In
what ways to life on land? In what respects do toads
differ from frogs?

The Frog’s Mouth

Materials.

Preserved or freshly killed frogs in dishes or shallow
pans of water; forceps and a bristle.

Observations.

Open the frog’s mouth as widely as possible and, if
necessary, insert a splinter to hold the jaws apart.
Identify the following structures:—

Tongue.

Draw it forward until the free end extends
from the mouth and is outspread; observe its form, extent,
and attachment.

Teeth.

Find those on the jaws and on the roof of the
mouth.

Nostrils.

Push the bristle inward through a nostril to
determine its direction and extent.

Vocal cords.

These form a hard white mass in the
floor of the mouth, well back behind the tongue.

Glottis,

the slit inclosed between the vocal cords, opening
into the trachea.

Esophagus,

the passage to the stomach, at the posterior
end of the mouth.

Eustachian tubes,

small passages outward to the ears at
the junction of the upper and lower jaws.

Questions.

1. Describe the probable action of the frog’s tongue in
   catching a bug.
2. What advantage can you ascribe to the peculiar
   mode of attachment of the tongue?
3. Of what use is the notch in the inner end of the
   tongue? (Note its position when the tongue lies at rest
   in the mouth.)
4. If the frog chewed its food, how would the existing
   structure of the nostrils be very inconvenient?
5. Recall either the frog’s habit of feeding or the
   structure of the nostrils. Do you think the nostrils are of
   much service in smelling? State the reason for your answer.
6. Of what use are the vocal cords and why are they so
   muscular? Consider their use in sound making and also
   their condition during swallowing.
7. Of what use are the teeth? Recall the form and use
   of the fish’s teeth.

Suggested drawings.

1. The mouth, wide open and with tongue extended.
2. A diagram showing the path of air and of food
   through the frog’s mouth.

The Organs of Digestion, Absorption, and Excretion

Materials.

Freshly killed or preserved frogs in dishes or shallow
pans of water, forceps, and, if the pupil is to do any dissecting,
scissors.

Directions and Observations.

The specimens may have been opened by the teacher, or
may be dissected by the pupil as follows:—

Placing the frog on its back, with forceps firmly grasp
the skin of the abdomen and the muscles beneath, just in
front of the hind legs, and with the scissors cut straight
forward in the middle line until the floor of the mouth is
reached; this will separate the arms. Care must be taken
not to cut too deeply, but this may be avoided by keeping
the skin uplifted. Now cut sidewise in front of each hind
leg in order that the body wall may be laid aside. Under
the arms the heart will be seen; it will be studied as a part
of the circulatory system.

Identify the following organs:—

Liver,

the large red or brown mass, consisting of several
divisions and lying close up under the arms.

Bile sac,

small, green, and between the liver lobes.

Alimentary canal.

1. Mouth.
2. Esophagus.
3. Stomach, the elongated, light-colored, firm,
   and muscular portion.
4. Small intestine, a slender, more or less closely
   coiled, tubular portion.
5. Large intestine, a thin-walled enlargement at
   the posterior end of the canal.
6. Duodenum. This is a muscular portion of the
   small intestine immediately following the stomach,
   against which it is folded.

Pancreas,

a yellowish, pulpy mass lying in the fold
between the stomach and the duodenum.

Spleen,

a dark red globule, usually smaller than a pea,
lying nearly free among the folds of the small intestine.

Fat bodies,

yellow fringe-like structures, sometimes found
near the stomach.

Kidneys,

a pair of elongated dark red organs, behind the
spleen and against the back. Note their numerous blood
vessels. Possibly the ureters, or urinal ducts, can be discovered
and traced to their junction with the bladder, a
clear membranous sac in the posterior extremity of the
body cavity.

Peritoneum,

a thin membrane lining the body cavity and
attaching the vital organs to the backbone.

Note.—Specimens secured in late fall, winter, or early spring may
contain, if female, a large number of dark-colored eggs; or if male, two
white testes, located near the kidneys and similar to them in form,
though smaller.

Questions.

1. Name the parts of the frog’s alimentary canal.
2. Name the glands or organs which are accessory
   to the canal.
3. How long is the esophagus? How does the presence
   or absence of a neck affect the esophagus?
4. How does the thickness of the stomach wall compare
   with that of the intestine, and how do you account for the
   difference?
5. Measure the length of the trunk of the frog’s body
   and that of the outstretched alimentary canal. How many
   times the length of the one is that of the other? How
   does this ratio compare with that of an herbivorous
   animal? (The sheep’s food canal is about thirty-two
   times the length of its body.)
6. What is the color of the bile, as seen through the
   walls of the bile sac? This color is characteristic of carnivorous
   animals; in herbivorous forms it is yellow. Find its
   color in some omnivorous form, as man.
7. Name the organs concerned in excretion.
8. 
   What holds the internal organs in place, and from
   what are they suspended?
9. The spleen is called a “ductless gland.” Give its
   function, and explain why a duct is not necessary to it.
10. Since the frog swallows its food alive and entire,
    what work must the stomach do? What digestive organs
    would be absent from the mouth, or else poorly developed?
11. Since the frog is carnivorous, what digestive ferments
    are probably present, and what ones absent from the alimentary
    canal?
12. Fat bodies are largest in the fall, and are rarely
    found in the spring. How can you account for this?
13. When through with the general study of the alimentary canal,
    you may open the stomach by cutting it lengthwise. Describe the
    character of the stomach lining as to folds and villi, stating the advantage
    of each being present and the reason for the direction of the folds. Tell
    how the food is propelled onward through the alimentary canal. Give
    the scientific name for this action.

Suggested drawings.

1. The viscera (internal organs) undisturbed.
2. The alimentary canal extended.
3. The excretory system.

The Organs of Circulation and Respiration of the Frog

Materials.

The materials used in this exercise are the same as those
used in the preceding exercise.

Observations.

The pupil should identify the following structures:—

Pericardium,

a membrane that surrounds the heart and,
in the case of the frog, separates the body cavity into two
portions, the abdomen and the pericardial chamber.

Heart,

lying between the shoulders and in front of the
false diaphragm. It is conical in form and composed of
three chambers.

Ventricle,

the pink, conical, and muscular portion of the
heart, pointing backward and outward.

Auricles,

right and left. These are anterior and dorsal
to the ventricle, thin, membranous, and dark-colored.

Arterial trunk,

the single large blood vessel, usually
empty of blood, and white. Note its origin and trace it as
far as possible, at least until you see it divide to encircle
the throat.

Sinus venosus,

a large membranous sac dorsal to the
heart and connected with the right auricle.

Lungs,

two small oblong, pink, spongy sacs, lying between
and behind the shoulders.

Questions.

1. Of how many chambers does the frog’s heart consist?
   Name them, and describe them as to size, color, and structure.
2. Which chamber receives blood from the body, and
   which receives blood from the lungs?
3. Name the large arteries and give the regions which
   they supply. Name the large veins and give the regions
   from which they come.
4. Describe the lungs as to size, both when inflated and
   when uninflated. Describe their color; entirety or subdivision;
   texture.
5. In the inflated lung, notice the interior partitions or
   chambers, which are called vesicles. How do they affect
   the amount of surface exposed for gas exchange in breathing?
6. Measuring the lung collapsed and again when inflated,
   calculate its approximate volume in each case and state
   how much air it may take in during an inspiration.
7. Describe the diaphragm and state its probable use as
   a factor in respiration or as a partition.

Advanced questions.

1. Apparently the pure and the impure blood must commingle upon
   entering the single ventricle, but by a simple device this scarcely occurs.
   How would such commingling affect the purity of the blood as
   it reached the tissues, and hence affect waste removal, oxidation, body
   temperature, activity, and intelligence?
2. What are the chambers of the fish’s heart? of the mammalian (human)
   heart? How may the heart of the frog be regarded as intermediate
   between these others? How and where might the growth of a
   partition within it bring about the higher structure? (This actually occurs
   in certain reptiles.)
3. The lungs are said to be outgrowths of the alimentary canal.
   Explain how their connection would tend to show this.

Suggested drawings.

1. The heart and lungs in their normal position.
2. The circulatory system, as seen in the injected specimen.
3. A copy of the diagram or model of the circulatory
   system.
4. A diagram of the respiratory tract from the nostrils
   to the lungs, by arrows showing the course of the air.

The Nervous System of the Frog

Materials.

Specimens which have the brain exposed and other
specimens whose viscera have been removed so that the
spinal nerves can be seen; pans or shallow dishes of water
and forceps.

Observations.

The nerve tissues are generally white in color unless
they have been specially treated and stained. The pupil
should identify the following structures:—

A. Brain, those enlargements of nerve tissue situated
in the head and composed of four principal parts, as follows:—

1. Cerebral hemispheres, a pair of elongated lobes, the
   anterior enlargements.
2. Mid brain, or optic lobes, a pair of large ovoid structures,
   projecting diagonally forward and sidewise.
3. Cerebellum, a slender, transverse ridge, close behind
   the midbrain.
4. Medulla, the anterior end of the spinal cord, widest
   in front and containing a triangular depression.

(Frequently a pair of smaller enlargements is to be seen in front of
the cerebral hemispheres; they are the olfactory lobes, and from them
nerves pass forward to the nasal chamber.)

B. Spinal cord, extending along the spine, giving rise
to nerves.

C. Spinal nerves, ten pairs of nerves which are connected
with the cord through dorsal (sensory) and ventral (motor)
roots, and which penetrate the body and its appendages.
The first enters the neck; the second and third join and
enter the arm; the fourth to sixth penetrate the skin and
muscles of the trunk; the seventh to ninth join by a plexus
to form the sciatic nerve which supplies the leg, and the
tenth enters the posterior portion of the body.

Questions.

1. Which lobes of the brain are paired? Give at least
   two possible causes or reasons for their double structure.
2. The optic lobes are connected with the eyes. Compare
   their size with that of the other parts. Of how much
   use do you think they are to the frog?
3. If folds or convolutions in the surface of the cerebrum
   indicate intelligence, thoughtfulness, or mind, what do you
   infer as to the frog’s mental condition and power to think?
4. Has the frog brain or “brains”? Explain.
5. Name several things done by an animal’s brain.
6. Which of the spinal nerves are specially large? Why
   should they be large?
7. What advantages are there in the frog’s having a dorsal
   nerve cord instead of a ventral one, as the earthworm has?

   What would be the effect of cutting or breaking the dorsal root of a
   spinal nerve? the ventral root? the entire spinal cord? How do you
   explain the convulsions of the brainless (beheaded) chicken or frog?

8. What kinds of impulses originate outside of the nerve center, and
   what kinds in the center?
9. Sensations reach the cord and brain through the dorsal root of the
   spinal nerve. What kinds of messages travel through the ventral root,
   and in what direction do they go?

Suggested drawings.

1. The brain.
2. The spinal cord and its nerves.
3. The nervous system.
4. A diagram of the cord and its nerves, showing the
   kinds and the directions of the nerve impulses.

The Endoskeleton of the Frog

Materials.

Prepared frog skeletons mounted in glass-covered boxes
or in other cases suitable for individual study; other vertebrate
skeletons for reference.

Observations.

The pupil should examine his specimen and identify the
following structures:—

A. Skull:—

1. Cranium, or brain case, the central and hinder portion.
2. Nasal bone, a triangular bone lying in front of each
   large opening, or eye orbit, and attached to the anterior
   end of the cranium.
3. Premaxillaries, a pair of small bones which form the
   tip of the nose.
4. Maxillary, a slender bone forming the side of the
   upper jaw.
5. Dentary, the bone of the lower jaw, corresponding to
   the maxillary.
6. Occipital foramen, the posterior opening or entrance
   into the cranium, normally covered dorsally by cartilage
   and most easily seen in a separate skull.

B. Vertebral Column:—

1. Cervical vertebra, the first vertebra, supporting the
   skull.
2. 
   Dorso-lumbar vertebræ, vertebræ with small lateral
   processes.
3. Sacrum, the ninth vertebra, bearing extra long lateral
   processes or “arms.”
4. Urostyle, the last vertebra, lying in the median line,
   a long, slender, blade-like bone, really formed by the fusion
   of several vertebræ.

C. Vertebra:—

1. Centrum, the solid, nearly circular portion.
2. Lateral process, one of the paired projections, extending
   outward on either side.
3. Neural spine, the single projection, extending toward
   the dorsal side.
4. Neural arch, formed largely by a connection between
   the lateral process and the neural spine. The arch above
   and the centrum below inclose the neural canal.

D. Pectoral, or Shoulder, Girdle:—

1. Sternum, the “breastbone,” extending along the
   median ventral line.
2. Coracoid, a heavy bone extending from the sternum
   sidewise to support the arm.
3. Clavicle, the “collar bone,” a light bone in front of
   the coracoid.
4. Scapula, the “shoulder blade,” a broad, thin bone
   which arches around to the dorsal side.

E. Pelvic, or Hip, Girdle:—

1. Ilium, a long, slender, curved bone, with its mate uniting
   to form an inverted “wishbone”; it is joined to the
   sacrum.
2. Pelvis, the region of the socket at the junction of
   the ilia.

F. Fore Leg, or Arm:—

1. Humerus, the single bone of the upper arm.
2. Radius, the bone of the lower arm on the thumb
   side; in the frog united to the ulna.
3. Ulna, the bone of the forearm opposite the radius.
4. Carpals, small bones of the wrist.
5. Metacarpals, a single series of long bones forming
   the palm of the hand.
6. Phalanges, the bones of the fingers and thumb (singular
   phalanx).

G. Hind Leg:—

1. Femur, the thigh bone, next to the body.
2. Tibia, the larger bone of the lower leg on the inner
   side; in the frog united to the fibula.
3. Fibula, the smaller bone of the lower leg.
4. Tarsals, the small bones of the instep.
5. Metatarsals, the long bones of the instep.
6. Phalanges, the bones of the toes.

Questions.

1. Whereabouts in the frog has nature made an attempt
   to inclose delicate or vital structures in bony cases?
2. Examining the inside of the mouth, find the teeth.
   Judging from their size and structure, of what use are
   these teeth?
3. What advantages can you see in having the arms and
   legs attached to girdles instead of having them fastened
   directly to the vertebral column? How has their development
   affected the shape of the trunk, as opposed to that
   of the fish?
4. Make a comparison of the two girdles as to their attachment
   to the spine and their consequent rigidity or freedom
   of movement.
5. 
   How many vertebræ are there in the spinal column?
   What advantage can you see in having the column composed
   of many small vertebræ instead of a few large ones?
   Enumerate those having a special form or structure, and
   state the use of each.
6. On the vertebræ notice any irregularities, prominences,
   or roughenings. For what are such bones better
   adapted than smooth bones would be?
7. How is the frog’s humping permitted? How are
   the urostyle and the pelvis connected, if at all? Has this
   any effect on motion? (See living frog.)
8. In parallel columns, keeping corresponding parts in
   a line, tabulate the bones of the fore and hind limbs.
9. State how extra length has been attained in the hind
   leg, and give the purpose or the result of this lengthening.
10. In the forearm notice the fusing of the radius and
    ulna. How would these parts act in rotating the hand, as
    compared with your own, where they are free? Compare
    also the tibia and fibula. Where in the frog’s leg is turning
    made possible by the use of parallel bones?
11. Compare the frog’s hand and foot as to number of
    fingers and toes; as to length and spread. Have any fingers
    or toes only two phalanges?
12. How would an inner skeleton affect the growth and
    the size of an animal, as compared with an outer skeleton,
    like the clam’s?
13. How would the lack of an outer skeleton influence
    sensitiveness, activity, and intelligence?

Suggested drawings.

1. The skull and trunk, with appendages of one side.
2. Each set of bones separately, as the skull, the column,
   etc.

Comparative Study of Amphibia

Materials.

Various amphibia, either dead or alive, such as newts,
mud puppies (necturus), salamanders, and several species
of frogs and toads, especially tree toads.

Observations.

Answer the following questions with respect to each
animal:—

1. What regions of the body are present? What is the
   general shape and size of the body?
2. For what kind of locomotion are the limbs fitted?
   How?
3. Have the hands and feet any special adaptations?
   If so, what are they and for what purpose?
4. With what organs does the animal breathe? If with
   gills, are they external or internal?
5. Judging from the specimen, what do you think is the
   habitat? Give reason for your answer.

Summary from the Comparative Study of Amphibia

1. Which of the amphibia in this study are fish-like in
   character? What are the fish-like characters? Do you
   think these fish-like amphibia are of a lower or higher type
   than the others? Give reasons for your answer.
2. Show how the variation in (a) the form of the body, (b)
   color patterns, and (c) the structure of the legs and arms
   of the amphibia are related to habitat and mode of life.

Amphibia: A General Review and Library Exercise

1. The usefulness of the American toad.
2. The breeding habits of the common frog; of the Surinam
   toad; of the obstetrical toad; of the “smith.”
3. The development of the axolotl.
4. 
   The habits of the tree frogs and their variable coloration.
5. The croaking of frogs and of toads.
6. The flying frog of Ceylon.
7. The distribution and habits of the hellbender; of the
   mud puppy; of the Congo “snake.”
8. The general absence of the amphibia from arid
   regions.
9. Frog farming for city markets.
10. Protective devices of various amphibia.
11. Toads and warts.
12. The homing and water instincts of toads.
13. Hibernation, seasonal or prolonged, of toads and
    frogs.
14. The changes in the respiratory and circulatory system
    during metamorphosis.
15. Ontogeny and phylogeny, as illustrated by amphibia.
16. The structural defects which would prevent an ambitious
    frog from becoming a highly trained and skillful
    animal.
17. The classification of amphibia, with examples.
18. The kinds of frogs and toads found in the region
    where you live.

C. Studies of Living Reptiles

Showing Diversity of Adaptation among closely related
Animals

The Snake

1. What is the shape? What regions are present? How
   do you distinguish between the trunk and the tail? Has
   the tail any use? What are the advantages of a body
   without limbs?
2. 
   Describe the snake’s path in locomotion. How is
   locomotion accomplished? Is the absence of limbs a hindrance
   to the animal in its locomotory activity?
3. Describe the appearance and movements of the
   tongue. Of what use are these movements of the tongue?
4. What evidence is there that the snake breathes with
   lungs?
5. What sense organs do you find? Compare the ears
   and eyes with those of the frog. What explains the peculiar
   staring appearance of the eyes?
6. What is the color scheme? Does it appear to be protective?
   If so, how?
7. Of what does the exoskeleton consist? How are the
   scales arranged? What variations in the size of the scales
   do you find? What special use have some of the scales?
   How fitted for this? How does a snake moult? Appearance
   before and after moulting.

The Florida Lizard

1. Describe the body as to regions and shape. Is the
   tail of use?
2. What are the lizard’s locomotory abilities? How is
   it fitted for living in trees?
3. Feed the lizard flies or meal worms and describe its
   method of capturing them.
4. Compare the lizard’s respiration and sense organs
   with those of the snake and frog.
5. What is the usual color of the lizard? What have you
   discovered about its power to change colors? How may
   this be of use to it?
6. Of what does the exoskeleton consist? Is the entire
   body covered? How are the scales arranged? How does
   the lizard moult?

The Turtle

1. In what important ways does the body of the turtle
   differ from those of the snake and lizard?
2. What methods of locomotion has the turtle? For
   which method is it best fitted? How? Why are its movements
   in water so much less clumsy than on land? (Compare
   weight on land with weight in water.) Compare the
   efficiency of the locomotion of a turtle with that of a lizard
   and suggest a reason for the difference.
3. What do turtles eat while in the laboratory? Since
   turtles have no teeth, how can they bite off their food?
4. What can you discover with respect to the respiration
   of the turtle? Does it breathe when under water?
5. What sense organs has a turtle? Which appears to
   be most highly developed? How do you know?
6. In what various ways is the turtle protected against
   enemies? (You should state several.) Are you afraid of
   a turtle? If so, why? Why does the turtle need more
   protection than the snake or lizard?
7. Describe the color pattern of the turtle you are studying.
   Is this arrangement of colors the same for others of
   the same species?
8. Describe the arrangement of the epidermal plates of
   the turtle’s shell. Are the arrangement, number, and form
   of plates the same for all turtles of this species? Compare
   with the plates of other species. What variations do you
   find?

Reptiles: A General Review and Library Exercise

1. Characteristics of reptiles.
2. Orders of reptiles. Characteristics and examples of
   each order.
3. 
   Poisonous snakes found in the United States. The
   poison fangs of a rattlesnake. Habits of the rattlesnake.
4. Cures for snake bites, fabled and real.
5. Snake charming.
6. Famous poisonous snakes and their habits.
7. The characteristics and habits of alligators.
8. The characteristics and habits of marine turtles.
   How they differ from pond turtles.
9. For what is each of the following noted? Where
   does it live? The terrapins? the horned toad? the Gila
   monster? the chameleon? the glass snake?
10. Reptiles of former (geological) times compared with
    those of the present.
11. Care of eggs and young. Swallowing of young by
    snakes.
12. Food of snakes. Defend the proposition that non-poisonous
    snakes are beneficial and should not be killed
    wantonly.
13. Investigate and write an account of the economic
    value of reptiles.

D. Studies of Birds

Vertebrates specialized for Flight

The Living Pigeon

Materials.

Living pigeons in cages, and, if practicable, other birds
such as chickens, canaries, and sparrows.

The Body.

1. What divisions of the body are present?
   Compare the relative size of these divisions with that of
   other vertebrates studied. Can you account for the great
   increase in bulk of the trunk over the other divisions?
   How do you account for the longer neck?

Flight.

1. What is the shape of the body? How is
   the body made smooth? To what is the shape and smoothness
   adapted? (Recall the appearance of a plucked pigeon
   or chicken.)
2. Observe the size of the wings by measuring their
   width and spread (measured from tip to tip when outspread).
   Where on the body are they attached? How is
   this point of attachment advantageous? What is the shape
   of the upper surface of a wing when spread? of the lower
   surface? How is this shape advantageous in flight?
3. Where are the largest and strongest feathers? How
   are they arranged with respect to each other: (a) to prevent
   air passing through on the down stroke of the wing?
   (b) to permit folding?
4. What is the shape and width of the tail when outspread?
   when folded? In what way does the tail assist
   in flight?

Walking and Perching.

1. Identify the parts of the leg
   as in the frog. (See study of frog.) With what exoskeletal
   structures is each part covered? How many toes are
   there? Does the pigeon walk on its foot or on its toes?
   Where is the ankle joint?
2. The bird’s legs are arranged to support the body.
   How is this brought about? Compare with the lizard and
   frog in this respect.
3. Explain how the legs are adapted (a) to preserve the
   balance of the body, and (b) for perching. Are they well
   or poorly adapted for locomotion? Explain. For what
   other purposes are the legs sometimes used?

Feeding and Drinking.

1. What is the form and character
   of the jaws of the pigeon (called the beak)? Offer
   food, and watch the pigeons eat. How does a pigeon seize
   and swallow food? Does it chew the food? Locate the
   crop. If the pigeon chewed its food, would it have a crop?
   Why? How does a pigeon drink? How does the chicken
   drink?

Respiration.

1. What parts move in breathing?
2. Compare roughly the body temperature (by touch)
   of man, the pigeon, and the frog. Which has the highest
   temperature? which the lowest? How can you account
   for the higher temperature of the bird? (Which of
   the three must be able to endure long-sustained effort?
   What is the effect on your own body of long-continued
   effort?)

Sense Organs.

1. Identify the eyes, ears, and nostrils,
   and describe their location. What are the advantages in
   having the eardrum at the bottom of a canal? Is there
   any disadvantage? What is the probable function of the
   inner thin eyelid? How does it work?
2. Investigate the power of response of the special
   senses. Which seems to be the most alert? State the
   experiments which you used and your reasons for your
   answers to this question. Which senses are most serviceable
   in finding food? in protecting against enemies?

Protection.

1. In what different ways are feathers
   protective to the bird? Study the arrangement of the
   feathers to find how protection is increased in this way.
   How do the feathers and parts of feathers which lie next
   the body differ from those which are on the outer surface?
   What parts of the body are unprotected by feathers? How
   are these protected, if at all?
2. Note the flexibility of the neck. Through what
   part of the arc of a circle can the pigeon turn its head?
   How is this especially important to birds?
3. What means of defense has the pigeon when
   attacked?

Summary.

1. Make a list of the important adaptations of the
   pigeon, (a) to flight, (b) to feeding, (c) to perching, and
   (d) to protection.
2. Which is the most highly specialized, the fish, frog,
   snake, or bird? Give reasons for your answers.
3. In what various ways are feathers of use to the bird?

Suggested drawings.

1. Side view of the head.
2. A foot.
3. A wing.
4. Side view of the pigeon.

Supplementary Studies of the Pigeon

These topics and questions should be answered from
experience with pigeons and observations of their habits
and behavior, and from books to be obtained from the
school and public libraries.

1. The homing instinct of the common blue pigeon and
   of carrier pigeons.
2. Nesting habits, number of broods and number of
   young in each brood, feeding the young. Why is this
   method of feeding the young necessary?
3. Varieties or breeds of pigeons. How the various
   varieties were produced; how they are kept true; reversions
   of type.
4. Darwin’s experiments with the pigeons; object of
   the experiment. Whitman’s experiments.

The Exoskeleton of the Bird: Plumage

Materials.

Living birds, as perhaps pigeons, or mounted or stuffed
skins, separate feathers, portions of feathers, microscopes.

Observations.

The pupils should study the arrangement of the feathers
and their variations in form and size, and should identify
the following principal kinds:—

Contour feathers,

those feathers, generally broad, which
cover the body, giving to it its outline and color.

Coverts,

those feathers which cover joints, such as the
joints of the wing and tail.

Primaries or pinions,

the long stiff feathers of the outside
of the wing, used in sustaining the bird in flight.

Secondaries,

the shorter, more symmetrical feathers lying
next and over the primaries.

Down,

soft feathers found on young birds and next to
the skin on some adults.

Thread feathers,

best seen about the eyes, ears, and
beak.

Quill,

the bare stiff portion, one end of which is inserted
in the skin. Examine its internal structure.

Vane,

the broad expanded portion, the part ordinarily
seen on the bird.

Shaft,

the mid-rib of the vane.

Barbs,

the delicate outgrowths of the shaft making up
the vane.

Barbules,

the subdivisions of the barbs, some of which
are provided with hooklets. These may well be studied
microscopically.

Questions.

1. How is the plumage arranged to offer least resistance
   to the air in flight? How does a bird sit when
   exposed to the wind?
2. In a column write the names of the parts of a
   feather, and opposite each part state its particular use.
3. 
   Of what use are the hooklets on the barbules?
4. State and explain the peculiar position of the shaft
   of the primary feather; of that of a contour feather.

   The plumage of many birds contains all stages of feather specialization,
   from down to pinion. Find as many of them as you can on your
   specimen.

5. What reason can you assign for the fluffy base and
   the compact end of the contour feather?
6. How much of the feather of a full-grown bird seems
   to be supplied with blood vessels? How does this bloodless
   or full-blooded condition affect the weight of the
   feather; of the plumage; of the bird?
7. How would the above condition affect the temperature
   of the blood and of the body? Would it tend to
   cool the animal or to conserve its heat?
8. Show how the air lying motionless amongst the
   plumage may serve the same purpose as that in the packing
   of a fireless cooker or a “thermos bottle.”
9. How would the above condition affect the growth
   and repair of the feather? What connection has it with
   moulting?
10. What kind of feathers forms most birds’ “baby
    clothes”? What kind forms the adults’ “underclothes”?

Suggested drawings.

1. A typical feather.
2. A feather of each kind.
3. A bird with wings outspread, showing positions of
   feathers.
4. The minute structure of a feather.

Birds and Migration

To illustrate Distribution

Work in the Laboratory

Materials.

Bird skins or mounted birds, at least one representative of
each order and, better still, of each family of the birds
which pass through or remain in your neighborhood; specimens
in a museum may also be used. Some guide to the
identification of birds, as Walter’s “Wild Birds in City
Parks” or Reed’s “Bird Guide.” A good diagram of a
bird.

Directions.

Your object here is to familiarize yourself with the appearance
of birds of different types, and with the terms
used in describing them. Study first a diagram of a bird
and learn the terms and their applications.

An important item in the description of a bird is its
length. This is obtained by measuring from the tip of
the beak, over the curve of the head, to the end of the tail.
This measures a curved line and gives a greater length for
a bird than the straight line you would naturally estimate.
Train your eye by watching house sparrows (so-called
English sparrows) and fixing their length as a unit. They
are called six inches long, and in the field other birds may
be measured by them. The robin is ten inches long, and
may be used to measure the larger birds.

In describing the colors of birds, great discussions often
arise because pupils do not use terms correctly. Consult
Chapman’s “Birds of Eastern North America” for a color
key or chart, and train yourself to observe colors carefully
and name them correctly. You will find more colors among
birds than are given there, but the chart will help you a
great deal.

Study in the laboratory as many birds as you can. Try
to get one of each order at least and, among the perching
birds, one of each family. The answers to the following
questions should be recorded upon the blank outlines of
birds, or else in the form of a table.

Questions.

1. How long is the bird?
2. What is the general color of the upper surface; of
   the lower?
3. What are the markings or peculiarities of the head, if
   there are any?
4. Note any peculiarities of the tail, as to shape, length,
   or color, if there are any.
5. If the wings are not like the back, note their color, and,
   if there are wing bars, note their number and color.
6. What are the markings on the breast, if there are any?
7. Note any other markings, as rump spot, etc.
8. What sort of beak has the bird?
9. What sort of feet has it?
10. Identify the bird, using any key or guide you have.
    Do not ask any one to help you until you have exhausted
    your own resources.

Comparative Study of Birds

1. In what ways do the feet of birds vary? Give examples
   to illustrate your answer. What are the principal
   results of these variations?
2. In what ways do the beaks of birds vary? Give examples
   of the variations and of the special uses of the
   beaks.
3. 
   How do water birds differ from land birds; flesh-eating
   birds from seed eaters; insect-eating birds from
   seed eaters; shore and swamp birds from land birds?

Work in the Field

Materials.

(1) Birds in the field, field or opera glasses, and bird
guides. (2) Some extra time, as field work is rather slow.
(3) Considerable energy, as birds rise early and may be
up and away before the usual hour for your appearance.

Directions.

The object of this work is to become acquainted with the
living bird, to learn not only its name, but also some of its
ways. You will need to spend time to do this, and as a
rule the more time you spend the more you will see.
Every time you go out after birds, record at the time every
kind of bird you see, so that at the end of the season you will
know not only when each kind of bird came, but also how
long it staid. When you see a new bird, record immediately
its colors, markings, actions, notes, and anything else
which may help you later to identify it. Do not trust to
memory nor to the inspiration of the classroom. After
weeks of observation, write the following summary.

Summary of the Results of Field Study of Birds

1. Over what length of time have your observations extended?
   Where have you studied? What have you found
   to be the best conditions for studying birds? How many
   birds have you identified?
2. When in the year do birds migrate; when in the
   twenty-four hours?
3. In spring migration which birds come first; which
   come last? What reason is there for this order?
4. 
   What may retard migration? What may hasten it?
5. What could prevent certain birds from ever coming
   here, or, if they did come, from staying?
6. Name some birds which stay here permanently;
   some which come only for the winter; some which come
   for the summers; some which merely pass through, going
   and coming.
7. Can you see anything which may determine whether
   a bird will nest here or farther north? If so, what is it?
8. Why is the house sparrow so successful?
9. Why are blue jays so nomadic in winter?
10. What months do the herring gulls stay here? When
    do they leave? Where do they go when they leave?
    What do they do while they are gone? When do they
    return? What is their economic value?
11. How many birds’ nests have you seen this spring?
    To what kinds of birds did they belong? If you have been
    able to study one in particular, give its history as far as you
    know it.
12. Tell what you have learned by your own observation
    this spring concerning the kinds of food birds eat, and
    their methods of obtaining food.
13. What bird songs have you learned to know? When
    do these birds sing most? Does a bird have more than
    one song?
14. What birds have you seen near your home? What
    attached them to the vicinity? How might you attract
    more birds?

Birds; Review and Library Exercise

1. What are the distinguishing characteristics of birds?
2. Give the orders of birds, with the characteristics of
   each order and an example of each.
3. 
   Define and give illustrations of the meaning of the
   expressions: “land birds;” “water birds;” “shore birds;”
   “swamp birds;” “scavengers;” “policemen of the air.”
4. Discuss the temperature of birds, the amount of energy
   they show, and the oxygen they use.
5. Beaks of birds.
6. Feet of birds.
7. The crop and gizzard. Why absent in many birds?
8. What is there in a bird’s construction which enables
   it to twist its head so far around? What are the advantages
   in being able to do so?
9. Account for the oiliness of plumage of water birds;
   for the complete feathering of legs and feet in some forms.
10. Define moulting and discuss its advantages and disadvantages.
11. Give reasons why you would not expect a bird to
    hibernate.
12. Name two or more kinds of birds which show
    “recognition marks.” What sort of birds would you expect
    to find with such marks? Why?
13. Is a bird’s egg alive when it is laid? Why does it
    have so much food stored in it? What direct interest have
    we in this fact?
14. How are the eggs of various birds protected while
    they are developing?

    Note.—Do not be satisfied with only one way. A bird seldom is.

15. Compare præcocial and altricial birds as to their
    stage of development when hatched; the location and
    character of the nest; the care given by the parents; the
    singing habit of the parents; the success of the type.
16. Name at least three insect-eating birds and tell how
    many insects it is estimated each will destroy in a day.
    Effect in a garden?
17. 
    [**check nested paras]If you had an orchard to protect from insects
    would you spray it with poison, or would you police it
    with birds?

    Note.—Consider both sides. There is much to be said on each.

    If you decided that you needed more birds, how would you
    get them?

18. Suppose you had a city lot in the suburbs, 50 feet
    wide by 200 feet deep, with a house covering the first 50
    feet. Make a plan of the back yard to show what you
    could do to attract the birds to it in the summer; in the
    winter. Remember that birds must have protection against
    enemies as well as against changes in weather, etc.
19. For what purposes are birds killed by man? Which
    of these do you consider legitimate? Which birds may not
    legally be killed at any time of the year in this state?
    Which may at certain seasons? Which may at any time?
    When should an “open season” be permitted? How long
    should it last?
20. Give a short biography of Audubon. Describe the
    purpose of the Audubon Society and some of the work
    accomplished by it.
21. When were the house sparrows, or, as we call
    them, the English sparrows, introduced into this country?
    Where? Why? Have they proved a success from our
    standpoint? From their own? Why have they increased
    so enormously? What part of the country is still free
    from them? Why? Give the reasons for and the methods
    of fighting English sparrows.
22. The history of the passenger pigeon.
23. What has the quail or bobwhite to do with our food
    supply?
24. Poultry keeping.
25. 
    Name three bird magazines and give a characteristic
    of each one.
26. Fossil birds and the light they shed on the probable
    ancestry of birds.

Study of the Migration of Animals in General

The migration of birds is only one case of a phenomenon
which is comparatively common. From your text and
reference books find other examples of migration. What
are the causes which make animals migrate? What
methods do various animals use? What are some results
of these migrations? Summarize your study in the following
thesis:—

The distribution of animals.

1. The necessity for this distribution.
2. Methods of distribution—voluntary—involuntary.

   Note.—See in review the methods used to spread corals, hydroids,
   and other sedentary forms, starfish, clams, etc., as well as those used by
   the various vertebrates.

3. Time when migration occurs. Consider here the young
   of most animals, and the movements of many birds, as well
   as movements caused by some accidental occurrence.
4. Distance that animals move from the place of their
   birth.
5. Factors which determine the routes of distribution.
6. Factors which limit distribution.

Migration maps.

1. A map to show the migration route of the birds of
   your region.
2. A map to show the migration of the potato beetle (or
   English sparrow or any other animal the extension of
   whose range has been studied).
3. 
   A map of the world, showing the zonal areas.
4. A map of North America, showing the distribution
   of the ungulates, with the boundaries and barriers marked.
5. A map of North America, showing the distribution of
   the fur-bearing animals.
6. A map of the world, showing the distribution of the
   human races.

E. Studies of Mammals

To illustrate Man’s Relation to Other Animals; the Connection
between Mode of Life and Structure

The Rabbit

The effects of domestication upon an animal. A burrowing
type of rodent.

Materials.

Living rabbits—young rabbits are more desirable for
laboratory study.

Observations.

The Body.

1. What divisions of the body are there?
   Compare the length and use of the neck with that of the
   pigeon. Describe the character and length of the tail.
   What use has it, if any?

Locomotion.

1. What methods of locomotion has the
   rabbit? Which is most commonly used?
2. Study the limbs, and find the ankle and wrist. Does
   the rabbit walk on its foot or its toes? Note the number
   and character of the toes and fingers and their claws.
   What is the effect of the nonretractile power of the claws
   upon the uses to which claws can be put?
3. 
   What uses have the fore or the hind limbs other than
   locomotion? Explain how the usual sitting or resting
   posture is advantageous for quick locomotion.
4. By means of printer’s or writing ink smeared over
   the soles of the feet, and a long piece of clean white paper
   get prints of a rabbit’s tracks as it hops over the paper.
   Explain how the peculiar formation of the tracks occurs.

Feeding.

1. Offer a rabbit various kinds of food. How
   does it test the food before eating? Does the rabbit ever
   use its forelimbs to assist in feeding? If so, when and
   how? How is the food eaten? How are the teeth fitted
   for the rabbit’s method of feeding? Does your rabbit
   drink? If so, how?

Respiration.

1. What movements of the body are concerned in breathing?
2. Compare the frequency of
   the breathing movements with your own. Can you distinguish
   the heart beats? If so, how and where? Count
   them.

Sense Organs.

1. Note the position of the eyes, shape
   of their surface, shape and size of the pupil. What external
   protecting structures are present,—such as eyelids,
   eyelashes, eyebrows? Study the movements of the eyelids.
   Is there a third eyelid as in the bird? Compare the
   use of the neck in enlarging the range of vision with that
   of the bird. Is the rabbit’s range of vision greater or less
   than your own?
2. What is the location of the nostrils? What advantages
   are gained by the prolongation of the face forward?
   Note any peculiarity in the form or movement of the nostrils.
   How do you explain these movements? Are the
   nostrils more or less useful than those of other vertebrates
   you have studied? How?
3. Note the shape, size, and position of the external
   ears and explain what relation, if any, these characters of
   the ears have to hearing. Note the various movements of
   the ears and the reasons for these movements.
4. What special organs for touch has the rabbit?
   Under what circumstances are these of use? What parts
   of the body are most sensitive to touch?

Protection.

1. What home-making habits do you observe
   in the rabbit? What habits relating to secrecy,
   comfort, and safety, do you observe?
2. Study the fur and hair of the rabbit. How do you
   distinguish between fur and hair? What variations do
   you find in the fur and hair? What parts of the body are
   uncovered? Why? What are the various functions of
   the fur and hair covering of rabbit?
3. Have rabbits any means of defense or offense?
   Explain.

Social Habits.

1. Notice and describe anything in
   the behavior of the rabbits which may be classed as social,—such
   as play, fondness for company, display of affection,
   homing instincts, care of young, etc.

Supplementary Study of Wild Rabbits

If you cannot answer these questions from observations
of wild rabbits, the answers may be obtained by reading
some good natural history. Ernest Thompson Seton’s
story of a rabbit’s life is good for the purpose.

1. What method of locomotion is more highly developed
   in wild rabbits than in domestic rabbits? Why?
2. When do wild rabbits do their feeding? Why? In
   what ways do they sometimes do damage in feeding?
3. What senses will probably be more alert than those
   of the domestic rabbit? Why?
4. Where do wild rabbits usually make their homes?
   Why? How do they guard against being cornered in
   their homes?
5. In what ways do they guard against surprise when
   feeding? What are the principal enemies of rabbits?
   What devices do they employ to escape enemies when
   pursued by them? What is thumping? When used?
6. How many young rabbits are usually produced at
   one time? How many litters in a season? How long
   does it take a young rabbit to mature?
7. How are the young of rabbits guarded against danger
   from enemies and weather? What are the various causes
   that tend to keep down the numbers of rabbits?
8. Give an account of the plagues of rabbits in Colorado
   and Australia, including the reasons for the great increase
   in numbers and the methods used to destroy the rabbits.

Summary of the Study of Rabbits

1. What has been the general effect of domestication
   upon rabbits?
2. What are the most important characters and habits
   that fit the wild rabbit for its life?

The Guinea Pig or White Rat

Materials.

Living animals.

Observations.

1. What regions of the body can you identify? What
   is the relative length of the neck, ears, legs? What about
   the tail?
2. Describe the color scheme of the animal. Is it protective
   or the result of breeding? What is the character
   of the covering?
3. 
   Describe the method and rate of locomotion. Would
   this method of locomotion enable the animal to escape from
   enemies (e.g. dogs)?
4. What is the shape of the foot? What is the shape
   and length of the claws? For what are they adapted?
5. What sounds do the animals make?
6. What is the appearance and shape of the eye? What
   is the color of the eye?
7. State the size and shape of the external ear. What
   movements are characteristic?
8. What motions of the nostrils do you see?
9. Feed the animal various kinds of food. How does
   it eat? State any facts you observed, to show that it has
   or has not a choice as to food.
10. Watch the animal for some time to determine its
    mental characteristics. Is it alert? curious? timid? Does
    it show much intelligence? affection?

What is the relation between mental development and success in the
struggle for existence?

Summary.

1. What are the general characteristics of the animal?
2. To what kind of life is it adapted?
3. What are some of the characteristics that make the
   animal a good pet?

The Squirrel

Materials.

Living specimens in cages, mounted specimens, pictures,
charts, lantern slides, etc.

Directions.

Before taking up the study of the squirrel in the laboratory
a trip should be made to some park or wooded region
and the habits of squirrels noted. Take your camera and
try to take some snapshots. After the laboratory exercise
visit some museum or zoölogical garden and study the relatives
of the squirrel.

Observations based upon field work.

1. What different postures does the squirrel assume?
2. What does it do when frightened?
3. What use have the forelegs other than locomotion?
4. How does a squirrel go up a tree? down? from
   branch to branch? State all the forms of locomotion you
   have noticed.
5. What is the appearance of the tail? What is the
   position of the tail when the squirrel is sitting? running?
   on a branch? Describe any motions of the tail you noticed.
   Is there anything expressed by these motions or
   are they without meaning?
6. Tempt the squirrel with some nuts. State the evidence
   that leads you to think that the squirrel is alert,
   timid, curious. Do you think the squirrel acts most from
   instinct or as the result of intelligence?
7. In what various ways does a squirrel attempt to escape
   notice? What does it do when you chase it?

Observations in the laboratory.

1. What divisions are there to the body? What is the
   length of the neck? the length and appearance of the
   tail?
2. What is the relative length of the legs as compared
   with the body? How does the length of the front and
   hind legs compare?
3. Does the animal walk on its toes or on the sole of
   its foot? How many toes on each foot? What is the
   length of the claws? For what could they be used?
4. 
   Offer the squirrel various kinds of food and see if it
   has a choice. Describe its methods of eating.
5. Note the position of the eyes, the shape of their surface,
   and the shape and size of the pupil. How many
   eyelids do you notice? Why do the squirrel’s eyes appear
   so “bright”? Are eyebrows, eyelashes, or tear
   glands present?
6. Note the size, shape, and appearance of the squirrel’s
   external ears.
7. What movements of the nostrils do you notice? For
   what does a squirrel chiefly use his nostrils? What explanation
   can you suggest for the nostrils, eyes, and ears
   having the same relative position in all vertebrates?
8. How does a squirrel protect itself?
9. Smear the feet of a squirrel with ink and allow it to run over a
   roll of clean paper as in the case of the rabbit. How do its tracks differ
   from those of the rabbit?

Summary.

1. What are the general characteristics of the squirrel?
2. To what kind of life is it adapted?
3. What adaptations has the squirrel to protect it from
   its enemies?
4. What characteristics make the squirrel a good pet?
   What objections to it?

Library Exercise on Rodents

1. General characteristics and examples of rodents.
   The teeth of rodents.
2. Show how variation in habitat depends upon structure
   among rodents by comparing, for example, squirrels,
   beavers, and woodchucks.
3. Variations in the tails of rodents. What are the
   causes of this variation?
4. 
   Pocket gophers and their economic relations.
5. Species of mice. Their habits.
6. The dancing mouse.
7. Damage by mice. Plagues of field mice in Nevada.
   Method of extermination.
8. Habits and kinds of rats.
9. Economic importance of rats. Methods of extermination.
10. Rats and the bubonic plague.
11. Squirrels, kinds and habits.
12. The economic value of rabbits.
13. The groundhog myth. Habits of woodchucks.
14. The beaver—their habits and sagacity. Methods
    of trapping them.
15. Prairie dogs—their habits and economic importance.
    How exterminated?
16. What are porcupines?
17. Variation in the homes among rodents. Usual
    means of defense.
18. Make a list of rodents in a column, and in another
    column opposite each name write the various ways the
    animal is of economic importance. Sum up with a statement
    showing the most important ways rodents are of
    value to man and harmful to man.
19. Defend the proposition that rodents are on the
    whole harmful animals and should be exterminated.
20. How some rodents contribute to the science of
    medicine, more especially to bacteriology.

The Cat or Dog—Carnivora

Materials.

Living specimens of cats or dogs. Pictures, books,
lantern slides, etc. Supplement the laboratory study with
trips to museums and zoölogical gardens to observe the
relatives of the cat.

Definitions.

Carnivora.

An order of mammals, chiefly flesh-eating,
with claws and well-developed canine teeth.

Carnivorous,

flesh-eating.

Herbivorous,

plant-eating.

Omnivorous,

eating both plants and animal food.

Digitigrade,

walking on the toes.

Plantigrade,

walking on the soles of the feet.

Vibrissæ,

long hairs on the face—”whiskers.”

Observations.

1. Into what regions is the body divided?
2. What is the shape of the head and the length of the
   neck?
3. Are the legs relatively long or short? How do the
   front and hind legs compare in length? How many toes
   on each foot? Is the cat digitigrade or plantigrade?
4. How many pads on the sole of the foot? What
   use can you suggest for these structures? What is the
   size and shape of the claws? Are they retractile or nonretractile?
   For what purposes may the claws be used?
5. Describe the tail as to length and appearance.
   Movements.
6. What is the size and appearance of the external
   ears? What movement do you notice?
7. Are the eyes large or small? What eyelids can you
   find? What other accessory structures? What is the
   shape and direction of the pupil?
8. What other sensory structures do you find? What
   is their function?
9. Watch the animal eat. Does it chew or “fletcherize”
   its food? What teeth seem well developed? Is the movement
   of the jaws simply up and down, or is there a lateral
   movement as well?
10. Try to find out some of the mental characteristics
    of the animal, i.e. is it sluggish or active? Is it alert? Does
    it show curiosity? fear? What evidence of intelligence?

Supplementary studies.

1. Smear the feet of a cat with ink and allow it to run on
   a sheet of clean paper. Make a diagram to show tracks.
   Do the same in case of a dog. How do these tracks
   differ? Why?
2. What is the difference between a cat and a dog as to
   the manner of eating a bone?
3. As you see dogs and cats outside do you see any
   evidence in either case of a tendency to gather in packs
   (gregariousness)?
4. What different emotions are expressed by a dog’s
   tail? a cat’s tail?
5. What sounds do cats and dogs make? Significance?
6. Contrast the sleeping habits of cats and dogs.
7. How large is the litter in case of dogs and cats?
   Condition of young at birth? How long before the eyes
   of the young are open? Care of young.

Summary.

To what kind of life does a cat or dog seem best adapted:
(a) as to food? (b) protection from enemies?

Carnivora; Review and Library Exercise

Characteristics.

1. The general characters of carnivora.
2. Five important families. The characteristics and examples
   of each family.

Morphology and physiology.

1. The dentition of the cat, the dog, and the bear. Variation
   in the “chewing teeth.”
2. Three types of paired appendages among carnivora.
   Relation to habitat.
3. The difference in structure and use of the posterior
   legs of the seal and walrus.
4. The alimentary canal of a cat and rabbit compared.
5. The tongue of cats and dogs contrasted as to structure
   and use.

Economics.

1. The difference between hair and fur.
2. The fur-bearing carnivora. Families, and habitat.
3. Trapping.
4. Game laws and game wardens. Hunters’ licenses.
5. Hunting big game.
6. Carnivora harmful to man.
7. Carnivora useful to man.
8. Carnivora as pets.
9. Chief types or breeds of domesticated dogs. Characteristics.
   Special value of each.
10. Chief types or breeds of domesticated cats.
11. Dogs as burden bearers.

Natural History.

1. Distribution and range of carnivora. Carnivora of
   the United States.
2. Winter habits among carnivora.
3. Food of carnivora. Various methods of obtaining it.
4. The hunting habits of the dog and cat family.
5. The habits and distribution of the raccoons.
6. The color schemes of the more important families
   of the carnivora.
7. 
   Seasonal variation in color.
8. Distribution and habits of the ferrets and weasels.
9. How carnivora protect themselves from enemies.
   Which carnivora have been most successful in resisting
   man’s advance?
10. Peculiar and interesting carnivora to be seen in
    museums and zoölogical gardens.
11. Origin of the domestic dog.
12. Intelligence of dogs.
13. Fox-hunting.
14. Coyotes and their relation to stock raising, etc.

The Ungulates

Materials.

Pictures, charts, lantern slides, and books showing cow,
sheep, hog, goat, horse, etc. Diagram of skeleton.

Directions.

Since it is impossible to have living ungulates in the
laboratory, this study should be supplemented by trips to a
museum and to a zoölogical garden. Observe also such
hoofed animals as may be common in your neighborhood.
Use your camera and make “snapshots,” showing characteristic
attitudes of these animals.

Definitions.

Ungulates,

an order of mammals characterized by the
possession of hoofs.

Ruminant,

a division of ungulates, which “chew the
cud.”

Perissodactyl,

a division of ungulates with an odd number
of toes.

Artiodactyl,

a division of ungulates with an even number
of toes.

Carnivorous,

flesh-eating.

Herbivorous,

plant-eating.

Omnivorous,

eating both plant and animal food.

Observations in the laboratory.

Note.—Answer the following questions for one or more of the following:
The cow, sheep, goat, hog, and horse. If desired, the questions
may be answered in the form of a table.

1. What is the relative length of the neck? What is
   its direction with reference to the body? Of what importance
   is this length and direction?
2. What is the length and appearance of the tail?
   What is its use?
3. What is the relative length of the legs? Locate the
   heel, knee, and elbow. (Reference should be made to a
   diagram of a skeleton.) When the leg is long, in which
   bone is this lengthening accomplished (compared with
   human skeleton)?
4. How many toes on each foot? Is the animal an artiodactyl
   or a perissodactyl? Is it plantigrade or digitigrade?
5. What is the relative size and position of the ears
   (external ear)?
6. What is the relative size and position of the eyes?
   nostrils?
7. Are horns of any kind present? If so, note the size,
   shape, and direction. Are they present in both sexes? If
   not, in which one? If in both, note any differences distinguishing
   the sexes.

Suggested drawings.

1. Head, side view.
2. Entire animal, side view.

Observations in the field or at home.

1. Note how the animal uses its lips, tongue, and teeth in
   feeding. Is it a ruminant?
2. In what order does the animal use its feet? Look
   up the definition of walk, run, gallop, canter, trot, lope,
   single foot, pace. Which of these forms of locomotion
   are optional with the animal?
3. Describe the process when the animal lies down
   and gets up.
4. Describe the covering of the animal, noting its
   length, fineness, etc. What variations in different regions
   of the body?
5. Is the animal alert or sluggish? Upon what senses
   does it most depend? What mental characteristics are
   most marked, e.g. curiosity, fear, suspicion.
6. Note any movements of the ear. What is gained by
   these movements?
7. What is the position of the eye? What is the shape
   and direction of the pupil? Reason?
8. What means has the animal for getting away from
   its enemies.

Observations based upon museum trip or natural history.

1. Identify as many ungulates as you can; for example,
   buffalo, musk ox, big-horn sheep, Rocky Mountain goat,
   chamois, antelope, giraffe, red deer, elk, moose, reindeer,
   wild boar, peccary, rhinoceros, zebra, hippopotamus.
2. Answer the following questions about each:—
   1. What is the family, scientific name?
   2. What is the size of the animal? the relative length
      of the hind and fore legs? the relative length of the
      neck?
   3. What is the nature of the covering of the animal?
   4. 
      [**corrected: d was a]Are any horns developed? If present, what is their
      size, shape, direction, and appearance?
   5. What is the habitat of the animal? its distribution
      and social life?

Summary.

In a short thesis summarize the facts you have found
out about ungulates, using the following outline:—

1. Why called ungulates? Variation in number of toes.
2. General fact about the food of ungulates. The two
   divisions.
3. The general adaptations for protection.
4. The social life of the ungulates.
5. The native ungulates of the United States.
6. Commercial uses and value.

Ungulates: Review and Library Exercise

Characteristics.

1. Classification of ungulates based upon number of
   toes, kind of horns, “chewing the cud,” etc. Some of
   the more important families with examples.

Morphology and physiology.

1. The variation in the number and kinds of teeth.
   The dentition (or dental formula) of horse and cow.
2. The various types of horns. Shedding of horns and
   sexual variation.
3. The structure and function of the stomach of a
   ruminant. Meaning of the cud-chewing habit.
4. The structure of the stomach of a camel.

Economics.

1. Ungulates which have been domesticated.
2. Breeds of cattle—their distinguishing marks and
   valuable points.
3. 
   Breeds of horses—their distinguishing marks and
   valuable points.
4. Breeds of sheep—their distinguishing marks and
   valuable points.
5. Breeds of hogs—their distinguishing marks and
   valuable points.
6. Angora goats.
7. The making of butter and cheese. Kinds of cheese.
   Substitutes for butter.
8. The packing industry. Ungulates useful as food.
9. The various methods of preserving meat.
10. Cattle ranches and “round-ups.” Free cattle in
    winter.
11. Cattle raising in your state; in other countries.
12. Transportation of cattle. Stock cars, care and
    feeding.
13. Useful products derived from ungulates.
14. Tanning. Varieties and use of leather.
15. Diagrams showing chief cuts of meats.
16. Sheep husbandry. Shearing.
17. Ungulates as beasts of burden. Advantages and
    disadvantages.
18. Government inspection—quarantine.

Natural History.

1. Geographical distribution of ungulates. Habitat and
   range.
2. Native ungulates of North America.
3. How, when, and by whom cattle and horses were
   introduced into America.
4. The geological history of the horse.
5. The story of the buffalo.
6. Deer hunting.
7. 
   Methods of protection from enemies among ungulates.
8. Breeding habits and care of young in case of
   ungulates.
9. Intelligence in the case of horses.
10. Strange and peculiar ungulates to be seen in museums
    and zoölogical gardens.

The Horse

The pupil is expected to study carefully the account of
Eohippus or Hyracotherium in his text or any other available
reference book, and to supplement that work and this
brief sketch with original observations upon horses on the
street, at a local store, or wherever possible or convenient.

From the early horses which migrated from North
America there arose in Asia and Africa the ass, famous in
the history of early civilization and still used in some
localities as beasts of burden or for the breeding of mules,
which are the crosses between ass and horse. There also
arose the zebra and the most primitive of modern horses,
Przewalskii’s horse, a wild pony of western China, about
forty inches high and almost identical with the drawings of
the horse made by early man, 30,000 years ago. Doubtless
the modern ponies of Ireland, Iceland, and Shetland are descendants
of the original Przewalskii type and not, as is
often claimed, true horses stunted by rigors of climate and
scant fare.

The horse is characterized largely by the presence of a
lock of hair between the ears, a full mane and tail, small
ears, large hoofs, and peculiar neigh. The ass has no forelock,
a scanty mane and tail, long ears, small hoofs, and a
distinct bray.

By means of various crusades and raids, the modern
horse was introduced into Europe from Asia, where it is
clearly traced in history to the reign of King Solomon.
Here, in Europe, because of local conditions and demands,
it assumed differing type forms. The roadster type is
closest to the Arabian in character. The draft or heavy
type was bred in western Europe when heavy armor came
into use for rider and horse, and the coach or carriage type
was developed when armor was abandoned for gunpowder.
Finally explorers and colonists brought the horse back to
America, its original home.

The various types and varieties may be briefly described.

A. The draft type has short legs, short neck, large round
body, and ranges in weight from 1400 pounds to 2000
pounds.

Varieties:—

1. Percheron: generally about 1700 pounds in weight,
   16 hands (64 inches) high, gray or black, blocky body, steep
   rump, clean legs, and quick action.
2. Shire: generally about 1800 pounds in weight, 17 hands
   high, bay or brown, white marked feet and face, hairy
   legs and feet, and slow action.
3. Belgian: generally about 1800 pounds in weight,
   16 hands high, chestnut or roan in color, compact body,
   short, steep rump, and small feet.

B. The coach or carriage type has legs and neck of
medium length, a body full-chested but not blocky, and a
weight varying from 1150 pounds to 1400 pounds.

Varieties:—

1. Hackney: generally of full, broad, powerful body,
   short legs and back, high action and high carriage of neck
   and head, bay or chestnut in color, 15 hands high, and
   1400 pounds in weight.
2. 
   Coach: generally lighter than the Hackney, with
   longer legs and long stride; height, 16 hands; weight,
   1300 pounds.
3. Cleveland bay: averaging 16½ hands in height,
   1350 pounds in weight, high, broad hips, strong action, and
   bay color.

C. The roadster type is long and lean of limb and
body, and averages about 1100 pounds in weight.

Varieties:—

1. Thoroughbred: of small head, long neck, level back,
   of variable color, 14½–16½ hands high, about 1000 pounds
   in weight.
2. American saddle: an American production; not a
   distinct breed, but a roadster of high quality.
3. American trotter: a superior type of good speed.
   The off forefoot and the nigh hind foot act together, the
   nigh fore and the off hind feet together, giving a two-beat
   gait.
4. Pacer: similar to the trotter, but using both off feet
   and both nigh feet together, giving a swinging gait.

The horse is very similar to man in its physical and
mental character, being subject to the same ailments and
treatment and having the same impulses of affection,
hatred, fear, jealousy, obedience, willfulness, memory,
and perhaps reason. It is of all animals most careful in
its eating and drinking; because its stomach is small,
the food should not be bulky but concentrated, grain
forming a goodly portion of the ration.

Perhaps the most important point in the structure of
the horse is the form of the leg and foot. The shoulder
should slope slightly backward and the pastern joint, immediately
above the hoof, slightly backward. The hips, or
“quarters,” should slope downward somewhat, and the hock
should be comparatively wide to afford ample leverage
for the pulling muscles. The legs should be straight
as pillars when seen from front or rear. The outer walls
of the hoof support most of the weight though the frog
should normally touch the ground. In nature the hoof
wears away properly of itself, but the shod hoof needs
regular trimming attention, while the frog must not be
trimmed, for it is the soft growing part that nourishes
the hoof. In this treatment the foot is comparable with
the human finger and finger nail.

Observations.

If access to a living animal is impossible or inconvenient,
the pupil may use reference book or pictures
for most of these points. A measuring tape or ruler
should be at hand, and the assistance of an experienced
person is a valuable aid. If several horses are studied,
they should be distinguished by name or number.

Record the color, condition, weight, and height of the
horse at the shoulder. (Height is given in “hands,” a
hand being the breadth of the palm, or 4 inches.) Note
the slope of the shoulder, of the back and the hips,
the general form of the head and neck, and the facial
expression. Find the chestnuts, warty growths on the
inside of each leg. Examine the foot, finding the V-shaped
frog in the center, surrounded by the horny hoof.

Find the pulse by passing the fingers downward from
the upper curve of the neck, along the inside of the jaw;
count the pulse. Notice the position and motion of the
ears with their lining of hair, and the position of the
eyes, the form of the pupil, and the probable range of
vision. Watch the horse use its lips, and examine the
mouth and teeth, finding the grinding teeth far back in
the mouth, the incisors in front, and the space where
the canines are missing.

The male may have canines in the upper jaw.

On the surfaces of the incisors are the depressions,
or “cups,” by means of which age is determined.

At six years the cups leave the lower center teeth; at seven the
adjoining teeth; and at eight, the outer lower teeth. At nine years
they leave the upper center incisors; at ten, the adjoining teeth; and
at eleven, the outer teeth above. At the age of ten years a spot appears
in the outer upper incisors, at fifteen years the groove has worn to the
center of the tooth, and at twenty-one years the groove is worn to the
bottom of the tooth.

Questions.

1. Describe the horse you studied as to its name or
   number, its color, markings, weight, and size. Of what
   type and breed is it a specimen?
2. Upon how much of the foot does the horse walk?
   How does this affect ease or speed of action? How does
   an athlete imitate this in sprinting?
3. How many toes has each foot? What advantage
   or disadvantage can you see in this unusual structure?
4. How is the hoof constructed to distribute the weight
   over a surface broader than the leg? How general is this
   among terrestrial animals?
5. What is the difference in the position of the chestnuts
   of the fore and hind legs?
6. Where in the foreleg is a springiness permitted by
   curvature? Where does the back leg accomplish the same
   thing?
7. How do you account for the elongating of the
   face?
8. 
   Explain the uses of the lips, telling how they are
   fitted for their work.
9. Tell where the bit lies in the horse’s mouth, and how
   the structure permits this.
10. Where are the ears situated? How does this
    peculiar position affect the range of hearing and general
    alertness? Of how much movement are they capable?
    Describe the lining of the ear, and state its use.
11. What is the rate of the pulse?
12. Measure the height at shoulder and at croup,
    length of body from withers to rump, of head, of neck;
    thickness of body from the shoulder to the chest and of
    distance of chest from ground. Point out any equalities
    or ratios you find.

Topics for investigation.

1. The meaning of the terms gee, haw, nigh, off, run,
   gallop, trot, pace, single foot, rack.
2. The location, cause, and effect of these troubles:
   heaves, blind staggers, knee sprung, shoe boil, quitter,
   ring bone, spavin, capped hock, flat foot, hoof bound,
   glanders, mange, sweeny, hide bound, and thrush.
3. The record time for a trotted and a paced mile.
4. The meaning of “one horse power.” How much a
   horse can pull on good roads.
5. Record prices for valuable horses.
6. Current prices for horses; for ponies; for mules.
7. The origin and the use of the mule.
8. Balanced rations.
9. The number and care of the young, and their relative
   development at birth.
10. Other animals used as beasts of burden in peculiar
    conditions or localities.

Homology of the Vertebrate Skeleton

Materials.

Prepared skeletons of an amphibian, a reptile, a bird,
another mammal, and man. If any of these be lacking,
lantern-slide illustrations may be used in a partially darkened
room.

Observations.

Having studied the frog’s skeleton in detail, the student
can readily compare each of these types with it. Compare
in a very general way the skulls, the girdles, and the limbs;
their form and use. Note variations in the form and number
of the vertebræ and the number of the ribs.

Questions.

1. In which types of vertebrates are the joints between
   the skull bones bound with cartilage? How does the
   joining change in later types?
2. What dissimilarities occur in the series as regards
   closure or boxing in of the eye orbits, nostrils, and skull
   bones? How would these changes in joining and closure
   affect strength, rigidity, and protection?
3. What evidence is there that such improvement has
   affected brain capacity and intelligence?
4. State how the attachment of the skull to the vertebral
   column changes as the animal man assumes an erect
   position.
5. Are the vertebræ of these types alike in structure?
   What is the general form of an horizontally placed vertebra,
   as in the horse or a reptile, and of a vertically placed
   one, as in man? If you see any differences, account for
   them.
6. Wherever possible, find the vertebræ of the neck
   (cervical), and note the number of them in each case.
7. 
   How is flexibility of the column accomplished in
   certain types or in certain places of one type? How is
   rigidity gained? State instances in each answer.
8. Examining the interior of the turtle’s “shell,” find
   out and explain how the vertebræ have been modified to
   form the upper “shell.” How has the under portion
   (plastron) been formed?
9. In round numbers, which skeleton has the greatest
   number of vertebræ and which the least?
10. Which skeleton has the greatest number of ribs,
    and which has the least?
11. In a summarizing statement explain any variations
    you find in the pectoral and pelvic girdle for strength
    (rigidity); flexibility. This answer may be written as a
    table, naming the bones, opposite each stating its condition,
    and then what it affords or is adapted to.
12. What is accomplished by having two bones in the
    shank of the leg? In what types or forms is there but
    one, and which one is it?
13. Can you assign any advantages in power, agility,
    length of leg, or position of leg and foot accruing from a
    long ankle? (See horse, frog, et al.)
14. Enumerate the types or forms, and opposite each
    state the number of fingers and toes.
15. Make a table, heading one column “Form or type”;
    another, “Habitat”; and a third, “Habit.” Judging from
    the structure which you see or from your previous knowledge
    or experience, fill in the table, stating whether the
    type is aquatic, terrestrial, or aërial; whether it burrows,
    walks, runs, or climbs, etc.
16. From your statements in 15, explain how the
    peculiar mode of life affects the structure of these types.

CHAPTER VII
ADAPTATIONS FOR THE PRESERVATION OF THE SPECIES

A. Methods of Reproduction

1. The Simple or Asexual Method of Reproduction

Materials.

Slides or diagrams, showing a dividing amœba, a dividing
paramecium, a dividing vorticella, reproduction in
some form of sporozoa, budding hydra, gemmules of
spongilla, and some species of worm as Dero or Nereis in
the process of dividing.

Definitions.

Spore,

a cell capable of developing into a new organism.

Asexual reproduction,

reproduction by division of the cell
or body.

Sexual reproduction,

reproduction by means of the conjugation
of two reproductive cells known as the egg and
sperm cells.

Fertilization,

the fusion of the male or sperm cell with
the egg or female cell.

Ovary,

an organ producing eggs.

Spermary,

an organ producing sperm cells.

Cross fertilization,

fertilization in which the sperm and
egg cells are produced by different individuals.

Diœcious,

the different kinds of reproductive organs
found in different individuals.

Monœcious,

the different kinds of reproductive organs
found in the same individual.

Directions.

Note.—Refer to your notes, if the animals mentioned in these exercises
have been already studied. This exercise may be largely review.

Study the methods of reproduction in the specimens or
diagrams before you. Determine first, in what respects
the methods of reproduction are similar in all; second, in
what respects there is a variation.

Questions.

1. What has an amœba gained by dividing? What
   powers has each new cell that the original amœba had
   lost? What would have been the fate of the amœba if it
   had not divided into new cells?
2. What various forms of cell division did you find?
3. What is the simplest method of reproduction?

2. The Complex or Sexual Method of Reproduction

Materials.

Slides or diagrams showing hydra and sponge reproducing
sexually. Conjugating paramecia, fertilized and unfertilized
starfish eggs.

Directions.

Identify the reproductive organs or gonads of the hydra.
These are slight swellings on the surface. The one
nearer to the mouth end is the spermary and that near the
attached end is the ovary.

Questions.

1. How is an egg cell produced in hydra? In general
   how do the reproductive cells of sponges and hydra
   originate?
2. 
   What is gained by limiting the process of reproduction
   to special cells?
3. What is the difference between the appearance of
   the nucleus of the fertilized and the unfertilized egg?
4. What is the advantage of cross fertilization? How accomplished
   in Hydra? What reason can you suggest for the spermary’s position?
5. Describe the conjugation of a paramecium.
6. Describe the process of maturation and fertilization in a starfish
   egg.

Suggested drawings.

1. Diving Amœba or Paramecium.
2. Budding Hydra.
3. Hydra showing gonads.
4. Starfish egg—fertilized and unfertilized.

Summary of important points in the study of methods of
reproduction:—

1. What are the two principal methods of reproduction?
   How do they differ?
2. Why is reproduction necessary?

B. Development

1. The Hen’s Egg

Materials.

Hen’s eggs, hydrochloric acid.

Definitions.

Germ spot,

a white spot, imbedded in the “yolk.” This
is the point at which development begins.

Yolk,

the yellow portion of a bird’s egg. This is a food
material, rich in fat.

Albumen,

the white, viscous portion of a bird’s egg.

Chalaza,

the spiral portion of albumen always seen in
the bird’s egg.

Directions.

Boil an egg at least ten minutes in water deep enough
to cover it. Note which side is uppermost and mark this
part of the shell for reference. Remove the egg and pick
away the shell from about half the egg, leaving the shell
on that portion which was underneath when placed in
water. With a sharp knife remove this half of the egg.
Note the thickness of the shell. Test its composition (use
hydrochloric acid). Find the membrane lining the shell
and note that at one end it separates into two parts to inclose
an air space.

1. What is this for? How does it change after an egg
   has been incubated for a week or more?

   Break an uncooked egg in a saucer. Note the germ spot. Note
   also the difference in the consistency of the “white” (albumen) and
   yellow portion (“yolk”).

2. Why does the latter retain its shape?
3. Why do the white and yolk not mix unless shaken or
   beaten together?
4. Look for the chalaza.
5. What do you think is the use of this structure?

Weigh a fresh egg, place it in a dry atmosphere for a week, and weigh
it again. Record result. Why may eggs be kept a long time perfectly
fresh if coated with paraffin or if put in “water glass”?

Suggested drawings.

1. The egg as it appears in the saucer.
2. The egg after part of the shell has been removed.

2. Early Embryonic Development of an Egg

Materials.

Slides or diagrams, showing various stages in the development
of some animal through the gastrula stage.

Definitions.

Cleavage stages,

two, four, eight, sixteen cells, etc., arising
by repeated division, starting with the egg.

Blastula,

a hollow sphere, the wall of which is composed
of a single layer of cells.

Gastrula,

a stage formed from the blastula by pushing
in one side of the latter, so as to form a more or less cup-shape
structure.

Observations.

1. Is there any considerable difference between the size
   of the egg and the size of the blastula and gastrula? Has
   development taken place by an increase of size or by an
   increase of complexity?
2. Contrast the blastula and gastrula as to number of
   cavities, number of cell layers, number of external
   openings.
3. Suggest protozoans that resemble the egg and blastula
   respectively. What invertebrates resemble the gastrula
   in body plan?

Suggested drawings.

1. Some of the cleavage stages.
2. A blastula.
3. A gastrula.

3. Postembryonic Development or Metamorphosis of a Mosquito

Materials.

Some specimens of the larvæ and pupæ of the mosquito,
ordinarily known as wrigglers. Either specimens
or diagrams of egg packets should also be provided.
Mounted specimens of adult of both sexes.

Definitions.

Postembryonic development,

the changes taking place in
the development of an animal after birth or hatching.

Larva,

the active feeding stage. It is the first stage in
postembryonic development, and follows the gastrula stage.

Pupa,

usually a resting or quiescent stage. It is the
stage following the larva stage.

Observations.

1. Describe the appearance of the egg packet both as
   seen with the unaided eye and with a hand lens. Find
   the trapdoor.
2. What is the difference between the appearance of the
   larva and the pupa? How do their resting positions differ?
3. What does the larva do when disturbed? Describe
   any characteristic motions that you notice.
4. Contrast the pupa with the larva under the same conditions
   and note any differences.
5. Where do you think the external openings of the
   respiratory organs of the larva and those of the pupa are
   located? Give reasons for your answer.
6. Into what does the pupa change? Where must the
   pupa be at this time? Is it easier for the pupa to stay at
   the surface or at the bottom?
7. Examine an adult mosquito. State the kind of mouth
   parts, the number and appearance of the wings, the appearance
   of the antennæ. How does the male and female
   differ in this respect?

Suggested drawings.

1. A diagrammatic drawing representing the jar of
   water and showing the various positions assumed by the
   wrigglers.
2. Careful drawings of each stage.

4. Postembryonic Development or Metamorphosis of a Butterfly
or Moth

Materials.

The eggs, caterpillars, pupæ, cocoons, and adult of some
moth or similar stages of a butterfly.

Definitions.

Prolegs,

short, unsegmented appendages found in the
larva.

Caterpillar,

the larva of a moth or butterfly.

Spiracles,

openings into the trachæ or breathing tubes.

Tubercles,

knob-like projections.

Chrysalis,

the pupa stage of a butterfly.

Cocoons,

the covering spun by the larva before changing
to the pupa.

Observations.

1. State the color and appearance of the larva. If tubercles
   or spines are present, state where. Where are the
   spiracles? How do you distinguish the head, thorax, and
   abdomen in the case of the caterpillar?
2. What kind of mouth parts has the caterpillar?
3. How many prolegs has the caterpillar? Of what
   use are they?

   How does the number of prolegs differ from that of the caterpillar in
   the case of the grub? maggot? currant worm?

4. What is the advantage of the cocoon? What is its
   color, appearance, and material? Is it composed of a
   tough substance, or is it easily torn? Where are cocoons
   found out of doors? Where would you look for chrysalids?
   (Explain differences in locations.)

   Describe the cocoons of tussock moth, clothes moth, leaf roller.

5. What is the difference between a Cecropia cocoon
   which contains a living pupa and one that has been parasitized?
   What is the appearance of a parasitized caterpillar?
6. What rudimentary structures can you identify in the
   pupa? What kind of mouth parts has this stage?
7. Which of these stages is the active stage? Which
   stage is quiescent? What is really going on in the quiescent
   stage? In which stage does the insect grow? feed?
   If the insect were harmful, in which stage would it do the
   damage? How?
8. Describe what occurs when the pupa changes into
   the adult. What is the appearance of the wings in the beginning?
   What changes take place?
9. What kind of mouth parts has the adult? Describe.
10. Describe the antennæ.

    How do the antennæ of moths and butterflies vary?

11. What is the size and appearance of the eggs? Are
    they laid singly or in groups?

Suggested drawings.

1. A caterpillar, side view.
2. A pupa, ventral view.
3. An adult, dorsal view.
4. A few eggs.

5. Development of the Chick

Materials.

An incubator, a brooder, a setting of eggs.

Directions.

Read carefully the directions for setting up and regulating
the incubator. Remember that the temperature should
average 103 degrees and should not vary more than two
or three degrees above or below this. Candle the eggs
from time to time and note difference in appearance, as
development proceeds, especially as to transparency and
size of the air space. An egg that is transparent after ten
days is probably infertile and should be removed. Eggs
which are developing properly will show from this time on
a well developed air space, and will be quite opaque. The
veins often give a spider-web appearance.

Twice each day remove the tray of eggs and allow to
cool slightly. Once a day the eggs should be turned before
the tray is returned to the incubator.

Questions.

1. Describe the appearance of the shell when the chick
   is about to come out. In about how many days after you
   put the eggs in the incubator did you first note this change?
   You should watch the incubator carefully from the eighteenth
   day on.
2. What proportion of the eggs hatched? What reasons
   can you suggest for the failure of some to hatch? Did any
   which were pipped fail to hatch? If so, break them open
   and see if you can discover the trouble.
3. How does the chick get out of the shell? How long
   does it take for it to get out after the shell is chipped?
   How does a chick look as soon as it has come out of the
   shell?
4. With what is a chick covered when it is first hatched?
   How long before feathers begin to develop?
5. How long before a chick needs food? How does it
   recognize it?

Summary.

1. What are the two kinds of development?
2. What are the stages in embryonic development?
3. 
   What two general types of postembryonic development
   as determined by the amount of the food supplied in
   the egg?

C. Protection and Care of Young

Library Exercise

Materials.

Books and diagrams showing as many methods for the
care of young as possible.

Observations.

1. To what extent is care given to the eggs and young
   in the case of fish? Is the number of eggs large or small?
   Contrast this condition with that of the robin. What general
   conclusion is suggested?
2. Describe the egg-laying habits of five or more of
   the following: grasshopper, cecropia moth, tussock moth,
   leaf miner, case bearer, leaf roller, sphinx moth, gall insects,
   ichneumon flies, spiders, earthworm. How is the developing
   animal protected in each case? How is food assured?
3. Contrast the method of the honeybee and the solitary
   wasp as to the method of caring for and feeding the young.
4. Describe the nests of five or more of the following:
   spider, honeybee, bumblebee, paper wasp, mud dauber,
   digger wasp.
5. Describe the nests of the following: stickleback fish,
   sunfish.
6. Describe the nests of ten birds common to your
   neighborhood.
7. Describe the homes of the following: woodchuck,
   mole, squirrel, rabbit, muskrat, prairie dog, beaver, bear.
8. In case of birds which of the parent birds builds the
   nest and cares for the little birds?
9. 
   How are the young cared for in the following cases:
   crayfish, cyclops, pipefish, Surinam toad?

Summary.

1. What general methods are there for protecting the
   young?
2. What various devices for assuring plenty of food for
   the developing animal?
3. What is the relation between the care given the young
   and the number of eggs produced?

D. Adaptations for the Preservation of the Species

Review Questions and Library Exercise

1. Show how the sexual method of reproduction tends
   to produce variations.
2. What is meant by the term heredity?
3. What are chromosomes? What do some zoölogists
   believe to be the relation between these chromosomes and
   heredity?
4. What are dominant and recessive characters? What
   is meant by “Mendel law of heredity”?
5. What is meant by the term parthenogenesis? What
   are some of its advantages and under what conditions does
   it take place? Name some animal in which parthenogenesis
   commonly takes place.
6. What is sex dimorphism? Give some examples.
7. What were the experiments of Professor Loeb and
   others in connection with artificially fertilized eggs?
8. How do eggs vary as to the kind of shell, amount of
   food, size, etc.? What is the effect of the amount of food
   upon the rate of development? On the stage of development
   at which the egg is hatched?
9. 
   Contrast præcocial and altricial birds.
10. What is the effect of ground nesting and tree nesting
    upon the number of eggs and the care of the young?
11. Describe the metamorphosis of grasshopper, June
    beetle, honeybee, dragon-fly, cicada, may-fly, ant-lion,
    caddis fly.
12. Compare the development of the crayfish, crab, and
    lobster. What names are given to the larvæ? What is
    the significance in the fact that the lobster hatches in the
    “mysis stage”?
13. What are some of the peculiar names given to the
    larvæ in the case of echinoderms, worms, and mollusks?
    Why should these have received special names?
14. Name the three primitive germ layers. State the
    principal organs derived from each in the higher animals.
15. What is ontogeny? phylogeny? What is the meaning
    of the law “The ontogeny is an epitome of the phylogeny”?
16. Who was Weissman? What important contribution
    did he make to zoölogy?
17. With what phase of zoölogy is the name of T. H.
    Morgan associated?

CHAPTER VIII
POULTRY

Materials.

Either pictures or specimens of the different breeds of
fowl.

General Information.

Under the term poultry are included chickens as well as
turkeys, pigeons, ducks, geese, etc. Chickens are most
generally raised, since they do not require such special conditions
as the others. In this exercise only this form of
poultry is considered.

The hen has been domesticated from prehistoric times,
being probably derived from the so-called jungle fowl of
India (Gallus bankiva), which is still to be found in its
native habitat. Through constant attempts to improve the
domestic fowl along the lines of greater egg-production,
size, etc., there have been developed a great many different
breeds of fowl. These may be divided into seven
groups, as follows:

1. The American Class.
2. The Asiatic Class.
3. The Mediterranean Class.
4. The English Class.
5. The Dutch Class.
6. The French Class.
7. The Ornamental and Exhibition Classes.

The American Class includes fowls raised both for egg-production
and for eating. It includes the following well-known
breeds: the Plymouth Rocks, the Wyandottes, the
Rhode Island Reds, and the less-known breeds of Javas,
Dominiques, and Jersey Blues. These all lay good-sized
brown eggs, are good winter layers, and stand confinement
well. The standard weight varies from six and one half
pounds to seven and one half pounds for the hen, and from
eight and one half pounds to nine and one half pounds for
the cock, the Plymouth Rocks being the heaviest of the
breeds.

There are three principal varieties of Plymouth Rocks—the
Barred Rocks, with grayish-white plumage regularly
crossed with bars of blue-black, the White Rocks, and
the Buff Rocks. All have single upright combs, which,
with the wattles and the ear lobes, are bright red, a large
bright eye, and yellow legs.

There are also three principal varieties of Wyandottes.
The Silver-laced Wyandotte has a silvery-white plumage,
with black markings in various parts of the body. The
Golden Wyandotte is similar in its markings, but has yellow
where the Silver-laced has white. The White Wyandotte
is pure white. All have rose combs, red ear lobes,
and yellow legs. They are on the average about a pound
lighter than the Plymouth Rocks.

The Rhode Island Reds are a much more recent breed
that has of late become very popular. They are of a
reddish-brown color, about the weight of the Wyandotte,
with yellow legs. There are both single combed and rose
combed varieties.

The Asiatic Class includes those breeds raised chiefly
for the table. The Brahmas, Cochins, and Langshans are
the chief breeds. They are considerably heavier than other
breeds, and are specially characterized by the feathers on
the legs and feet. They all lay brown eggs, and are in
many cases good layers.

The Brahmas include two principal varieties, the light
and the dark. The general color is black and white, and
they have yellow legs, red wattles, ear lobes, and comb,
the latter being of the kind called a pea-comb, which is of
small size in the cock.

There are four varieties of Cochins, the Buff being
much more raised than the Partridge, the White, or
the Black. The Partridge somewhat resembles a dark
Brahma, but has red and brown plumage. Cochins have
single combs, yellow legs, and a general fluffy character
to the plumage, that of saddle and hackle meeting, thus
giving a characteristic appearance to these fowls. The
eggs are not quite so large as the other two breeds of
this class.

The Langshans are smaller and more active than the
two breeds just described. They have black legs, the feet
are not so heavily feathered, and in general these fowls
are much less awkward in appearance. There are two
varieties, the White and the Black.

The Mediterranean Class includes those breeds raised
chiefly because of their great egg-production. They are
active birds, often troublesome because of their ability to
fly over high enclosures, so that when kept in the city it is
usually necessary to clip one wing. They are not so good
winter layers as a rule, but are non-setters. They all lay
white eggs. The chief breeds included are the Leghorns,
the Minorcas, and the Black Spanish.