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State Qollege of Agriculture

At Gornell University .
Ithaca, N. Y.

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STUDIES IN ZOOLOGY

AN INTRODUCTION TO THE STUDY OF ANIMALS
FOR SECONDARY SCHOOLS AND ACADEMIES

BY

JAMES A. MERRILL, S. B. (Harvard)

DIRECTOR OF SCIENCE DEPARTMENT, STATE NORMAL SCHOOL
SUPERIOR, WIS.

NEW YORK - CINCINNATI - CHICAGO
AMERICAN BOOK COMPANY
CopyRIGHT, 1902, By James A. MERRILL.

ENTERED At STATIONERS’ Haut, Lonpon.

STUDIES IN ZOOLOGY.
W. Pet
PREFACE

THIs volume is not intended to add anything to the science
of Zodlogy. It is not for the investigator, it is for the be-
ginner. The author has found that laboratory guides are
as a rule too dry and conventional to accomplish the best
results and he has accordingly attempted to make these
directions simple and suggestive as well as comprehensive.
The plan of these studies was worked out in the Manual
Training High School, Kansas City, Mo., where it was
thoroughly tested with students of all grades of the high
school. The book has also been tested in two Normal
Schools and in several high schools and has been found to
warrant the claims made for it.

Information about animals comes to the child from three
sources, viz.: from a study of the animal itself, from a
study of the environment, from reference books and lectures
by the teacher. This book emphasizes the first and second
of these sources and it is expected that the teacher will see
that the third is not neglected.

~The author has gleaned from so many sources that it
would be impossible to acknowledge them all, but he desires
to make special mention of the assistance of his associate,
Mr. A. N. Young, on the Branch Vermes and on various
other parts of the book. All the tables of classification are

3
4 PREFACE

credited to their proper authors. The attempt has been made
to get classifications that can be understood by the students
of the grade in which this book will be used, rather than
those intricate tables which can be used only by a trained
naturalist.

For any errors in the classifications or in other parts of
the book, the author alone is responsible; and the corres-
pondence of his fellow teachers concerning any part of the

book which may be improved, is earnestly solicited.
J. A. MERRILL.
State Normal School, West Superior, Wis.
CONTENTS

PAGE

INTRODUCTION. 4) ze a a ee wee w we ww Soe ®
Laporatory EQUIPMENT . . . 2. ee ee es . 12
REFERENCE BOOKS 3 4 2 & «@ 3 » “we =e & & 2 e = TA
Directions For Cottectinc INsects . . . . . . 2... IS
JARTEFROPODS) a> ho ae Ae Ch hoe eh Re 20-105
The Grasshopper By $20) oh 9 Soe ve libs A Yoke a Rt ee 4 20
The Cricket . . . . . . gs ee oe ae
The Meadow Locust , sere all ae ago ae Sg 35
Whe Mantis: Goo So ee me eg nalts fy oa: aeog5
The Butterfly . Br Bie Jae: Ai bo) Gee ke wet thes 40
The Moth . . . fe Oe 8 ee : 42
The Squash Bug. . .. . ee ae . . 49
The Beetle. . ‘ tata sks wom Ob on 4
The Honey Bee Ee eae Se oe Oe 65
The House Fly . . bo <p ele 73
The Dragon Fly a 5 Gy Se we a od 2 » 99
The Spider. . . . . bes Gin Sp 1G. EE SO, ME i ge BB
The Centipede . eM : SO ROS a AE a 12
The ‘Crayfish 2: « #4 «= # = & « 2 a) GAMs 93
PRoTOZOANS . . . = . i) Ops. in ers a oe 107-1II
SPONGES Cs Soe 8 8 we pe eerT6
6 CONTENTS

CoELENTERATES
Sea Anemone .
The Fresh Water Paes
The Starfish

Worms
The Earth Woda.
The Nereis .
The Leech .
A Planarian Worm
The Liver Fluke
The Tapeworm

Mo.ttusks
The Fresh ae Mae
The Snail

VERTEBRATES .
The Fish
The Frog
The Pigeon
The Rabbit

APPENDIX

GLOSSARY. gap ae. Ses S84 Se Be we ee RG

PAGE

. 117-124

. 117
. 118

- 121

125-137
. 125
. 130
» 131
. 132
. 133
» 135

138-148
. 138
- 144

149-215
- 149
. I61

- 177
- 198

. 216

. 227
INTRODUCTION

Tuat Zodlogy is an important subject in secondary edu-
cation, no teacher of culture and experience will deny; but
that it has not always met the expectation of those who
introduced it into the course, will be admitted by all. Per-
haps the cause of this is the difference in point of view
between the scientist and the practical educator as to what
constitutes the subject matter for a beginner’s course. But
whatever be the point of view it would seem that the legiti-
mate results of the study of animals at this stage are the
training of the powers of observation, a sympathetic appre-
ciation of animal life, and a knowledge of nature’s method
of producing the changes that are going on daily.

This book is intended to accomplish the results above set
forth. It is intended to arouse an interest in the rudiments
of Zodlogy, and to put the child in contact with the problems
suggested by the animals that surround him. It is not in-
tended that all of these problems are to be solved by the
students who use this book, or that all of the questions in
the book are to be answered correctly or even definitely, but
the student is led to think that with the animals before and
around him he should feel free to strive to solve any problem
which naturally arises in his mind. The questions are asked
in such a way and in such language as to suggest further

7
8 INTRODUCTION

thought, and though some of them may appear indefinite,
the student is thus led to organize all the knowledge he has
and all that he can legitimately obtain toward the answer.
A normal child is not content with knowing the structure
of an animal nor the comparative structure of several ani-
mals; he wants to know how the animals in question use
that structure in living. He wants to know how they select
and obtain their food, how they treat their fellows, especially
those of their own species, and how they successfully over-
come the vicissitudes of climate and the onslaughts of their
enemies. He delights to look upon the animal world as a
struggle for existence—a struggle which requires all the
strength, instinct and intelligence which the animal can
command. In other words the child prefers to approach
Zoélogy through animal ecology, and this book therefore
emphasizes the ecological factors in every study. Animal
ecology cannot be taught from books, however valuable
they may be if rightly used, neither can it be successfully
studied from dead forms in the laboratory; but it requires
the study of living, active forms not in the laboratory only
but in their natural environment. Field trips in which the
teacher organizes the work and directs the observation and
collecting, will be found of inestimable value and should
be taken as often as circumstances will permit.

Dissection of type forms is required in all cases, and
should be thoroughly done; but it is regarded as a means
of finding how the animal solves certain life problems rather
than as an end in itself. The student looks beyond the dissec-
tion to the animal’s adaptation to its environment, and the
dread of dissection with which every teacher has to con-
tend, rapidly disappears.
INTRODUCTION 9

Comparative anatomy becomes a large part of the study
of every form, as each additional animal furnishes a new
solution to an old problem. Materials are thus accumulated
and the points of structure of greatest value are clustered
around the life problems as apperceptive bases.

Classification is the natural outgrowth of comparative
anatomy and is given considerable emphasis. The author
believes that this has been too much neglected in recent
years and that the time has come to reinstate it in a rational
way in the courses in Zodlogy. But the required work in
classification should consist of an arrangement of the com-
parisons made from laboratory and field study and need not
at this stage include the technicalities of the specialist.
However, the use of the manuals of insects and birds may
be taught so that students can pursue these delightful stu-
dies further if they so desire.

‘Collections of insects can be made with very little effort
and most students at this age are inclined to make them.
Such collections, besides the disciplinary value which is
great, have a very great value as illustrations of variation
and adaptation, the two things which have been prominently
associated throughout the work. The laboratory should
if possible contain a working collection of insects and birds
at least, so that the students may use them in comparing
and classifying their own specimens.

This book is not intended to take the place of the teacher,
but rather to awaken an appreciation and a demand for the
teacher’s best effort. It is insisted that the teacher tell the
student as little as possible about the things which he can
discover for himself, but through all this work the teacher
is the guiding spirit and should give to it his most earnest
10 INTRODUCTION

thought. After the student has done all he can in laboratory
and field, lectures by the teacher and references to text-
books and library resources, will be found necessary to
broaden and deepen the view of the subject.

It is believed that it is not necessary to have a regular
text-book in the hands of the pupils to accompany this guide,
since the student is thereby led away from his dependence
upon nature so strongly insisted upon in every study. If,
however, it is thought best to use a regular text the author
would recommend Animal Life, by Jordan and Kellogg,
which is a clear statement of the ecological factors; or
School Zodlogy, by Burnett, which is a definite presentation
of the animal kingdom, including many forms not given in
these pages. ,

The teacher will recognize the value of careful drawing,
but it is believed that if students adopt a scale ‘before at-
tempting to draw, the accuracy of the observation will be
increased. In many cases this scale has been suggested,
and the teacher may encourage the formation of this accu-
rate habit by requiring the scale attached to every drawing.

The observations made under the direction of this book
or of the teacher, should be carefully written in a note book
in clear, concise language. It is better that the notes and
drawing be in ink and that neatness and accuracy be insisted
upon from the beginning.

After a study of animals in this way it is believed that
students will have a desire to go into the deeper problems
of Zodlogy in the College or University.

The course outlined in this book will require about one
year’s work of one period each day. If the allotted time is
shorter, the teacher may adapt this course by omitting cer-
INTRODUCTION II

tain forms or certain parts of the anatomy of several forms.
The work on insects, for instance, is so arranged that any
insect may be taken first and some of the forms may be
omitted entirely or the work reduced so that the necessary
time may be saved. It is believed that a reasonably thor-
ough study of a few types is better than a superficial study
of many types, and that a sympathy with living nature based
upon a knowledge of her laws, is of greater importance
than a deeper study of anatomy only.
LABORATORY EQUIPMENT

A laboratory properly lighted and equipped adds greatly
to the interest and value of the study of Zodlogy. A well
lighted and ventilated room on the north side of the build-
ing, so arranged as to get but little direct sunlight during
working hours is preferable.

The following equipment, which can be obtained at mod-
erate cost, is suggested:

(1) Tables large enough to accommodate four pupils
each, with a drawer for each pupil, with slate or plate glass
tops. The number of tables would be determined by the
number of students to be accommodated.

(2) Compound microscopes, at least two to each table.

(3) A dissecting microscope for each student.

(4) Scissors, scalpel, tweezers, and two mounted needles
for each student. (Studerits can easily mount common
needles for this purpose. )

(5) An aquarium large enough to hold twenty to thirty
gallons of water. Several smaller ones may be made to
answer the purpose.

(6) Slides, cover glasses, jars for holding specimens,
and dissecting trays. (Candy trays may be successfully used
for dissecting trays.)

(7) Astudent’s microtome and accompanying apparatus.
12
LABORATORY EQUIPMENT 13

(8) An insect cabinet, charts, models and a number of
forms foreign to the neighborhood, mounted or preserved
in alcohol. These forms may be obtained by buying them
from supply houses, but the enterprising teacher will be able
to get many desirable specimens by exchange with teachers
and students in distant localities. The cost of equipping
a laboratory for zodlogy need not be great. If the financial
condition of the school district make it necessary to econo-
mize, ordinary tables or desks may be used, hand lenses
will take the place of dissecting microscopes, and glass jars
may be used as aquaria.

However, no economy should lead to the attempt to teach
zodlogy without compound microscopes and dissecting in-
struments. Text-book zodlogy is of no value.
REFERENCE BOOKS

There should be a library of reference books for the
zoology classes consisting of all the standard works; but
if such is not possible under existing conditions, the teacher
will often be able to get a few volumes. It is better to have
a few good books duplicated than to have a miscellaneous
collection. The following are recommended and are ar-
ranged in the order of their importance:

Jordan and Kellogg, “ Animal Life.”

McMurrich, J. P., “Invertebrate Morphology.”

Parker and Haswell, “Tesxt-book of Zoélogy.’

Comstock, J. H., “ Manual for the Study of Insects.”

Lang, “ Text-book of Comparative Anatomy.”

Holland, “ The Butterfly Book.”

Darwin, “ The Formation of Vegetable Mould.”

Jordan, D. S., “A Manual of Vertebrates.”

Cones, Elliott, “4A Key to North American Birds.”

Tryon, “ Structural and Systematic Conchology.”

14
DIRECTIONS FOR COLLECTING INSECTS

I. Mareriats.—At the beginning of his work in Zodlogy
the student should provide himself with the following arti-
cles and should keep them in proper condition and repair:

(1) A Cyanime Bortte.—This is made by putting a
lump of cyanide of potassium, twice the size of a grain of
corn, into any wide-mouthed bottle, covering with water
and stirring in enough plaster of Paris to make it hard
and firm. After this has dried for an hour, put in a piece
of cotton and keep the bottle ever afterwards tightly corked.

(2) Forceps.—A pair of forceps of steel or wire should
be provided for collecting spiders, bumble bees and wasps.

(3) Aw Insect Net.—A net for collecting: butterflies
and dredging ponds may be made by bending a stout quar-
ter-inch wire into a circle about one foot in diameter, leaving
enough at the ends to be fastened on a wooden stick three
to five feet long. Over this stretch a flour sack or a piece
of mosquito netting.

(4) Spreapinc Boarp.—It may be made of two pieces
of thin whitewood or pine board, fastened together by
braces, especially at the ends, and left wide enough apart
to admit the bodies of the insects to be spread; strips of cork
or pith, in which to fasten the pins, may then be tacked
or glued below so as to cover the intervening space. The

15
16 DIRECTIONS FOR COLLECTING INSECTS

braces must be deep enough to prevent the pins from touch-
ing anything on which the stretcher may be laid; and by
attaching a ring or loop to one end, the stretcher may
be hung against the wall out of the way.—Riley.

(5) Mountine Pins anp Box.—These should be kept
handy for mounting the specimens as soon as they are in
proper condition.

Il. Locarities. (1) Exectric Licuts. — Electric
lights are so easy of access and provide such an abundance
and variety of animals that they are naturally the first fields
visited. They should be visited at all seasons from April
to November, so that the complete range of specimens fre-
quenting them will be obtained. The most abundant speci-
mens under the lights are beetles; but moths, bugs, grass-
hoppers, crickets and spiders may also be found there. Col-
lecting is most profitable at the lights during warm, damp
(not rainy) nights and it is useless to visit them on a cold,
dry night. The beetles will be found under the lights, the
moths generally on the post near the lights, the spiders and
centipedes in the grass near by.

(2) Woops.—A profitable place for collecting is also
found in the woods or on rocky ledges. Here the insects
are more timid and are found under stones or logs, in de-
cayed trees or stumps, or under the bark of decayed trees.
The most common forms are beetles, centipedes, several
genera of hymenopters, bugs and spiders. Heavy logs or
stones should not be moved since they contain usually no
specimens, and the lighter ones should be replaced after the
specimens are obtained.

Care should be taken not to injure the specimens in catch-
ing them since an injured specimen is worthless.
DIRECTIONS TOR COLLECTING INSECTS 17

All the mature specimens found should be taken, since
this will furnish an opportunity of exchanging with others,
not only of the same class, but with collectors at a distance.

If snail shells are desired the smaller forms will be found
in the leaves or in the mosses down close to the rocks.

(3) Open Praces.—This includes prairies and places
where the woods are not thick. Such places usually have
flowers and other vegetation so that specimens, such as
grasshoppers, butterflies, bees, and some forms of beetles
are abundant.

The flowers attract the butterflies, bees and sometimes
the beetles. For catching them the net is convenient, but
care must be taken that the butterflics are not allowed to
flutter in the net for fear of spoiling their wings. The
best method of killing moths and butterflies is by dropping
gasoline over the ventral side of the thorax and abdomen.

The grasshoppers are found hopping or flying over the
grass, but some of the smaller forms must be looked for
in the leaves or on the fence, the color of which they imitate.
Occasionally boring insects are found in dry clay banks on
the sides of the roads or streams. It may be mentioned
here that some of the most beautiful beetles are found on
or near the bodies of dead animals.

(4) Ponps anp StreAMs.—These are explored with the
net and are very rich in animal forms. The beetles which
swim through and on top of the water, the bugs which glide
over and dart through it, and the larve of dragon flies which
crawl on the bottom of the pond, are found at all times
during the collecting season in great numbers. In the
spring, fresh-water shrimps, and the eggs of frogs, toads

and salamanders are often found. In addition to these,
STU. IN ZOOL.—2
18 DIRECTIONS FOR COLLECTING INSECTS

crayfish are found in all stages of growth during spring
and summer. An aquarium to rear and study the forms of
life found in the pond, is very profitable as well as inter-
esting.

III. Mountinc.—As soon as caught the specimens
should be put in the cyanide bottle and allowed to remain
until they are dead. They should then be taken out of the
cyanide bottle and put in a box which contains some cotton.
When the collector comes home, the specimens should be
removed and mounted.

The butterflies, grasshoppers and bees should have the
insect pin thrust through the thorax, leaving one fourth to
one third of the pin above the specimen.

They may then be placed in the spreading boards, the
wings stretched forward as in flight, and fastened down
with strips of paper or cloth pinned at the ends. In this
position they should remain until thoroughly dry, the length
of time necessary varying from three to ten days.

The beetles should be mounted by thrusting the pin
through the right wing cover near the prothorax; while all
other insects, as bugs, flies and dragon flies, by thrusting
the pin through the thorax.

The specimens may then be placed in a cigar box, or an
insect box, which should be neatly lined with white paper,
and should contain cork at the bottom, either in sheets or in
pieces about one inch square.

When the box is full, two or three moth balls should be

placed in it to keep out the insects that infest collections.
IV. Naminc.—After the specimens are properly mount-

ed, they should be named and labeled. The label may con-
sist of a number on a piece of white paper through which
DIRECTIONS FOR COLLECTING INSECTS Ig

the pin has been stuck. This number should refer to the
number in the notebook in which is recorded the name of
the family, genus, and species, the sex, the location and date
of capture. These data may be supplemented by any inter-
esting items about habits or variations.

The naming of the specimens may be accomplished by
the use of Comstock’s or Packard’s manual of insects.

The characteristics called for by the book should be
closely noted to prevent mistakes, and the drawings or pic-
tures in the book should be closely compared with the speci-
mens.

Should the specimens be transferred to a cabinet, the name
of the family, genus and species may be placed on a larger
card and mounted with the specimen.

Good care should be taken of the collections, and they will
always remain objects of gratification and pride.
ARTHROPODS

THE GRASSHOPPER

Melanoplus differentialis

GENERAL APPEARANCE.—Observe the shape, color and
size. Measure length and greatest width.

On your drawing tablet make a line of the exact length
of the specimen and cross it at the proper place with one as
long as the greatest width of the specimen. This diagram
represents the longitudinal and lateral axes of the animal.

Lay the specimen down with the anterior end (head)
from you, the posterior end toward you. Note the main
differences between the dorsal (upper) side and the ventral
(lower) side. On the ventral side note three well-marked
divisions of the body, the head, the thorax, and the abdomen.
Do you find these three divisions on the dorsal side? Give
reason for your opinion.

What is the nature of the covering? Is it the same all
over the body? It is called Chitin. Make a drawing of
the animal from the left side showing wings and legs in
place (2).

Tue Heap.—(1) Turn the animal with head toward
you. Note the general appearance from front, sides, and
top. Study the face. Near the upper part find the large
eyes and the jointed antennae (feelers). Count the seg-
ments in the antenne. Is the number the same in both?

Why? Is there evidence that one has been broken off?
20
THE GRASSHOPPER 21

How are the antennz joined to the head? What kind of
joint between the segments?

Above the antennz near the large eyes look for small eyes
or ocelli. Look closely for a third ocellus. Note the cover-
ing of the head. Do you find lines of division? When these
lines are deep and extend from one line to another they
mark divisions between plates. Do you find plates on the
face and sides of the head? How many? The one between
the eyes is called the epicranium. Follow it backward and
forward until you have traced its shape.

Below the epicranium is a bandlike plate, the clypeus,
and below this is the movable /abrum, or upper lip. Trace
each of these and find the irregularities of surface.

Below each of the large plates is a plate called gena, or
cheek. Trace these, noting shape and surface. Do the
plates now traced cover the entire surface?

Make a drawing of the face showing all the parts
named (x3).

(2) Lift the labrum to see the freedom of motion. Does
the living animal move the labrum up or outward? Observe
a live grasshopper eating to determine this.

(3) With the scissors or scalpel sever the labrum from
the clypeus and remove it. Lay it carefully on a piece of
paper outside up.

This exposes two hard, dark colored mandibles meet-
ing in the center. Note their method of coming together.
Of what use are they? Observe a living specimen to find
the direction of their motion. Grasp one firmly with the
tweezers and with a quick outward pull remove it. Remove
the other in the same way and lay both in proper order
below the labrum.
22 ARTIIROPODS

(4) Back of the place where the mandibles were are two
pairs of appendages and the tongue. Find the tongue be-
tween the first pair of mouth parts, lift it up and sever it
at the base with the scissors. Lay it back of the mandibles.

The next pair of appendages is the maxvillae, which must
be removed with extreme care. On removing and laying
them down they be found to consist of three parts. a.
The inner part, Jacinia, black and toothed at the tip; b.
the spoon-shaped flap fitting over the lacinia, the galea; and
c. the jointed maxillary palpus which looks like an antenna.
How many segments in it?

All three of these parts are attached to a base called stipes.
Find all of these parts in each maxilla and lay them in proper
position back of the mandibles.

There is still left the Jabium (lower lip). Does it consist
of two parts as the pair of maxille, or of one part as the
labrum?

(5) At its base find a ring, or collar surrounding the
neck, the gula. With the scissors remove the gula with the
labium and place it at the posterior end of the group of
mouth parts. Find its parts: (a) the submentum resting
on the gula (b) the labial palpi extending forward from
bases called palpigers, and (c) the lip proper, which is
bilobed like the labrum and divided by a lateral line into
two parts; the mentum, or lower, and the ligula, or upper
flap.

Count the number of segments in the labial palpi and
note their method of attachment at the base.

Make drawings of these mouth parts (x4).

Label the entire parts by figures and the subdivisions by
letters.
THE GRASSHOPPER 23

THE THorax.—(1) Remove the wings, that the thorax
may be more plainly seen.

Back of the head is the prothorax, or collar. Notice
its shape on the dorsal and lateral sides. The dorsal side is
called pronotum. Does it extend around the body? What
is the shape of the ventral side? What causes that peculiar
structure? It is called prosternal spine. Does the prothorax
on the dorsal side seem to be divided into segments? How
many ?

(2) Look carefully at the remainder of the thorax. Is it
divided into segments? What indicates the segments? Do
they extend all around the body? The segment next the
prothorax is the mesothorax, and the last one, the meta-
thorax. What peculiarity do you notice on the ventral side
of the thorax?

(3) The ventral side of the entire animal is called the
sternum, the lateral side the pleurum, and the dorsal side the
tergum. Note the differences in color and hardness of these
parts.

How many legs on the ventral side? Observe the place
and mode of attachment to the body. The sockets for at-
tachment are called coxal cavities. How many divisions in
each leg? In the front pair of legs find the following parts,
beginning with the body: coxa, trochanter, femur, tibia and
tarsus, or foot. The tarsus is subdivided into segments.
How many do you find? Notice the relative size, shape, and
markings of each segment.

Does each pair of legs have the same divisions with the
same relative sizes?

When a part of an animal is unusualy large or has a
peculiar shape for the performance of a special work it is
24 ARTHROPODS

said to be specialized. Do you find any part or parts of the
leg specialized? If so, how are the parts specialized and
for what purposes?

Make drawings of a first and third leg (X2). Mark the
specialized parts.

(4) Look closely at the sternum of the thorax. How
many segments in it? How are they joined together? How
does the number of segments compare with the number on
the dorsal side? Explain. The three front parts of the
sternum are called respectively the prosternum, the meso-
sternum, and the metasternuim.

Make drawings of the sternum of the thorax, showing
the first two segments of the legs (4).

Study the pleurum of the thorax. Do you find any other
markings beside the lines of division?

Look above the second pair of legs, in the groove dividing
the mesothorax, and the metathorax for a light colored
rough spot. This is a spiracle or breathing pore, and is one
of the places where air enters the body.

Look at it closely with a magnifying glass in a living
specimen and see it open and close as the animal breathes.
Look for another one of these on the front side of the meso-
thorax under the prothoracic collar.

Make a drawing of the left side of the thorax showing
the points observed (3).

(5) Geta fresh specimen and examine the wings. Move
the anterior wings out at right angles to the body. What
follows? Why? Note the place of attachment of the front
wings. How are they attached? Note the texture of the
anterior wings. They are called the tegmina, or wing
covers. Why should they be called wing covers?
THE GRASSHOPRER 25

Remove one of the wing covers, being careful to get all
of it.

How does its structure compare with the outer covering
of the body? Note the strong chitinous tubes running
lengthwise the wing and the smaller tubes running from one
to the other. How many principal veins do you find? Note
that the wing is narrow, dense, and straight.

Beginning with the lower edge of the wing, which is now
the front portion, find the large veins as follows: costal, the
vein nearest the margin, running about two-thirds of the
length of the wing; the subcostal, a very much larger vein
running nearly the entire length of the wing; the median,
much smaller and soon dividing into two veins nearly equal
in size; the submedian and internal which run close together
to the outer margin of the wing.

This divides the wing into three areas: the costal, the part
in front of the costal vein; the median, the largest, which
lies between the subcostal and the submedian veins: and
the internal, the part posterior to the internal vein. Find
and locate each.

What seems to be the use of the outer wings?

Make a sketch of the wing cover (X2).

With the needle or tweezers pull out the inner wings to a
position at right angles to the body. How did the size
before stretching compare with the wing covers? How
does it compare after stretching? Count the number of
folds. How do they compare with the tegmina in structure
and texture? Do you find the costal, median, and internal
areas? How is the wing attached to the body? What
makes the inner wing fold up when the animal quits flying?
Of what use is the inner wing? Is the animal a good flyer?
26 eARTHROPODS

Make a drawing of the inner wing slightly folded to show
the markings (2).

Tue ABpoMEN.—(1) Behind the thorax are the mov-
able segments of the abdomen. Move them back and forth
to show how they are joined together. How do these joints
differ from those in the thorax? Each segment is called a
somite.

Examine the tergum, the pleurum, and the sternum. How
do they differ from the corresponding parts of the thorax?
Is the covering of a somite continuous around the body?

Count the segments on the ventral and dorsal sides. Is
the number the same? Explain. Count the segments in the
abdomen of three individuals. How many on each?

(2) On the segment next the thorax find an indented
ear-shaped surface which contains a silvery membrane, the
tympanum, or ear drum. This is supposed to be the organ
of hearing. State the advantages and disadvantages of
having it located here.

Look at the pleurum just above the fold for a spiracle,
or breathing pore. How does it compare with the one on
the thorax? Count the number on each side of the abdomen.
Is there one for each segment? Is there one on the first
segment of the abdomen? If so, where? Can you see these
open and close in a living specimen?

Do any of the somites of the abdomen seem to be special-
ized?

(3) Observe the posterior somites in several specimens.
They vary with the sex. The females are more abundant
than the males and may be recognized by the presence of
four blunt points extending from the ventral side of the last
segments of the body.
THE GRASSHOPPER 27

Get several specimens of each sex.

Study the male first. Count the number of sterna on the
ventral side in front of the modified portion. The last
sternum is modified into a large convex subgenital plate
notched on the upper side.

On the dorsal side two additional segments can be seen.
The two appendages, the cerci, grow out from between the
tenth and eleventh segments.

Make a drawing of the abdomen of the male (2).

In the abdomen of the female the first seven segments
of the sternum are similar to those of the male. Observe
that the eighth plate makes the subgenital plate as in the
male. On the dorsal side find the ten segments like those
of the male. Back of the tenth find another making the
sharp tip of the abdomen.

On the ventral side back of the subgenital plate, find the
ovipositor which consists of six points arranged in pairs.
Each pair is pointed posteriorly, but the middle pair, or true
ovipositors, which act as guides in placing the eggs, are en-
tirely hidden by the anterior and posterior pairs. These
last two pairs are brought tightly together and forced into
the ground almost as deep as the length of the abdomen.
They are then separated, making a pit into which the eggs
are guided by the inner pieces.

Make a drawing of the left side of the abdomen (X3).

(4) The males of this grasshopper and of many other
species makes noises which are supposed to be interpreted
by others of the same species. Look on the inner side of the
femur of the male for a row of small spines. Examine
with lens of dissecting microscope or with hand lens. Draw
spines and also the inner side of the femur showing spines.
28 ARTHROPODS

These spines rub against the outer side of outer wings to
produce the sound. Is the noise made when the animal is
still or in motion? Give reason. Examine the outer wing
under the low power lens of microscope and determine if
possible which vein is specialized for noise making. Com-
pare the wing with that of female. Draw specialized wing
marking the specialization.

Some Microscopic Views.’—In order to understand bet-
ter the external structure of the grasshopper it will be
necessary to view some parts of it under the microscope.

Cut off a portion of the large eye with a scalpel, turn it
over and scrape from it all the black portion leaving it trans-
parent or nearly so. Put this transparent membrane of the
eye on a glass slide with the outside up, moisten it with a
drop of water, and place on it a thin cover glass. Place this
slide on the stage of the microscope ‘in the proper position
and observe it with a low power objective. What does this
show you about the large eyes? Each of these divisions
is called a facet. Observe the size and shape of the facet in
different parts of the eye. Are they all alike?

Make a drawing of this view.

Cut out a piece of the inner wing from near the center
and mount it as the eye was mounted. Observe it with the
low power objective. What do those veins now seem to be?
Note the different kinds of veins and the structure of each.
What do you think the veins are used for?

Make a drawing of this view.

With a scalpel remove from a segment of the abdomen
a thin section of the outer skin containing a spiracle. Scrape

Nore.—For suggestions on how to use the microscope, see Ap-
pendix, I.
THE GRASSHOPPER 29

the inside of this on each side of the spiracle until it is almost
transparent. Mount it as before with the outside up and
view it with the low power objective. Find a hard circular
ridge of chitin inside of which is a thin membrane with an
elongated opening in the center, sometimes open but gen-
erally closed. The elasticity of this inner membrane allows
the animal to breathe. Draw spiracle.

METAMORPHOSIS OF THE GRASSHOPPER.—The eggs of the
Melanoplus differentialis are deposited in the fall and remain
in the ground during the winter. In the spring the larve
emerge from the openings in the ground scarcely larger
than the eggs from which they came. They eat ravenously
and as they grow the membranous covering, at first thin
and elastic, becomes harder by the deposit of chitinous
matter, until the body cannot expand as it grows. The
animal then seeks a protected place, the hard shell is burst
behind the prothorax, and the animal crawls out of its old,
dry, hard skin and begins anew with a soft membrane.
After a short period of growth and rapid eating the shell
becomes hard again, the animal, considerably larger now,
bursts its shell and emerges as before. At about the third
molt the wings appear as very small projections from the
terga of the mesothorax and metathorax and at about the
sixth molt the now fullgrown animal is able to fly.

Get a number of grasshoppers representing the different
stages of growth and note the differences in the wings and
posterior divisions of the abdomen in three or four stages
of the same species. Do you find differences in any other
parts of the body?

Make drawings of the left side of three stages showing
the differences in form (2).
30 ARTHROPODS

The Schistocerca americana, the Dissosteira carolina and
some others hibernate through the winter in the adult state
and deposit their eggs in the spring.

INTERNAL ANATOMY.—(1) Get for dissection large
freshly killed female specimens of the Melanoplus differen-
tialis or Schistocerca americana. The largest specimens
obtainable will be found most satisfactory. Care should be
taken that the specimen be neatly handled and that the
parts be removed at the proper time.

After removing the wings, pin the specimen down on a
block, or under water, passing pins through the legs and
through the posterior end of the abdomen. With the scis-
sors cut through the abdomen on each side at the posterior
ends just above the groove in the pleurum and cut forward
to the thorax. Lift up the flap thus loosened, being careful
not to injure the parts beneath.

Just under the middle of this flap and generally adhering
to it find the small elongated tube, the heart, or dorsal
vessel, into which the blood collects from the sides and flows
toward the head.

Below the part removed is a layer of muscles running
both transversely and longitudinally. Remove and examine
carefully.

(2) Open the thorax by cutting on the mid-dorsal line
up to the head. Pull out the sides and pin them down.
Note the strong muscles. Do you find them arranged in
bands? Can you trace certain of the muscles to the wings
and others to the legs? How many to each? What do the
muscles seem to be composed of ?

Note the white flaplike bodies, the air sacs. Do you find
them connected in any way with white lines? Follow the
THE GRASSHOPPER 3).

white lines down to the sides of the body and see if you can
find where they stop? They may be connected with longi-
tudinal lines or with the spiracles. The white lines are
tracheae, or air tubes through which the air is conducted
to the body. The breathing apparatus, the spiracles, the air
tubes, and the air sacs are called the tracheal system. When
the animal is living how is the working of this system seen?

(3) The large yellowish masses near the posterior end
are the egg masses.

The thin membrane surrounding each mass is the ovary.
Carefully pull the white masses aside and try to find the
white tube, or oviduct, that leads from them to the ovi-
positor. Remove the egg masses with the oviducts from
the body.

Make a drawing of an egg mass and oviduct (X2).

Remove one of the eggs from the mass, place it on the
slide and without cover glass, examine it carefully by means
of the low power.

Do you see a membrane covering the egg?

Are both ends of the egg alike?

Make a drawing of the egg.

(4) The light colored substance between the viscera
and the walls of the body is the corpus adiposum. Remove
some of it and place it on the slide, cover it with a cover
glass and observe with low power objective. You may find
colorless blood, tracheal tubes which resemble coils of wire,
and muscles.

Describe in detail each group that you discover.

Notice how the tracheal tubes branch until the tubes
are very small.

Make a drawing of the trachee found.
32 ARTHROPODS

(5) Study next the digestive system. It consists of a
long tube, alimentary canal, extending the entire length of
the body. It is usually dark green in color and occupies the
central portion of the body.

With the scissors split the head down to the mouth. The
short tube leading back from the mouth is the esophagus,
Just back of it, in the region of the thorax, the tube enlarges
into the crop, an elongated receptacle for food. It is some-
times divided into two parts, ingluvies the front, and pro-
ventriculus the hinder portion.

On the side of the crop imbedded in the muscles, find
the salivary glands, which are grapelike in appearance. They
secrete the saliva, and pour it into the mouth. Find the
ducts leading from the glands to the mouth.

Back of this is a deep construction in which are found
the gastric caeca, a circle of appendages attached at the
sides and having both ends free. How many do you find?
What is their shape? The function of these glands is to
secrete a digestive fluid similar to the bile of other animals
which digests or aids in digesting the foods.

Back of these is the stomach proper, which is followed
by the iliwm, cylindrical in shape, but much smaller than the
stomach.

Between the stomach and the ilium are great numbers
of small white tubes called Malpighian tubes which open into
into the ilium. These act as the kidneys in higher animals.

The colon is a small tube connecting the ilium with the
larger part, the rectum, which is found in the ninth and tenth

segments reaching the exterior of the body at the anus, or
vent, at the eleventh segment.
Make a drawing of the entire digestive system (2).
THE GRASSHOPPER 33

Tue Repropuctive System.—The ovaries and egg
masses of the female have been mentioned but if the time
is not favorable so that the eggs are prominent it will be
best to study the organs in connection with this subject.

In the female, find the whitish ovary on either side of
the alimentary canal, and two white oviducts leading down
to the opening in its ovipositor.

Make a drawing of the ovary and and oviducts (X2).

In the male, find two elongated whitish bodies, the estes,
and leading from them the vas deferens, two narrow tubes
extending to the opening near the arms.

Make a drawing of the testes and the vas deferens (x2).

Tue Nervous SystEM.—(1) Remove the alimentary
canal carefully and notice the white string in the bottom
with occasional knots upon it. This is the nervous system
and consists of cords and ganglia.

(2) Above the esophagus find a large supra-esophageal
ganglion sending nerves to the eyes and antenne, and below
the esophagus, in front of the prothorax, and infra-esopha-
geal ganglion which sends cords to the mouth and forelegs.
From the first of these ganglia there are two cords, one pass-
ing on each side of the esophagus to the second.

(3) Then find one each in the divisions of the thorax,
somewhat larger than the first. These are the thoracic
ganglia.

Study these and see if you can trace cords to the wings
and legs.

Do you find ganglia in the abdominal region?

How many?

In what segments are they?

Make a drawing of the entire nervous system (X2).
STU. IN ZOOL.—3
34 ARTHROPODS

SumMary oF Stupy or GRASSHOPPER.—(1) The grass-
hoppers are found in open fields and on ground covered with
grass or weeds. They are light gray to green and some-
times almost black in color. How many different colors
have you found in grasshoppers? How do they compare in
size? Are grasshoppers injurious or beneficial? Why?
How do they destroy the plant which they eat? How do
grasshoppers defend themselves?

(2) What parts of the United States are visited by
grasshoppers most frequently?

In Europe, grasshoppers do very little damage, and are in
fact, rather scarce. Do you know of any country in ancient
times that was visited by them? Why do grasshoppers
migrate?

In ancient times in the oriental countries the damaging
genus was the Schistocerca, but the most devastating genus
in America is Melanoplus.

Mount as many different species of grasshoppers as you
can find.

THE CRICKET
Gryllus sp.

(1) What is the color of the cricket? What is its
method of locomotion? What are the principal differences
between the general appearance of the cricket and that of
the grasshopper?

(2) Turna cricket from dorsal to ventral side and notice
the general shape of the body. How many divisions? How
are they separated? Is the body segmented? How many

segments in the antenne? How many legs and where at-
THE CRICKET 35

_tached? How many segments in each leg? Look on tibia
of foreleg, what do you find? Can the cricket hear? How
many wings? What are their peculiarities ?

(3) On the abdomen of all, find stylets or slender pro-
jections. The abdomen of the female ends in a long ovi-
positor. Pick the ovipositor apart and see if you can find
as many parts as were found in the ovipositor of the grass-
hopper.

(4) The chirping sound of the cricket is made by the
male, by rubbing the outer wing over the inner. Look for
a cross vein with teeth on it on the under surface of the
outer wing which rubs on a correspondingly heavy vein on
the inner wing. Watch a living specimen to find how this
is done.

Make the following drawings :—

Front of head (X2).

Inner surface of outer wing showing teeth (<3).

Inner surface of front leg showing drum on tibia (2).

Dorsal view of female (2).

THE MEADOW LOCUST

Orchelium sp. or Conocephalus sp.

Where is this animal found?

Is it more like a grasshopper or a cricket?

Has it any characteristic common to both the others?

In what does it differ from the others?

What is its food? During what part of the day does it
travel?

How do the male and female differ? Of what use is such
a flattened ovipositor?
36 ARTHROPODS

Does the meadow locust make a sound? How?
Make the following drawings:

Left side of entire animal (x1).

Abdomen of male and female (X2).

THE MANTIS

Do you find the three divisions of the body? What is
the length of the longitudinal axis? The lateral? What
specializations are noticed in the body? In the head? In
the legs? How does the young mantis compare with the
old? Does it grow by molting?

Make the following drawings:

A dorsal view (XI).

The front feet (2).

The face (4).

CLASSIFICATION.—(1) Animals are classified by collect-
ing their resemblances and differences. Every animal in the
world has something in common with every other animal,
and these common characteristics enable us to put them
into one group called the animal kingdom. This separates
them from the other great group of living things called the
plant kingdom.

(2) The animals we have studied are different in many
things, but we have found that they are alike in a few things.
Make out a list of things which have the same structure
in all the animals studied. Then make out a list of differ-
ences in the same way.

Arrange them in a tabulated form as follows:

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38 ARTHROPODS

(4) Since these animals are different in all these char-
acteristics we separate them into groups called families.
This enables us to refer to them more definitely. The grass-
hopper belongs to the family Acrididae, the cricket to the
family Gryllidae, the locust to the Locustidae, and the mantis
to Mantidae. These names may be put into the diagram to
the right of the double line. The names of families usually
end in dae.

(5) The grasshopper, we have found, belongs to the
order Orthoptera and the family Acrididae, but since there
are a great many kinds of grasshoppers we are not yet able
to refer definitely to any one kind. Therefore a further
classification is necessary. We divide the family into genera
and the genera into species. Thus the grasshopper we stu-
died belongs to the genus Melanoplus and to the species dif-
ferentialis; the cricket belongs to the genus Gryllus, species
domesticus, etc. When we use Melanoplus differentialis we
refer to a species of grasshopper all of the individuals of
which are alike wherever they may be found.

(6) If we wish to locate a person where others may be
able to find him, we must give his country, state, county,
city, street, number on street and name; likewise if we wish
to classify an animal so that one may locate it, we must give
its kingdom, branch, class, order, family, genus and species

So we see that finding the names of animals is somewhat
like finding people.

(7) The order Orthoptera comprises six common fam-
ilies :

Acrididae, or grasshoppers.

Gryllidae, or crickets.

Blattidae, or roaches.
CLASSIFICATION 39

Mantidae, or mantises.

Locustidae, or locusts.

Phasmidae, or walking sticks.

If possible, finda sample of each and mount according to

directions.

Nore.—The walking stick and the cockroach, if easily obtained,
should be examined for external characteristics.
Directions for using the tables of classification are given

in the Appendix, II.

CLASSIFICATION — From Comsrocxk.

Table of Famiiies of Orthoptera.

A. Posterior femora fitted for walking, i. ¢., resembling those of the
other legs; ovipositor with the subgenital plate concealed; organs
of flight of immature forms in normal position; insects mute.

B. Anterior wings leathery, very short, without veins, meeting in

a straight line; posterior wings, when present, folded to the

middle of the anterior margin; tarsi three-jointed, the pulvillus.

wanting; cerci horny, resembling forceps.......... Forficulidae.

BB. Anterior wings parchmentlike, thickly veined; posterior
wings folded to the base; tarsi five-jointed; cerci snft, jointed or
without joints.

C. Body oval, depressed; head wholly or almost wholly with-
drawn beneath the pronotum; pronotum shieldlike, transverse;
legs compressed; cerci jointed; rapidly running insects.

Blattidae.

CC. Body elongated; head free; pronotum elongated; legs
slender, rounded; cerci jointed or without joints; walking
insects.

D. Front legs fitted for grasping; cerci jointed.
Mantidae.
DD. Front legs simple; cerci without joints....Phasmidae.

AA. Posterior femora fitted for jumping, 7. e., very much stoutcr or
very much longer, or both stouter and longer than the middle
femora; ovipositor horny, free (except with the Mole crickets) ;
organs of flight of immature forms inverted; stridulating insects,
40 ARTHROPODS

B. Antennae short; tarsi three-jointed; supposed organs of hear-
ing situated in the first abdominal segment; ovipositor short,
composed of four separate plates; stridulating organs situated in
hind femora and the costal area of the tegmina......Acrididae.

BB. Antennae long, setaceous; tarsi four or three-jointed; sup-
posed organs of hearing situated in the anterior tibiae, and also
in the prosternum; ovipositor elongated (except in the Mole
crickets) ; composed of four connate plates.

C. Tarsi four-jointed; ovipositor (when exerted) forming a
strongly compressed, generally sword-shaped blade; the strid-
ulating organs of male limited to the anal area of the tegmina.

Locustidae,

CC. Tarsi three-jointed; ovipositor (when exerted) forming a
nearly cylindrical, straight, or occasionally up-curved needle;
the stridulating organs of the male extend across the anal
and median areas of the tegmina.................. Gryllidae,

THE BUTTERFLY

EXTERNAL Features. — The cabbage butterfly (Pieris
rapae) or the yellow sulphur butterfly (Eurymus philodice)
are suitable specimens for study. Gather several from the
open places or gardens and note the flowers on which they

feed.
(1) Observe the distribution of colors over the body.

Do you find a definite arrangement of colors?

Do you find the three divisions of the body? What are
the characteristics of each?

(2) Notice the shape and length of the antennae; how
many segments? On the lower side of the head find the coil-
ed proboscis, or tongue. Uncoil it with a needle or with the
tweezers. The tongue is made of the galeae of the maxillae.
THE BUTTERFLY 41

On each side of the proboscis find a feathery labial palpus.

Note the eyes. Do you find simple eyes? How many
pairs of legs? For what are they used? Does the butter-
fly walk?

(3) Note the wings. How many? Where attached?
For what are they used? Do you find a backward extension
of the mesothorax consisting of two parts? These are the
patagia or wing lappers.

How many segments in the abdomen?

(4) Make the following drawings:

(a) Drawing of left side with wings folded (x2).

(b) Drawing of dorsal side with wings expanded (x2).

(c) Scrape powder off of wing and draw (high power).

(d) Scrape down off of body and draw (high power).

WINGS OF THE BUTTERFLY.—(1) Get a specimen of the
Anosia plexippus* and remove the wings. Note the differ-
ences in shape between the outer and inner wings. Do you
find any peculiar markings on them? The stripes indicate
the position of the veins. How are they arranged? Do
they look like those of the grasshopper?

(2) The front margin of the wing is the costal margin;
the one farther from the body is the outer margin, and the
one below is the hind margin. The first front vein is the
costal, the second is the sub-costal, the third is the radius.
Under this in the part near the body is a large cell without
veins, called the disk. On the outside of this cell runs the
media divided into three divisions. Below the cell is the
cubitus which is also subdivided. The last vein is the anal
vein.

*Note: This is the large brown butterfly with black veins on the
wings. It is common everywhere.
42 ARTHROPODS

Draw inner and outer wings (XI).

DEVELOPMENT OF ButTerFLy.—(1) Why is the cabbage
butterfly so called? Where are the eggs placed? What
does it look like when it is first hatched? The young is
called a larva. Does it molt like the grasshopper? Why
do you think so? Is the larva injurious?

(2) Between the larval and the adult stages, the cabbage
butterfly passes through a state of complete inactivity.
When the larva is through growing, it crawls into a quiet
place, assumes a hard brown coat, and is called pupa, and
after a short time emerges as a full grown butterfly, zmago.
Get sume specimens of larvae, put them in a box or jar cov-
ered in a way that will allow air to enter, feed them on
cabbage leaves and notice the stages of development. Note
especially how the pupa is suspended from the object to
which it is attached.

(3) In the larva notice the small web that comes out
under the head. It is spun by the modified labium. Of what
use is the web?

Make drawings of the larva and pupa (2).

Hazits,—Why do butterflies go to flowers? Why do
they go to cabbages? Of what use to them are their color-
ings? How do they defend themselves?

Do butterflies move about on cloudy days? Where do
they stay on such days? Where do they stay at night?

THE MOTH

Phiegethontius celeus

I, Tue Larva.—The larva of the Phlegethontius celeus is
the common so-called tomato worm, They may be collected
THE MOTH 43

in July or August and preserved in alcohol or formalin, but
it is more satisfactory to get them fresh from the vines if
they can be found at the time the study is in progress.

Other examples of the same family (Sphingidae) are the
tobacco worm, and the vine dresser found on grape vines.
These will answer all purposes for the study fully as well
as the tomato worm.

EXTERNAL FEeaTuREsS.—(1) Can you distinguish body
divisions? What is the color of the specimen? Is this
color an advantage? Why? What common name is ap-
plied to this larva?

(2) What cephalic plate is present in the middle of the
face? Do the antennae resemble the legs? Compare the
antennae with those of the imago.

(3) What kind of mouth parts has the larva? What
kind has the imago? Note the bi-lobed labrum. Draw.
Behind the labrum find the horny mandibles. Notice the
maxillae, and labium behind the mandibles. Draw the
labium and maxillae, posterior view.

(4) Find the true legs, and from them determine the
segments of the thorax. Are all the true legs alike? What
is their function? Draw. (4).

Draw entire specimen (XI).

(5) Count the false legs, or pro-legs. What segments
of the body bear them? Draw your finger over the tips
of the false legs. What happens? Why? For what are
these legs adapted? Draw a pro-leg enlarged.

(6) Compare a true and a false leg. Why are the false
legs so called? Are they segmented?

(7) Count the segments of the abdomen. How many
spiracles? How distributed? Draw a spiracle enlarged.
44 ARTHROPODS

INTERNAL STRUCTURE. — (1) Pin the caterpillar ven-
tral side down, in a dissecting tray, by placing a pin just
behind the head and another through the last segment
of the abdomen. Make an incision on each side about
midway between the rows of spiracles and the mid-dorsal
line. Raise this dorsal strip, being careful not to injure
the parts beneath, and cut it off.

(2) This exposes the transverse muscles. What motion
do these muscles produce?

(3) Just beneath ‘the transverse muscles find the longi-
tudinal muscles of the dorsal side. Contraction of these
muscles produces what motion?

(4) Separate the above muscles; find beneath a whitish,
stringlike organ, the heart. Trace it from anterior to pos-
terior end.

(5) On either side of and below the heart, extending
from the posterior end of the body to the thorax find the
delicate, yellowish-white coiled tubes, uriniferous or Mal-
pighian tubules. These rest on the alimentary canal. They
are probably analogous to kidneys.

(6) On either side of the alimentary canal find fan-
shaped groups of nearly colorless cords. Note that these
cords converge towards the spiracles. They are tracheae,
or air tubes. Remove one of the groups of tracheae with
its spiracle and examine with a microscope. Note the coils
of chitin. Draw.

(7) Beneath these fan-shaped groups find longitudinal
cords, similar in structure to tracheae, next to the wall on
either side. These are the longitudinal tracheal trunks.
How many?

(8) Make a diagram showing the above features (2),
THE MOTH 45

(9) Trace the alimentary canal to the mouth and find
the esophagus, or gullet, and the crop. Note a cluster of
salivary glands around the crop. Behind the crop find the
stomach and intestine. Find the posterior opening of the
intestine, the anus. Draw the alimentary canal as seen from
above.

(10) Remove the alimentary canal with extreme care.
Note the longitudinal muscles. What is their function?
Below and between these muscles note a small white cord
with enlargements. This is the ventral nerve cord. The
swellings are ganglia. At the anterior end the nerve cord
divides, forming a collar about the esophagus and a gan-
glion above it. Is there a ganglion in each segment?

(11) Make a diagram of nervous system enlarged
(X4).

(12) Upon what does this animal feed? At what time
of the year does it live?

(13) Is it injurious? Why do you think so?

(14) This larva, like the larva of all other insects, is a
ravenous eater, and as it grows it molts its skin to make
room for its rapidly increasing size.

After molting the last time it goes into the ground
arrayed in its pupa covering, a dark brown skin.

Il. Tue Pupa—()1 Look for pupae in the gardens
where tomatoes have been grown. They may be found in
October about four to eight inches under ground. Study the
head, thorax, and abdomen of a pupa. Do you find a pro-
boscis present? In what condition is it? Do you see any
indication of wings? Where?

(2) Is the animal living? How does it obtain food?
Does it breathe? Give reasons for your answer.
46 ARTHROPODS

(3) Draw specimen of pupa (x1).

III. Tue Imaco.—(1) Observe the general shape of the
body. Which animal studied is it most like? Compare it
with the cabbage butterfly in size and shape of abdomen,
wings and feet. Note carefully the color and markings on
wings and body.

(2) Has it a distinct head? What parts are present?
Are the antennae segmented? Measure length of antennae
and compare with length of body. Note the position and size
of the eyes. Are they compound? In what way do they
differ from the eyes of the grasshopper?

(3) Uncoil the proboscis and measure its length. How
does it compare with the length of the body? Is the pro-
boscis in one piece? Of what mouth parts do you suppose
it is composed? Let the proboscis recoil loosely.

(4) Make drawings of dorsal view of entire animal
(1). Draw axes.

Make the following drawings from microscopic views :—

The compound eye.

A side view of the proboscis.

A cross section of the proboscis.

Remove some of the covering from the thorax, from
the abdomen and from the wings and draw each
separately.

(5) On the mesothorax find a pair of thin flaps ex-
tending back over the base of the first pair of wings. These
are the patagia, and are an extension of the front of the
mesothorax. Do you think they are useful?

Rub the scales off the wings so that the veins may be
seen. Study the veins closely and compare them with those
of the Anosia butterfly.
CLASSIFICATION 47

Draw wings showing veins (x1).

(6) The feet of the male are very strong and have sharp
spurs growing from the tibia. Draw one of the first pair
of legs (X1). :

The butterfly and moth with all_their kindred families
. belong to the order Lepidoptera. Find the meaning of the
word.

CLASSIFICATION. From A. E. PorEnoe.
Table of the Principal Families of Lepidoptera.

Section 1. Lepidoptera Rhopalocera. Butterflies. Antennae fil-
iform, tipped with a knob or club.

A. Having six feet fitted for walking.
B. Wings broad, rounded, closed back to back, and erect in
repose.
C. Secondaries tailed,............ Swallow tails, Papilionidae.
CC. Secondaries not tailed.
D. Colors white or yellow, marked with black.....Pieridae.

DD. Colors blue or coppery............e.ee eee Lycaenidae.
BB. Wings narrow, stout, triangular, spread or thrown far back
in repose; antennae often hooked....... Skippers, Hesperidae.

AA. But four feet adapted to walking, anterior part imperfect.
E. Club of antennae not flat; secondaries of male with
raised black spot on a vein.
Milkweed butterflies, Danaidae.
EE. Club of antennae flat; colors various... Nymphalidae.
EEE. Club of antennae flat; colors nearly uniform, smoky
or leaf-brown; secondaries with eye-spots; base of veins
in primaries inflated......... Meadow browns, Satyridae.
Src. 2. Lepidoptera Heterocera. Moths. Antennae various, not
clavate.
A. Body stout, large, spindle-shaped; wings narrow; secondaries
about half as long as primaries; antennae prismatic.
Hawk moths, “ humming birds,” Sphingidae.
48 ARTHROPODS

B. Size small; bodies wasplike; wings more or less transparent ;
day fliers.

Peach borer, ash borer, squash borer, Aegeridae.

C. Size medium; head large, free; antennae filiform or pec-

tinate, sometimes slightly clavate.............+.. Zygaenidae.

D. Body large or medium, thick, wooly; head small and

sunken; antennae pectinate, more or less, and placed higher

on the head than usual...Spinners, silk worms, Bombycidae.

E. Body thick; thorax and abdomen often with dorsal

tufts; antennae setiform or slightly pectinate; wings

folded rooflike in repose....Cut worm moths, Noctuidae.

F. Body slender; scales fine; wings broad, thin, spread

out flat in repose; antennae usually pectinate; palpi

Stalls wat ddlalnamate ce weuoas aes Span worms, Geometridae.

G. Palpi in most species long and compressed, beaklike ;

wings deltoid in repose, or in some rolled around

the hod yee. se dcciwiaatavanan verresa ewan Sana Pyralidae.

H. Small moths; palpi short, beaklike; fore wings

(primaries) oblong, with a prominent “ shoulder,”

and crossed by bands which are sometimes metallic.

Leaf rollers, Tortricidae.

I. Size small or minute; antennae long, setiform;

wings pointed, heavily fringed on posterior mar-

SIM yaniiedieccne tes Fur and grain moths, Tineidae.
J. Primaries narrow, bifid or trifid; secondaries
tri yseasichesenees Plume moths, Pterophoridae.

The moths are sometimes called “ nocturnals,” or night
fliers, with the exception of Sphingidae, which fly in twilight
or daytime, and Aeegridae, which fly by day.

The butterflies, on the other hand, are called ‘“ diurnals,”
as they fly only by day.

The Lepidoptera are to be esteemed as injurious insects.
The only exception is the silkworm, which is, like the others,
a plant feeder.

For tracing butterflies and moths to their genera and
THE SQUASH BUG 49

species the student is referred to “ A Manual for the Study
of Insects,” by Comstock, or to “The Butterfly Book,” by
Holland.

THE SQUASH BUG

Anasa tristes

Where is this animal found? Is it injurious? At what
time of the year is it most abundant? Do you find the
three divisions of the body? What are the most peculiar
characteristics of the specimen as you view it from the
dorsal side: from the ventral side? Measure the length and
width. Draw axes.

Tue Heap.—(1) Look closely for the parts of the head
commonly found in insects, viz.: Eyes, ocelli, and antennae.
How many ocelli? How may segments in the antennae?

(2) On the ventral side raise the sharp, jointed beak
or proboscis. How many segments has it? It is composed
of a combination of mouth parts specialized. Of what use
can this specialization be? Can you distinguish the different
mouth parts?

(3) Find the labrum at the base of the proboscis. Lying
in a groove on the upper part of the beak are two pairs of
hairs. Lift them up with a needle. The shorter pair rep-
resent the mandibles, and the longer, the mawillae.

(4) The sheath which remains is made up of the Jabiwm
and the Jabial palpi. This accounts for the segments found
in it.

For what is the proboscis used? How does the animal
obtain its food? What is its food?

Tue THorax.—(1) Observe the relative sizes of the

STU. IN ZOOL.—4
50 ARTHROPODS

different divisions of the thorax. What is the shape of the
prothorax?

Note the numbers and places of attachment of the legs.
Are all the segments of the legs present? How many seg-
ments in the tarsus? How is the leg used?

(2) Between the middle pair of legs and the wings find
on each side a small rough surface almost round. Look
near it for a small opening, the osteole. From this osteole
exudes the offensive odor common to the squash bug.
When the fluid leaves the body it evaporates on the granu-
lar space. Can this specialization be of any benefit to the
animal ?

(3) How many wings? Lift up an outer one and study
its texture, shape and the way it lies on the body. Con-
trast the position of the outer wings when at rest with those
of the grasshopper. These outer wings are referred to as
half wings, can you tell why? Observe the inner wings,
What are their size, color and texture?

(4) With a needle pull one outer and one inner wing
out at right angles to the body and draw the dorsal view
of the body (Xz2). In this drawing locate the eyes, an-
tennae, and the base of the beak.

Tue ABDOMEN.—Count the number of segments on both
dorsal and ventral sides. Do you find spiracles? Where
and how many? Draw ventral side, showing osteole and
beak (X2).

DEVELOPMENT.—(1} How does the young squash bug
compare with the old one in appearance?

Is the metamorphosis complete or incomplete? Get a
number of specimens and raise them to maturity. Draw
them in various stages.
CLASSIFICATION 51

(2) This specimen and others with similar outer wings
belong to the order Hemiptera. Can you tell why? Is it
an appropriate name?

Haszirs.—What animal similar to this is a pest to the
farmers? How does it injure crops? Name other examples
of bugs that are injurious to people. ;

Are squash bugs very abundant? What do they depend
upon for protection? Have you ever seen them eating? Are
they difficult to find? Do you think they possess much intel-
ligence? Why? How do they spend the winter?

What measures could be used to prevent the ravages of
the chinch bug.

CLASSIFICATION—ADAPTED FROM Comstocx.—All bugs belong to
the Order Hemiptera. The Order is divided into two great greups,
Heteroptera and Homoptera.

Principal Families of Heteroptera.

A, Antennae shorter than the head, and nearly or quite concealed
in a cavity beneath the eyes.
B. Hind tarsi without claws.
C. Fore tarsi flattened with a fringe of hairs on the edge, and
without claws; head overlapping the prothorax: ...Corisidae.
CC. Fore tarsi of the usual form, and with two claws; head
inserted in the prothorax...........e.eeeeeeee Notonectidae.
BB. Hind tarsi with two claws.
C. Caudal end of the abdomen furnished with a respiratory
tube composed of a pair of grooved, threadlike organs.
Nepidae.
CC. Caudal end of abdomen without respiratory tube.
D. Legs flattened, fitted for swimming; caudal end of the
abdomen furnished with a pair of straplike appendages
(these appendages are retractile, and are frequently with-
drawn from: sight) s.ecccisssesseaseeeeevesss Belostomidae.
52 ARTHROPODS

AA. Antennae at least as long as the head, usually free, rarely
(Phymatidae) fitting in a groove under the lateral margin of
the pronotum,

B. Body of various forms, but, when linear, with the head
shorter than the thorax.
C. Last segment of the tarsi more or less split, and with the
claws inserted before the apex.

D. Body usually elongated; prothorax narrow; beak four-
jointed; second and third pairs of legs extremely long and
SIENGER ).. cacdaasnsicn datas edreaeiys aa wis aretha eons Hydrobatidae.

DD. Body usually stout, oval, and broadest across the pro-
thorax; beak three-jointed; legs not extremely long.

; Veludae.
CC. Last segment of the tarsi entire, and with the claws in-
serted at the apex.

D. Antennae four-jointed.

E. Wing covers of various forms or absent, but not re-
sembling network.
F, Beak three-jointed.

G. Wing covers when well developed, with a cuneus;
those forms in which the adult has rudimentary wing
covers have no ocelli...............205. Acanthiidae.

GG. Wing covers when well developed, without a cu-
neus; those forms in which the adult has rudimentary
wing covers have ocelli.

H. Ocelli wanting.

I. Body: lineaty sucves cs ovassamevnai nds Emesidae.
II. Body greatly flattened.............. Aradidae.
Ill. Body of ordinary form........... Reduviidae.

HH. Ocelli present, though sometimes difficult to see.
I. Beak very long, reaching to or beyond the in-
termediate COXa€.........c cece eee eee Saldidae.

II. Beak not reaching the intermediate coxae.
J. Front femora somewhat thickened, but much
less than half as wide as long....Reduviidae.

FF. Beak four-jointed.
G. Front legs fitted for walking.
CLASSIFICATION 53

H, Wing covers with cuneus. Membrane with one
or two closed cells at its base, otherwise without

VOIIS!.. 4. % Soe ae tees Se dihaduuntetee seu Capsidae.

HH. Wing covers without cuneus. Membrane with
four or five simple or anastomosing veins arising
from the base; or with a large number of veins
arising from a cross vein at the base.

I. Ocelli wanting; membrane with two large cells
at the base, and from these arise about eight
branching veins............e.000- Pyrrhocoridae.

II. Ocelli usually present.

J. Head with a transverse incision in front of
the ocelli, which are always present. . Berytidae.
JJ. Head without transverse incision.

K. Membrane with four or five simple veins
arising from the base of the membrane; the
two inner ones sometimes joined to a cell
near the: bases.cc.cisworseae ee ceees Lygaeidae.

KK. Membrane with many, usually forked
veins, springing from a transverse basal vein.

Coreidae.
D. Antennae five-jointed.
E. Scutellum nearly flat, narrowed behind.
F. Tibiae unarmed or furnished with very short spines.
Pentatomidae.
The Principal Families of the Homoptera,
A. Beak evidently arising from the head; tarsi three-jointed; an-
tennae minute, bristlelike.
B. With three ocelli, and the males with musical organs. Usually
large insects, with all the wings entirely membraneous.
Cicadidae.
BB. Ocelli only two in number or wanting; males without musi-
cal organs.
C. Antennae inserted in front of and between the eyes.
D. Prothorax not prolonged above the abdomen.
E. Hind tibiae armed with one or two stout teeth, and the
tip crowned with short stout spines......... Cercopidae.
54 ARTHROPODS

DD. Prothorax prolonged into a horn or point above the

abdomen 6.5. <s daaawden daw geass aeewads Membracidae,

AA. Beak apparently arising from between the front legs, or ab-

sent; tarsi one or two jointed; antennae usually prominent and
thread like, sometimes wanting.

B. Tarsi usually two-jointed; wings when present four in number.

C. Wings transparent.
D. Hind legs fitted for leaping; antennae nine or ten jointed.

Psyllidae.
DD. Legs long and slender, not fitted for leaping; antennae
three to seven jointed................e eee eee Aphididae.

BB. Tarsi one-jointed; adult male without any beak, and with
only two wings; female wingless, with the body either scale-
like or gall-like in form, or grublike and clothed with wax,
The waxy covering may be in the form of powder, of large tufts
or plates, of a continuous layer, or of a thin scale beneath which
tHE: MiTSECE TIVES). c.4 0 tiesayade couasesariavevevase svbsatectia haaniarcornsreraves "Coccidae.

THE BEETLE

Harpalus caliginosus

GENERAL FEATURES.—How does the covering of this ani-
mal differ from that of the insects previously studied? Can
you find the three divisions of the body frorn the dorsal
side? From the ventral? Do you think this animal is
fitted for the life it leads? In what ways? Draw longi-
tudinal and lateral axes.

Tue Heap.—(1) Look on the dorsal side of the head
for eyes. How many? What kind? Is there any signifi-
cance in their position? On the dorsal side find also the
labrum and the tips of the mandibles. How do the man-
dibles compare with the mandibles of other insects.
THE BEETLE 55

(2) Examine the ventral side of the head. Beginning
with the lower surface find the labial palpi and the tongue,
or glossa, situated in the central depression of the large, hard,
mentuin. On either side of the tongue find a pair of fleshy
paraglossae, generally lighter in color than the mentum.
Insert the scalpel in front of the paraglossae, loosen the
labium, and with the tweezers carefully inserted, grasp it
firmly and remove the parts studied. Lay them aside for
further study. On either side of the mentum find the bases
of the antennae. Notice their attachment to the head. Re-
move them and place them in proper relation by the side
of the labrum.

The mouth parts next exposed are the mavillae. Remove
them and look carefully for the three parts ; the Jacinia, galea,
and palpus. Place them above the other parts. Remove
next the mandibles and labrum and place them in proper
position in front of the others. Draw all the mouth parts
(X4).

Below the mentum is the enlarged gula divided into two
parts by a line. How does it compare with that of a grass-
hopper ? @

THe THorax.—(1) Observe the prothorax on both
dorsal and ventral sides. Note its shape in front and back,
its margins, and its size compared with the prothorax of
other insects studied. On the ventral side observe the first
pair of legs. Where are they attached? Are all the seg-
ments common to the legs present? Do you find the coxal
cavity?

(2) Do you find the mesothorax and the metathorax
on the ventral side? Trace the boundaries of the thorax
and see if you find any peculiarities not common to insects,
56 ARTHROPODS

Are the second and third pairs of legs attached to the
thorax? How many segments in each? Notice the shape
of the coxa and the coxal cavity in the second and third
pairs of legs. Notice the position of the trochanter in the
third pair of legs. Do you see any advantage in having it
in this position ?

Count the joints of the tarsus in each of the three pairs
of legs. This characteristic is used in the classification of
beetles.

Make a drawing of the ventral side of the thorax (X4).

(3) Lift up tr outer wings on the dorsal side and pull
them out at right angles to the body. These are the elytra.
Notice from what segment of the thorax they come. To
what in the butterfly and moth can they be compared? Do
you think they could be used in flying? Do you know of any
use to which they could be put? Do you find veins present?
Do you find a line of division between the mesothorax and
the metathorax? Look just under the elytra, above the
inner wing, for a degenerated appendage. What segment
of the thorax does it come from? What does it signify?
This appendage is shown more plainly in the water beetle
(Dyticus). .

Study the inner wings as they lie folded over the abdomen.
Can you make out the method of folding?

Straighten out the inner wing of the left side, being care-
ful not to tear it while the tangle is being unrolled. Pin it
down and look carefully at the wings. How do they com-
pare in texture with the wings of other insects? Note the
veins. Can you find the same veins and the same areas
that are present in the wings of the grasshopper? Draw
inner wing (4).
THE BEETLE. 57

(4) On the side of the abdomen now exposed look for
lines of separation into segments. How many segments
are there? Near the outer margin between the segments
find the spiracles. Look at them closely and make out their
shape and structure. Draw dorsal view of the animal as
now exposed (<2).

DEVELOPMENT.—The eggs of the Harpalus are laid in
protected places under boards and the larva, like the imago,
is carnivorous. It has strong jaws and three pairs of jointed
legs and is called a grub. From the larva it passes into
the pupa state, from which it afterward3!emerges an adult
beetle.

Hasits.—From the structure of this animal’s mouth parts,
what kind of food would it relish? Where is it found most
abundantly? Is it beneficial or injurious? Study the living
specimen. Note its excited motiofis in captivity. Can you
tell why? Estimate its strength by tying it by the third
leg to test its power of pulling, and also by putting a
weight on its back.

CLASSIFICATION.—The Harpalus caliginosus belongs to the
order Coleoptera and to the family Carabidae. The family
contains many common beetles, some of which you have
probably collected already. What other families of beetles
have you represented in your collection? What is the mean-
ing of the term coleoptera? How does it apply to this
order?

Watch the Harpalus under the electric lights to find its
habits of food getting. Does it fly? Try to make one fly
Some beetles of this family have no inner wings, and the
outer ones have grown together. Can you tell why? Could
their habits produce this effect?
58 ARTHROPODS

CLASSIFICATION.—The student will find the collecting of beetles ex-
ceedingly interesting on account of their great variety, and diversity
of external appearance. They may be traced to their families by the
following table, but the help of a specialist will generally have to
be secured in finding the genera and species.

Under surface of Harpalus caliginosus illustrating the parts most
used in the classification which follows (after Le Conte and Horn).

A. Antenna.

B. Mandible.

Cc. Ligula.

D. Labial palpus.
E. Maxilla inner lobe.
F. Outer lobe.

G. Maxillary palpus.
H. Mentum.

I. Genae.

K.

Gula, with the
gular sutures.
L. Buccal fissure.
V. Ventral segments.

 

1. Prosternum. to, Antecoxal piece.

2. Prosternal episternum. 11. Metasternal episternum.
3. Prosternal epimerum. 12. Metasternal epimerum.
4. Coxal cavity, closed behind. 13. Inflexed side of elytrum.
5. Inflexed side of pronotum. 14. Trochanters.

6. Mesosternum. 15. Posterior coxae.

7. Mesosternal episternum. 16. Femora.

8. Mesosternal epimerum. 17. Tibiae.

g. Metasternum. 18. Tarsi.
CLASSIFICATION 59

Table for Determining the More Common Families of the Coleoptera.
ADAPTED FROM COMSTOCK.

A. Head not prolonged into a narrow beak; palpi always flexible;
two gular sutures at least before and behind; prosternal sutures
distinct; the epimera of the prothorax not meeting on the middle
line behind the prosternum.................4. Typical Coleoptera.
B. Hind tarsi with at least as many segments as the others.

C. Tarsi usually apparently four-jointed, the fourth segment
being reduced in size so as to form an indistinct segment at
the base of the last segment, with which it is immovably
united; the first three segments of the tarsi dilated and brush-
like beneath; the third segment bilobed. In a single family,
the Spondylidae, the fourth segment of the tarsus, although
much reduced and immovably united with the fifth, is dis-
tinctly visible, the first three segments are but slightly di-
lated, and the third is either bilobed or not......Phytophaga.

D. Fourth segment of tarsus distinctly visible; segments of

“antennae with deep impressions containing the organs of

SPECIAL SEMSE 2 ie sosorey uid ats anpidisinand aecesaaegecate Beacee oa Spondylidae.

DD. Fourth segment of tarsus inconspicuous; organs of spe-
cial sense of antennae diffused. This group contains three
families, which are so connected by intermediate forms that
it is not easy to separate them, The following characters
will aid the student in separating the more typical forms:

E. Body elongate; antennae almost always long, often as

long as the body or longer. The larvae are borers.

Cerambycidae.

EE. Body short and more or less oval; antennae short.

F. Front not prolonged into a beak; usually the tip of

the abdomen is covered by the elytra. Both larvae and

adults feed on the leaves of plants...... Chrysomelidae.

CC. Tarsi varying in form, but when five-jointed not of the

type described under C, the joint between the fourth and

fifth segments being flexible.

D. Ventral part of the first segment of the abdomen divided

by the hind coxal cavities, so that the sides are separated
from the very small medial part.
60 ARTHROPODS

E. Metasternum with an antecoxal piece, separated by a
well-marked suture reaching from one ‘side to the other,
and extending in a triangular process between the hind
coxae.

F. Antennae eleven-jointed; hind coxae mobile, and of
the usual form; habits terrestrial.

G. Antennae inserted on the front above the base of
thé mandibles: .u sieciscgy ceesmesaa cower Cicindelidae.
GG. Antennae arising at the side of the head between
the base of the mandibles and the eyes... .Carabidae.

EE. Metasternum either with a very short antecoxal piece,
which is separated by an indistinct suture, and which is
not prolonged posteriorly between the coxae, or without
an antecoxal piece.

F. Metasternum with a very short antecoxal piece.

Amphizoidae.

FF. Metasternum without an antecoxal piece.

G. Legs fitted for swimming.
H. With only two eyes.'............. 004. Dytiscidae.
HH, With four eyes, two above and two below.
Gyrinidae.
GG. Legs fitted for walking........... . Rhyssodidae.
DD... Ventral part of the first segment of the abdomen visible
for its entire breadth.

E. Antennae with a lamellate club.

F. Plates composing club of antennae not capable of
close apposition, and usually not flattened. ..Lucanidae.

FF, Plates composing club of antennae capable of close
apposition, and flattened................. Scarabaeidae.

EE. Antennae either clubbed or not, but when clubbed
not lamellate.

F. Elytra short, leaving the greater part of the abdo-
men exposed; the suture between the elytra when closed
straight; wings present, and when not in use folded
beneath the short elytra; the dorsal part of the ab-
dominal segments entirely horny.
CLASSIFICATION 61

G. Abdomen Hexible, and with seven or eight seg-
ments visible below............000000% Staphylinidae.
FF. Elytra usually long, covering the greater part of
the abdomen; when short the wings are wanting, or
if present are not folded under tlie short elytra when
at rest; the dorsal part of the abdominal segments
partly membraneous.
G. Hind tarsi five-jointed.
H. Antennae elbowed, and clavate,
I. Elytra truncate behind, leaving two segments
of the abdomen uncovered........... Histeridae.
HH. Antennae rarely elbowed, and then not clavate.
I. Maxillary palpi as long as or longer than the

AMECTIAE: fe cece cise cntaenerniisiana Goes uc Hydrophilidae.
II. Maxillary palpi much shorter than the an-
tennae.

J. Tarsal claws of usual size; ventral abdominal
segments usually free; sometimes (Buprestidae)
the first two are grown together.

K. Abdomen with only five ventral segments,
L. Femur joined to the side of the trochanter.
M. Anterior coxae globular or transverse,
usually projecting but little from the

coxal cavtiy.

N. Anterior coxae globular.

O. Prosternum with a process which ex-
tends backward into a groove in the
mesosternum.

P. The first two abdominal segments
grown together on the ventral side:
Buprestidae.

PP. Ventral segments free.

Q. Prothorax loosely joined to
the mesothorax; front coxal cav-
ities entirely in the prosternum.

Elateridae.
OO. Prosternum without a process
ARTHROPODS

received by the mesosternum, al-
though it may be prolonged so as
to meet the mesosternum.
P. Posterior coxae separated.
Q. Body very depressed; middle
cavities not closed externally: by
a meeting of the mesosternum
and metasternum .. Cucujidae.
MM. Anterior coxae conical, and project-
ing prominently from the coxal cavities.
N. Posterior coxae dilated into plates
partially protecting the femora, at least
at their bases.
O. Antennae with the last three seg-
ments forming a large club.
Dermestidae.
KK. Abdomen with six or more ventral seg-
ments,
L. Anterior coxae either globular or con-
ical.
M. Anterior coxae globular.
N. Prosternum prolonged behind, form-
ing an acute process moving in the

mesosternum......... Elateridae.
NN, Prosternum not prolonged behind.
. Leptinidae.

MM. Anterior coxae conical.
N. Posterior coxae more or less conical
and prominent, at least internally, not
covered by the femora in repose.

O. Posterior coxae widely separated.
P. Eyes wanting or inconspicuous.
Silphidae.

OO. Posterior coxae approximate.
P. Antennae gradually thickened, or
clavate; posterior tarsi not wid-
CHed . cewcaea ix voices Uphidee,
CLASSIFICATION 63

PP. Antennae setaceous, filiform, ser-
rate, pectinate, or flabellate, rarely
with three somewhat larger termi-
nal segments, in which case the
tarsi are widened.

Q. Anterior coxaeelong, with dis-
tinct trochantins.
R. Abdomen with seven or
eight ventral segments
Lampyridae.
GG. Hind tarsi either only three-jointed or four-
jointed, but apparently three-jointed, the third seg-
ment being small and concealed in a notch at the
end of the second segment. (See also GGG.)
H. Wings not fringed with hairs.
I. Tarsi with second segment dilated.
J. Tarsal claws appendiculate or toothed; first
ventral abdominal segment with distinct curved
Coxal: “lineSicdaueed cena nes Coccinellidae.
GGG. All tarsi four-jointed.
H. The first four abdominal segments grown to-
gether on the ventral side.
I. Tibiae not dilated nor fitted for digging.
Colydtidae.
HH. Ventral segments of abdomen not grown to-
together,
I. Wings fringed with hairs.
J. Hind coxae contiguous and with plates cov-
ering the femora entirely or in part. .Silphidae.
BB. Hind tarsi with only four segments, the fore tarsi, and al-
most always the middle tarsi also, with five segments.
C. Anterior coxal cavities closed behind.
D. Tarsal claws simple.
E. Abdomen with five ventral segments.
F. Ventral abdominal segments in part grown together.
GG. Penultimate segment of tarsi not spongy.
Tenebrionidae,
64 ARTHROPODS

EE. Abdomen with six ventral segments,
F. Ventral abdominal segments free.......... Silphidae.
DD. Tarsal claws pectinate............eeeee eevee Cistelidae.
CC. Anterior coxal cavities open behind.
D. Head not strongly and suddenly constricted at base.
E. Middle coxae not very prominent.
F. Antennae free.
G. Prothorax margined at the sides.
H. Epimera of mesothorax reaching the coxae.
I, Metasternum long; epimera of metathorax

visible . 0... k cece eee eee eeeeee + -Melandryidae.
II. Metasternum le epimera of metathorax
COVERED aayai.cies iathaee Save Sans seseseeee  Cucujidae.

DD. Head strongly constricted at base.
E, Head suddenly narrowed behind.
F, Prothorax with the side pieces not separated from the
pronotum by a suture.
G. Tarsi perfect with distinct claws; eyes normal.
H. Prothorax at base narrower than the elytra.
I. Hind coxae large, prominent.
J. Claws cleft or toothed; front vertical.

Meloidae.
HH. Prothorax, at base, as wide as the elytra.

Rhipiphoridae.
FF. Lateral suture of prothorax distinct; base of pro-
thorax as wide as the elytra.
G. Antennae filiform.
H. Hind coxae platelike............... Mordellidae.
HH. Hind coxae not platelike........ Melandryidae.
AA. Head more or less prolonged into a beak; palpi short and
rigid; gular sutures confluent on the median line; prosternal
sutures wanting; the epimera of the prothorax meeting on the
middle line behind the prosternum............... Rynchopthora.
B. Elytra with no fold or with a very feeble one on the lower
surface near the outer edge; pygidium of male and female alike.
C. Labrum distinct........ dig as irda. aonanremminte Rhinomaccridae.
CC. Labrum wanting,
THE HONEY BEE 65

D. Mandibles flat, toothed on inner and outer sides.
Rhynchitidae.
DD. Mandibles stout, pincer-shaped............ Attelabidae.
BB. Elytra with a very strong fold on the lower surface near the
outer margin.

C. The last dorsal segment (pygidium) of the male divided
transversely, so that this sex appears to have one more dorsal
segment than the female,

D. Antennae with a ringed or solid club.
EE. Tarsi usually dilated, brushlike beneath.

F. Mandibles with a deciduous piece, which is lost soon
after emergence from the pupa state, and leaves a scar.
Otiorhynchidae.
FF. Mandibles without accessory piece in the pupa state,

and therefore without a scar in the adult state,
Curculionidae.

CC. Pygidium of both sexes undivided.

D. Pygidium horizontal; tibiae usually serrate. ...Scolytidae.
DD. Pygidium vertical or declivous; tibiae not serrate.

E. Antennae geniculate; labrum wanting; last spiracle cov-

ered by ventral segments..... abeeviediviecs .....-Calandridae.

THE HONEY BEE
Apis mellifica

GENERAL Features.—(1) The general characteristics
of the bee are the same as those of the other insects studied,
but there are certain specializations of structure that make it
a very peculiar animal.

(2) Observe the covering of the entire animal. Note
the manner in which the thorax and abdomen are joined.
Is it like the grasshopper in this? Is it the thorax or the
abdomen that-is modified? Such a structure is called a
pedicel.

STU. IN ZOOL.—5
66 ARTHROPODS

Tue Heap.—(1) Study the front part of the head.
How many ocelli? How are they arranged? . Note the an-
tennae. Are they like those of the grasshopper? How many
segments? Do you notice anything peculiar about the sur-
face of the head?

(2) Find the following mouth parts:—a, A thin small
flap, the labrum. Is it movable? b, A pair of strong jaws,
or mandibles, hard and black at the tip. For what are these
used? c, A proboscis, which will be found bent back under
the mouth. Remove it with the tweezers, being careful not
to injure any of the parts. Spread the parts out and find
the central, long, hairy tongue, the short Jabial palpi close
to the tongue, and the long, slender blades, the ma-illae.

Get these in the right position on a slide, under a cover
glass, and place under the low power of the microscope.
Make the following drawings:

The front of the head (X35).
The proboscis (X10).

Tue TuHorax.— (1) Observe the enormous develop-
ment of the thorax. Is such a thorax of special value to the
bee?

(2) Study the bee in flight. How are the wings dis-
posed when flying? When at rest? Are both pairs of wings
used in flight? Look for a small wing cover in front of the
fore wing. It is the tegula. To what in the beetle is it ho-
mologous? Study the method of attachment of the wings.
Remove one of the front and one of the hind wings.

Are the wings separate, or fastened together?

Study the venation of the wings. Do you find the costal,
median, and internal areas? Is the venation the same in
both pairs of wings?
THE HONEY BEE 67

Draw both wings (x4).

(3) Lay the wings in their natural order on a glass
slide. Examine the internal margin of the outer, or front
wing, and the costal margin of the inner, or hind wing.
Do you find there a method of attachment of the wings to
one another? Can you tell now how the wings are used?
These hooks are called hamuli. Make a drawing of these
margins showing how they are specialized.

(4) Examine the attachment of the legs to the body.
Are all the segments present? Are all the legs alike.
What specializations do you notice in the second and third
pairs? One joint of the tarsus and one of the tibia are en-
larged. This flattened portion is called the pollen basket.
The pollen basket is formed by an enlargement and curving
of two of the segments of the leg. Which segments are they?
Have you ever seen a bee carrying pollen? How is the
pollen fastened to the leg? Does each leg have a pollen
basket ?

Draw one of the third pair of legs (3).

Tue AspomMeNn.—(1I) How many segments in the ab-
domen of the bee? Is the number the same on the dorsal
and ventral sides?

(2) Find the sting by laying the bee on the dorsal side
and pressing on the abdomen about four segments from
the posterior end. The sting will appear between the seg-
ments. Seize the tip firmly with the tweezers and pull it
out with a quick movement. Lay the sting and the parts
that come with it on a slide and with the needles arrange
the parts carefully.

The large part back behind the sting contains the potson
glands and the sac for holding the secreted poison. Look
68 ARTHROPODS

for the ducts leading from the glands to the sac. With a
needle attempt to pry apart the sides of the sting.

Draw sting and glands (x4).

Draw ventral side of the abdomen showing where the
sting left it.

The sting of a working bee is an ovipositor similar to
that of a grasshopper, specialized. The worker is therefore
a female insect so modified that it has no sex, but is called a
neuter. Of what use is this specialization to the animal?

DrveLopMeNnt.—(1) The cells of the honeycomb are
prepared by the neuter, or working bees, but the eggs are
all laid by the queen, a large female bee which has an ovi-
positor. The eggs are placed in the bottom of the cell and
are soon hatched into maggots which are fed continually
by the workers.

(2) Like the larva of all insects, they eat voraciously
and grow by molting until they are ready to pass into the
pupa state. By this time the larva fills the cell nearly to
the top and it spins a vestige of a cocoon just above its
head. The working bees build a top across the cell and
the pupa awaits its final change.

(3) After a time varying in length according to the
weather, the change from a footless larva to a highly or-
ganized imago is completed and the animal bursts through
both coverings and is a full grown bee. Is this complete
or incomplete metamorphosis? What does the spinning of
the thin web by the insect indicate?

Bees and similar insects belong to the order Hymenop-
tera. Is the name appropriate?

Hazits.—(1) Did you ever see a bee on a flower? The
bumblebee on a clover blossom is a good one to watch.
THE HONEY BEE, 69

What is it seeking as it goes from flower to flower?

On the little stamens inside the flower is found the pollen,
or minute whitish seed powder, which readily falls out on
being disturbed. It is necessary that this be removed from
one flower to another in order that the pistil, or central stalk
may have the pollen dust spread upon it. The bee gathers
a little of this pollen, but a greater amount of it adheres to
its hairy body, and as it goes from flower to flower some of
the pollen is rubbed off and reaches the proper place on the
pistil of the flower. But while the bee uses some of this
pollen, its great object in visiting the flowers is to collect
the sweet fluid, the nectar, which is secreted by the small
glands at the base of the flower. By secreting this nectar at
the base, the flower compels the bee to press open the parts
of the flower and rub all the internal parts with its body,
thus accomplishes the cross fertilization of the plants.

What specializations in the bee are peculiarly adapted
to the structure of the flower?

(2) Inacolony of bees there are three kinds of insects,
females, or queens, males, or drones, and neuters which are
females with ovipositor specialized into a sting, or aborted
as in the ants.

In the hive of the honeybee the larvae are all alike
at first, but after awhile the workers feed some of the
larve on one kind of food and some on another. This
develops them into different kinds, such as queens, drones or
workers. It seems that the kind of food given the larva
determines the sex and form of the animal.

(3) Many Hymenoptera build some kind of a home
and take some care of the young. In the family Apidae, bees,
the cells are generally built from a waxy substance excreted
70 ARTHROPODS

between the segments of the abdomen. In some of the cells
young are reared, in some, beebread is stored, and in others,
honey.

The honey is stored for use during inactive periods.
When are these periods? Does the honeybee eat during the
winter, or does it hibernate?

In the family Vespidz, wasps, the cells are made out of
lint obtained from weather-worn houses or wood. These
rear their young as in the preceeding family, but do not
make honey or store food. They hibernate during winter.
Where do they stay?

In the family Formicidz, ants, the dwelling is generally
made by burrowing under ground and, in many species this
is carried on until the burrow is large and complex. When
these burrows are attacked by an enemy that is likely to
destroy them, the ants carry the young to a safe place.
During the summer most species of ants store away food
for use during periods of inactivity.

Other families have other methods of building or of
keeping food. Can you tell the habits of the mud wasp?

(4) In some families of the Hymenoptera specialization
of structure has gone so far that it has resulted in a kind of
self-regulating political economy. By reason of their struc-
ture certain tasks are imposed on some animals and other
tasks on others. However, they all partake of the common
store and are entitled to many of the privileges resulting
from the aggregate of their labor.

It takes a whole colony of bees or ants to perform the
work necessary to the life of one individual; and the entire
community working together, with common interests and
in perfect harmony represents a higher state of intelligence
CLASSIFICATION 71

than is found in other insects. Compare this plan with
human industry and government. Industries and govern-
ment make civilization and civilization indicates the common
intelligence of mankind.

CiassIFICATION.—From A. E. Popenor.—The bees are very diffi-
cult to trace to the species. The following table will be found
convenient,

Table of Principal Families of the Hymenoptera.

SEcTION I. Stingers. Females provided with a sting,
modified ovipositor.

Apidae. Honeybees, bumblebees, etc.

Bodies hairy, stout, abdomen sessile; wings not folded in repose;
prothorax a narrow collar; mandibles of usual shape; but labium,
tongue and maxillae long, slender and used as a haustellum; hind
tibiae and first tarsal joint broad and concave in most species, used
as a pollen basket; legs of moderate length.

Vespidae. Hornets, wasps, etc.

Bodies more slender, smooth, firm; abdomen sessile; wings (at
least fore ones) folded lengthwise in repose; prothorax extending
back on sides to base of anterior wings; antennae more or less cla-
vate, elbowed; legs moderate.

Crabronidae. Sand wasps.

Bodies firm, moderately slender, strongly punctured, slightly
hairy; head large squarish; antennae elbowed, the long second joint
received when at rest in a vertical frontal groove; fore feet adapted
for digging, broad, spiny; legs of moderate length.

Bembecidae. Horse guards.

Bodies somewhat flattened, stout, rather smooth; head large;
labrum long, triangular; feet stout, for digging, but of moderate
length. Large black and yellow insects, feeding on flies, which they
seize about animals or along roads.
72 ARTHROPODS
Sphegidae. Mud wasps.

Bodies rather long and slender; prothorax prolonged into a neck
in front; abdomen petiolated; legs long, spiny; mandibles long,
curved, sharp; antennae long and filiform.

Pompilidae.

Bodies rather long and slender; prothorax prolonged backward
to base of wings; wings large and broad; legs long and spiny,
slender; antennae long and filiform, not elbowed, usually coiled;
colors chiefly velvety black or indigo blue, often with red spots;
wings opaque, black, blue or yellow.

Mutillidae. Stinging ants, cow killers.

Males winged, females apterous; bodies hairy, black, red or yel-
low, spotted or banded; ocelli generally absent; females found run-
ning along hot roads or paths; males found about sunflowers, etc.
Formicidae. Ants.

Males and females winged at maturity; neutters wingless; bodies
rather smooth, slender; colors usually red, yellow or brownish
black, rather shining. Living in colonies in all situations; females
largest, males and neuters smaller.

SEcTION 2. Piercers. Provided with an unmodified ovi-
positor, or at least without poison glands.

Chrysididae. Cuckoo flies (parasitic).

Ocelli present; antennae thirteen-jointed, elbowed; maxillary
palpi five-jointed, labial, three-jointed; ovipositor stinglike, long-
jointed, but no poison gland; abdomen ventrally somewhat hollowed
out; body firm, coarsely punctured; colors usually shining green
or black.

Ichneumonidae. Ichneumon parasites.

Bodies long, slender; ovipositor long, usually exserted; antennae
long, slender, filiform, many jointed, not elbowed; internal para-
sites on other insects, very beneficial.

Proctotrypidae. Egg parasites.
Bodies very small, slender; antennae usually long and slender;
THE HOUSE FLY 73

wings nearly without veins, covered with minute hairs; highly bene-
ficial insects, living in the eggs of other insects.
Chaletdidae. Chalcis flies.

Small, generally polished, metallic; hind thighs frequently thick-
ened; antennae six to fourteen jointed, elbowed; wings often with
but few veins; beneficial, parasitic.

Cynipidae. Gall flies.

Small; abdomen compressed, short, second or second and third
segments much broader than the remaining; a long, slender ovi-
positor lying concealed in a ventral groove; antennae straight, thir-
teen to sixteen-jointed.

Tenthredinidae. Saw flies.

Head, thorax and abdomen less markedly distinct than in other
Hymenoptera; wings large and broad, many cross veins; antennae
straight, filiform, clavate or pectinate; ovipositor saw like; larvae
caterpillarlike, living on leaves, and known as slugs.

Uroceridae. Horntails.

Bodies cylindrical with parallel sides, long; antennae long, fili-
form, rather stout; ovipositor stout, exserted, attached to middle
of abdomen, and extending beyond the tip of body; larvae very
destructive wood borers.

THE HOUSE FLY

Musca domestica

GENERAL CHARACTERISTICS.—Notice the method of union
of the head with the thorax and the thorax with the abdo-
men. Observe the covering of the body. Of what use is
the hair? Note the markings of the body. How many
segments in the abdomen? Do you find an ovipositor?

Tue Heap.—(1) Note the large surface covered by the
eyes. Do you find simple eyes? Remove the head, plac-
74 ARTHROPODS

ing it on a slide, and put it under the lens of the dissecting
microscope or the low power of the microscope without a
cover glass. Look for the antennae. When you find them
remove one with a scalpel and tweezers.

Make a drawing of the head as it appears from the front.

Draw one of the antenne. Draw longitudinal and lateral
axes.

(2) Find the tongue bent back under the head. Straight-
en it out and examine the joint. Seize it carefully with the
tweezers, and pull it out. Put it on a slide properly spread
out and put over it a cover glass. Examine under low
power. Note the shape, markings and structure.

Find the following parts:

a. The main shaft, the tongue, is divided into two spread-
ing parts, the labial palpi, at the end. Do you find the parts
smooth or rough? Is there a system of projections? What
is their arrangement? These are tracheal tubes and serve
to keep the tongue well spread.

b. On the head near the base of the tongue find two slen-
der projections, the mandibles, which are small in this species
and almost undeveloped in the male, but are very prominent
in the females of the mosquitoes and horseflies.

c. The jointed, hairy, maxillary palpi on the shaft of the
tongue.

Draw proboscis of fly enlarged.

Tue THorAx.—(1) How many pairs of legs? Where
attached to the body? How many fully developed wings?
Behind the wings is a pair of membranes, the alulets. Are
these attached to the wings or are they separate?

(2) Under the alulets are a pair of small white appen-
dages ending in a knob. Where are they attached to the
THE HOUSE FLY 75

body? Do you know of any use to which they may be
put by the fly? They are called balancers. What organ in
the other insects do they take the place of?

Make a drawing of the wing (x4).

Remove the balancer, put it under low power of micro-
scope, and draw.

(3) Remove one of the legs from the body. How many
segments? Remove the tarsus and put it under the low
power of the microscope. Note the two hooks and the pads.
Study the structure closely. The pads are called pulwvilli and
are used to secrete a sticky fluid by means of which the fly
adheres to smooth surfaces or to the ceiling.

Draw the tarsus.

Draw dorsal view of fly (X2).

The fly belongs to the order Diptera, a group of insects
having two wings.

DeEVELOPMENT.—(1) The eggs of the fly are laid in
decaying waste matter and after a short time the larva, a
headless, footless maggot is hatched. Like other larve
it eats ravenously for a few days, molts several times, and
finally assumes a tough brown covering which is the crys-
alis of the pupa state.

After remaining about a week in the pupa state it emerges
as a full grown imago.

(2) It is an easy matter to raise house flies and watch
their metamorphosis.

Draw larva and pupa (4).

Hapits.—Flies are scavengers and are therefore of the
greatest benefit in the economy of nature. Why is this?
It is also suspected that flies carry and distribute the germs
of typhoid fever, and that mosquitoes carry and distribute
76 ARTHROPODS

malarial fevers. What time of the year are they most abun-
dant? Why? What effect does cleanliness have on the
number of flies and mosquitoes? How do they spend the
winter? How do they defend themselves?

What are the habits of the mosquito, the horse fly and
the botfly?

CLassiIFICATION.—From A. E. Porenor.—By this table flies can
be traced to their families; for further identification consult
a specialist.

Table of the Principal Families of Diptera.

SEcTION I. Nemocera. Antenne of more than six
joints ; palpi four or five-jointed.
Culicidae. Mosquitoes.

Ocelli none; thorax without transverse suture; costal vein con-

tinued around the margin of the wing, fringed with scales; larvae
and pupae aquatic.

Tipulidae. Crane flies.

Ocelli none—except in one genus; thorax with a V-shaped
transverse suture; legs very elongated; haustellum short, terminated
by two large, fleshy lips; palpi longer than proboscis; four-jointed.

SEcTION 2. Brachycera. Antenne short, not having
apparently more than three distinct joints; palpi one or two-
jointed.

Stratiomyidae.

Third joint of antennae annulated, sometimes divided into several
portions; tibiae without spurs. Costal vein reaching only to middle
of wing; three basal cells much prolonged.

Tabanidae. Breeze flies, horseflies.
Third joint of antennae annulated, rarely divided into distinct
joints, always without style or bristle; haustellum of the male with
CLASSIFICATION 77

four, or the female with six, bristles; marginal vein running round
the whole border of the wing; tegulae rather large.

Asilidae. Soldier flies.

Third joint of antennae simpie; under lip forming a horny sheath
about as long as head; body long, clothed with stiff bristles; thorax
narrowed before; face bearded below; predaceous.

Bombyliudae. Bee flies.

Third joint of antennae simple; body short and thick; wings
extended horizontally on each side of body; proboscis long, por-
rected in front of head; ocelli three; legs long and slender; body
generally thickly clothed with hairs, which are easily rubbed off.

Syrphidae. Syrphus flies.

Proboscis with four internal pieces, long, elbowed near the base,
terminated by two large labial lobes; antennae three-jointed, last
joint largest, dilated, simple, bearing a bristle. Insects of moderate
or large size, variegated in color.

Dolichopidae. ,

Antennae short, third joint oval, or pallette-shaped, emitting a
long seta, or bristle; legs long and slender, strongly bristled.
Small, slender flies, generally of brilliant metallic colors; found on
leaves and in damp places.

Oestridae. Gadflies, botflies.

Antennae short, inserted in rounded pits; middle part of face
very narrow; mouth very small, organs rudimentary; tegulae large;
bodies rather large to quite large, hairy.

Tachinidae. Tachina flies.

Bristle of antennae bare, or with very short pubescence; thorax.
short; body bristly, stout; abdomen oval or cylindric, first segment
much shortened; many of the gray species with tip of abdomen
reddish.

Muscidae. House flies, blowflies.
Antennal bristle entirely plumose, or pectinate; body not slender;
78 ARTHROPODS

thorax short; proboscis short, thick, generally retractile; small or
medium insects; larvae, maggots, usually scavengers.

Ortalidae. Gallflies.

Abdomen pointed; wings generally spotted or banded; front
prominent; mouth wide; proboscis thick; larvae bore in stems of
herbs.

Hippoboscidae. Sheep ticks.

Head flattened, sunken thorax; wingless, degraded, parasitic
forms.

THE DRAGON FLY
Libellula sp.

GENERAL CHARACTERISTICS.—What is the most striking
difference between this insect and the others studied? How
are the wings held? Is there an unusual freedom of the
head? Of what value is it? Make a diagram showing the
longitudinal and lateral axes.

Tue Heap.—How much of the head is devoted to the
eyes? The eyes of some species of dragon fly are thought
to have as many as twelve thousand five hundred facets
in each eye. Are ocelli present? Do you find antennae?
What accounts for the condition in which you find the an-
tenner

Draw front of head (X2).

Beginning with the labrum find all the mouth parts as in
the grasshopper, and remove them with forceps.

Draw mouth parts (x4).

Tre THorax.—(1) Study the attachment of the legs
to the body. How many segments in the legs? Of what
use are the legs of a dragon fly?
THE DRAGON FLY 79

(2) Observe the peculiar color and venation of the
wings. How do they differ from the wings of a bee and a
house fly? Examine the attachment of the wings to the
body. What motions have they?

How do you account for the large thorax of the dragon
fly?

Draw one wing showing venation (x3).

Draw entire dorsal view of dragon fly (x1).

ABDOMEN.—Count the number of segments and observe
the attachment of the abdomen to the thorax.

How many spiracles do you find? On what segments?

The dragon fly belongs to the order Neuroptera. Is the
name appropriate?

DEVELOPMENT.—(1I) The eggs are deposited in water
where they are soon hatched into nymphs which crawl
along the bottom of the water. The nymph is carnivorous
and very voracious, consequently it grows rapidly and
molts often. Before molting the last time it crawls
out of the water and fastening itself to some convenient
projecting place and breaking the shell along the dorsal
side, it comes out of its shell into a new world of light and
air which contrasts strangely with its former abode in
darkness and filthy water.

(2) Nymphs may be easily obtained by dredging ponds
with a net. Get a few and put them in jars filled with water.
Feed them on insects and small crustaceans obtained by
dredging the ponds.

(3) Study the nymph carefully. Do you find three
divisions of the body?

How does each part differ from the corresponding part
in the adult?
8o ARTHROPODS

Note the general shape of the head, the large eyes, prom-
inent jaws and large labrum. The most peculiar thing is the
enormous development of the lower lip, or labium. Open it
with the needle and note its structure. What use can the
animal have for such an organ.? Do you think such a struc-
ture would help in gathering food? Why? Watch a live
specimen gathering food. This can be better noted
after putting in fresh dredging from the pond.

Draw front view of head (X4).

(4) Note the legs. How and where are they attached?
Compare them with the legs of the adult.

Observe the rudimentary wings. Are there two pairs?
To what are they attached?

(5) Count the segments of the abdomen. Do you find
spiracles along the sides? Since the nymph lives in water
it breathes air from the water instead of from the atmos-
phere as in the adult. The water is taken in at the anal
opening, carried over trachael gills, and after purifying
the blood, is expelled again at the same opening. Study
this method of respiration. Find and draw gills.

Draw nymph (x2).

(6) Get a number of specimens of different sizes illus-
trating different stages of growth and make a series of
drawings showing the development of the dragon fly.

Hasits.—Watch the dragon fly in motion. Why has it
such a jerky, uncertain motion? Does it seem to have the
power of going in a definite direction? What is its food?
How does it obtain it? Why is it called mosquito hawk?
Why does it spend so much time near water? How does
the dragon fly spend the winter? At what time in the
spring does it appear? Is the development complete or in-
CLASSIFICATION 8I

complete? Can you think of a plausible reason for calling
it a dragon fly?
CLassIFICATION.—From A. E. PopENog,
Table of Principal Families of Neuroptera.
A. Four or two distinct wings.

B. Antennae inconspicuous, subulate, short and slender.
C. Fore and hind wings nearly of same length; tarsi three-

POTEEM ws uasacssducee ccna, cytnaveuaseoatnsaielase-tavarenau Dragon flles, Libellulidae.
CC. Hind wings either smaller or wanting; tarsi four or five-
JOInbed: cekavercscaytomes etuar tees Day flies, Ephemeridae.

BB. Antennae usually inconspicuous; setiform, filiform, clavate,
capitate, or pectinate.
D. Tarsi two or three-jointed; wings unequal,

E. Hind wings smaller.............. Bookmites, Psocidae.
EE. Hind wings of same size or broader than fore wings.
Perlidae.

DD. Tarsi four-jointed; wings unequal.
White ants, Termitidae.
DDD. Tarsi five—sometimes apparently but four—jointed.
F. Hind wings with no anal space, not folded.

G. Mouth more or less rostrated..... .....Panorpidae.
GG. Mouth not rostrate................ Hemerobidae,
FF. Hind wings with a folded anal space.
EL. Wangs: reticulate: sccccaue oeansw-vecceaeus Sialidae.
HH. Transverse veins rather few..... Phryganidae.
AA. Wings rudimentary or wanting.
B. Mouth rostrate ........... i GRS Koa aeRO Ae Panorpidae.

BB. Mouth not rostrate.
C. Tarsi five-jointed.

CC. Tarsi four-jointed .......... ctacchiseiate cusettecunied Phryganidae.
CCC. Tarsi: threes Gimted: s..c.ccandves os seers Termitidae.
D. Wings absent; or two, rudimentary, leathery. ...Psocidae.
DD. Four rudimentary wings, veins visible........ Perlidae.

Notr.—According to recent classifications the order Neuroptera
is divided into several groups each of which is an order. The Drag-

emtr tat ZANT —A
82 ARTHROPODS

on Fly belongs to the Order Odonata according to Comstock and
contains but one family, i. e., Libellulidae. The classification here
given is convenient and contains a number of families which would
not otherwise be included.

SUMMARY OF INSECTS STUDIED.

Write answers to the following questions in clear definite
statements :

(1) How are insects covered? How many divisions
to the body?

(2) How many mouth parts, when fully developed?
What are they?

(3) How do insects see? Feel? Hear? Taste? Do
they smell?

(4) How is locomotion accomplished ?

(5) What is the breathing process?

(6) What is the method of digesting food?

(7) How is the blood circulated through the body?

(8) What is the plan of the nervous system?

(9) How are insects reproduced? Through what stages
do they pass ¢

(10) How are their characteristics grouped for classi-
fication ?

(11) Make a list of similarities and differences in a
diagramatic form as in the study of Orthoptera, and in the
list of differences put in the entire number of insects studied,
letting each order be represented by one insect.

This will give the class and order definitions of insects.
SUMMARY 83

CLASSIFICATION.—Just as we collected the different grass-
hoppers into the family Acridide, and the grasshopper,
cricket, cockroach, and locust into the order Orthoptera,
so now we group all the animals we have studied into the
class insecta. As a representative of the family the grass-
hopper has certain characteristics; as a representative of
the order, certain other characteristics; and as a member of
a class, the grasshopper and the others just studied have the
structures in common which have been outlined under the
head of similarities.

But in the last comparison since the definition of the class
was found by similarities and the definition of the order
by the differences, we should find the differences now about
the same as the likenesses when we made our first compar-
ison. Find if this is true.

How could we get similarities for the orders Coleoptera,
Hymenoptera and Lepidoptera that would be the same as
the differences we have found?

THE SoctaL Lire or INsects.—It has been noticed how
perfectly each animal is fitted for the sphere of life in which
it moves. Whatever it does it seems to be especially fitted
for doing. Thus the entire structure is specialized, some of
the organs in one direction and some in another; but what-
ever may be the shape or texture of the organ, it helps the
animal to live in the surroundings in which it is placed.

The difficulties of these surroundings are many and catise
every year the death of millions of insects, so that if some
provision were not made in the structure of the animal to
enable it to battle against these adverse circumstances the
entire class would become extinct. It is really then a battle
against death which the insects wage and their specialized
84 ARTHROPODS

organs are their weapons of defense. The following are
some of the things against which they continually struggle:

(1) Ewemtes.—Every insect is surrounded by myriads
of hungry aggressive foes which it must combat or elude if
it lives.

To do this some animals have modified mouth parts for
fighting; others, hard shells; others, wings for sudden and
rapid flight; others, legs developed for leaping; others,
glands for emitting an olfensive odor; others, a sting;
others adopt the color of some article, as leaf, bark or stone,
which is not food for their enemies; others imitate the color
of an animal which is not relished by their enemies; others
burrow into the ground; while many have compound eyes,
by means of which they detect the approach of an enemy in
time to escape. This vigilance applies in some cases not to
the insects themselves only, but is.exercised toward the off-
spring, by placing the eggs in protected places, and by de-
fending the young in all stages from attack.

(2) Foop Suppty.—The food problem is an important
one and every insect is well prepared to get some certain
food in a certain way. Some have mouth parts for tearing
or masticating dead or living prey; others, for sucking
blood or sap; others, for getting nectar from flowers;
others, for using the pollen of flowers; others, for biting
or masticating the entire leaf; others, for boring into woody
stems or roots and devouring them; others, for penetrating
grain; others, for rasping and absorbing liquid; others for
living on decayed vegetable matter, while some do not have
mouth parts in the mature state and hence live without food
until they die of starvation or accident.

In nearly all of these the food is obtained by the mouth
SUMMARY 85

parts alone, but in some the front legs are used for seizing
and holding the food, and in others the legs are used for
transporting food. Usually the food is devoured where it
is found, but in some cases it is stored, and occasionally it
is stored for the young only.

(3) CLimate.—tThe rigors of the climate form a seri-
ous check to the success of insects, and to meet it they adopt
the method best suited to their structure. The number of
spiracles and the great air capacity of insects render it
impossible for them to lead a normal life in cold weather.
Therefore the problem with which they have to contend is
how to maintain life when food is exhausted and when the
temperature is too low for muscular activity.

All, or nearly all of the insects that live over winter in the
adult state are for a greater or less length of time in a dor-
mant state, 7. ¢., a state in which they eat nothing, and
breathing as well as circulation of blood is almost stopped.
This is called hibernation, and the animal is said to hibernate.

In addition to hibernation some of them build houses,
and store tood for use when food is scarce, others go deep
into the ground on the approach of winter, others seek pro-
tection in decayed logs and under bark, others in straw or
corn husks, while others scarcely attempting to seek protec-
tion select any place partially hidden from view, and remain
all winter or until they are frozen.

Many of the insects that do not hibernate as adults spend
the winter in the pupa state, while others remain in the
egg. The eggs and the pupe are usually protected against
inclement weather by being in the earth, in sheltered places
or by having thick, warm cocoons. The placing of the
eggs and weaving of the cocoons are accomplished by spe-
86 ARTHROPODS

cialized organs. But in spite of all this care many insects
perish every winter, and during severe winters nearly all
of certain species are killed. To offset this annual slaugh-
ter and to prevent annihilation by the ceaseless struggle
of the insect with his surroundings, the reproductive power
of nearly all insects is extremely great. Unless checked
by some agency almost any insect would multiply so rapidly
that it would, in a short time, become a serious menace to
the welfare of man.

If the winter season should become longer and colder,
what would become of those animals that make little prep-
aration for it? How could they prevent this result? If
by circumstances an animal is driven into a region of longer
or more severe winter what would be the result ?

If the food supply of certain insects should become almost
exhausted, how could they still survive?

If the enemies of a certain species of insect should be-
come weaker or more powerful, would it affect the insect ?

What effect will this struggle with environment have on
the insect after it has gone on, generation after gentration
and year after year?

The larva of the honeybee which is snugly tucked away
in a cell, and fed with every delicacy which it could wish,
is covered over when it has finished growing by a soft, tough
covering by the faithful workers. It would seem that this
would be sufficient, but it is not, for the larva spins above
its own head a weak, worthless fragment of a cocoon.
Why does it do this? If the cell and cover were not there
would it need this cocoon? If the cell were not there do
you think it would build a better cocoon? Does this sug-
gest anything of the past history of the bee?
SUMMARY 87

Which do you think would specialize and change their
‘parts more rapidly, the bee or the grasshopper? Why?

Would all species of the same genus change with the
same rapidity? Would the same’species all be alike? This
produces what we call varieties in certain species.

For example, all dogs belong to the same species, but
there is quite a difference between the Newfoundland and
the Poodle. The different varieties of dogs have been pro-
duced by taking advantage of the natural differences of
dogs and subjecting the animals to different surroundings
- which have developed different physical and mental traits.

In the same way insects of a certain species being already
somewhat different, when subjected to varying conditions
become different enough to be placed in different varieties
and sometimes in different species.

. Make lists in answer to the following questions:

(1) What insects use the mouth parts for biting?

(2) What insects use the mouth parts for sucking?

(3) What insects use their legs for crawling or walk-
ing?

(4) What insects use their legs for alighting only?

(5) What insects use their front wings for balancers
only?

(6) What insects use their hind wings for balancers?

(7) What insects fly with both pairs of wings?

(8) What insects fly with one pair of wings?

(9) What insects have no wings?

(10) What insects in the mature state eat animal food?

(11) What insects in the larval state eat animal food?

(12) What insects in the mature state eat plant food?

(13) What insects in the larval state eat plant food?
88 ARTHROPODS

(14) What insects in the mature state eat no food?

(15) What insects build homes for their young?

(16) What insects show a care for the young in the
deposition of eggs? ,

(17) What insects abandon their young?

(18) What insects hibernate in the mature state?

(19) What insects hibernate in the pupa state?

(20) What, insects spend the winter in the egg?

(21) What insects spend all their lives above ground?

(22) What insects spend part of their lives under
ground?

(23) What insects are injurious in the larval state?

(25) What insects are beneficial in the larval state?

(25) What insects are harmful in the imago state?

(26) What insects are beneficial in the imago state?

THE SPIDER
Epeira sp.

GENERAL CHARACTERISTICS.—How does this animal differ
most strikingly from the insects? Observe that there is no
line of division between the head and the thorax. This united
portion is called the cephalothorar. How is the abdomen
united to the cephalothorax? What insects have a similar
method of union?

Tue CEPHALOTHORAX.—(1) On the dorsal side of the
cephalothorax find the eyes. Are they simple or compound?
How many? Do you think they are located in the best
place? Do you find antennae? Draw dorsal view of the
entire spider (2).
THE SPIDER 89

(2) On the ventral side find the appendages. How
many in all? How many are legs? How many are mouth
parts?

Observe the front pair, the mandibles, Are they seg-
mented? How do they end at the lower part? How are
they attached to the head? What motion or motions have
they? These mandibles are called the chelicerae, poison
fangs. Near the base is the opening of a duct that leads
to a gland which secretes a poisonous substance. This
gland is perhaps of the same nature as a salivary gland,
and the fluid stuns or paralyzes the prey of the spider. Re-
move mandibles with the scissors. ,

Behind these are the marillae, with their palpi. What
are the palpi used for? Are they really a necessary part of
the spider’s mouth parts? Remove the maxillae with scis-
sors. Do you find the labium or the labial palpi?

(3) How many pairs of legs? How are they attached
to the body? How many segments? Do the legs of the
first pair have as many segments as the others? If the
insects have three pairs of legs and labial palpi, and the
spiders have four pairs of legs without labial palpi, what
does this suggest as to the origin of the extra pair of legs of
the spider? Remove the tarsus of one of the legs and put
it under the low power of the microscope. What covers
the leg? Find three hooks at the end. Observe them close-
ly to find the distinct shape of each hook.

Draw end of tarsus as it appears under the low power
objective.

Have you ever seen spiders with legs missing? Did you
ever see them with some legs short? They have the power
of reproducing legs when they have lost them by accident.
go ARTHROPODS

Tur AspoMEN.—(1) Examine the dorsal side of the
abdomen to see if there is any indication of segmentation.

(2) Look on the ventral side of the abdomen, near its
union with the cephalothorax. Do you find small openings?
These are the Jung sacs which the air enters and purifies
the blood. How do they differ from the spiracles of in-
sects? Look in the opening, to find if possible, how the
blood is purified. On the median line a little further back
may be found the opening of the reproductive organs.

(3) At or near the posterior end find the spinning ap-
paratus, which consists of blunt protuberances called spin-
nerets. How many are there? Look closely to see if you
can distinguish any markings on the surface. Each spin-
neret consists of numerous openings through which exudes
the material that is hardened by the air into a solid flexible
thread. All the threads of the spinnerets unite to produce
the web of the spider. A small spiracle may be found in
front of the spinnerets.

(4) Are these spinnerets evidences of segmentation?
Do you think the abdomen has ever been composed of sep-
arate segments the divisions of which showed around the
body? If so by what process has the segmentation been
reduced to its present condition?

Draw ventral side of the abdomen (4).

DeEvELOPMENT.—(1) The eggs of the spider are usu-
ally placed in a sac, or cocoon surrounded by a slik web.
In some species the cocoons are carried around by the
mother spider who will sometimes die rather than abandon
it. In other species the cocoons are concealed by bark or
covered with dirt or pebbles, while some abandon the eggs
as soon as they are laid.
THE SPIDER gi

(2) When the eggs in the sac hatch, being bound up
tightly in the cocoon, the young spiders eat one another
until they are large enough to get out or unitl the mother
opens the cocoon for them. The young spiders grow rapidly
and molt often, until finally the adult form is reached. The
adult form hibernates during the winter under bark, logs,
or in other protected places.

(3) Get a young spider, observe it closely and see how
it differs from the adult. Draw a dorsal view (X2).

CLASSIFICATION.—Spiders belong to the class Arachnida,
This class is composed of the orders ticks and mites, scor-
pions, harvest spiders, and the spiders proper, Araneida.
This last mentioned order contains all our common spiders,
has about thirty-two families which are separated into gen-
era by the position and grouping of the eyes.

Hasits.—(1) Spiders are among the most interesting
of animals, and have been observed from ancient times.
The following experiments can easily be performed with
them.

a. Get a large spider and put it under a tumbler.

b. Place before it a lump of salt, then a lump of sugar,
then a piece of bread with vinegar on it. Observe its actions
in each case, then put before it a live fly and watch it. Do
you think the spider has taste or smell? Sound some mu-
sical instruments near it, and see if it gives signs of hear-
ing. Repeat these experiments on the following day. Can
it crawl out of the tumbler? Why? How does a spider
get to the ceiling of a house?

c. Throw a fly or some other insect into the web of a
spider and observe its method of entangling and winding
is securely. What does it do with it? What do you think
g2 ARTHROPODS

the web is for? How do the spiders without webs get food?

(2) The webs of spiders are interesting objects of study
and may be seen almost anywhere, where special caution
is not taken to keep them away. Get a small bit of spider
web and put it under the low power of the microscope.
Can you tell its structure? Find a spider web out in the
open field or garden and study its structure? Can you detect
anything like a plan in its formation? Ifso make a drawing
of it. The web of the common geometrical, or garden
spider is a good one to study.

(3) Have you ever seen spider webs flying in the air?
Where did they come from? Some spiders can sail through
the air by throwing out a tangle of their web so that the
breeze will carry them with it. Are spiders injurious?

(4) What are the enemies of spiders? Do spiders ever
protect themselves? In what ways? Is there a connection
between the colors of spiders and their safety?

THE CENTIPEDE

Scalapocryptops, sp.

GENERAL CHARACrERISTICS.—This animal is a harmless
one and may be examined either before or after it is killed.
It is commonly called the small centipede.

How many divisions to the body Are all alike?’

Observe the appendages. How many? Where located?
Note the covering of dorsal and ventral sides.

Tuer Heap.—(1) Study the head from the dorsal side.
Do you find eyes? Antennae? Where are the antennae
located? How many segments in each?
THE CRAYFISH 93

(2) Study the ventral view of the head. What mouth
parts are there? Are the mandibles segmented? Where are
the mandibles located with reference to the other mouth
parts? Are they similarly located in insects? What do
these facts teach with reference to the mandibles? Do you
find indications of mandibles under the labrum?

Tue Bopy.—How many segments? How are they joined
together? How many feet? Count the segments. How do
they end? Look between dorsal and ventral sides for spir-
acles. How many? Compare this animal with the larva
of butterfly? Of beetle?

Make drawing of dorsal side (2). Also ventral side
(X2).

DEvELOPMENT.—The centipede belongs to the class My-
riapoda and is one of the most timid of the class. Its eggs
are hatched into a form similar to the adult, and the animal
grows by molting and adding segments back of the head.

Hasits.—Where is this animal found? What does it
do when discovered? Do all “thousand legs” act in the
same way? From its mouth parts what do you think is the
nature of its food? How does the centipede defend itself?
Do you think it is poisonous? Do you believe the stories
told about the deadly effects of the centipedes of Texas?
Why not?

THE CRAYFISH
Cambarus sp.
GENERAL DrrecTIoNs.—Crayfish may be found in ponds
and streams at any time of the year, except in winter. They
may be kept for a short time in a vessel with a small amount
94 ARTHROPODS

of water at the botton, or they may be preserved in alcohol
by placing them in fifty per cent alcohol for a day, and
afterward changing the alcohol to seventy-five per cent,
and finally ninety-five per cent. If placed in alcohol the
shell should be punctured in several places, so that the al-
cohol may reach the internal parts. It is well to mix with
the alcohol a small amount of glycerine, about one fourth
of the amount of alcohol, in order to keep the body of the
animal soft and flexible after drying.

Tue Live SPECIMEN.—(1) Observe the general shape.
The front division is the cephalothorax, and all the poster-
ior part, the abdomen.

(2) Note the walking appendages. How many? Shape,
size, structure? How many does the animal use in walk-
ing? What other use is made of them?

(3) Notice the hinge in the front claw. Put a pencil
in the claw and if the animal grasps it, test the strength of
the muscles of the claw.

(4) Touch one of the eyes with a pencil and note what
follows. Notice the range of vision of the eye, and also the
range of muscular movement.

(5) Study the animal in water, thrust a pencil at it
quickly, and note how it darts backward. Study the under
part of the abdomen and see how this movement may be
accomplished.

(6) Describe briefly the different motions possible to a
crayfish and tell how each is accomplished.

Tue ExternaL Partrs.—(1) Kill the specimen with
chloroform, or by plunging it in boiling water. (The for-
mer method is better for study of internal structure, while
the latter is better for study of external parts.)
THE CRAYFISH’ 95

(2) The united head and thorax are called the cephlo-
thorax.

(3) The continuous covering of the two is the carapace;
above and between the eyes is the rostrum.

(4) The hinder, flexible part is the abdomen. Count its
rings, or segments. Bend (flex) the abdomen, and straight-
en it repeatedly, observing how the segments are joined
together and how they move upon one another.

(5) Separate the third abdominal ring (counting from
the front) from the rings in front of and behind it. To do
this hold the cephalothorax and fore part firmly between
the thumb and fore finger of the left hand with the
posterior end of the abdomen projecting toward the right
hand; then grasping the needle with the right thumb and
forefinger, thrust the point of the needle obliquely forward
between the third and fourth segments and work it right
and left, severing all connection between them; with the
scissors cut the membrane between the under sides of the
rings and entirely separate them.

(6) In like manner detach the third segment from the
second. Observe the following parts:

a. The upper part — the tergite.

b. The under part —the sternite.

c. The side piece — the pleurite.

d. Two appendages — the swimmerets.

Find that each swimmeret consists of a main stalk and
two branches. Examine these branches thoroughly. Lay
the ring on its front side and make a drawing of the com-
plete ring. Compare the other rings of the abdomen with
the third. Draw ring with swimmeret (x2).

In the male crayfish the swimmerets on the first abdom-
96 * ARTHROPODS

inal segments are /highly developed; in the female they are
degenerated and almost absent. Examine a number of
specimens to illustrate this.

(7) The last segment is called the telson. It forms
the middle flap of the caudal, or tail fin. Has it swimmer-
ets? Are there swimmerets on the sixth segment? Com-
pare the flaps on the sides of the caudal fin with the swim-
merets of the other segments. If they have the same parts
and seem to have the same origin they are said to be hom-
ologous. Are all of the swimmerets homologous with those
of the third segment? Draw caudal fin (x1).

(8) Are the appendages of the thorax borne upon rings?
After looking carefully for rings, observe the appendages.
Are they homologous with one another?

(9) Remove one half of the carapace with scissors and
forceps. This exposes the gills. Observe the gills closely,
noting structure and place of attachment. Move the legs
back and forth and see if there is any indication of a con-
nection between the gills and the legs.

(10) Remove a gill and study its structure under the
microscope. Make out a main stalk and numerous filaments.
Study from books or other sources, the method of circula-
tion in the gills and the process of oxygenation of the blood.
Make a drawing of gill (X1), also a diagram illustrating
the method of purifying the blood.

(11) Study the last thoracic appendage or hindmost
walking leg. Count its segments observing carefully the
peculiarities of each. Notice the number of joints and the
motions allowed by each. With the forceps seize the basal
segment and pull off the leg.
THE CRAYFISH 97

(12) Remove in like manner all the thoracic legs being
careful not to leave any part behind on the body. How
many gills are present on each? Are any gills left behind?
Do you see indications of rings? Lay the legs on a piece of
paper in the order that you pulled them out. Compare
them all with the first taken out. In the legs bearing claws
do you find any new part added, or is the pinching appara-
tus produced by a change in parts that are already present?
How do the legs which bear the big claws differ from walk-
ing legs? Compare them segment with segment. Draw,

(Xt).

(13) In front of the big legs, or great chelae, are sev-
eral pairs of appendages surrounding the mouth. Probe
between them to find the mouth. The appendages in front
of the great chelae are the hindmost of three pairs of jaw
feet called mazillipeds. Gently raise them to see how they
cover the other mouth parts. Note that these maxillipeds
have an inner branch covering the corresponding part of
the other maxilliped and an outer one. Are these branches
attached to one another or to a basal segment? Seize the
lower part and remove the whole maxilliped. Compare it
with a swimmeret of the third abdominal segment. In the
same way remove the second and first maxillipeds keeping
them in order. Are gills attached to the maxillipeds?
Make drawing of gill showing structure.

(14) Anterior to the maxillipeds are the two pairs of
maxillae. These are very thin and lie close to each other,
so that if great care be not taken they will be pulled off
together. Insert the forceps deep down and remove them
one at a time. Notice at the base of the first maxilla re-

STU. IN ZOOL.—7
98 ARTHROPODS

moved, a thin spoon-shaped structure—the gill scoop. It
lies in front of the gill chamber. Move the second maxilla
of the other side to see how it works. The gill scoop swing-
ing back and forth, pushes the water out at the front end of
the gill chamber. The water thus expelled is replaced by
fresh water, which comes up under the lower end of the
carapace about the bases of the legs.

(15) The mandibles are short, hard, toothed, each bear-
ing a jointed appendage which lies in a groove around
the mandible. This is the mandibular palpus. Closely fit-
ting against the posterior surface of each mandible is a thin,
leaflike structure — the metastoma. Remove the mandible
and the metastoma and lay them in the series with the
others. Count them to see that they are all there. Remove
the corresponding appendages of the other side, lay them
in a row facing those of the.side before removed, and make
a drawing of the series (2).

(16) The long projections in front of the head are the
antennae. Move them about in all directions, find the large
segment at the base, under the head. On this basal seg-
ment find a small white cone with an opening at the summit.
This is the aperture of the grecn gland in the head which
acts as a kidney in throwing off certain waste products of
the body. Remove the antenne with the whole of the big
segment. What is the probable use of the bladelike branch
of the antenna just under the eye? Is there any similarity
between the antennz and the swimmerets? Are they hom-
ologous?

(17) Above the antenne are the antennulac. Remove
one of them and compare it with a swimmeret.

(18) Look at the base of the antennule for a mem-
THE CRAYFISH 99

brane surrounded by bristles called setae. This is the en-
trance to the ear sac, the supposed organ of hearing. Probe
it with a needle.

(19) Study the eye. Note the stalk on which the eye is
located. Is it segmented? Is it hinged at the base? Is
the eyestalk like a swimmeret? Remove the outer covering
of the eye, scrape the inner dark part away and mount the
outer part under a cover glass. Examine under microscope.
Draw.

(20) After removing all the appendages from the ceph-
alothorax and cleaning the framework, look again carefully
for traces of rings. If these can be found, study them care-
fully at the point of fusion and make a drawing of one side.
How does this framework differ from the carapace? From
the soft fleshy part of the abdomen? How many rings in
the entire specimen? Is there a pair of appendages to each
ring?

(21) Study carefully the carapace. Do you find a mem-
brane under the hard crust? Is the carapace homologous
with the pleurites of the abdomen? Put a piece of it in boil-
ing water, note result; put a piece in dilute hydrochloric
acid, note result. Explain what happened in each case. Has
the carapace any connection with the framework of the
thorax proper? What do you think is the origin of the
rostrum? Of the carapace?

(22) Make large drawings of dorsal and ventral sides.

INTERNAL STRUCTURE.—(1) Place the crayfish, ventral
side down, on a block of wood, or in a dissecting tray, and
thrust pins through the telson and through each of the
great claws. Remove the carapace and the gills, leaving
the framework and appendages. In removing the carapace,
100 ARTHROPODS

be careful that the delicate organs on the dorsal side may
not be molested.

(2) This exposes the heart, an oblong, whitish body
surrounded by a membrane, the pericardial sinus. This sac
receives the blood from the gills after it has been mixed
with oxygen. Carefully remove the sinus and expose the
heart. Look for holes on its upper surface and for small,
white tubes running from it toward the head. There are
two holes in the top of the heart, two beneath, and one on
each side. These are guarded by liplike valves on the inside,
so that when the heart contracts, the blood is driven out
through the arteries to the various parts of the body. The
blood on leaving the arteries moves out into the viscera of
the body and is finally collected in irregular reservoirs which
communicate with the gills. The path of the blood is from
the body to the gills, from the gills to the heart, and from the
heart to the body. Draw heart (x2).

(3) The principal arteries that may be found are as fol-
lows: Superior abdominal artery which passes back from
the heart, resting on the reproductive organs and the mus-
cles. Study it carefully and make out the different branches.
The sternal artery branches off from this near the heart.
The ophthalmic artery runs from the middle of the ventricle
anteriorly passing over the stomach. Find branches run-
ning to the stomach and head. The antennary arteries
arise near the antero-lateral angles of the heart. These sup-
ply the antennz, the green gland and the lateral walls of
the stomach. Make a drawing showing the dorsal view
of the circulatory system. Through the wall of the ventral
side of the abdomen may be seén the inferior abdominal
artery. Cut away the wall of the abdomen and follow the

>
THE CRAYFISH IolI

artery posteriorly to the telson and anteriorly to the sternal
artery. :

(4) The organs extending lengthwise under the heart
are the reproductive organs. In the female are found the
ye-lowish ovaries in which at certain seasons of the year
the spherical eggs may be seen. Note the position of the
masses and their relation to the other viscera. Examine
the tube leading from the ovaries to the surface at the
third thoracic leg. This is the oviduct. In the male the
reproductive organs are similar in shape to those of the
female though smaller in size. Study the color, position
and shape. The was deferens is the tube leading to the
surface at the first thoracic segment. Follow it.

(5) Carefully cut away the roof of the head. Find the
stomach with a thin wall in which is a hard framework. Re-
move the soft tissues from around it. Do you see the esoph-
agus, or gullet, extending from the mouth to the stomach?

(6) The large reddish or brownish masses around the
posterior end of the stomach are the lobes of the iver. Pick
one to pieces and study its structure.

(7) Observe the white muscles which extend forward
from the abdomen along the sides of the body cavity.

(8) Beginning at the anterior end of the abdomen cut
through the tergum on each side down to the telson. Seize
this roof with the forceps and remove it, cutting the muscles
with the scissors if any adhere. The mass that you now
see is the mass of abdominal muscles.

(9) Running lengthwise in the middle is the intestine.
Follow it up to the stomach. Follow it down to the poster-
ior end, the anus, and observe any variations in size. Draw
the entire alimentary canal.
102 ARTHROPODS

(10) Note the shape and outer appearance of the stom-
ach. Probe through the mouth into the stomach, and note
the varying hardness of the different parts. Find the in-
sertion of the muscles of the stomach. Are there any
pouchlike extensions of the pyloric portions? The organ
is chitinous in places and resembles the outer carapace.
Open the stomach with the scissors. Note the hardened
areas and make out the uses of the projections. Draw
interior view of the stomach.

(11) The nervous system being on the ventral side
has not yet been injured. It consists of a series of ganglia
connected by nerve cords. The following may be found:

The supra-esophageal ganglion, composed of two ganglia
fused together, is under the rostrum behind the antenne.
From this mass the two cords, or commntissures, pass around
the esophagus and unite to form the infra-csophageal gan-
glion. Behind these, the ganglia and commissures extend
to the posterior portion. Study them. Do the ganglia corre-
spond to the number of body segments? Do you find the large
nerve cords by which the muscles and other parts are sup-
plied with nerves? These are really bundles of nerves which
divide and sub-divide until the single nerve only remains to
act upon the tissue. Make enlarged drawing of the nervous
system.

DeEvELOPMENT.—In the early spring the eggs of the cray-
fish are laid and carried on the swimmerets of the female.
When the eggs are hatched the young still cling to the
swimmerets until they are able to care for themselves. The
shell is molted several times during the growth of the
animal and occasionally after it has reached maturity. In
molting, the carapace splits and the animal extricates itself
THE CRAYFISH 103

by great physical effort. Accidents frequently occur during
molting in which the animal loses one or more appendages,
but as they are quickly replaced, it soon recovers its complete
form. The hard parts of the stomach are shed at each
period of molting. Why? Why does the crayfish molt?
What is the condition of the animal when molting has
been completed? Read the complete life history of the
crayfish.

Hasits.—What food do crayfish relish? How can
they choose their food? Can they live out of water? How
do they breathe out of water? How do they spend the
winter? How do they defend themselves? Do they fight
often? Are they courageous when attacked? How do
they show it? If they lose appendages how do they repro-
duce them?

CLASSIFICATION.—Summarize the principal types you
have studied, by a comparison, including similarities and
differences, of the grasshopper, spider, centipede and cray-
fish. Tabulate the summary as before.

 

STM ILARITIES.
Sea )-y. —
vee Appendages. aes Metamorphosis. Branch.

 

 

 

 

 

 

 

DIFFERENCES.

Name of Regions “Number of — ae N. f Class.
Type Animal. of Body. Appendages. Respiration. ame of Class:
Grasshopper.

Spider.
Centipede.

 

 

Crayfish.

 

 

 

 

 
104. ARTHROPODS

While they are all alike in the characteristics necessary to
put them in a single group, a branch of the animal kingdom,
yet they differ sufficiently to put them in different classes.

The branch to which these four types belong is Arthro-
poda, a word which refers to the segmentation of the legs.

The class to which the crayfish belongs is Crustacea, a
word which refers to the covering of the animal.

The crayfish belongs to the order Decapods, family As-
tacidae, and the Genus Cambarus.

The following synopsis of the more common forms of
Crustacea is abridged from McMurrich’s Invertebrate Mor-
phology. Examples are given under each division.

CLASS CRUSTACEA

I. Subclass Entomostraca.—Number of segments varies; abdo-
men without appendages; larva a Nauplius.

1. Order Psytroropa—Number of segments variable; appen-
dages with branchiae.

1. Suberder Brancuioropa.—Body plainly segmented and seg-

ments of thorax more numerous than six.
Branchipus (sand flea).
2. Suborder CLapocerA.—Body indistinctly segmented; with

bivalved shell; four to six thoracic appendages...... Daphnia.
2. Order Ostracopa.—With bivalved shell; body indistinctly seg-
mented; two thoracic appendages...............000 0000 Cypris.

3. Order Coperopa.—Without shell; five pairs of thoracic limbs;
many forms parasitic and degenerate.

1. Suborder Eucoreropa.—First thoracic segment only fused
with head; abdomen cylindrical and segmented except in
highly degenerated forms. ........... ccc cee eee eee eee Cyclops.

4. Order Cirruipepta.—Sessile or parasitic; segmentation indis-
tinct; six pairs of thoracic appendages; pass through Cypris

SEARIC fc: wisar ace Sar ah Migtmnnc olan gadiaesinra 4:4 aoe nlsnMAS eee GCL OSS
CLASSIFICATION 105

II. Subclass Matacostraca.—Number of segments constant; tho-
racic segments eight; abdominal seven or eight.
1. Order LeptostracHa.—With bivalved shell; abdomen with
eight segments.
2. Order THoracostraca.—With carapace covering the whole or

a part of the thorax; abdominal segments seven.

1. Suborder ScuHizopopA.—Thorax completely covered;  tho-
racic appendages biramous............cceseeeeceveeee Mysis.

2. Suborder Cumacea.—Last four or five thoracic segments

not covered by the carapace; eyes sessile or rudimentary.

3. Suborder Stomatorpopa.—Last three or four.thoracic seg-
ments not covered by the carapace; eyes stalked; five maxil-
Tipe sei s.cu. Ses avaeeaisnnticeses-aed 6 4 SNM tees BS a Qeannlolentanes Squilla.

3. Order Decaropa.—Thorax completely covered; five posterior
appendages uniramous and three maxillipeds; otocysts in an-
tennules.

I. Suborder Macrura.—Abdomen usually well developed.

Crayfish, Lobster.

2. Suborder Bracuyura.—Abdomen small and concealed be-

neath cephalothorax more or less perfectly............. Crav.
4. Order ArtHrRostrAca.—No shell or carapace as a rule; with
seven (or six) walking limbs; eyes sessile.

1. Suborder Isopopa—No carapace; first thoracic segment
fused with head; body flattened dorso-ventrally; branchiae on
abdominal appendages........... Sitges Oniscus (sow-bug).

3. Order Ampuipopa.—No carapace; first thoracic segment
fused with head; body flattened laterally; branchiae on thor-
ACIS AP PCNdaSeS: Ges iiocd sialauercuacs sooes we b's as Mehtawear ed Gammarus.
PROTOZOANS.

How to Finn Tuem.—Protozoans. may be obtained in
large quantities by any of the following methods:

(1) Ina vessel boil some dry hay in water. Pour con-
tents of vessel into a jar and allow it to cool. Into this
infusion put some fresh hay. Amoebae will appear in two
or three days.

(2) Take a pond lily or other water plant from the
water of a pond or pool and put it in water allowing it
to remain a week or more, until the plants are partially
decayed. This water will generally contain a cilliate infus-
orian, Paramecium. It will also often contain many other
genera of protozoans.

(3) Scrape the slimy mud in the bottom of a pond or
pool and place it in a bottle or tumbler with several inches
of water on it. Allow it to stand for several days in a dark,
warm place, and pour into it occasionally a little fresh
water. Many different kinds of Protozoans will generally
be found in this and it will often contain amocbac, and some-
times cyclops (a crustacean), and larval mollusks. Proto-
zoans may generally be distinguished by a flattened form and
the lack of definite appendages.

How to Stupy Tuem.—With a pipette, or medicine

106
PROTOZOANS 107

dropper, take some of the water from the above prepara-
tions and place it on a glass slide near the middle. Carefully
clean a cover glass and put it loosely on the slide. Change
the water on the slide as often as necesary. The specimens
may be fed by putting water at the edge of the cover glass
and letting it run under the slide by capillary attraction.

(1) General Examination: Look carefully at the slide
with the low power of the microscope and see how many
different forms you can find. Notice shape and variations
in size. What determines the shape of the body? Is there
a distinct head? How are the motions of the body pro-
duced? Do you find blood? A heart or organ correspond-
ing to a heart? Do you find gills? Eyes? Nervous sys-
tem? Do you find an alimentary canal or any part of one?
Do they seem to choose their food or the path they travel?
Is there a protection for the body? Draw four or five dif-
ferent forms in a general way showing the outline of the
organs studied.

(2) The Ameeba: This specimen is generally distin-
guished by its irregular outline and its uncertain motions.
Examine it carefully and note its general outline in the
different positions. What is its shape? Is the shape the
same in different positions? Do you find pseudopodia
(parts of body extended into fect)? What is the shape of
a pseudopodium? How many has a single specimen?

Make sketches of the animal at different times showing
the pseudopodia.

Distinguish the following parts:

a. LEctosarc (outer, clear, layer of protoplasm). How
much of the body does it form?

b. Endosarc (inner, granular mass of protoplasm).
108 PROTOZOANS

Study the nucleus. Position? Shape? Size? Is it in the
same relative place in the different specimens? Drop a small
drop of aceto-carmine on the side of the cover glass and
watch the effect on the amceba. Is there more than one
nucleus?

Find contractile vacuole. It may be known by its pul-
sating movement. Position? Shape? Number? Has it
any definite contents? What function does the vacuole
seem to perform? Make an enlarged drawing of the amceba
naming the parts.

(3) The Paramecium (slipper animalcule): Examine
as you did the amoeba. How does it compare with the
ameeba in size? In shape? Does it change its shape during
its movement. Find the cuticle, or cell wall. Note its ex-
treme transparency. Is it present over the entire surface?
Is it entire or has it openings?

Find the ectosarc and endosare and compare with those
of the amoeba. Do you find food vacuoles, i. ¢., particles of
food-ingested substances?

Do you find contractile vacuoles? How many? Where
situated? Examine several specimens to see if the vacuoles
are constant in number and position. Find the nucleus, and,
if possible, a micro nucleus beside it. Note size and position.
Compare nucleus with that of the amoeba.

Do you find cilia covering the body? Do they cover the
body entire? Why? Examine a single ciliuj and draw it.
Are the cilia all of the same size and shape?

The trichocysts are seen directly beneath the cuticle. How
are they arranged? What is their shape and structure?

Do you find the mouth? What is its position? Shape?
Is the position constant? Is the shape of the mouth perma-
PROTOZOANS Iog

nent? How is the mouth closed? Compare with the amceba
in this respect.

Find the esophagus and anal opening. Are the positions
of the two constant?

Does the animal appear to have a nervous system? Does
it seem to perform actions of its own accord? Does it
seem to be irritated when other objects come around it?
Do the cilia on the different sides codrdinate in movement?
Has the slipper animalcule the sense of touch and of taste?

Make a large drawing of the paramecium showing and
naming the parts studied.

Note.—If amoebae cannot be found, the white blood corpuscle of

the frog or of any mammal may be used, as they have all the com-
mon characteristics of amoebae.

(4) The Vorticella: It is likely that some of the slides
prepared will show this simple form of life. It may be
readily distinguished by the fact that it is bell-shaped in
form and has a stem by which it is generally attached to
leaves or sticks in the water. Examine under microscope.
Note its shape and length and compare it with Amoeba and
Paramecium. Do you find the ectosarc, endosarc, nucleus,
and vacuole as in the Paramecium? Study the base by
which the animal is attached. How is it attached? Re-
move one with a needle. Is it difficult to remove? Do you
think it could remove itself and attach itself? Why? Does
it grow singly or in colonies? Study the stem. Does it
seem to have the same structure as the body? Does the body
have the power of movement? Look at the size of the heads.
Do you find any in the process of division? Do you find a
mouth? Where? Of what use are the cilia? Reproduc-
tion may take place by simple fission as in the Amoeba. and
IIo PROTOZOANS

by conjugation of a free swimming head with a stalked
head?

Draw several forms and show as much of the structure
as possible by the drawings.

Compare Amceba, Paramecium, and Vorticella, bringing
out especially the increasing complexity of structure.

SUMMARY.

One celled animals are not only simple and primitive in
form, but the life processes in them are carried on with
the least mechanism possible. As the entire cell is in con-
tact with the food medium, the organization for nutrition
is necessarily almost wanting. Yet there is a perceptible
increase in complexity as we go from the Amceba to the
Vorticella.

Other Common Forms: Protozoans are everywhere pres-
ent and furnish part of the environment in which all ani-
mals must grow. The number of species is very great
and they inhabit in countless numbers and conditions every
part of the known world. They are supposed to have
been the first forms of life on the earth, and during this
time they have developed many variations in form and mode
of life.

Parasites: Many protozoans are parasitic in habit, their
size, and simplicity rendering them particularly well fitted
for such life. In the human body, the germ of disease which
causes dysentery, and the malarial parasite which by mul-
tiplying causes malarial fever, etc., are protozoans. Gre-
garinidz are also parasites and live in the intestines of the
centipede, crayfish and other animals.

Marine Forms: The water of the ocean, though clear in
PROTOZOANS III

appearance, contains myriads of protozoans. So abundant
are they that a celebrated naturalist has said that they fur-
nish food, directly or indirectly, for all the animals of the
sea.

Many of these forms are protected by shells, which are
secreted by the microscopic animal. In this way they are
partially protected from surrounding dangers.

The Globigerinz are forms that extract calcium carbonate
from the sea water and make it into calcareous shells. On
the inside of these shells the animal lives and through the
perforated surface, protoplasmic arms, called pseudopodia,
are extended. These animals live in countless numbers in
the surface water of the ocean and when they die their
shells fall down, forming a mass of calcareous matter at the
bottom of the ocean. After a very great length of time has
elapsed, this mass solidifies into limestone, or chalk beds.
This has been going on for ages and many of such beds have
been elevated to the surface, and form the mineral strength
of the most fertile soils known.

The Radiolarie are forms with shells of a siliceous nature
and their shells form flint beds in the ocean, which may
afterward become land.
SPONGES

THE Sponce SKELETON.—Examine carefully a piece of
commercial sponge. Note the location of the smaller and
larger openings and their relation to one another. Make
out the general circulation of the water in the sponge and
make a diagramatic section of the sponge showing the
system of circulatory tubes.

Tear off a piece of the sponge and mount it in water under
a cover glass. Are the fibers single threads or branched?
Describe briefly the structure and make a drawing showing
the points noted.

THE SIMPLE SPONGE (GRANTIA CILIATA).—(1I) Gen-
eral Method of Examination:—The entire specimen should
be examined with the unaided eye and then with pocket
lens. Keep it in fifty per cent. alcohol in watch crystal while
examination proceeds. For making sections after the gen-
eral work is completed a sponge should be run through the
alcohols and stained (sce Appendix, IIT), then mounted in
paraffin and cut into thin sections with the microtome. These
sections may be mounted in balsam after dissolving out
the paraffin with turpentine. Another specimen should be
prepared by allowing it to stand twenty-four to thirty-six
hours in two per cent. solution of chromic acid. This dis-

112
SPONGES. 113

solves the spicules leaving the cellular tissue hardened. The
decalcified sponge may then be passed through the alcohols
and finally cut and mounted as before.

The spicules may be obtained for mounting by boiling a
piece of sponge in potassium hydrate (caustic potash) which
dissolves the flesh and sets free the spicules. Then after
washing thoroughly allow spicules to settle and pour off the
water. The spicules at the bottom may be removed with the
pipette and mounted on the slides as other material.

(2) Study the shape of the entire specimen. Is it sym-
metrical? Can you distinguish an upper and lower end?
How? Is the sponge attached or free? Is its shape modi-
fied to suit this attachment? How? Do you find anything
unusual in the shape of any of the specimens? Can you ex-
plain it? Do you find evidences of budding? If so, from
what part of the parent sponge does it grow? Explain
the process of budding.

At the upper end look for a large opening, the osculum,
surrounded by spicules. Can you tell its use? Do you see
anything on the sides which in any way compares with the
opening at the end? Do you find spicules on the sides?
Put the specimen on a slide and examine with the low
power without using cover glass. What do you find?
Measure your specimen. Make a large drawing (x3)
showing the points studied.

(3) Cut the specimen longitudinally with the scalpel
and examine the internal structure. The osculum at the
end should be studied carefully. The internal chamber is
the cloaca, or gastral cavity. What is the shape of this cav-
ity? How far down does it extend? Does its diameter
vary? Study a side of the body wall with the high power.

STU. IN ZOOL.—8
Ii4 SPONGES

Do you see the spicules? What seems to be their office?
Do you find the radial canals, or incurrent orifices extending
outward from the body wall? Draw one half of the sponge
as it appears now and show the parts studied.

(4) Examine a slide made according to direction and
trace out the parts studied, 7. e., the cloaca, radial tubes and
fleshy portion. Study the arrangement of spicules and note
how they are disposed about the openings. Make a large
drawing of the section.

(5) The spicules mounted according to direction may
now be studied and the different forms noted. Note in
what part of the body each shaped spicule is found? Can
you suggest any reasons for these shapes? Draw spicules.

THE Compounp Sponce (FresH WatTer).—(1) Ex-
amine a fresh-water sponge. Note the general appearance
and compare with the simple sponge just studied. Is it at-
tached or free? Study its surface. Can you find the open-
ings? Of what use are they? Are they all the same size?
Do you think they all carry water in the same direction?
Explain how a simple sponge may grow into this form. Draw
complete form.

(2) Is this sponge soft like the commercial sponge?
What causes the difference? Has it fibers or spicules?
Remove a small portion of it and find out the nature of
its framework. Study the spicules as in the simple sponge.
Are they siliceous or calcareous? Why? Draw spicules.

(3) Observe the mottled appearance of the sponge. The
small round bodies are called gemmules. Where are they
located? Remove a few and study them under the low
power of the microscope. Note the shape, size and ar-
rangement. Do you find spicules of a peculiar nature
SPONGES 15

imbedded in the mass of gemmules? Spicules and gem-
mules may be better studied if a portion of the sponge con-
taining them be placed in weak nitric acid and allowed to
remain until the fleshy portion is destroyed, and afterwards
mounted. On the outer coat of the gemmule look for the
foranunal aperture through which the embryonic sponge
emerges. Draw gemmules and accompanying spicules.
Make a diagram representing a section of the entire sponge.

Read McMurrich’s “ Invertebrate Morphology” on the
structure and growth of sponges.

SUMMARY.

(1) What part of a sponge is valuable commercially?
Do all sponges have skeletons? Are all skeletons of sponges
alike? What determines the commercial value of a sponge?

A sponge represents a simple combination of cells which
differ very little from a mass of protozoans; but while each
cell of the protozoan performs all the functions necessary
to sustain life, the cells of the sponge are slightly differentia-
ted so that different functions for the life of the whole may
be performed by cells specialized for the purpose. Although
the specialization is slight, and each cell, even when it is
enclosed in the mass, gets its own food and in a measure se-
cretes it own protective spicules; yet as the sponge becomes
more complex, the organization increases and the cells
become more dependent.

This organization of unlike cells which results from dif-
ferentiation of like cells gives rise to the metazgoans as con-
trasted with protozoans. The sponges are generally con-
sidered the simplest form of metozoans. Read a larger
zoology on the life processes of sponges.
116 SPONGES

Economic VALUE.—Sponges have long been known as
articles of commerce. The valuable sponge is the one pos-
sessing the horny, fibrous frame-work and its value depends
upon its softness, fineness of fiber and size. They abound
in the tropical regions and the ones that are found in the
Mediterranean Sea are most highly prized.
COELENTERATES

SEA ANEMONE

Metrideum sp.

Observe the shape and general contour of the body.
Distinguish between the upper and lower disks. Study the
lower disk. What does its shape and form indicate as to its
use? Is the animal free in the water or attached to some-
thing? If attached, how? Draw the lower or basal disk
(sr).

Examine the upper disk. Find the mouth, the lips and the
tentacles. Are the tentacles arranged in a definite order?
Are they of the same length? Is the mouth alike in all
parts? Notice the extremities of the mouth to find any
thickening or specialization of any kind. Draw the animal
from the side showing the cylindrical barrel and the upper
disk.

With a scalpel cut the body into two parts at right angles
to the barrel.

This exposes the tube on the inside which extends down
from the mouth. This is called the esophagus. Look below
the esophagus for another coelenteric chamber limited by the
wall of the body of the animal and divided, or partially so,
by radially arranged partitions called septa, or mesenteries.
Examine the septa closely. How many extend to the ccelen-

117
118 COELENTERATES

teric canal? How far do the others extend? Make out the
primaries, the secondaries and tertiaries. How many of
each? What seems to be their function?

Make an enlarged drawing of the base of the animal
showing the arrangement of the septa (X2).

Look on the inside of the mesenteries for muscles, small
strips about midway between the mesenteries. Between the
mesenteries are found the reproductive organs, the excretory
organs and circulatory fluid which nourishes the body, which
is composed of the digested food and sea water. This is
circulated principally by the movements of the body.

Enumerate the motions of the anemone which you think
possible from its form and structure.

Tue CoraLt.—Study the common star coral and see if
you can trace any relation between the framework of the
coral and the plan of the sea anemone.

Explain the relation, if any be found, and discuss the pro-
cess of coral building and reef making.

THE FRESH WATER HYDRA
Hydra fusca

Specimens of fresh-water hydra may usually be obtained
in pools of water near the school and because of their gen-
eral distribution are good forms for study. The living forms
may be watched in a basin of water, and then hardened in
alcohol for sectioning.

(1) Note the general form of the animal. Find tlre body,
the tentacles and the base. Can you make out a definite struc-
ture to the outside of the body? If possible find one with
buds growing from the side. Note the number, arrange-
THE FRESH WATER HYDRA T1Q

ment, size and length of the tentacles. Between the ten-
tacles, in the central disk, find the mouth. Note its position,
size, shape, etc. Make a drawing of the specimen (5).

(2) Under a microscope study the tentacles. Note the
large circular bodies dotting the surface. These are thread
cells or nematocysts. Note their size, number in various
parts of the tentacles, and apparent structure. Watch them
under the microscope using low power. Tap the slide with
pencil and note what follows. (This usually causes the
extension of the lasso threads from the cells). Study the
lasso threads and note their uses. In a watch crystal of
water containing fresh hydra put an infusion containing
paramecium. If the hydra uses them for food notice the
method of capture. Draw a tentacle showing a lasso thread.

(3) If a bud is found study its relation to the body.
How does it differ from a tentacle? It is a young hydra
growing out from the parent hydra. What will finally
become of it? This form of reproduction is called budding.
Hydra reproduces also by eggs, which are developed in the
ectoderm of the body. Cut a hardened specimen length-
wise with a sharp scalpel or scissors. Do you find an inner
cavity? What relation does it have to the mouth? Has
it an opening into the body? What becomes of the indigesti-
ble portions of the food of the hydra? Make a drawing of
the longitudinal section of the hydra (X5).

(4) In like manner using a hardened specimen make a
cross section of the body just back of the base of the tenta-
cles. Do you find the parts found in the longitudinal sec-
tion? Draw (Xs). What seems to be the office of the cells
on the outside of the body? Of the cells in the sac on the
inside of the body?
120 COELENTERATES

(5) In the reproduction of the hydra, the egg leaves the
body surrounded with a shell-like secretion of its covering.
In this condition the egg sinks to the bottom of the
water and may remain for sometime before developing
further. After a lapse of considerable time, if conditions are
favorable, the animal develops into an adult hydra. By
this power of remaining inert, the hydra can pass success-
fuily through vicissitudes of coldness and dryness that
would otherwise destroy it.

SUMMARY.

The structure of the hydra is very simple. Its body
consists of an outer layer of tough cells which is called
ectoderm, and an inner layer of softer cells, endoderm.
Between these two layers is a row of scattered, poorly de-
veloped cells, called mesogloea. In the process of growth
from the egg, the outer primitive layer called blastoderm
is folded at one point producing a saclike interior like the
folding in of one sidy of a hollow rubber ball. From this
the animal develops into the adult form with its tough
ectoderm on the outside and the hollow digestive tract, sur-
rounded by the cells of the endoderm, on the inside.

The sea anemone is a higher form with a more compli-
cated though similar structure. Its development from the
egg is similar to that of the hydra, but the mesogloea is so
developed that it forms muscles on the sides of the mes-
enteries. Indeed the mesogloea is so well developed here
that it perhaps deserves the name that it receives in the high-
er animals, viz.: mesoderm. Find the meaning of these
words.

The animals that secrete coral are called coral polyps,
polyp being the name applied to each individual of the col-
THE STARFISH I2I

ony. The harder parts of the coral are secreted by the ecto-
derm, but in some kinds as the sea fan and red coral, an
additional layer of loosely connected particles of carbonate
of lime is secreted in the mesoglcea.

THE STARFISH

Asterias sp.

GENERAL SuGGESTIONS.—The starfish is the best repre-
sentative of this branch for laboratory study. Specimens
may be obtained from any of the supply laboratories, and
may be kept in two per cent. formalin or seventy per cent.
alcohol for an indefinite period. Dried specimens may be
made to serve the purpose of this study if soaked for a
while before using in hot water. A few specimens with
water vascular system injected should be obtained with
the others, and kept on hand for reference.

If possible a few specimens of sea urchins and sea cu-
cumbers should be on hand for comparison.

Driep SPECIMEN.— (1) Examine the specimen as a
whole. Note its shape, length of arms, and differences be-
tween the two sides.

(Each arm is a ray, the sides are oral and aboral, the
‘central body is the disk.)

(2) Note the covering of the aboral side. Remove one
of the spines, examine it carefully as to length, attachment,
and size.

(3) Note the arrangement of the spines on the oral and
aboral sides. Find between two of the arms on the aboral
side an oval plate covered with radiating grooves; this is
the madreporic body. Examine and draw the aboral side

(XA).
122 COELENTERATES

ALCOHOLIC SPECIMEN.—(I) Briefly review the points
noticed in the dried specimen. Notice especially the ar-
rangement of the spines on the oral side, and the ambu-
lacral feet, in the furrow. Observe the arrangement, size
and attachment. Note the arrangement of spines around the
mouth. :

(2) Compare the spines of different areas as to size,
shape and degree of flexibility. Look around the spines
for a ring of sniall projections. These are the pedicellariae.
Remove one and put it under a microscope. Find a stalk
bearing pincherlike parts for grasping.

These are used to clean the spines and remove foreign
matter from the body. Make drawing.

(3) Press apart the ambulacral or tube feet and exam-
ine the opening, and if a yellowish line is found it is the
nerve cord. Trace it back toward the disk and find a
nerve ring surrounding the mouth. Look in one of the
other rays to sec if it is present in all. Follow the nerve
to the end of the ray and find the eye at the end. Draw
nervous system. The eye spot is borne on a distinct plate.
Draw oral side.

(4) The arm opposite the madreporic body is the anterior
ray. Cut through the aboral wall near the outer end with
scalpel, and from this point cut with scissors toward the
disk about two inches. Raise the flap to see that you are
not injuring the internal organs and cut to the disk. The
branched body under the aboral side is the liver. Along
the middle line of the aboral wall is the extensor muscle —
a yellowish streak. Along the floor of the ray find little
sacs, (sometimes distended, but generally flat in alcoholic
specimens). These ampullae are the ambulacral vesicles.
THE STARFISH 123

Find the connection between them. Observe the specimen
which is injected with coloring matter. Near the base of
the ray on each side are the reproductive bodies.

(5) Cut along the sides of the two rays lying on either
side of the first ray cut, and extend the opening nearly across
the disk, being careful not to cut into the body parts.
Raise up the parts severed and find the membraneous
stomach,

Pass the bristle in at the mouth and explore the interior.

(6) Observe the lobes of the stomach. Do they extend
into the rays? Lift one of the lobes and see if you can find
how the muscles are attached. Trace the liver toward the
stomach, do you find where the opening is?

(7) Do you find the anus on the top of the stomach next
the aboral side?’ Remove the roof from the three rays and
make a drawing showing the organs exposed.

(8) Remove the stomach by cutting across the esopha-
gus. This exposes the crooked S-shaped stone canal ex-
tending downward from the madreporic body. Trace this
canal to its lower end and find that it forms a ring — the
circum-oral water ring — which conveys the water from the
madreporic body to the ampuliae and thence to the am-
bulacral feet. This system of circulation is the water vas-
cular system.

(9) Cut across a ray in two places about an inch apart
and notice all that is included in the part thus cut out.
Remove the liver, noting how it was attached to the body

wall.
Notice the part through which the ambulacral feet ex-

tend.
Probe with a needle the middle portion of the ambulacral
124 COELENTERATES

furrow and see if a channel can be found through which
the water runs.

(10) Make out how the ampullae are connected with
the tube feet. Remove an ampulla and its corresponding
foot and make drawing. Make drawing of cross section of
ray showing all the points you have found.

(11) Scrape the aboral side of a ray to see if there 1s
anything of a skin or of a membraneous structure at the
base of the spines. Do the spines seem to be attached to
the skin? Do the aboral tentacles come off with the skin?
Do you find a skin under the hard plate?

The hard part is prohably developed from the membrane.

(12) Make a drawing of the water vascular system in
the disk and in one ray.

SumMAry.—The animals of this branch are not much
sought after for food by other animals in the ocean. The
spiny skin after which the branch is named is generally
modified into some form of defense. What is the nature
of this defense in the forms you have studied? Some forms,
as the sea urchin, act as scavengers, but otherwise they are
of no value. Do you notice any general plan in the structure
of all? Notice the forms, sizes, and relative freedom of
motion of the spines in the various forms.

CLASSIFICATION.—The relationships of the common forms may be
seen by the following outline of the Branch Echinodermata:

Class 1. Asteroidea. Starfish.
Class 2. Ophiuroidea. Serpent Stars.

Class 3. Echnoidea. Sea Urchins.
Class 4. Holothuroidea. Sea Cucumbers.
WORMS

THE EARTHWORM

Lumobricus sp.

GENERAL SUGGESTIONS.—The earthworms burrow in the
ground to considerable depth, swallowing the earth re-
moved from the burrow. The digesitve juices dissolve out
the organic substance from the soil swallowed, and these
are absorbed. At night they leave their burrows and crawl
about. In the daytime, when at rest, they lie in their bur-
rows with the head at the surface of the burrow. In
winter they go deep down into the earth below the freezing
point. Fresh specimens may be kept all winter by providing
them with earth and a convenient place in which to burrow.
Specimens carefully prepared by running them up from
fifty per cent. to ninety-five per cent. alcohol should be kept
on hand for study of internal anatomy.

ExTERNAL MorpHotocy.—(1) Examine a live worm.
What is its general shape? Are both ends alike? Which
is the head end? Are the two ends alike in shape? How
do they differ? Has the worm the same diameter through-
out its length? Are both dorsal and ventral sides alike
in shape?

125
126 WORMS

(2) Note its color. Is it the same on both sides? Notice
a streak of red in the mid-dorsal line. This is the dorsal
blood vessel showing through the body wall. Can you see
blood moving in it? In what direction? Look on the
ventral side for a similar red line, the ventral blood vessel.

(3) Has it eyes? Where? Can it feel? Hear? Con-
sult reference books to answer these questions.

(4) Note the circular rings which make up the entire
body. Count them. Are they all the same size? Each
ring is called a segment or annulus.

(5) Notice the thick white girdle, the clitellum, near the
anterior end. How many segments is it from the front end?
This is connected with reproduction. Is it in the same
position in all worms? Sketch the entire worm.

(6) Kill a worm in chloroform. Strip off the outer
skin, or the cuticle, and examine with the microscope. Note
markings and thickenings. Sketch.

(7) Place a live worm on a piece of paper and watch its
movements. Draw it backward, ventral side down, over the
finger. Is there any resistance? With a dissecting micro-
scope look for spines. Where are they located? How many
tows? Are they in each segment? These are called setae
(sing., seta). Can you now determine how the animal
moves? Boil a piece of the body wall of an alcoholic speci-
men in caustic potash to free the setae. Wash in water.
The setae will fall to the bottom. Pour off the water and
mount some of the residue in glycerine or balsam for study.
Draw.

(8) Look for the mouth. Where is it? In front of
the mouth note a projection, the prostominm. Look for
the anus. Where is it? Look for two slitlike openings in
THE EARTHWORM 127

the fifteenth segment on the ventral side. They are the
openings of the vas deferens. Exactly in front of these on
the fourteenth segment are the two openings of the oviduct.
These are not very easily seen.

DIssEcTION OF THE EartHworm.—(1) Kill a large
worm by placing it in ether, chloroform, or alcohol. Ex-
tend the worm under water in the dissecting pan, dorsal
side up. Put a pin through the extreme anterior and poste-
rior ends. With a fine-pointed pair of scissors cut through
the body wall on dorsal side near the posterior end. Con-
tinue the cutting forward along the mid-dorsal line, being
careful not to cut deep enough to injure the organs below.
Pin back the body wall on both sides, slanting the pins so
that they will not interfere with dissecting. Notice a milky
liquid exuding from the cut. With a pipette put some of
this liquid on a slide and examine with the high power
lens. White blood corpuscles should be found moving
about in it. Draw.

(2) Notice the dark-colored digestive tract extending
from mouth to anus. What gives it its color? Can you
now see clearly the dorsal blood vessel referred to above?
Trace it out. Notice the oval white bodies dorsal to the
digestive tract near the tenth segment. These are reproduc-
tive organs. Notice the muscular walls between the seg-
ments. These were partially cut through in laying back
the body wall. What is their relation to the digestive tract?
To the body wall? Compare these with the external seg-
ments. Note the relation. These portions are called septa.
These divide the body cavity, or coeluwm, into small cham-
bers. What is the shape of a septum? Represent by a
sketch.
128 WORMS

(3) Trace the digestive tract from the mouth to the
anus. That part extending from the mouth to about the
tenth segment is the pharynx. From this point to the seven-
teenth segment is the narrowest part, and is called the
esophagus, or gullet. This opens backward into a dilated.
portion, the crop. Just behind the crop is another dilated
part, the gizzard. The remainder of the alimentary tract
to the anus is the intestine.

(4) Notice a brownish coat covering the intestine. This
is the so-called liver.

(5) Remove the digestive tract, being careful not to
injure other structures. Just below will be seen the ventral
blood vessel already mentioned.

(6) Scrape carefully the other loose tissue from the
floor of the body cavity, and below in the mid-ventral line
will be seen the white nerve cord. Remove the tissue from
it, tracing it forward, being careful not to break it. Now
place it under a dissecting microscope, still attached to the
body wall, and examine. Is it a single or a double cord?
Do you see enlargements along this cord? How many?
They are called ganglia, Are there any nerves arising from
them as side branches? Trace it further forward till you
find where it divides, forming a collar around the esophagus.
This is called the esophageal collar. Just where the cord
begins to divide is a large double ganglion, the infra-eso-
phageal ganglion. Above the esophagus, where the two
parts of the esophageal collar unite again, is the supra-
esophageal ganglion. It is double also.

(7) You can also now see the nephridia, little white
coiled tubes between the septa. These are organs of excre-
tion. Study one and see if you can trace it in its windings.
THE EARTHWORM 129

(8) Put a living earthworm in water. Does it seem
to be comfortable? What vital process is cut off while it
is in the water? Did you find any provision for breathing
in the animal? Do you think it breathes? Take it out of
the water and see if it revives. Can the earthworm breathe
in dry air? Since the blood vessels appear to be near the
surface, can you suggest its method of breathing? Why
do so many earthworms come to the surface after a rain?
Describe the process of respiration.

(9) The anatomy of the earthworm may be better un-
derstood by studying a cross section. Use a specimen that
has been hardened in ninety-five per cent. alcohol. Cut a
piece about two inches long from the center of the worm,
and wash out the intestine so that it may be further studied.
Cross sections of this piece may be made thin enough for
class study by holding the piece between the thumb and
forefinger of the left hand and cutting sections with a
razor. Examine the body wall. The cuticle is a thin chiti-
nous layer of an iridescent luster. Below this is the epi-
dermis, which consists of a single layer of cells elongated
in the vertical direction. Below this is a layer of connective
tissue, the dermis. This can scarcely be distinguished. The
next layer of the body wall is the circular muscles. The
layer within the circular muscles is the longitudinal mus-
cles. These are featherlike, and stand at right angles to
the circular muscles. They are interrupted, and appear to
be divided into bundles. How many? By examining two
or three cross sections the exact position and arrangement
of the setae may be made out. Can you see where the
nephridia open to the exterior? Study.the nephridia and
see if you can make any clear statement about their shape

STU. IN ZOOL.—9Q
130 WORMS

and position. In the center is the intestine. Notice a large
fold of the intesine hanging from the dorsal side. This
is the typhlosole. Of what use is such a structure? Just
dorsal to the ventral bundle of longitudinal muscles may
be seen the nerve cord. Do you see nerves extending to
right and left of it? Just dorsal to the nerve cord and
ventral to the intestine is the ventral blood vessel. Make
a sketch of the crass section, showing all the parts studied.
- (10) Cut an earthworm in two, place the pieces in some
moist earth in a box. Keep moist, and see what becomes
of them.

The earthworm belongs to the class Annelida.

Economic VaLuE.—Every student should read Darwin’s
“Vegetable Mould” in connection with the study of the
earthworm. If we consider the vast work of mixing the
soil with subsoil, the opening of passages for water and
air, and the working over of minerals unfit for absorption
by plants, then we may have some slight idea of the inesti-
mable value of the earthworm to man.

THE NEREIS

The Nereis lives in burrows in sand on the seacoast near
low-water mark. In the breeding season it leaves its bur-
row and swims about.

(1) Note its color. Its length. Its shape. Are the
anterior and posterior ends alike? Tas it a dorsal and
a ventral side? Note the appendages along each side. Is
there a pair to each segment? They are called parapodia.
Cut off a parapodium close to the body and examine with
THE LEECH 131

a dissecting microscope. Notice the larger fleshy portion.
This is a branchia. What is it used for? On the dorsal
side of the branchia is a small projection called the dorsal
cirrus. Below the branchia are three sets of setae. What is
their use? Just below the last bunch of setae is another
cirrus called the ventral cirrus. Just beneath the ventral
parapodium may be seen the openings of the nephrida.
Draw (x4).

(2) Examine the anterior end of the body. Note the
prostomium. Does it project over the mouth? Notice the
slender projections from the front segment. These are
tentacles. How many pairs? What is their function? Note
the two fleshy projections. These are palpi.

(3) Do you find eyes? How many? Where are they?
Slit the worm open, beginning at the head, for seven or
eight segments. Note the large proboscis. This is now
folded in. It may be rolled inside out like the fingers of
a glove. Do this and note the two powerful jaws. Does
this suggest its kind of food? What is its food? Draw
proboscis showing all the parts,

THE LEECH

Leeches live in water. They may be found on the under-
side of old boards, rocks or other objects near the edges of
ponds and ditches.

(1) Examine a live leech. Note color. Is the color
the same all over the body?

(2) Has it organs of locomotion? Place one in water.
132 WORMS

Can it swim? How? Take it out of the water. Can it
move? How? Can it live out of water very long?

(3) Notice the sucker at the anterior end of the body.
Look in this sucker for the mouth. What is the sucker
used for? Has it another sucker? What is it used for?
Do you find an anus?

(4) This animal is called a blood sucker. Why?

(5) Draw the entire animal, ventral view. In what
respects is it like the earthworm? How does it differ
externally? Draw (x2).

A PLANARIAN WORM

Planaria are usually abundant in fresh water ponds or
lagoons at all times of the year. They may be found crawl-
ing over water plants such as philotria, chara, pondscum,
etc. Pull these plants up with a hook and place them in
jars in the laboratory. Soon the sides and the top of the
vessel will be covered with planarian worms.

(2) Examine a living animal in water under compound
microscope. Note its color. Is the color the same on both
sides? Why? Is this of any advantage to the animal? Has
it an anterior and a posterior end? A dorsal and a ventral
side? Describe fully its shape. Is its shape adapted to its
mode of life? How? Look on the dorsal front end for
eyes. How many? Color? Examine the ventral side as the
worm crawls over the glass vessel. Do you find a mouth?
Where is it situated? How does the worm move? How
does it hold fast to an object? Notice its slimy feel. Make
a sketch (4).
THE LIVER FLUKE 133

(3) Place the animal on a slide and put a cover glass
over it in order to flatten it. Back of the middle portion
look for a cylindrical muscular body. This is the pharynx,
which connects with the mouth by a very short esophagus.
The pharynx can be protruded through the mouth. Do you
find a digestive tract leading from the pharynx? Trace it
to the anterior and posterior parts of the body. How
many main pouches has it? Has it an opening to the ex-
terior? How does it get rid of indigestible food material?

(4) This peculiar arrangement of the alimentary tract
suggested the name of the order, Triclada, to which Pla-
naria belong. What does the word mean? Draw, showing
points mentioned (Xs).

(5) Look underneath the eyespots for a light-colored
ganglionic mass, the brain. How many parts to it? Are
there nerve cords arising from it? How many? Draw.

(6) With the high power examine the margin of the
animal for cilia. Do you find any?

(7) Cut a Planarian in two and place the two pieces in
a tumbler of water. Examine every day, and note what
becomes of them.

Planaria belong to the class Turbellaria.

THE LIVER FLUKE

SuccESsTIONS FoR CoLLEcTING.—(1) The Liver Fluke,
Distomum, inhabits the larger bile ducts of the sheep,
where it lives upon the biliary matter. This part of the
sheep’s liver may be obtained from the slaughter house,
the bile ducts opened and the contents scraped out into
134 WORMS

water. The worms may be cleaned by placing the contents
in a warm normal salt solution.

(2) Specimens may also be obtained from the lungs or
the urinary bladder of the frog if the above source is net
convenient. #

(3) To mount Distomum, place the worms between two
cover glasses on a slide; leave in ninety per cent. alcohol for
twenty-four hours; stain faintly in borax -carmine, and
mount in balsam.

OBSERVATION.—(1) Examine a living worm under the
compound microscope. Do you find the anterior and pos-
terior ends? Dorsal and ventral sides? Give reasons for
your answers. Is it colored? Why? What gives it its
color? Has the surrounding bile a tendency to color it?
Describe fully its shape. Does its shape suit its mode of
life?

(2) Has it eyes? Why? Examine the anterior end,
Here is situated the anterior oral sucker, in the center of
which is the mouth. Do you find any other suckers? What
are they used for? The mouth leads into a thick muscular
pharynx lying just behind. That part of the alimentary
tract lying just behind the pharynx is called the esophagus.
Trace the remainder of the-alimentary tract. How many
branches? Are there any external openings? Compare the
alimentary tract with that of the Planaria.

(3) At the posterior end may be seen the excretory pore
and by careful observation the excretory tube may be traced
forward from it for a short distance. Draw the entire worm,
showing points mentioned.

State resemblances and differences between Distomum
and Planaria.
THE TAPEWORM 135

DEVELOPMENT.—(1) The rediae, one of the stages of
development of the Fluke, may be found in the liver of
the common pondsnail, Limnoea. Break the shell of the
snail and remove the animal. Place the body of the snail
in a shallow dish of water, and with the aid of the dissect-

-ing microscope pick the liver to pieces with dissecting
needles. This will probably free the rediae.

Note their size and shape. Do you find a mouth? A
pharynx? Anintestine? Eyes? Do they need eyes? Draw
(X Io).

(2) Do you find germ cells, or young rediae inside the
animal? Draw.

When we find an animal living upon another, deriving its
nourishment from the latter, the former is called a parasite
and the latter its host. Explain how this applies in case of

the snail and the fluke.

Notz.—This animal has a very interesting life history, which may
be worked out by the students from references or given by the
teacher in a lecture.

THE TAPEWORM

(1) The Tapeworm is found in the alimentary canal of
the rat, the cat, the dog, the rabbit, and many other verte-
brates, including man. Sufficient supply for class use may
generally be obtained by killing a dog or a cat and looking
at once for tapeworms. Open the intestine for one or two
feet, beginning at the stomach. Scrape the wall of the in-
testine closely so as to secure the heads which are buried
in the tissue of the canal. They may be kept alive for
136 WORMS

several days in common water to which a little white of egg
has been added.

(2) Examine the Tapeworm for dorsal and ventral
sides; anterior and posterior ends. Has it any color? If
not, why?

(3) Examine the head (Scolex). Do you find anything
by which it may attach itself to the intestinal wall? What
is the nature of the attaching organ? Do you find a mouth?
Has it an alimentary tract? If not, how does it secure its
food? Has it organs of locomotion? Does it need any?
Is the worm segmented? Each division is called a pro-
glottid. Are the proglottids all alike in shape and size?
Can a proglottid live free from the rest of the animal?
Try it.

(4) Just back of the scolex is the neck. Is it segmented?
Trace a worm from the head backward, noting differences
in segmentation and size of proglottids.

In what respects is the Tapeworm like Planaria and Dis-
tomum? How does it differ?

Tapeworms belong to the order Cestoda.

Note.—Both Trematoda and Cestoda have interesting life his-
tories which should receive considerable attention on account of
economic and medicinal reasons.

CrassiFicaTion.—The following table will give an idea of the
relationships of the common animals of this branch.
1. Class PLATYHELMINTHES.

1. Turbellaria. Planaria.

2. Trematoda. Fluke.

3. Cestoda. Tapeworm.
2. Class NEMATHELMINTHES.

1. Nematoda. Trichina.

2. Acanthocephala. Hook-headed worms, parasites.
CLASSIFICATION 137

3. Class ANNELIDA .
1. Subclass Cuartopopa.—Metamerism usually well marked; with
dorsal and ventral rows of setae along the sides of the body.
1. Order PotycHarta.—Marine forms; with the setae usually
upon lateral lobes of the body (parapodia).
1. Suborder ARCHIANNELIDA.—Without parapodia.
2. Suborder Errantia.—Elongated swimming or creeping

forms; metameres more or less similar............... Nereis.
3. Suborder SEpENTARIA.—Usually tubicolous; anterior meta-
meres more or less different from the rest........... Serpula,

II. Order OxtcocHarta.—Aquatic or terrestrial forms; with setae,
but without parapodia; hermaphroditic.

i. Suborder NamomorpHa.—For the most part aquatic; fre-
quently reproducing nonsexually; nephridia serve as repro-
AUGHVE MAUCES? ciesraete ss Hodeens Seis ae Aa AEN Oe ESS Nais.

2. Suborder LumpricomorpHa.—For the most part terres-

trial; not reproducing nonsexually; special reproductive ducts.

Earthworm.

II. Subclass Hrruprinea.—Metamerism well marked; without setae;
with anterior and posterior suckers.

1. Order GNATHOBDELLIDAE.—Mouth with three more or less well

developed teeth; pharynx not protrusible.............. Leech,

2. Order RHYNCHOBDELLIDAE.— Without teeth and with protusible

Phar yax .ccaccaoesd cv eee eae See we Clepsine.

III. Subclass GepuHyrea.—Metamerism indistinct; without para-
podia.

1. Order EcutureAr.—With setae........... aiaina lasidie-ss Echruls.

2. Order SIPUNCULACEAE—Without setae........ Phascolosoma.
MOLLUSKS

THE FRESH WATER MUSSEL

Anodonta, or Unio

GENERAL SUGGESTIONS.—(1) The mussel is found in
all streains and lakes of this country, and is therefore an
easy specimen to procure. If it is desirable to use the com-
mon quahog (venus), which is for sale in the markets at
all seasons, the following directions with slight additions
about the orifices, incurrent and excurrent, will be found
applicable.

(2) Specimens may be obtained from the streams and
ponds with a rake or dredge of any kind that will reach
to the bottom of the water. At certain times they may be
found near the shore, and when the water has fallen con-
siderably they may be found in the mud and sand.

(4) If an aquarium, or a tub, be filled with water
and a bed of sand be put in the bottom, mussels may be
kept alive for an indefinite period.

(4) Have present during the study several shells that
may be made to fit together in the right order, and if pos-
sible other bivalve shells, as oyster, quahog, mya, and other
forms that may be convenient.

(5) The preserved material may be kept in seventy per

138
THE FRESH WATER MUSSEL 139

cent. alcohol or two per cent. formalin, but at least one
muscle should be cut and the liquid allowed to penetrate the
interior.

(6) It is desirable that the students go to the natural
habitat to collect the specimens if possible.

Tue EXTERNAL STRUCTURE.—(1) The Living Animal.
Study the animal in its natural surroundings. Note the
covering, the shell, and the tendency of the animal to keep
it shut so tight that nothing can enter between the margins.
Does it ever open the shell? Why does it? What makes it
close it? Note the feshlike fringe where the shell opens and
closes. Touch this fringe with a needle or scalpel. Is it
sensitive? Does the animal seem to have control over it?
What relation does it assume to the bottom of the water?
Watch for movment. Does it move on the sand or through
the sand? How is this movement accomplished ?

(2) The Shell. Hold the shell in your hand with the
narrow edge down and the beak, umbo, pointing from you.
The part on your right is the right side, the front is the
anterior end, and the top is the dorsal side. Where is the
left side? The ventral side? The posterior end? How
many parts has the shell? It is called a bivalve. Why?
Does it have bilateral symmetry? Select two shells that
fit together like the shells of the animal you have. Examine
umbo and the hinge on the dorsal side, the margin on the
ventral side. Is there an indication of an epidermal cover-
ing on the outside of the shell? Notice the lines on the
outside. What point do they seem to surround? Are they
lines of growth? Examine them carefully? How many?
Look at the one next the margin and compare its outline
with the margin. If the animal should add more to its
140 MOLLUSKS

shell, what would the present margin become? What has
each line of growth been? What does this suggest con-
cerning the past history of the animal? On the dorsal side
of the shell behind the umbone, look for the edge of the
shell. What color is the shell at the. union of the two
valves? Is it the same material as the other part of the
shell? This is the spring of the hinge. Draw outside of
the shell, and name all the parts you have found.

(3) Study the inside of the shell. Note the differences
between it and the outside. The inside is called peari.
Why? Observe the line parallel with the margin, the pallial
line. Note the hinge and the modification of the shell for it.
Can you find out now how the hinge works? Fit the parts of
the shell together and find of what use each part is. Draw
inside of shell. Break the shell across, or saw it, and note
its structure. Can you tell now how each line of growth
was added? When a line of growth is added is it added on
the margin only? Can you account for the position and
shape of the umbones? Draw a section of shell. What
is the composition of the shell? Drop a little weak hydro-
chloric acid on a piece of the shell and note what follows.
What does this show?

(4) The Body. (a) Open the shell by thrusting the scal-.
pel under the right valve at the anterior and posterior ends,
and severing the rigid, tense muscles. The shell now opens.
Note the mantle, a membraneous covering of the body. Is it
attached to the shell? Where? Is it the same thickness
throughout? Examine the margin of the mantle, and com-
pare it with the margin of the shell. Do you think there
is any connection between them? How is the shell formed?

(b) Follow the mantle carefully around to the posterior
.

THE FRESH WATER MUSSEL 141

end. Is the upper part still separate from the lower? Note
the method of union. Find two openings, or siphons. With
a needle or bristle trace the openings of each backward
toward the body. The water enters at the incurrent siphon,
bathes the gills, and passes out at the excurrent siphon.
Which is the incurrent orifice? Which the excurrent?

(c) The gills have perhaps already been observed lying
flatly on the body under the mantle. Observe them carefully.
What is their general appearance? How many on the right
side? Are they attached to one another? Can you find
out how the water which enters at the siphon reaches them?

Remove a piece of gill with the scissors and lay it on a
slide in water. With a needle try to find whether it is
single or double. What shape would a section across the
gills of one side be? Put a small piece under the micro-
scope and find the minute structure. The water tubes may
be seen, and if the specimen is fresh the action of the cilia
is also visible. Draw the structure as seen through the
microscope.

Under the gills may be seen the body. Follow it an-
teriorly and find the fleshy, muscular foot, and the labial
palpi surrounding the mouth. How many labial palpi?
Examine the mouth. Has it jaws or teeth? What kind of
food does the mussel eat?

InTERNAL STRUCTURE—(I) On the dorsal side near
the hinge the stringlike heart may be seen through the
thin mantle wall. Locate it carefully and then sever the
mantle wall and remove it from the body. This exposes
the ventricle of the heart with a tube, the intestine, running
through it. On either side of the heart find a white mem-
brane extending from the gills to the heart. This is the
142 MOLLUSKS

auricle, somewhat conical, with the small end at the heart.
Do you find its opening into the heart? The blood is gath-
ered into the auricle from the gills, thence to the ventricle,
where it is received and sent out mainly through an artery
leading forward toward the foot, from which it is distributed
through the body and returned to the gills. Has any other
animal you have studied a circulation like this? Draw dia-
gram of the circulatory system as it appears to you. Remove
the animal from the shell. Observe the large muscles at
anterior and posterior ends, the adductors, which hold the
valves of the shell together. Do you find other muscles at
the anterior end attached to the shell back of the anterior
muscle? These are the retractor muscles. What do they,
retract? Of what value are they in the movement of the
foot? Turn the animal over, fold back the mantle, and
make drawing as now exposed, showing and naming all the
parts studied.

(2) Using an alcoholic specimen, find the mouth, and
insert a bristle into it, and follow with the scalpel, cutting
from the outside. The alimentary canal is rather crooked,
but may be followed if care is used. Do you find the liver?
The kidneys? Follow the intestine through the heart and
find where it empties into the siphon. Which siphon does
it empty into? Draw digestive system.

(3) The nervous system is somewhat difficult to trace,
but the general plan may be worked out. It is best to use
alcoholic specimens for this work. The cerebral ganglia
may be found at the base of and between the labial palpi.
These nerves go to different parts of the body, and with
care nerve cords may be traced downward toward the foot
to a larger group of pedal ganglia located where the foot
THE FRESH WATER MUSSEL 143

joins the body a little back from the mouth. A nerve may
also be traced to the visceral or posterior ganglion, on the
under surface of the posterior adductor. Note the irregu-
larity in the plan of the nervous system. Draw nervous
system.

(4) The reproductive organs are found in the posterior
region on each side, and open into the gill cavity. The
eggs of the mussel are hatched in the gills and the young
mussels may be found there if the animal is studied at
the proper time. After awhile they pass out into the water
through the siphon.

SUMMARY.—(1) What are the advantages and disad-
vantages of a shell like that of the mussel? Can it be suc-
cessfully attacked by any animal that you know? What
is the origin of the pearl in the shell? The pearl of com-
merce is usually made by this or some other species of
bivalve when something of an irritating nature gets between
the shell and the mantle. Why does the animal deposit
pearl under such circumstances? Formerly pearls were all
obtained from pearl oyster, but recently many of con-
siderable value have been obtained from the mussels of
the rivers in the northern part of the United States.

(2) Compare an oyster shell with that of the mussel just
studied. Are the valves of the oyster alike? Does either
valve show signs of being attached to something? Since
it lives in the ocean, would the oyster need such support
more than the mussel? Why?

Oyster raising is a great industry in certain sheltered ,
places along the eastern coast of the United States. The
greatest menace to the oyster beds is the starfish, which
devours the young oysters.
144 MOLLUSKS

THE SNAIL
Limnaea or Physa

GENERAL SUGGESTIONS.—These animals may be found in
almost any lake or stream, and can therefore generally be ob-
tained fresh for study. They may be kept alive in water in
the laboratory for an indefinite period by keeping the water
fresh and providing for them cabbage leaves or other
plants suited to their taste. They may be killed extended
_ in warm water, and put in fifty per cent. to seventy per cent.
alcohol, or two per cent. to three per cent. formalin for
preservation.

THe ExtTerNAL Form.—(1) Study the living snail in
a glass jar. Note its extended body and the relation it
bears to the shell. Has it a distinct head? Do you find
eyes? Does the animal have vision? What seems to be
the use of the tentacles, or feelers? Observe the fleshy
foot. How does it use this for movement? Study the
mouth? Can you determine how it eats? Does it bite the
leaf on which it feeds? Does this animal have a mantle?
Where? Can you tell how it breathes? Do you find a
breathing pore? On a living animal note the method of
disappearing within the shell. Is the disappearance com-
plete enough to be of any advantage?

(2) The Shell. Is the shell in one piece, univalve, or
in two pieces, as the mussel? Find the apex (the pointed
end); the. aperture (the opening); and the /ip, or outer
edge of the aperture. Do you find lines of growth? Begin
with the lip and trace the lines of growth around as in the
bivalve? How does this shell differ from one valve of the
THE SNAIL 145

bivalve? How large was the animal when it began to build
this shell? The line around which the shell coils is called
the columella, and all the part included in the whorls is
called the spire. Draw shell.

(3) Take an alcoholic specimen and break away the
shell to expose the lower part of the body. Find the parts
noticed before, and further up notice the respiratory orifice.
What relation has it to the mantle? With a scalpel cut open
the orifice and find the structure of the interior? What
seems to be its origin and use? What is the advantage in
having it located at the edge of the shell?

(4) Find the mouth. Note its position, size and shape.
Cut open the flesh surrounding it and look for teeth. What
is the use of that ribbon-shaped tongue? Remove it entire
with the muscles at either end. It is called the radula, and
works by moving back and forth like a handsaw. Draw
entire radula with muscles. Put a piece of it under the
microscope and observe the teeth. Draw.

The systems of digestion and reproduction are situated
up in the spire of the shell, with openings near the mantle
rim.

REPRODUCTION.—The eggs are laid in thin transparent
capsules, and may be found in the aquarium where the
snails are kept for a short time. These may be studied
in a watch crystal under the low power of the microscope,
and their development watched from day to day. The
shell appears as a cap on a small matrix, and continues
to enlarge until it covers the animal, after which it coils
as the animal grows. Under the direction of the teacher
this life history of the snail becomes a very interesting and
profitable study.

STU. IN ZOOL.—IO
146 MOLLUSKS

Mussels and snails are the most common representatives
of the great Branch, Mollusks.

SumMary.—What special preparation is made by the
snail for its life in the water? Can a snail remain for an
indefinite period under water? What change in structure
would be necessary to enable the snail to breathe in water?
The gastropods that live in the sea have that specialization.

Land snails are used extensively for food, but water snails
are not generally considered edible.

Which has a stronger shell, a land or a pond snail? Can
you give a reason for this?

The cephalopods constitute another class of Mollusks.
They have arms, or tentacles, surrounding the head, and are
usually destitute of external shell except the Nautilus which
has a coiled, chambered shell.

Are the cephalapods which have no shell as able to pro-
tect themselves as shelled Mollusks? Is passive protec-
tion among animals as successful as active, aggressive pro-
tection? Give examples of each.

BrancH mMoLLusca.—Adapted from McMurricu.

I. Class AMPHINEURA.—Visceral hump not developed; bilaterally
symmetrical; shell represented by scattered spicules or by a series ©

of calcareous plates; anus terminal.
1. Order SoLenocastres.—Shell represented by scattered calcir-

COUS SPICES: co sicn cunieweredowsceveeaes ieiaecg cea wali Neomenia.
2. Order PotypLacopnora.—Shell formed by eight plates on dor-
Sal surtace Oh bod yiwceicans acide ionsmonmuceicdaw a Chiton.

II. Class Gastrropopa.—Visceral hump usually well developed;
body asymmetrical; shell univalved and usually spirally coiled,
sometimes absent; anus not terminal.

1. Order ProsopraAncuiA.—Ctenidia present, situated in front of
the heart; auricle in front of ventricle; mantle edge not fused
with body,
CLASSIFICATION 147

Dentition taenioglossate.

With creépitig: habity . .. ccsc cece eb ea siwenreeice e's Strombus.
With pelagic habit (Heteropoda)..........0.005 Atalanta.
Dentition rachiglossate. ......... teeseee. Murex, Buccinum.
Déntition:. toxiglossates scx.s% caenvoewatens te odes Conus.

2. Order. OPIsTHOBRANCHIA.—Ctenidia frequently absent, when
present behind the heart; auricle behind ventricle; mantle when
present not fused by its edges to body-wall; shell frequently

absent.
Mantle present (Tectibranchia).
Foot with broad flat sole; with creeping habit......... Bulla.
Foot with winglike parapodia, pelagic............. Pteropoda.
With shell (Thecosomata)..........0ceeceeeeeees Styliola.
Without shell (Gymnosomata)..........2..eeeeeeee Clione.
Mantle not developed (Nudibranchia).........000cee eens Doris.

3. Order Pu_tmMonata.—Ctenidia wanting; mantle fused by its
edges to body-wall; terristrial or aquatic.

Eyes at base of tentacles (Basommatophora)...... Pond Snails.
Eyes at tip of tentacles................. Land Snails and Slugs.
IlI. Class ScarHoropa.—Visceral hump developed; bilaterally sym-
metrical; shell cylindrical, open at both ends......... Dentalium,

IV. Class LAMELLIERANCHIA or PELECyPopA.—Visceral hump not
developed; bilaterally symmetrical; mantle forms two lateral
folds; shell bivalved; anus terminal.

I. Order Protroprancuia.—Gill a true ctenidium; pleural gan-

glia not united to cerebral............... 0. eee ee eee eee Nucula.
2.. Order Firrprancnia.—Gill filaments elongated and bent up-
wards at ends; cerebral and pleural ganglia fused..... Mytilus.

3. Order PsEupOLAMELLIBRANCHIA.—Gill filaments turned up at
ends and with interlamellar junctions; cerebral and pleural
wane ba. UNiled 25). c0u aqcieei te dy wie teahemoa te AALS nat Oyster.

4. Order EvLaMELiipraNcuta.—Gill filaments united to form a
platelike gill; cerebral and pleural ganglia united.

Venus (Quahog).

5. Order SeprreraAncuta—Gill reduced to a muscular perforated
septum between the mantle and suprabranchial chambers.

, : Cuspidarta.
148 MOLLUSKS

Heart with two auricles; two nephridia............. Haliotis.
Heart with a single auricle and a single nephridium.

V. Class CEPHALOPoDA.— Visceral hump developed; bilaterally sym-
metrical; mantle a circular fold; foot (propodium and mesopo-
dium) forming armlike structures provided with suckers and sur-
rounding the mouth.

1. Order TrerraprancHia.—With four ctenidia and with external
chambered shell. c:.4%0sss0ceuuesandav sees ees tea teres Nautilus.
2. Order DrpraANcHIA.—With two ctenidia; shell if external not
chambered, usually internal.
With eight arms to foot (Octopoda)...... Octopus (Devil Fish).
With ten arms to foot (Decapoda)........... Loligo (Squid).
VERTEBRATES

THE FISH
Perca sp.

[Note.—These directions with but slight alterations will answer
for the study of any fish in the markets.]

EXTERNAL MorpuoLocy.—(1) Straighten the fish out
in the dissecting pan and measure its longitudinal and lat-
eral axes. How does the dorsal differ from the ventral
side? How is the head joined to the body? How does the
right side differ from the left? Animals that have the right
and left sides alike are said to be bilaterally symmetrical.
Has the fish perfect bilateral symmetry?

(2) How many fins are there? How are they arranged
with reference to one another? The fins at the anterior
end on the side are the pectoral fins. Examine one care-
fully. Of what does it seem to be composed? The spines
that run through it are called rays. Are all the rays bony?
Examine a piece that is not bony through the microscope,
low power.

How is the fin attached to the body? Are all the fins
attached in the same way?

Draw pectoral fin (2).

149
150 VERTEBRATES

Back of the pectoral fins on the ventral side find a second
pair, the ventral fins. Examine them and compare with the
pectoral fins.. Are they separated or attached on the ven-
tral side?

Compare these two pairs of fins to the upper and lower

‘limbs of a person. Back of the ventral fins is found the anal

fin. Study it and compare it with the others. With refer-
ence to the right and left sides, where is it?

Do you find a fin on the dorsal side? Note its shape and
position. It is the dorsal fin. Is it made of hard or soft
spines? Are the rays segmented? How is it attached to
the body? On the posterior end of the fish, find the caudal
fin. Note its structure and compare it with the others.
How is it attached to the body? What motions has it? Are
the lobes equal or unequal?

(3) Examine the covering of the body. Is it like any
covering yet studied? Take out one of the scales, examine
it where it was attached, and examine the skin at the point
where it was removed. Does it look anything like the scales
on the wing of the butterfly? Note the shape and size of the
scales at the different parts of the body. Do the fins and head

“ have scales? Scrape carefully both sides of a scale and place

it under the low power of the microscope. What is its struc-
ture? Has it grown out from the body like a feather? Do
you think it has had a rapid growth? Make a drawing of a
scale (10). If the scale is round it is called cycloid, if
it is toothed it is ctenoid.

(4) Do you notice spots of coloring in different parts
of the body? Is the coloring on the outer parts of the scales
or on the skin under the scales? These spots are pigment
cells and are simply bundles of coloring matter. Can you
THE FISH 151

determine their shape? Are they the same color in all
parts of the body? Do the fins have pigment?

(5) Find the lateral line on each side extending nearly
the entire length of the fish. Is it on the scales, in them,
or under them on the body? Remove one of the scales along
this line and examine. Insert a needle in the place to see -
if the line is continuous. What is its function?

(6) Study the skin on the head next to the mouth.
Compare it with the skin on the other parts of the body.
Observe the covering of the inside of the mouth. How does
it differ from that on the outside?

Do you find teeth? Where are they located? Do they
have a regular arrangement? Study the shape, size and
firmness of attachment of a tooth. Compare it with a scale.

Pull the lower jaw down; this will draw out the bones of
the upper jaw the premavillary bones. Study their shape,
size and attachment, both at the top and at the bottom.

Draw a premaxillary bone (4).

Behind the premaxillaries are the bones of the maxillary
proper. Observe their shape and note how they fit the pre-
maxillary. The lower jaw is composed of the submaxillary
bones which are similar to the lower jaw bones of other
animals.

Do you find teeth on the upper jaw? On the lower?
Look in the upper part of the mouth for teeth. If teeth are
present there they are situated on the vomer. Find the
shape and size of this bone.

Notice the covering of the tongue. Rub the finger over
it to ascertain the nature of the covering. Notice the
covering on different parts to find the variation of the
papillae, or taste bulbs. Do you think a fish can taste?
152 . VERTEBRATES

Where is the tongue attached? For what is it used?

(7) Note the location, size and color of the eyes. Are
they simple or compound? Do you find eyelids? Can a
living fish change the direction of its vision? How many
nostrils? Are they connected with each other or with the
mouth? Probe with bristle to find out.

(8) Lift up the gill cover, operculum, which lies flat on
the surface of the body in front of the pectoral fin. What is
the nature of the gill cover? How many bones in it? What
is its covering? Of what use is it?

Look just under the gill cover for a membrane which
lies close to the edge of the cover and is attached to it fur-
ther back. How does this membrane compare with a fin?
This is the branchiostegal membrane.

(9) Beneath the branchiostegal membrane are the red
gills. Raise them with the needle. How many? How
attached? Are they separate from one another? Note
shape of each. Note that the gill consists of the bony frame-
work, or arch, the filaments on the posterior edge, and the
gillrakers on the anterior side. How do the filaments and
the rakers differ from one another? Open the mouth and
depress the tongue. How does it affect the gills? What
do you think about the principal uses of the gill rakers? Of
the filaments ?

Explain the process of passing water through the gills of
the living fish.

Remove the first gill below the operculum by loosening
it carefully at the ends. Is it fastened by a true joint or
is it merely a continuation of the arch into the framework
of the body? Study the filaments. What gives them their
red color? Pick out a single filament. Is its color as red
THE FISH 153

as before? Look up next to the arch for a blood vessel.
Is it an artery or a vein? How is the blood purified in the
gill? Study the filaments under the low power of the mi-
croscope and also under the high power. Make drawings
of each.

Draw entire gill (<2).

Look on the under side of the operculum for a red spot.
What do you think it is? Observe it closely, noting its
position, shape, color, etc. (This is not present in all fishes).
Do you think it is a rudimentary gill?

Draw a fish from the left side (X™%).

THE SYSTEMS OF THE VISCERAL Caviry.—(1) Hold the
fish in the left hand with the tail towards you and thrust
the point of one blade of the scissors through the body wall
between the ventral and the anal fins just in front of the
anus (near the anal fin), and cut forward to the ventral
fins. Look carefully at the organs within; cut upward
toward the dorsal region of the fish as far as the abdominal
cavity extends being especially careful not to cut anything
but the body wall, as the air bladder lies in this part of
the body. Now cut forward to a point a little above the pec-
toral fin. Turn the flaps forward or cut them off, and note
the silvery membrane, the peritoneum, lining these flaps.

In the front part of the body cavity is a reddish or brown-
ish mass, the liver. Find the hepatic vein passing forward
from the liver through the thin partition in front. How
many lobes to the liver? Turn it aside and find under it
a greenish or yellowish sac, the gall sac. This sac contains
a secretion of the liver called bile. With a needle find how
the gall sac is connected with the liver. Can you find an
opening of the gall sac into the stomach? Into the intes-
154 VERTEBRATES

tine? What use has the bile?

(2) Lay the fish on the right side and turn the liver
downward gently tearing away its threadlike attachments.
This uncovers a pinkish sac, the stomach. Pass a probe
back into the stomach through the mouth. Note its shape
and relation to the intestine. When the intestine comes
out of the front end of the stomach, it is said to be caecal. Is
the stomach of this fish caecal? Do you know of any ad-
vantage this may be?

Observe the intestine as it leaves the stomach. How
does it compare with the stomach in size? As you follow
it down does it get larger or smaller?

(3) In many fishes, there are near this point of union
of stomach and intestine several wormlike branches matted
together. These are pyloric cacca. How many? How
arranged?

(4) Trace the intestine to its external opening, the
anus, and notice the thin membrane by which it is held in
place. That is the mesentery; observe blood vessels in it.
Find a small, deep red body near the intestine, the spleen.

Draw entire alimentary canal (x1).

(5) In this intestinal cavity, you have probably already
seen the reproductive organs. These organs vary in size
with the season of the year and consist of one structure
in the female and two in the male. Examine these as to
size, color and composition. In the female search for a small
tube, the oviduct, leading from the larger mass, the ovary.
Where does it lead? In the male search for an opening
from each of the lobes, or spermaries which unite into a
tube or duct, the vas deferens as before. Find its place of
opening.
THE FISH 155

Draw reproductive organs of the specimen that you have
(Xt).

(6) If the fish is studied during the spawning season,
the entire body cavity of the female will be filled with eggs.
The ovaries will then have to be removed before studying
the alimentary canal. In this case the reproductive organs
should be studied first.

(7) Back of these and above, is the urinary bladder;
a sinall, pink sac. In the upper part of the body cavity is
the air bladder. Make a diagrammatic drawing of the organs
above noted, showing position. Look closely to sce if there
is any connection between the air bladder and the stomach.
The air bladder is supposed to have originated from a fold
in the stomach or some part of the alimentary canal.
Scrape away the peritoneum and note the thin wall of the
air bladder. Do you see blood vessels in it? Remove the
air bladder. Of what use is it?

(8) Above the air bladder find the dark red kidneys.
Trace one of the kidneys to its termination in the urinary
bladder. Remove all the organs studied, except kidneys.
Draw.

(9) Return to the partition between the body cavities.
Notice again the gathering of the blood in the hepatic veins.
Cut carefully through it to see the heart. Remove the peri-
cardial membrane out to the sides. The red angular portion
of the heart lying hindermost is the ventricle; the darker,
more irregular portion lying (when in natural position)
above the ventricle, is the auricle. The larger blood cavity
back of the auricle, is the venous sinus, and the light colored
body in front of the ventricle is the arterial bulb. This nar-
- rows forward into an artery which branches, one branch
156 VERTEBRATES

going to each gill. After passing through the gills they
reunite to form the dorsal aorta which passes backward just
beneath the spinal column, and after going over the entire
body returns to the gills. This is called a single circulation.
Draw heart (3). Make a diagram of the circulatory
systein.

(10) Open the mouth. See the thin membrane form-
ing the floor of the mouth on each side of the tongue. Cut
through this thin membrane close to the inner border of the
lower jaw. Continue the cutting backward on each side
of the gill cover and the branchiostegal membrane and
wholly separate them. Turn back this flap and again ex-
amine the gill. Note the joints in the gill arches. Where
the gills unite above and below are the pharyngeal teeth.
The bones supporting these teeth are the pharyngeal bones.
They represent a fifth gill arch. Where is the gill?

(11) Examine the Nervous System.

a. With a scalpel open the skull from the dorsal side.
Note the successive coverings of the cranium (1) a tough
skin, (2) a cartilege, thicker, (3) a gray soft membrane
of cellular tissue, still thicker. After removing the last the
brain is exposed. Observe the color and relative size of
parts.

Notice the general shape and structure of the brain. How
many lobes do you find? Are the lobes in pairs?

Trace the brain back to the spinal cord, the white exten-
sion from the base of the brain.

Observe the largest lobes of the brain. These are the
optic lobes. What shape are they?

In front of these are the cerebral lobes called cerebral
hemispheres. Note their shape, size, location, etc. Lift
THE FISH 157

these up carefully at the end and find the small olfactory
lobes, from which small nerve cords may be traced, toward
the nostrils.

b. Back of the optic lobes is the cerebellum. Note its
size, shape and location in socket. The enlargement back
of this has important work of its own to accomplish and is
known as the medulla oblongata. Draw brains (x4).

c. The nerves to the eye, optic nerves, may now be seen
by lifting up the olfactory and the optic lobes. How do they
appear at the base of the lobes? How many nerves go out
from the brain? Trace the nerve to the eye (cut out the skull
where necessary). Does the nerve branch before leaving the
eye? Remove the eye from its socket and notice the muscles
attached. Are they arranged in pairs? How many?

d. Dissect the eye from the front. Cut the cornea, or
front part, at one side and allow the thin aqueous humor to
run out. What is the use of this humor? Do you think
it could help vision in any way? With the scissors remove
all of the cornea. What is now exposed? With a needle
lift up this curtain, the iris. How thick is it? What is its
color? What is the opening called? What is meant by the
color of the eye in any animal? Look closely around the
edge to see if there is any increase in thickness.

Remove the iris by cutting around the eye next to the
outer wall. Back of the pupil find a thickened ball of trans-
parent matter suspended in a transparent liquid mass. This
is the crystalline lens suspended in the vitreous humor, of
which it is a specialized part.

Remove the crystalline lens and lay it on a piece of news-
paper. Can you see the letters through it? How does it
affect them?
158 VERTEBRATES,

In the same manner put some of the vitreous humor on
a printed page. How does it affect the appearance of the
page?

Return to the eye and observe the inside of the ball.
Find a filmy gray mass on a black coat. This is the expan-
sion of the optic nerve, called the retina, over the black cho-
roid coat of the eye. Do you find these two coats all over
the eyeball? Stick the needle from the outside through the
optic nerve into the inside. Where does it penetrate the
choroid coat? Scrape the black coating off of the interior
of the eye and see if there is anything left. This coat is
tough and durable and gives shape to the eye. It is the
sclerotic coat. Make a large diagram showing a section of
the eye from the front to the rear, including all of the parts
studied.

THE SKELETON.—(1) With a scalpel cut down by the
side of the dorsal fin to the ribs. Remove the flesh from
both sides of the fish from the head to the caudal fin.

Note the arrangement of the muscles under the skin
and the position of the small bones. Are the spines of the
dorsal fin attached to the central back bone, or skeletal axis?
Are the ventral and pectoral fins attached to the backbone?

(2) The bones to which the pectoral fins are attached
form a ring around the body called pectoral, or shoulder
girdle. Are these bones attached on the dorsal side? On
the ventral? What is the advantage of this girdle?

(3) Do you find a similar girdle at the ventral fins?
Make out its parts as before. This is the pelvic girdle.

After cleaning away the entire skeleton remove a vertebra
from the spinal column about half way between the pectoral
and the ventral fins.
THE FISH 159

Note the main part, the centrum, and the processes ex-
tending above and below. Above the centrum find a cavity
formed by two spines which grow together. This cavity
is called the neural arch. What do you find in it?

(4) Below the centrum are the ribs branching out so
as to form an arch. This is called the haemal arch because
the main artery of the body runs down the vertebral column
in it. Draw an end view of this vertebra.

(5) Remove a vertebra with its processes from the
column behind the anal fin. Look carefully for the two
arches. Draw (X2).

(6) These two cavities are in the main the same in all
vertebrates. The neural cavity contains the spinal cord and
is enlarged to give place to the brain, while the haemal
cavity is enlarged into the visceral cavity which contains the
heart and alimentary canal.

Make a sketch of the skeleton of the fish showing the
location of the parts studied.

ReEpropucTiIon.—The eggs of fishes are called spawn and
are deposited usually once each year. The fish generally
seeks a secluded spot in which to place the eggs, but when
they are hatched or before, they are used for food by other
fishes or even by the one that laid them. To offset this de-
struction a fish sometimes lays thousands of eggs.

(2) Some of the food fishes from the ocean as cod,
herring, salmon, .often go many miles up the river to spawn.
These are breathers of salt water at all other times, and
will die if placed in fresh water at any other time than
during the spawning season.

Some of the eels, a class of vertebrates lower than fishes,
after hatching, go up the rivers and creeks for hundreds
160 VERTEBRATES,

of miles from the ocean and are oftentimes two years old
or more when they reach the ocean. Small eels are found
in nearly all the streams tributary to the Mississippi river.

SumMary.—(1) Watch a fish in water. Can it turn its
eyes? Can it lower and raise itself in the water? Can it
swim in a definite straight line? Observe the use that it
makes of its fins. When the fish is swimming slowly does
it use the same method as when moving rapidly? Of what
use is the dorsal fin? The anal? Of what use are so many
fine bones found in many fishes?

(2) Does a fish swim with the current or against it?
If it should go down a stream which direction must its
head bef Why?

(3) What constitutes the principal food of fishes? In
order to catch a fish what kind of bait must be used? Can
the same bait be used for all fishes? Can a fish be deceived
with things that are not food? How does that deception
take place? What is a game fish?

(4) How do fishes spend the winter? Can they be
caught in the winter? How? What is the source of oxy-
gen that the fish gets from the water? Could fishes live in
places where the water is frozen over all the year? Why?

CLASSIFICATION.—(1) Notice that the fish has disclosed
an entirely new structure to us. As in the arthropods the
nervous system extends along the longitudinal axis, but
instead of lying down on the ventral skeleton, it lies on the
dorsal side and is held up by a succession of large bones
articulating with one another so as to form a strong frame-
work, or backbone. This framework forms a support for all
the organs of the body, and to it are attached bones which
form the internal skeleton.
THE FROG 161

The neural arch is enlarged in the head to form the skull
for the brain while the Aaemal arch is enlarged below to
hold the vital organs. Animals with these characteristics
are called vertebrates.

(2) The class Pisces, or fishes, occupies a median posi-
tion between the lowest and highest classes of this branch.
The principal subclasses are as follows:

(1). Selachians — fishes with cartilaginous skeletons. Examples,
sharks and rays.

(2). Ganoids— fishes with cartilaginous and bony skeletons, and
usually having ganoid scales. Example, garpikes.

(3). Teliosts—fishes with skeletons composed aitogether of
bony matter and having cycloid or ctenoid scales. Examples, all
common food fishes.

(3) Read about the various food fishes, the manner
of catching, preparing, and using them. For what other
purpose are fishes used besides food?

Find out all you can about the fish industry.

(4) In order that we may understand the position of
fishes in the branch vertebrates, the classes are given below:

(1). Tunicates. 2. Lancelets. (3). Lampreys. (4). Fishes.
(5). Frogs. (6). Reptiles. (7). Birds. (8). Mammals.

THE FROG.

Rana sp.

[Note.—If the living specimen cannot be obtained nearly all of
the following questions can be answered from an alcoholic speci-
men.]

GENERAL SuGcEsTIONS.—(1I) The frog is the most com-
mon and best known form of the Amphibians. It is harm-

less and is always interesting to the observer. Specimens for
STU. IN ZOOL.—II
162 VERTEBRATES

study can be obtained at almost all times from April to De-
cember, and while the structure may be studied at any time,
it is desirable to study the development in the spring, when
the eggs may be easily obtained and observed in process of
change. There should be if possible at least three speci-
mens for each student and at the beginning of the study
one should be prepared for the study of the skeleton. If
the teacher has a microtome, much interest may be aroused
from the study of the egg in different stages of develop-
ment. Frogs may be kept for an indefinite period by feed-
ing them on small water animals. They are especially
fond of crayfish, but care must be observed to keep the
larger frogs separate from the smaller, as they do not hesi-
tate to eat a smaller one of their species.

(1) Where are frogs most abundant? When danger ap-
proaches what protection do they seek? Why? Cana frog
remain under water for an indefinite period? Why? What
are its enemies on land? Does it find enemies in water also?

(2) Notice the covering. Is the frog moist after it has
been removed from the water for sometime? Is this an
advantage to the frog? Can you find out whether the
moisture comes from the body or the air? Study closely
the color of the dorsal covering. Is it the same in all frogs?

ExtTerNAL Morpuotocy.—l. Tue Livinc SpecIMEN.—
Is it the same in the same frog at all times? Can you think
of any advantage in the coloration as you see it now? De-
scribe the surrounding conditions suitable to the color of
the frog you have before you. If it changes describe the
probable cause for such change. Observe the color of the
lower surface. What apparent difference is there in the
colors of the upper and lower surfaces? Notice on the
THE FROG 163

sides how they grade into each other. Is the color of the
lower surface the same in all frogs? Does it change as does
the color of the upper surface?

(3) Observe the frog in a sitting posture. Note the
position of the front limbs, and also the hind limbs. Note
the disposition of the toes of both front and hind feet. Ob-
serve the well defined hump on the back. Pass the fingers
down the back and see what makes the hump. Is it similar
to the hump on the back of a cat in a sitting posture?

(4) Notice the general shape of the head. Is it joined
toa neck? Observe and describe the articulation of the head
with the body and the motions resulting from such articu-
lation. Note the position and shape of the eyes. Discuss
these items with reference to the safety of the animal.
Have the eyes eyebrows or eyelids? Touch an eye with
the finger or a pencil. What follows? Describe the eye
cover. It is called the mctitating membrane. Do other ani-
mals have such a membrane? Compare the frog’s eye and
the human eye in this particular. Notice the throat, nos-
trils, and the sides of the body. Can you detect the process
of respiration? Describe the process as it appears from
this view. What do the movements of the nostrils and throat
indicate? Look over the body for indications of heart
action. How does it compare with your own pulse?

(5) See the frog jump and study the process of move-
ment. Does it jump straight forward or at an angle?
Is there any advantage in this? Is the body adapted for such
a movement? In what ways? Watch the swimming pro-
cess. How do the movements of the legs compare in the
two methods of locomotion? Is the body adapted for swim-
ming? In what ways?
164 VERTEBRATES

EXTERNAL Form.—(1) In the chloroformed specimen
notice the general shape of the body and compare it with
that of the fish and insect.

Observe the divisions of the body into head, thorax and
limbs; with the fingers try to determine where the bones
are and thus trace the main features of the skeleton. Has
ita tail? Describe briefly the general plan of the framework.

(2) Study the head. Note the appearance of the dor-
sal side of the head. Find the nostrils, anterior nares;
note their lining, color and size. Find the ears, tympanic
membranes; study their size, shape and markings. Be-
tween and below the eyes, find a round spot, the brow spot
or pineal eye. Note its location between the eyes and the
nose. Look carefully for eyelids. Do you find the external
parts of the eye similar to those of the fish? Draw the
posterior of the head (x2).

(3) Open the mouth as wide as possible; study the
tongue, noting its size, shape in front and back, its point
of attachment and the freedom of motion possible to it.
What use is made of this free motion of the tongue? Is
there anything else about the tongue that will help in catch-
ing prey?

Remove the tongue and study its surface. Do you find
papillae or tastc bulbs? Does there seem to be a regularity
about the furrows? Observe the upper part or roof of the
mouth. Do you find a soft palate, the tonsils? Describe
what you find and compare the tongue and roof with like
parts of the mouth of the fish. Draw the tongue from the
top (3) and make a diagrammatic section from the side
showing its attachments to the bottom. Study the jaws;
note shape, size and movement. Do you find teeth in both
THE FROG 165

jaws? Where? Of what value are the teeth? Does the
frog masticate its food? The back part of the mouth, the
region of the throat, is caled the pharynx. Pass a bristle
into the nostrils and see where it enters the mouth. Make
an opening in the tympanic membrane and insert a bristle
through the mouth. This is the eustachian tube. With
the bristle find an opening into the esophagus and a narrow
opening at the front into the bronchial tube. Make a list of
the openings that communicate with the pharynx and state
briefly the use of each.

This prepares us for a study of those systems that are
centered in the protected thoracic cavity.

INTERNAL StTRucTURE.—I. Tue THoracic Caviry.—(1)
It is well to dissect the frog under water or in a very weak
solution of formalin. Pin the frog securely on the dorsal side.
With scissors or scalpel cut along the midventral line sev-
ering the thin outer skin from the posterior end of the body
to the mouth. At right angles to this line cut on both sides
under the front limbs, turn the flaps back as far as possible
and cut them off, thus exposing the body wall, the abdom-
inal muscles. Note the arrangement of muscular tissue and
follow them both ways to their places of attachment. What
effect would their contraction have? What position would
that give the body? This muscle is called rectus abdomin-
alis. Note the broad fan-shaped muscle running from the
central portion of the breast bone to the front limb. It is
called the pectoralis. What is ‘the function of this muscle?
How is its work performed? Look in the muscular walls
for evidences of circulation of blood. Follow the blood ves-
sels as far as youcan. Do you find many blood vessels going
to the surface? Of what use can they be at the surface?
166 VERTEBRATES,

Draw this view, showing the muscles and blood vessels.

(2) Open the muscular walls along the mid-ventral
line from the posterior end to the shoulder girdle being
careful not to injure the soft breast bone. Cut across near
the middle on both sides and turn back the flaps thus expos-
ing the vital organs. Do you find the peritoneum?

II. Tue Dicestive System.—(1) Open the mouth and
pass a probe through the esophagus into the stomach. Push
the lobes of the liver aside and study the stomach. Note
its shape, location, size and color. Compare it with the
stomach of the fish. Is it caecal? Carefully trace the in-
testine from the stomach down to the anus. In the first
fold find a pale V-shaped mass, the pancreas. What is the
function of the pancreas? Note the difference between
the small and the large intestine and observe the enlarge-
ment, the cloaca, above the anal opening. Draw the digestive
organs, including the liver and esophagus.

(2) Study the liver. How many lobes? Do you find
the gall bladder? Where? Describe it. Trace the gall duct
from the liver to the intestine. Squeeze out the gall into
the intestine. Find the spleen, a dark red body in the mes-
entery near the large intestine. Is it connected in any way
with the intestine?

III. THe Orcans or Crrcutation.—(1) The heart is
found above the liver. Note its shape and position. Com-
pare it with the heart of the fish. The lower pointed part
is the ventricular portion, the upper part is the auricular
portion. Do these portions appear to be further divided?
Study the blood vessels at the auricular end of the heart.
The firmer ones are arteries and the flabby ones, the veins.
Note the large arterial trunk extending upward and sub-
THE FROG 167

dividing. Can you tell which division of the heart this
comes from? This arterial trunk is called the aorta. Find
its point of division, from which two branches (right and
left carotid) go to each side. Dissect away carefully the
surrounding tissues and disclose the divisions of each branch.
Where does the first branch leave the main artery? Where
does it seem to go? It is called the anterior carotid and
supplies the head. Follow the artery along to the next
branch, where it divides going to the lungs and the skin.
What is the office of this blood vessel? Is there a reason
for its going to the skin? Does this help to explain why
the frog can stay so long under water? Trace the third
artery, noting its anterior and posterior divisions. Where
does the anterior division go? Trace the posterior division
back to the formation of the large dorsal artery by uniting
with the corresponding branch of the other side.

(2) Follow the dorsal aorta back. Does it give off
branches? Where? What is the object of each? Follow
it down to the posterior end, and note its separation into
two divisions, the iliac arteries, which go to the legs.

(3) Trace the veins back toward the heart. Do you
find a corresponding vein for each artery? Do you find a
dorsal vein in close proximity to the dorsal aorta? Can
you trace the ventral blood vessel that was seen before the
opening of the body wall, back to the dorsal vein? Study
closely the circulation of the kidneys. From what vessel
does the blood which enters the kidney come? To which one
does it go after circulating through the kidneys? The cir-
culation through the kidneys is called the renal circulation.
Trace the vein formed from both kidneys forward to the
liver and notice the additions made to it from the mesenteries,
168 VERTEBRATES,

This is the portal vein. Trace the veins back into the mes-
enteries and make out their connection with the intestines.
This is the portal circulation which carries most of the
digested food, as new blood, into the regular channels of
the circulation. Follow this large blood vessel into the
dorsal vein, now the postcaval, and into the right auricle
of the heart. Lift the apex of the heart and see the large
veins, the precaval, entering the same auricle from the an-
terior part of the body.

\4) Find if you can a blood vessel to the left side.
Trace it back to the lung. Is it divided? You have already
found the method of supplying the lungs with blood, now
find the passage back to the heart. Compare this method
of oxygenating the blood with that of the fish. Make a
diagrammatic drawing of the entire circulation.

(5) Remove the heart and study it. The membraneous
covering is called the pericardium. Remove it and study
the form, shape, and general structure of the heart. Note
the number and location of the openings into the heart
and the aortic arch going from the heart.

Draw the heart (2).

Cut the heart from right to left exposing the inner cham-
bers. How many? The upper ones are the right and
left auricles, the lower one the ventricle. Note the struc-
ture of each and explain how the work of the heart is ex-
pedited by the structure. Study the valves at the base of the
auricles and explain their use. Compare the heart with
that of the fish. Make an enlarged drawing of the inner
view of the heart.

(6) What is the condition of the blood when it flows
into the right auricle? What is its condition when it emp-
THE FROG 169

ties into the left auricle? What is its condition when it
leaves the ventricle? Does this circulation of impure blood
affect the temperature of the body? How? What is a
cold blooded animal?

(7) Slightly chloroform a frog and tie the toes apart
on a notched board so that the web may be placed on the
stage of the microscope. Under the microscope notice the
blood vessels and the biood moving in them. Do you see
the arteries and capillaries? Can you distinguish between
arteries and veins? Do you see corpuscles in the blood?
Draw what you see much enlarged. Increase the amount
of chloroform until life is extinct and open the body as be-
fore. The heart will probably be still pulsating. Watch
the movements. Circulation of blood in capillaries may be
plainly seen also in the tail of the tadpole.

(8) Remove a drop of blood and mount it on a slide.
Notice the pale red circular disklike bodies, the corpuscles,
and the fluid, plasma, engulfing them. Do you find also
irregular white masses? These are white blood corpuscles
and are really living cells, similar in some respects to amoeba,
which live in the blood and have an aimless uncertain mo-
ton. Draw red and white corpuscles.

(9) The circulation of the kidneys has been described.
Remove from the body, the alimentary canal, the liver and
lungs, and expose the kidneys and the reproductive organs.
Trace the urinary tube, the ureter, from the kidneys down to
the cloaca. Draw the urinary system. What is the office
of the urinary system?

IV. Repropuctive System.—Look close to the dorsal
side for reproductive bodies; in the male these are testes,
rounded, somewhat yellowish bodies; and folded or lobed
170 VERTEBRATES

ovaries in the female. Trace the connection of each of these
with other systems of the body, and with the cloaca. Find
the oviducts, irregular, somewhat convoluted tubes through
which the eggs pass to the cloaca. Is this connected with
the ovaries? If not how do the eggs reach the ovaries in
passing out of the body?

V. Respiratory SysteM.—(1) Remove the lungs from
the body, following them up to the mouth and being careful
not to injure the larynx. Notice how the larynx fits into the
V-shaped hyoid cartilage. Draw outer view of lungs.

(2) Open lungs and note the structure. Can you trace
the plan of circulation in the walls of the cells or chambers?
How is the blood aérated? Have you studied another
method of cleansing blood in the frog? Compare the pro-
cesses of respiration through the skin and through the
lungs. Do you see anything about the circulatory and res-
piratory systems to make the frog cold blooded and slug-
gish?

VI. Nervous System.—(1) After removing the ab-
dominal viscera just referred to, there may be seen white
nervous cords on the dorsal side. Observe them closely.
Are they arranged in pairs? Trace them from their origin
in the vertebral column to the various parts of the body
to which they go. Note the difference in size. Do they go
singly to the body? A union of two or more nerves forms
a plexus. How many do you find? One near the posterior
end is called the sciatic plexus. Trace the nerves to their
union into the sciatic nerve which supplies the legs. The
one at the front legs is called the brachial plexus. Begin-
ning with the nerve in front of the brachial plexus, count
the nerves toward the posterior end. They are known by
THE FROG 171

their position from the first, which is called the hypoglossal,
in order down to the tenth. What nerves form the brachial
plexus? Find the fourth, fifth and sixth. Of what nerves
is ‘the sciatic plexus made? Note the enlargements on the
nerves near the spinal column. Nerves coming from the
spinal cord are called spinal nerves. Turn the animal on
the dorsal side and with the scalpel lay bare the spinal cord
and the nerves just observed leading out from it. Do the
nerves come out by one root? Do you find a swelling on
the nerve just as it leaves the spinal cord? Draw the spinal
system of nerves, showing what you saw on both sides.
The brain may be exposed by cutting into the soft bone
covering it. Remove the bony covering from the cervical
vertebra to the front of the skull. Find the tough mem-
brane surrounding the brain just under the skull, the dura
mater. Remove this and find another softer membrane
closely enveloping the skull, the pia mater. Do you find
these coverings on the spinal cord also?

(2) The lobes of the brain are now exposed. Compare
the different parts with those of the fish, in location, name,
and size. Beginning with the anterior portion find the
olfactory lobes, almost hidden by the central hemispheres.
Behind the cerebrum find the pineal body, which in some
reptiles supplies a nerve to the pineal eye before noted.
What does this fact suggest to you? Find next the optic
lobes and trace the nerves to the eyes. What are the
nerves called?

(3) Find next the cerébellum and the medulla oblongata,
Note the division of the brain into halves. What is such
symmetry called? Why? How do the different parts com-
pare with those of the fish? Draw the dorsal view of the
172 VERTEBRATES

brain (X2). Turn the brain to one side, cut the nerves
that become visible on the under side, and sever the cord
below the medulla. The nerves that go out from the lower
surface are cranial nerves. The olfactory and optic nerves
have been noted, the others supply sensory nerves to the
organs of hearing, taste and touch; and motion to the
different movable parts of the head, and to the heart, lungs,
etc. Draw ventral view (2).

(4) Examine the eye. Find the cornea, the iris, the
pupil, and the optic nerve. Do you find a crystalline lens?
Do you find the different coats, the sclerotic and the choroid?
Compare with the eye of the fish. Make a diagram showing
the structure of the eye.

(5) Study the ear. Examine the membrane, the tym-
panum, and remove it. Look carefully beneath it for the
labyrinth. Trace the membranes back, find the shape and
arrangement of the tube and if possible find the auditory
nerve at the end. Draw a diagram of the section of the ear.

VII. Tue SxeLeton.—(1) For this study it is prefer-
able to take a fresh specimen or one kept in weak alcohol
or formalin. The flesh should be carefully removed with
the scalpel and the bones allowed to remain at for least
forty-eight hours in weak potassium hydrate. This will
enable one to remove the flesh and leave the bones attached
by the ligaments.

(2) Note the general framework of the skeleton; the
head, the spinal column, the shoulder girdle and fore limbs,
the pelvic girdle and hind limbs.

(3) Tur Heap.—Note the general shape and size com-
pared with the framework. Note the size and position of
the upper and lower jaws, the mavillaries. Study the mode
THE FROG 173

of attachment of the lower jaw to skull. Look again for
teeth on the jaws.

Make out the following bones of the skull:

a. Beginning with the front of the skull, the one at the
top is the premavillary, back of this are the bones of the
upper jaw, the maxillary, and in the angle of meeting of
the maxillaries two irregular bones, the vomers. Look on
the ventral side of each vomer. What do you find? Are
these teeth of any value to the frog?

b. Back of the vomers find the nasal bones which ex-
tend back to the angular, quadrilateral girdle bone or sphen-
ethmoid. From this the parieto-frontal bones extend to
the base of the skull. Notice how these bones form a bridge
from the maxillaries over the brain.

c. On the base of the skull find the prodtic bones leading
out on either side to the squamosal, a triangular hammer-
shaped bone which is connected with the maxillary bone
anteriorly by the pterygoid and posteriorly by a small bone,
the guadratojugal. Draw dorsal view of skull (X1).

d. On the under side of the skull find the large cross-
shaped bone, the parasphenoid, which forms the floor of
the cranium. From this bone the slender palatines extend
to the maxillaries on either side. Note how the skull is
composed partly of bone and partly of cartilage. How
does it compare with the skull of the young frog in this
respect? Do you suppose the skull of the young frog has
proportionately as much bone as the older one? Why?
What is the difference between cartilage and bone?

(4) Tue Sprnat Cotumn.—At the base of the skull
look for 2 large opening, the occipital foramen, through
which the spinal cord passes into the vertebral column.
174 VERTEBRATES

Find the vertebrae. How many? At the posterior end
find the peculiar flat branched bone, the uwrostyle. Separate
the fifth vertebra from the others and study the bone. Find
the main body or centrum, the neural arch through which -
the spinal cord passes, and the processes on either side.
How many processes are there, and of what value are they?
Compare the vertebrae with the corresponding bone of the
vertebral column of the fish. Draw lateral and end views.

(5) Tue Limps.—a. Study the shoulder or pectoral
girdle. Trace out the sternum, or breast bone, the flat shoul-
der blade, or scapula, the collar bone, or clavicle, and the
coracoid by which the pectoral arch is attached to the ster-
num. Note how the clavicle, scapula, and sternum are
braced with reference to one another. Draw the shoulder.

(6) Observe the bones of the fore arm. The humerus,
the long bone joined to the shoulder, the radius, the larger,
and the w/na, the smaller of the bones of the fore arm grown
together; the carpus, or wrist bones; the metacarpus, a
transverse row of cylindrical bones; the phalanges, or fin-
gers ending in the smaller tips of the digits. Draw arm.
Study the joints, move them back and forth to find the free-
dom of movement, and note the method of articulation.
Sever the tissue at the elbow joint and study it. Note the
white ligaments which are modified from the covering of
the bones. Study their attachment and the method of
crossing the joint. Are these ligaments elastic? Note the
modification of the bones at the joints. Of what value is
it? Note the covering of the bones at the ends. Of what
value is it?

Draw the joint showing the things referred to.

The joint at the shoulder is called a ball and socket joint;
THE FROG 175

the one at the elbow, a hinge joint; and the one at the wrist,
a compound joint. Describe the characteristics of each.

c. In the same way the bones of the hind limbs, or pel-
vic girdle, may be studied. Find the bones composing the
socket in the spinal column, the femur with the ball fitting
into it; the double bone, tibia and fibula, united but shown
by the grooves; the tarsus, metatarsus, and phalanges in
order similar to those of the fore limbs. Draw. Is the pel-
vic girdle an arch? Why do you think so? Draw it and
compare with the shoulder girdle.

CLASSIFICATION.—The position of the frog in the branch of ver-
tebrates is given in the study of fishes. It remains to give the class-
ification of the class Amphibians.

Class AMPHIBIA.

Body long, eel-like, with persistent gills.

Hind limbs absent................ Order Trachystomata (sirens).

Gills not persistent, gill openings usually absent.

Tail present, 4 appendages (rarely 2) present. Order Urodela.

(Salamanders).

Body short, larvae tailed, adult tailless, four limbs. Order Anura
(Frogs, toads).

Families of Anura.

1. Thoracic region capable of expansion.

a. Upper jaw toothless, toes webbed —terrestrial. Bufoni-
dae (toads).

b. Upper jaw with teeth, fingers and toes more or less dilated
at tips forming disk, order Arboreal. Hyledae (Tree frogs).

2. Thoracic region incapable of expansion.

Toes webbed and usually fingers, upper jaw containing teeth,
tympanum conspicuous — Family Ranidae (Frogs).

DEVELOPMENT.—The development of the frog is an easy
and interesting subject and should be watched by every stu-

dent. In the early spring the eggs may be obtained in
176 VERTEBRATES

almost any pond, and may be identified as small dark bodies
floating in a jellylike mass. They should be put in a shal-
low basin, in a warm room with plenty of sunlight in it, and
to insure growth the water should be changed every day.

If everything goes well the student may study the changes
that take place from the day the eggs are collected. -By
putting the eggs under a dissecting microscope or the low
power of the compound microscope, the student may see the
segmentation of the yolk, the expanding and extending of
the mass and finally the appearance of the head and tail of
the young frog, or tadpole. The animal now moves about
freely, breathes by external gills, and grows rapidly.

Study a specimen every day until the external gills give
way and the internal gills are used. Find how the water
reaches the internal gills. Study the structure of the gills
under the microscope and make drawings.

Note the appearance of the hind legs. Study their form.
Are they perfect when they first appear? Draw the animal
in this stage. Dissect to see the structure of the alimentary
canal and heart, and the relation of the gills to the heart.

When the front legs appear the gill opening closes.
Where do the front legs appear? What takes place then?
Do the young frogs spend all the time in water now? Do
they spend much of their time on land? What is the food
of a tadpole? Of a frog? Dissect the tadpole in which
the front legs have appeared. Do you find any change in
the digestive system? Study the structure of the lungs. Do
they seem to be related closely to the alimentary tract?
Do they seem to be folds in the pharynx? Draw. What
advantages does this change from water life to land life
bring? What disadvantages?
THE PIGEON 177

Make drawing of tadpole in various stages of develop-
ment.

SumMARy.—What are the principal changes in environ-
ment as the frog goes from the water life to the land life?
What are the changes of structure undergone to meet these
conditions? What are the advantages of the change to the
frog? What are the disadvantages? What does this change
suggest as to the past history of the frog?

THE PIGEON
Ectopistes migratorius

ExTERNAL MorpHoLtocy.—(1) The pigeon should be
killed with chloroform and the feathers removed from nearly
all of the body. Lay the specimen down with the head from
you and the ventral side up. Note the extension of the
vertebral column anteriorly forming the neck, and the short,
blunt extension of the vertebral column into the tail.

(2) Observe the shape, form and place of attachment
of the wings and legs. Move them to ascertain the range
of motion of each. How many principal segments in each?
Are the limbs especially modified? Explain. How many
toes? How located? Study the toes and their freedom of
motion. Are the feet webbed? What is the nature of the
pads? Of what use are they?

(3) Observe the size and shape of the liead and its at-
tachment to the neck. Turn it in various directions to test
its range of motion. Observe the nostrils. How many?
Where located? Do you find eyelids? How does a bird
wink its eye? Find on the inside lower corner a membrane,

STU. IN ZOOL.—12
178 VERTEBRATES

the nictitating membrane, which serves the purpose of a
third eyelid. Can you find a nictitating membrane in your
eye? Find the ears. Of what do they consist? Are they
protected? Open the mouth by pulling down the lower bill,
or mandible. Note the method of attachment to the head.
Is it attached directly or does it have another bone at the
point of union? Move it back and forth to test it. Is the
upper mandible movable? Grasp the base of it with the fin-
gers and attempt to move it up and down. Look in the
mouth. Do you find a lower and an upper jaw as in the
frog? Do you find any indication of teeth either above or
below? Observe the tongue. Can it be extended like the
tongue of the frog? Do you find any indication of nerves
of taste? Give reason for your answer.

(4) Study the covering of the body. Is there a covering
where the feathers have been removed? What is it? Study
one of the hairlike projections under the microscope. Draw
(X2). Scrape the skin gently with the scalpel, put a por-
tion of the material obtained under the low power of the
microscope. Compare it with the scales of the fish. Study
the various parts of the body. Is it covered entirely with
feathers? Locate carefully the feathered and unfeathered
areas. Is this feature an advantage to the bird? Study the
covering of the legs and feet. How does it compare with the
covering under the feet? How do the parts of this covering
join on the sides? Draw several of these plates showing this
union (4). Study the nails and the bill, What is their
method of union with the body? Do they grow out of the
body? How do they compare in color, texture and hard-
ness with the scales on the toes and legs? What seems to be
the special use of the nails?
THE PIGEON 179

(5) Remove a large feather from the wing and study it.

a. Notice the place on the wing from which it came.
Is the feather torn from the wing, or does there seem to be
a natural depression? Is there anything left in the depres-
sion? If so remove it and study it carefully to see if it
resembles any other part of the covering.

b. Study the lower part of the feather, the quill, Does
it show evidence of direct union with the flesh, or does it
seem to come out of a socket? Observe the point of the
quill. Does it have an opening in it? Is there any evidence
there of a direct connection with the body? Cut a section
of the quill and observe the interior. Do you think it grew
from the inside or the outside? How does the quill com-
pare with the other coverings of the body?

c. The remaining part of the feather consists of the
shaft, or rhachis, extending up the middle of the feather ; and
the vane, or flattened part, attached to the rhachis. Separate
the parts of the vane and note their attachment to the rha-
chis. Do they extend into the rhachis or do they come from
the epidermis only? What do you think is their origin?
Study the parts, or barbs of the vane. Why do they cling
together? If you pull them apart, do they return at once
to their former condition? Put a few of them under the
low power of the microscope. What do you find? The
small projections from the barbs are the barbules.

Draw several barbules enlarged.

Make a drawing of the entire feather (X34).

d. Look among the feathers for an undeveloped feather,
the “pinfeather.” Study its connection with the body. Has
the feather emerged? What do the walls seem to be com-
posed of? Cut across the pinfeather. What do you find
180 VERTEBRATES

on the inside? How does the feather grow? Where does
it get its nourishment? Does it have any direct communi-
cation with the blood in the body? What causes the dif-
ference in plumage in the different birds? Does the pin-
feather explain this? Returning to the original feather
now can you find any trace of the old pinfeather capsule
upon it? When do you think a feather stops growing?

e. How many different kinds of feathers do you find?
Those from the last segment of the wing are primary quills,
those on the next to the last segment are the secondary
quills, those at the tail are the rectrices, those covering the
bases of the quills are the coverts, and the remainder are
the contour feathers. Get one of each, put them in a group
and study their differences.

f. Make a list of the various kinds of covering found on
the bird.

InTERNAL Srructure.—I. The Bopy Watit.—(1) Ob-
serve the ridge on the ventral side and follow it backward
and forward to its limit. With the scalpel cut through the
skin on the right of this ridge and sever the flesh from the
hard portion. This bone is called the keel, or sternium.
Note its shape. Cut the flesh backward to the end of the
bone and pull it outward. This exposes two muscles. What
is their shape? What are their relative sizes? One is called
pectoralis major and the other, pectoralis minor. Can you
tell to which muscle each name belongs? How are the mus-
cles attached to the keel bone? Follow them up to the wing
and find how they are attached to the wing bone. Where
the muscle ends in a whitish tissue is it a part of the muscle
or something added to the muscle? This whitish substance
is called a. tendon. What seems to be its origin?
THE PIGEON ‘181

(2) Remove the muscles from both sides of the sternum
and expose the bones connecting it with the framework of
the body. Observe the union of these bones with the ster-
num. Is there a movable joint? Is there anything between
the bones at their union? What is it? These are the cora-
coid bones, and they unite with the scapulae which run back
over the ribs. Do you find another bone present in front
of these? Note its shape, length and way of attachment.
What name is generally applied to it? It is the clavicle
which in other vertebrates forms a principal part of the
shoulder girdle, but in the bird it is not as highly devel-
oped as the coracoid bones.

(3) Loosen the coracoid bones from the shoulder, cut
away the ribs from the side of the sternum and remove the

- sternum, the coracoids and the clavicles. This exposes the
internal organs. With the scissors cut the skin up to the
throat and spread it out on the sides.

II. Tse ViraL OrGANS OF THE VISCERAL Cavity.—
(1) Beginning with the head, find the opening at the back
of the mouth. Loosen the sides of the jaw, note the esopha-
gus, and follow it down the neck, loosening it from the sur-
roundings organs as you proceed. Running along by the
side of the esophagus will be found the trachea, or wind-
pipe, which may be separated from the esophagus and
studied apart.

(2) Is the esophagus the same size all the way down?
What is the object of the enlargement? What is it called?
What advantage does it give the bird? How does the bird
swallow? Can it swallow with head down? Why? Tie
a string tightly around the esophagus, behind the crop, cut
the esophagus in front of the string, and remove it. Ex-
182 VERTEBRATES

amine the contents of the crop. What do you find? What
does it show concerning the food of the pigeon?

(3) Observe the base of the tongue. Do you find
a bone there? What is its shape? Through an opening in
this, find the zrachea. Is it open or closed? In life is it
open? When the bird swallows its food, does it go di-
rectly into the esophagus or does it pass first over the
trachea? Do you see am apparatus there to prevent the
food from passing into the trachea? Insert a tube into
the trachea and inflate the lungs. Do the entire lungs
come up at cnce, or do they expand part at a time? What
part first? Observe the trachea from the throat down to
the lungs. Is it the same size all the way down? Where
is it largest? The enlargement at the top is called the
larynx, and the one just above the lungs is called the
syrinx. The latter is the place where the organ of voice
in birds is located. The divisions of the trachea are called
bronchi. Are they the same size?

(4) Study the pear-shaped organ, the heart. Carcfully
lift up the lobes of the lungs and see if there is any con-
nection between the lungs and the heart. Do you find
blood vessels running to and from the heart? How can
you tell which vessels run to the heart and which ones
run from the heart? Find the pulmonary artery and pulino-
nary vcin. Do you find the great aorta? Follow it as far
as you can, noting the branches that go out from it. Find
the venae cavae — the large veins that gather the blood from
all parts of the body, and bring it back to the heart. On
which side of the body is it? Why?

(5) With a small stout cord tie in two places each of
the vessels carrying blood to or from the heart, as far from
THE PIGEON 183

the heart as you can. Draw the cords tightly, and after a
secure knot is made, cut off the blood vessels between the
cords and remove the heart. Preserve the heart in alcohol
for further study.

(6) Remove the lungs and dissect them further. Follow
the bronchial tubes out in their subdivisions as far as pos-
sible. Do you see tubes other than bronchial tubes in
the lungs? What are they? (Blood vessels). How can
you tell them from bronchial tubes? Remove a small piece
of the lung and place it under the low power of the micro-
scope. From its appearance and from what you have found
out, of what do you think the lung is composed ?

(7) Study the alimentary canal. Trace the esophagus
down to the slightly dilated stomach. Observe the tube
closely to find traces of muscular bands or coats. Do you
find any such structure at the end where it has been cut off?

Below the stomach is the gizzard, the large rigid body
lying in the folds of the alimentary canal. Turn it to one
side. Where does the alimentary canal enter? Where does
it leave the gizzard? Is the gizzard caccal?

(8) The part of the alimentary canal lying just back
of the gizzard is the duodenum. In a fold of the duodenum
is the pancreas. What work is performed by the pancreas?
Where are the ducts leading into the intestine? The liver
has already been noticed perhaps. What part of the body
cavity does it occupy? Turn the lobes aside and find the
gall sac. What does it contain? Of what use is it? How
does this liquid get into the alimentary canal? Find two
ducts leading from the liver to the duodenum. Note the
folds in the intestine below the duodenum. How are they
held in that position? What is the nature of this mem-
184 VERTEBRATES

brane? What is it called? Observe the blood vessels in
it. Where are they smallest? Where largest? Where do
they carry the blood? These vessels unite in the portal
vein, which carries the absorbed food to the liver, from
whence it goes to the heart. Follow the alimentary canal
down to the cloaca, the enlargement at the anal portion. In
front of the cloaca is the rectum, which extends from the
small rectal glands to the cloaca, and in front of this extend-
ing to the duodenum is the small intestine.

Place the parts of the digestive system that have been
studied so that they can be seen and make a diagrammatic
drawing showing all in their proper relation.

(9) With a small cord tie the small intestine in front of
the rectum in two places and sever the canal between them.
Remove the alimentary canal. Cut off the gizzard and ex-
amine the arrangement of the muscles on the outside. The
hard, light-colored portion acts as a cartilage for the at-
tachment of muscles. How many muscles can you find
on the outside? Cut the gizzard across at right angles
to the edges. Note its internal structure. What do you find
in itr How does the pigeon masticate its food? Have
you found a similar contrivance in any other animal?

Draw cross section (1).

(10) The reproductive organs are found in the dorsal
side. The male is distinguished by two oval bodies, the
testes, and the female by an ovary which often has eggs
of different sizes in it. Sometimes these show all the
different stages of development. These reproductive or-
gans are connected with the cloaca by a duct, the oviduct
in the female, and the vas deferens in the male.

Draw reproductive organs (1).
THE PIGEON 185

Behind the reproductive organs, lying in the cavity of the
roof of the body, are found the soft kidneys. What is their
position? How many? How many divisions in each? Do
you find a duct leading from the kidneys? Where does it
go?

Draw kidneys (X1).

II. Ture Heart.—Cut open the pericardium if it has not
been already destroyed. Note the rough outside and the
soft inside enclosing a thin oily substance. This lubricates
the heart while it is engaged in its ceaseless work of. pump-
ing the blood through the body. Can you tell which is the
right and which is the left side of the heart? Lay the
heart down with the point toward you and the blood vessels
from you. Trace the line of fat around the upper part of
the heart. Above this are the auricles, small chambers with
flabby walls. Can you find blood vessels opening directly
into them? How many empty into each? Which side of
the heart is the hardest? Compress it with the fingers to
find out. The soft side is the right side and the hard, the
left. Lay the heart before you in its natural position and
draw (X2). Cut the end off about a half inch from
the point. Note the relative development of the right and
left ventricles. Why is this? Look at the upper part of the
heart. From which ventricle does the great aorta come?
From which does the pulmonary artery come?

The blood leaving the aorta is carried by the arteries to
the capillaries in all parts of the body and comes back
through the venae cavae. What ventricle sends it? What
auricle receives it? The blood leaving the pulmonary artery
is carried through the capillaries in the lungs and comes
back through the pulmonary veins. What ventricle sends
186 | VERTEBRATES

it? What auricle receives it? Through how many open-
ings? This is a double circulation. Are there any mark-
ings on the outside of the heart which show the boundaries
of the ventricles? Cut the heart through from right to left,
severing the auricles and ventricles. Note the openings be-
tween the auricles and ventricles. When the blood comes
into the left auricle, what hinders it from running into the
left ventricle if it be expanded? When the ventricle con-
tracts, what hinders the blood from going back into the
auricle? Look just below the auricle to find some walves
which are forced together in the contraction of the ventricle
and prevent this. Notice how they are anchored to the
walls of the ventricle. These are called the mitral, or bi-
cuspid valves. In like manner the valves on the right side
are called tricuspid valves. Can you give a reason for the
names? With a probe find where the blood leaves each of
the ventricles through the arteries? The blood goes rapidly
through the body and the temperature is eight or ten degrees
higher than in any other animal. The heat is made in the
capillaries, where the oxygen is used in burning up waste
tissue. Explain the process.

Draw the heart thus exposed (2).

Make an outline of the different systems and organs in the
visceral cavity. a

III. Tue SkeLEtoN.—(1) The skeleton may now be
stripped of all the flesh so that the bones may be studied.

(2) The shoulder girdle has already been found. Re-
move the last remaining bone, the scapula, with the wing.
Place it beside the coracoid and clavicle already removed
to see how the girdle is made to support the wing. Observe
the wing bone, the humerus, its shape, length, attachment
THE PIGEON 187

to the coracoid, and freedom of motion. Note the wing
bones, radius and ulia, which are below the humerus. Ob-
serve their form, size, relation to one another. Note the
peculiar extension of the ulna back of the joint. Of what
advantage is this? Below are found the carpus, metacarpus,
and phalanges, strangely modified into a hand in which the
phalanges are short and degenerated.

Draw bones of wing (XI).

(3) The pelvic girdle may be studied in the same way.
The bones of the leg are femur, tibia, tarsometatarsus and
phalanges. Do you see any indication of a fibula? Can
you find the place of union of the tarsus and metatarsus
to form the tarsometatarsus? How are the phalanges ar-
ranged? Make a drawing of leg (<4).

The bones forming the pelvic girdle are: (a) the acetabu-
lwm, which receives the head of the femur; (b) the ileum,
which extends a considerable length before and behind the
acetabulum; (c) the ischiui, projecting horizontally back-
ward from the acetabulum; (d) the pubis, which extends
downward and backward on the ischium. These bones are
very much modified to suit the peculiar structure and
habits of the bird. Study and explain the relation of the
habits of the bird to its structure.

(4) The spinal column may next be studied, begin-
ning at the head. Sever the head from the first vertebra
of the neck, being careful not to injure the bones. Note
that the spinal column consists of four regions: (a) the
cervical vertebrae, sixteen in number; (b) the thoracic, five
in number; (c) the sacrum, fourteen or fifteen vertebrae
fused together to support the ilium; (d) the caudal, four
or five free ones and a terminal pygostyle.
188 VERTEBRATES

Remove the eighth vertebra and study it separately. Note
the centrum, the neural arch, and the transverse processes,
which are really small ribs. The opening at the base trans-
mits the cervical artery. The other irregularities are called
cygapophyses. Of what use are they?

Draw end view (X2).

(5) The first vertebra next to the head is called the
atlas, and the second aats. Study their relation to one an-
other and how they fit together. Can you see why the
respective names were given? Have all the vertebrae true
ribs? Observe how the ribs project from the spinal column,
and also how they are supported.

(6) Study the skull. The opening into it from the spinal
column is the foramen magnum. The bones surrounding
this are the occipitals. The bar connecting the front with the
back part is the quadratojugal bar. At the back end of
this is the quadrate bone attaching the lower jaw to head.
The upper part of the skull is composed of the parietal,
the frontal and the nasal bones, ending in the premavillary,
or upper mandible.

Draw the under and upper surfaces of the skull.

IV. THe Nervous System.—(1) Cut off a portion of
the roof of the skull, being careful not to injure the eyes
or the internal parts. This exposes a portion of the brain
which is similar in appearance to the brains of the other
animals studied, but is more compact and fits its cavity
closer. Remove the surrounding bones and lay the brain
bare.

(2) Examine the surface of the brain. Can you name
the parts? How do the parts compare with the same parts
of the brain of the frog? Of the fish? What part is most
THE PIGEON 189

highly developed here? Find the pineal body (in the angle
between and behind the hemispheres), the optic lobes, the

olfactory lobes and the medulla oblongata. What are the
uses of each?

Draw dorsal view (x2).

(3) Cut the brain along the cavity between the hemi-
spheres, thus exposing the right and left halves. How
many cavities do you find? The front one is the third ven-
tricle, the next the Sylvian aqueduct, and the last, the
fourth ventricle.

Draw left half (x2).

(4) Trace the nerve to the eye. What do you find when
you trace it back to the brain? This crossing is the optic
chiasma. Remove part of the bone from around the eye
socket. Note the lining of the eye and the eyelids. Are
the eyelids movable? Are they both movable to the same
degree? Break away the bone until the muscles are ex-
posed. How many pairs of muscles? Can you find the
muscle of the nictitating membrane?

Dissect the eye. Do you find the parts of a perfect eye?
Describe each of the parts. What is the difference between
the iris of the fish and that of the bird? Can birds see
as well in the night as in the day? What structure of the
eye enables some birds to see better at night than others?

(5) Note the roots of the cranial nerves as they leave the
brain for different parts of the head. Do the places to
which they go suggest their function? Do you find nerves
leading off from the medulla oblongata and the spinal cord?
What are they called?

Conscious or Unconscious Activity.—(a) The or-
ganization of the nervous system of the pigeon, consisting
190 VERTEBRATES

of ganglia and nerve threads, is essentially the same as in
all of the other animals studied. The ganglion in the head
is called the brain, and is supposed to be the thought center,
but is not always the largest ganglion in the invertebrates.
The ganglia, composed of gray matter, are supposed to pro-
duce on irritation a certain nerve force which is conveyed
along the nerve threads like electricity along the telegraph
wire. In the higher vertebrates if the irritant is without the
nervous system, and more especially if it is without the body,
the force which originates in the small granglia is sent to-
ward the brain, and if it reaches it, produces a sensation. If
the nerve force is originated within the brain, as in thinking,
the force, if carried outward by the nerves to the muscles,
produces motion. Hence we see the connection between
sensation and motion. This is conscious activity.

(b) However, there are many activities that do not de-
pend upon the brain, but are carried on by the nerve cen-
ters below the brain, the principal one of which is the
medulla. The beating of the heart, the digestion of food,
and the secretion of fluids by glands are of this class. All
of the processes which are connected directly with the sus-
tenance of life are carried on without the brain, and in a
manner in which the animal is unconscious. There are
many kinds of unconscious activity some of which are
partly conscious. Do all animals have conscious activity?
Do all have unconscious activity?

V. Repropuction.— (1) The pigeon is reproduced
from eggs which are deposited in a nest carefully built in
some secure place, and are cared for by the mother pigeon
until they are hatched. The eggs of a hen will answer the
purpose for study quite as well as those of a pigeon.
THE PIGEON IgI

(2) Boil an egg about four minues, or until it is hard.
Note the outside covering first with the unaided eye, then
with the magnifying glass. What is the general shape of
the egg? What is the nature of the surface? Break the
eggshell and pick it off without injuring the membrane be-
neath. Study this membrane as you did the outer shell.
Does it have the same general appearance? Does it have
the same texture? Do you think this membrane has grown
to its present size? Has the shell grown, or was it merely
deposited? Cut the egg across at right angles to its longer
axis. What do you find in its composition? Draw (X%).

(3) After the egg is deposited it remains inert until
subjected constantly for a considerable time to a temperature
equal to that of the body of the bird. How is this secured?
When this condition is reached, the embryo which has al-
ready begun to grow, enlarges, using in the meantime the
yolk and the white for food, until finally it bursts the shell
and comes forth in ali respects like the adult except in size.
In its immature condition it is fed by food prepared by its
parents until it is able to select its own food.

(4) In the development of birds the egg during the
period of incubation passes through the fundamental process
of segmentation, as.do the eggs of all other animals. The
first layer of cells developed on the outside of the yolk
is called the blastula, or blastoderm, which, after folding
in at one end leads to the development of the three primitive
germ layers already referred to, the ectoderm, the mesoderm
and the endoderm (called by some authors, respectively,
epiblast, mesoblast and hypoblast).

From the ectoderm arise the cuticle and its modifications,
the entire nervous system, including the brain, spinal cord
19zZ VERTEBRATES

and nerves, parts of the eye and the bones of the internal
ear. From the mesoderm arise the muscular system, the
organs of the circulatory system, the bones of the skeleton
and the reproductive system. From the endoderm arise
the lining of the digestive tract, the liver and other glands,
and the lungs. Each part appears as an aggregation of
cells in its own particular location, and grows by further
development until it is complete and united with other de-
veloped organs around it. Sometime before the chick leaves
the egg the organs are all completed and in perfect working
order. When it leaves the egg it is essentially like the adult
form, which it becomes in a greater or less time by nutri-
tion and growth.

(5) The nesting of birds is a most interesting charac-
teristic and can be studied in the field with great profit. Do
all pigeons build nests alike? Do all sparrows? If condi-
tions should change, do you think the birds would change
their way of nest-buiding?

Hasits.—Why are pigeons usually found around barns
or cotes made for them? Are they ever found wild? Do
they migrate in the winter? Are they gregarious or soli-
tary? Are doves gregarious? Do doves migrate? Why do
some birds migrate? How do doves defend themselves
from their enemies? How do other birds defend them-
selves? What kind of food does the pigeon use? Do the
shapes of the bill and toes indicate any specialization for
food-getting ?

CLASsIFICATION.—The pigeon belongs to the great class, Aves,
which includes all living genera of birds and some of those found
fossil. The different orders of birds are classified mainly on the
CLASSIFICATION 193

structure of the bill and toes. The following classification is simple
and though old, will be found of value in the classroom.
I. Sternum smooth; wings rudimentary.
Subclass I, Ratitae. Ostriches.
II. Sternum keeled; wings well developed.
Subclass II, Carinatae. Doves.
Orders of Carinate Birds.
1. Wings small and short; diving birds.
Pygopodes. Penguins, grebes and loons.
2. Wings long, pointed; anterior toes webbed.
Longipennes. Petrels, Gulls and Terns.
3. Feet wholly webbed, including the inner toe.
Steganopodes. Pelicans and Cormorants.
4. Bill lamellate, 4. e., both mandibles with teethlike projections.
Lamellirostres. Ducks and Geese.
5. Waders; legs long, naked above heel, bill usually long and

SLEH OH ios dine netnde aise eases Grallatores. Cranes and Snipes.
6. Land birds; four toes, three in front, one behind, tibia often
Spurred iccaisian's Gallinae. Domestic Fowls, Quail and Grouse.

7. Toes alike, 6; bill horny and convex at tip.
Columbae. Pigeons and Doves.
8. Bill curved, hooked and large; feet large; not yoke-toed.
Raptores. Hawks and Owls.
9. Feet yoke-toed; bill stout, strongly hooked. .Psittaci. Parrots.
10. Toes in pairs, two in front, two behind; wings with ten

primaries....... iia une Ween away Picariae. Woodpeckers.
11. Perching and singing birds; feet adapted for grasping; hind
toe opposed to others............. Passeres. All common birds.

Following is a synopsis of the Families of Order Passeres from

Jordan’s Manual of the Vertebrates.

Families of Passeres.

A. Tarsus with its hinder edge rounded; encircled by a single
horny envelope divided into scutella anteriorly and on outer side.
this sometimes extending all round (though separated by a seam
along inner side), but often widely separated on inner side, or
behind, or both, the intervening space occupied by granular scales,
reticulations, or plain naked skin; musical apparatus imperfect;
STU. IN ZOOL.—1I3
194 VERTEBRATES

primaries 10, the first about as long as second. (Clamatores.)
B. Inner toe free at base from middle toe; tarsus not reticulate
behind; bill hooked at tip, with long rictal bristles.
Tyrannidae, The Flycatchers.
AA. Tarsus with its hinder edge compressed, forming a sharp,
nearly undivided ridge (except in the Larks, which may be known
by the long, nearly straight hind claw); musical apparatus highly
developed; primaries properly ten, but the first short, or spurious,
or sometimes rudimentary and misplaced, so that but nine are
evident, in which case the first developed primary is about as long
as second. (Oscines.)

C. Hinder edge of tarsus not compressed, rounded and scutel-
late like anterior edge; hind claw very long, straightish;
developed primaries 9............004- Alaudidae, The Larks.

CC. Hinder edge of tarsus compressed, forming a sharp ridge,
for the most part undivided.

D. Primaries apparently but 9 (the first minute and dis-
placed); the first developed (7. e. second) primary about as
long as the next; bill not hooked at tip.

E. Bill not fissirostral, the gape little longer than the
culmen; outer primary never twice as long as inner.
F. Bill * conirostral,” stout at base, with the commissure

forming a more or less distinct angle at base of bill,
“the corners of the mouth” drawn downward.
G. Bill rather long, often longer than head, without
notch at tip or bristles at the rictus.
Icteridae, American “Orioles,” and “Blackbirds.”
GG. Bill shorter than head, often notched near tip,
and usually with bristles at the rictus.
Fringillidae, The Finches.
FF. Bill not truly conirostral (the corners of the mouth
not evidently drawn downward).

H. Bill stout (conical in our species, the cutting
edge with one or more lobes or nicks near its
middle) ; nostrils placed high, exposed; (plumage
chiefly red or yellow, in our species).

Tanagridae, The Tanagers.
CLASSIFICATION 195

HH. Bill rather slender, not conical; angle of gonys
not before nostril.
I. Hind claw short and curved, mostly shorter
l than its toe; tertials not elongate, not nearly
reaching tips of primaries.
Mniotiltidae, The Warblers.
Il. Hind claw long and straightish, mostly longer
than it toe; tertials much elongate, nearly reach-
ing tips of primaries. .Motacillidae, The Wagtails.
EE. Bill fissirostral,— the culmen very short, the gape very
broad, its length more than twice the culmen; wings very
acute, the outer primary more than twice length of inner-
MOSE: dca vs Sag xatrarcnive sae% Hirundinidae. The Swallows.
DD. Primaries evidently ten, the first developed, but short,
rarely half the length of the next; (first primary obsolete
in some Vireos, known by the slightly hooked bill).
J. Tarsus distinctly scutellate.

K. Tarsus not longer than middle toe with
claw; bill short, depressed; (head crested;
tail tipped with yellow, in our species).

Ampelidae, The Chatterers.

KK. Tarsus longer than middle toe and claw
(or if not, other characters not as above).
L. Bill strongly hooked and toothed at tip,

somewhat like a hawk’s bill.
Laniidae, The Shrikes.
LL. Bill slightly hooked at tip; plumage
more or less olivaceous.
Vireonidae, The Vireos.
LLL. Bill not evidently hooked at tip.
M. Tail feathers stiff, pointed; bill de-

curved......... Certhiidae, The Creepers.
MM. Tail feathers more or less soft and
rounded.

N. Nasal feathers directed forwards,
usually covering the nostrils.
O. Large birds; (wing more than 4).
196 VERTEBRATES

Corvidae, The Crows and Jays.
OO. Birds of small size; (wing less
than 4).
P. Bill not notched.
Paridae, The Nuthatches and Tit-
mice.
PP. Bill notched toward the tip,
very slender.
Sylvidae, The Old World War-
blers.

NN. Nasal feathers erect or directed
backward, not covering nostrils; bill
rather slender, the culmen convex;
first primary not very short.

Troglodytidae, The Wrens and

Mocking Birds.
JJ. Tarsus booted, without distinct scutella ex-

cept near the base’ rictal bristles present.
Q. Birds of small size; (Wing
less than 3); young unspotted.
Sylvidae, The Old World War-
blers.
QQ. Birds of moderate size;
(wing more than 3); young
spotted.

Turdidae, The Thrushes.

SUMMARY.—Why is the normal temperature of the body
of a bird several degrees higher than that of any other
animal? Do you suppose it would be warmer if it were
stripped of its feathers? Does it hurt a goose to pluck its
feathers? What would become of the feathers if they were
not plucked?

Do you think birds are sensitive to pain? Do you think
the singing birds should be killed? Do you think wings
and bodies of birds are proper ornaments for hats?
THE PIGEON 197

How does the food of birds reach the blood? How does
the blood reach and become part of the tissue? How does
the tissue waste away and get out of the body?

What is the process of locomotion in birds? Is it any
harder for a bird to fly than it is for an insect? Why?
Can a bird move in the air without flapping its wings? Are
any of the birds awkward flyers? Is there any connection
between the keel and the flight of the bird? Why?

Make a list of the birds that migrate. At what time
of the year do they migrate? Why do they not all migrate?
Make a list of the singing birds and of the birds that do
not sing.

Are birds friends or enemies of insects? In what way
do they affect insects, and at what stages of development?

Are birds injurious or helpful to man? Should they be
protected by law?

Make a list of birds that are helpful to man, and also
a list of those that are injurious.

Investigate the following birds; find where each belongs
in the classification given, and also whether useful or in-
jurious to man:

Owls. Bluebird.
Kingbird. Swallow.
Jay. Warbler.
Crow. Lark.
Robin. Woodpecker.
Oriole. Thrush.
Phoebe. Pigeon.
Cuckoo, Goose (Wild).
Blackbird. Vireo.
Bobolink. Martin.
English Sparrow. Woodpecker.

Hawk.

Quail.
198 VERTEBRATES

THE RABBIT

Lepas sylvatius

GENERAL SuGGESTIONS.—The common rabbit is the most
satisfactory mammal to dissect, and hence this study is
introduced here. The directions will apply with but few
changes to the cat or dog. If the specimens can be obtained
alive without being wounded, they should be studied to
find out movements, favorite positions, and keenness of
eyesight and hearing.

Kill the specimen with chloroform or ether, and when it
is quite dead cut the left jugular vein to relieve the body of
a part of its blood. If the instructor so desires, the arteries
and veins may be injected, but very satisfactory work may
be done without injection.

I. Externay Features.—(1) What colors are found on
the body, and how are they distributed? What colors are
present when viewed from the front? From the rear? Of
what value to the animal is the white color of the tail?

Note the hair on the different portions of the body.
Where is it the longest? The thickest? Note the hair on
the face and the nostrils. Of what value are the bristles?
Are they all the same length? Look below the nostrils at
the parting of the lips. Of what value is it? Note the
location of the eyes and ears. Does this arrangement benefit
the animal?

Study the covering at the toes of the feet. Is it of any
value to the animal? How? How many toes on each foot?
Compare the claws of the front and hind feet. For what
are the claws used?
THE RABBIT 199

(2) Cut the skin around the neck just back of the
head, and pull it over the head. Is the skin the same thick-
ness on the dorsal and ventral sides? Why? Notice the
muscles running to the ears. Note how they meet on the
neck. To what are they attached? What motions have
the ears? Of what value are these movements? Notice
the ring of cartilage around each ear. Describe it. Re-
move the skin from the head. Do you find indications of
bilateral symmetry? What are they? Cut down through
the muscles and see if you find other indications of bilateral
symmetry.

(3) Remove the brain in the following manner; Insert
the bone forceps or scissors into the skull just over the base
of the ear and cut forward to a point between the eyes.
Cut from the base of the other ear in like manner to the
same point. Then cut across at the base of the skull and
remove the bone. If the cutting has been carefully done
the brain will be uninjured. Remove the remaining bone
at the base of the skull, exposing the medulla oblongata.
Cut the spinal cord just behind the medulla, lift brain
from back forward, cut the nerves as far from the brain
as you can, and finally remove the brain and put it in sixty
per cent. alcohol or in Mueller’s fluid. Put the brain aside
for future study. Observe the inside of the brain cavity.
Do you find joints? What kind? Compare with brain
cavity of frog and bird. Explain the differences.

(4) At the base of the skull note the articulation of
the first cervical vertebra, the atlas, with the two projec-
tions, the occipital condyles, of the skull. Twist the head
to find out the freedom of movement. Study the articula-
tion of the second cervical vertebra, the avis, with the first,
200 VERTEBRATES

What provision do they have for articulation on the ventral
side? On the dorsal? Twist the first vertebra on the
second. Do you find the “axis”? Is it attached to the
first or the second vertebra?

II. OrGANS oF THE THORACIC AND ABDOMINAL CAVITIES.
(1) Open the skin along the mid-ventral line extending
from the breast bone to the pelvic arch. Sever the skin for-
ward to the neck and remove the skin from the entire body.
Notice the blood supply to the skin in the region of the
fore limbs, and also in the region of the hind limbs. Is
the skin attached loosely or closely to the body? After
removing the skin, note its softness. Would it make good
fur? Why?

(2) Study the distribution of blood vessels in the su-
perficiai muscles of the body on both dorsal and ventral
sides. Make note of any peculiar or prominent vessels.

(3) Look for indications of bilateral symmetry on dor-
sal and ventral sides. If it is a female, count the mammary
glands on either side and note their location. Study the
muscles of the body as now exposed. Name as many as
you can from your knowledge of the muscles of the frog.
Do you find any which are not present in the frog? (See
page 165.)

(4) With a sharp scalpel open the abdominal wall from
the breast bone to the pelvic arch. Look for the lining
of the cavity. What is its nature? What is it called?
Note the general position of the abdominal viscera and
their method of folding. Do they seem to be segmented?
Of what use can that constricted form of intestine be?

(5) Sever the ribs by cutting the cartilaginous attach-
ment along the side of the sternum. Pull them slightly
THE RABBIT 201

apart. Find and notice position of the following things in
order: Lungs, heart, diaphragm, liver, stomach, and in-
testines. Make a diagram of all the organs exposed.

(6) Study the diaphragm. Note its structure in differ-
ent parts. What use is made of that peculiar arrangement
of muscular fibers? Is the liver attached to the diaphragm?
Describe the liver. How many lobes? Look under the
large lobe on the right hand side for a depression in which
is located the bile sac. Trace its duct down into the mesen-
teries below the liver. Note the shape, location, and size
of the stomach. Is it caecal? At the distal end of the
stomach find the duodenum which folds back behind the
stomach then runs forward again for some distance. Lift
the stomach lightly and study the mesenteries attached to
the concave side. Find the pancreas, a light pink, fat-
like mass in the mesenteries, in the fold of the duodenum.
Trace the duct from the liver to its entrance, about a third
of an inch from the origin of the duodenum. Look for
the duct of the pancreas further down, beyond the bend.

(7) Tie the esophagus tightly with a string just above
the stomach and cut it above where it is tied. Notice a
large blood vessel, which divides going to liver and stomach
at the base of liver. Cut the mesenteries near the stomach
and the duodenum, and gradually unfold and pull away
the alimentary tract. Sketch the stomach (x4). Follow
the duodenum until it passes insensibly into the small in-
testine and thence into the caecum, a large, constricted
body, which ends in a thick fingerlike tube called vermi-
form appendix. Note the circulatory vessels in the con-
striction of the caecum and their connections with the mes-
enteries. Measure the caecum. Note the entrance and the
202 VERTEBRATES

exit from it, and make a drawing of it (x%). From the
caecum onward the alimentary tract is called the large in-
testine. Note its sacculated form in the upper part, becom-
ing smoother in the lower. The lower part of the canal
is called the rectum. Measure the length of the entire ali-
mentary canal, approximating as nearly as possible the
length of the esophagus, and make a diagram showing and
naming the different parts of the entire system. Tie the
lower part of the alimentary canal and sever it at the anus.
Remove the canal, tie the duodenum in two places about
an inch apart. Cut out a small section between, and study
the structure of the canal. Find the outer serous coat, the
inner muscular ring, and the mucous lining. What use
has each? This illustrates the structure of the entire canal.
Draw an end view (X2). If alimentary canal were shorter,
how would it affect digestion? If longer? What then de-
stroys the bilaterality of the abdominal viscera? Make a
list of the parts of the alimentary canal, and give the prob-
able uses of each. (This item is optional and requires a
lecture by the teacher or the use of reference books on
physiology.)

(8) The alimentary canal having been removed, the
urinary and the reproductive systems are plainly shown.

(a) Ifthe specimen is a female, note the ovaries and the
oviducts converging toward the dorsal opening.

(b) If it is a male, find the festes and the vas deferens.

Find the kidneys in the dorsal part of the abdominal
cavity. Note their relative position. Are they opposite? Is
there any advantage in their arrangement? Remove the
fat from them and trace the urinary ducts down to the
bladder at the pelvic arch. Draw the renal and reproductive
THE RABBIT 203

systems, showing their relation. Tie the bladder at its
base and remove it, cutting behind the place tied.

(9) CircuLaTion AnD CircuLatory SysteM.—(a) Cut
the diaphragm away and study the heart. Where is it? Is
it an advantage to have it on the side rather than in the
middle part of the body? Note its shape and relative po-
sition with reference to lungs and esophagus.

(b) Note the large dark blood vessel, the vena cava,
extending from the liver across to the heart. Where does
it enter the heart? Lift up the lobes of the liver and trace
the vena cava back and find the hepatic vein running from
the liver into the vena cava. Look in the mesenteries which
have been cut from the stomach and intestines for a large
dark blood vessel which seems to be formed from the veins
returning from the alimentary canal. Trace it to the liver.
It is the portal vein. What does it contain besides inipure
blood? Trace the large vein backward and note the veins
coming from the kidneys, the renal veins, to the place where
the veins from the legs unite to form it. Do you notice any
sudden change of size? Where?

Trace the veins on the right side of the heart forward
toward the head. Do you find a union of two veins just
anterior to the heart? The vein from the head, the right
jugular, unites with the vein from the shoulder, the right
subclavian. The union of these forms the right anterior
vena cava. Trace it to the right auricle. On the left side
find a similar vessel, the left anterior vena cava, formed by
the union of the left jugular and the left subclavian veins,
and crosses at top of left lung, emptying into the right
auricle. On the left side find a similar vessel, the left an-
terior vena cava, formed by the union of the left jugular
204. VERTEBRATES

and the left subclavian veins, and crosses at top of left
lung, emptying into the right auricle. Make a diagram of
the venous circulation as now shown.

Follow the left jugular vein and find, near its entrance
into the vena cava, a large white blood vessel opening into
it. This is the thoracic duct, which contains a large part of
the drain of the body and the unassimilated food from the
intestines. Trace it back to the mesenteries below the liver.
It is the principal duct of a great system of drainage and
cleansing, which works over the partially waste matter and
part of the new food by passing it through glands called
lymphatic glands. The pink gland just anterior to the
heart, the thymus, is one of them. The circulation through
this cleansing system is known as the lymphatic circulation.

Find the dark blood vessel running from the heart to the
lungs. Where does it seem to leave the heart? It is called
the pulmonary artery. Find the place of division into right
and left pulmonary arteries. How many branches of these
arteries do you find in the lungs? Do you find returning
blood vessels from the lungs to the heart? They may be
distinguished in a specimen not injected, by a lighter color
and thinner walls. Trace these returning veins, pulmonary
veins, from both lungs into the heart. How many? Where
do they enter? Make a diagram of the circulation of the
blood in the lungs. What work is done by the lungs?

Tie the posterior vena cava between the heart and liver
in two places, about a half inch apart, and sever it between
the ties so as to prevent bleeding. In the same way tie the
vena cava above the kidneys. Remove the liver.

Carefully cut away the thymus gland from above the
heart and expose the arteries, which are more firm in tex-
THE RABBIT 205

ture and lighter in color than the veins. Find a large
curved blood vessel, aorta, coming from the heart and
curving back on the dorsal side. From what part of the
heart does it come? On top of the arch a short distance
from the heart find a large branch turning to the right of
the animal, the innominate artery. This soon divides, send-
ing one branch, the Jet carotid, to the left side of the neck
and head, and divides into the right subclavian, going to the
right side and shoulder; and also the right carotid, going
to the right side of the neck and head. Trace these as far
as you can without mutilating the specimen. Returning to
the aorta, the left subclavian artery leaves the arch beyond
the innominate artery and goes to the left shoulder. Trace
it as far as you can. Just beyond the left subclavian on
the aorta there arises the first pair of intercostal arteries.
Others arise between each pair of ribs. From the sub-
clavian arteries on either side, an artery is seen running
posteriorly under the ribs. These are the mammary ar-
teries, and they return to the mammary veins which were
seen on the outside of the muscular wall.

(f) Trace the aorta, which is called the dorsal artery,
backward, lifting the left lung, to the posterior part of the
body. Just back of the diaphragm it gives off the coelic
artery, which further divides, giving one branch to the liver
and one to the stomach. Further back it again divides, fur-
nishing the renal arteries to the kidneys, the femoral ar-
teries to the hind legs, and the Jambar arteries, which go
dorsally to furnish blood to the strong muscles of the back.
Trace these arteries as far as you can conveniently, and
make a diagram representing the arterial circulation as you
have it exposed from the left side of the animal’s heart.
206 VERTEBRATES

(g) Make a tabulated list of the blood vessels on the left
side and those on the right side of the heart. Tabulate
the similarities and differences between the veins and ar-
teries. How does the blood reach the arteries from the
veins?

(h) Cut the veins and arteries as far from the heart as
you can and remove the heart with the delicate pericardium
that surrounds it. What blood vessels can you trace from
and into the heart? Make a drawing from the ventral
side showing all the tubes at the top of the auricles. Make
a diagrammatic drawing of the entire circulatory system.

(i) Dissect the heart as in the pigeon. (See page 185.)
Find all the valves. Make out their uses. Draw interior
view (X4).

(10) THe Resprratory SystEM.— (a) Above the
lungs notice the trachea. Remove carefully the enveloping
membrane, exposing the trachea from the lungs to the
mouth. Are there muscles connected with it? What is
its position with reference to the esophagus? Is it open
or collapsed? Why? Trace the trachea down to the lungs,
and note its divisions into the right and left bronchi. Do
these tubes further divide? How many lobes to the lungs?
Lift the lungs and sever them and the trachael tube from
the esophagus, being careful not to cut the lung tissue.
Study the muscles at the top of the trachea which sur-
round the /arynx. Remove the lungs and the trachea, being
careful not to injure the bone at the base of the tongue.
Spread out the lobes of the lungs and make a diagram of
the ventral view.

(b) With a blowpipe inflate the lungs through the
larynx. Note the amount of expansion.
THE RABBIT 207

(c) Remove a ring of the trachea about half way down.
Is it the same structure throughout? Draw the end view.
What is the advantage of this structure? Of what value
is the cartilage in the respiratory system? Cut a piece of
the lung tissue as thin as possible (with microtome, if there
is one in the laboratory; if not, with razor) and study under
the low power of the microscope. Do you find both air tubes
and blood tubes? Explain. Draw.

(11) Vocat Corps anp Voice.—(a) Study the larynx.
Note its situation in the throat. From the ventral side
note the epiglottis, a movable membraneous cartilage at the
top. Behind is the thyroid, a heavy circular cartilage ex-
tending almost around, On the ventral side find the cri-
coid, a flat thick cartilage in between the ends of the thyroid;
and behind are the lobes of the arytenoid cartilage. Draw
dorsal and ventral views. of larynx.

(b) Look down into the larynx and see the voice box,
in which can be distinguished a pair of membraneous vocal
cords. Where are they attached? How are they tight-
ened and relaxed? Locate the muscles that do this. For
what are these cords used? Make diagram representing
them open and also closed. Compare voice box with that
of bird. (See page 182.)

III. Tue Nervous System.—(1) Remove the kid-
neys and the muscles of the interior of the back, looking
for white-cords, or nerves, which may be found near the
yertebral column. Do you find a nerve cord on either side
with occasional attachments to the spinal cord? These
constitute the sympathetic nervous system. It is connected
with ganglia in different parts of the body, the largest of
which is the solar plexus in the region of the stomach,
208 VERTEBRATES

What is the use of the sympathetic nervous system?
(2) Just under the femoral artery of the hind leg find

the sciatic nerve, which may be traced into the leg and
also back to the vertebral colunin. What is the office of
the sciatic nerve? Do you suppose the rabbit ever has
an attack of sciatica? Look at the vertebral column on
both outside and inside and find the spinal nerves. How
many? To what parts do they go? Make a diagram of
the spinal system as you have found it.

(3) Remove the brain from alcohol and lay it down
with dorsal side up. The following parts are easily dis-
tinguished: The cerebral hemispheres, beneath which are
the olfactory lobes, and back of which is the cerebellum,
and the medulla oblongata, tapering posteriorly to the spinal
cord. Between the cerebrum and the cerebellum may be
seen the pineal body and the optic lobes. Draw dorsal view
of brain (X1). From the ventral side of the brain may
be seen the twelve pairs of cranial nerves, which may be
more easily found by reference to the drawing below. Find
the roots of each of these, and tabulate them, giving the
uses of each.

Compare the brain of the rabbit with that of the pigeon.
(See page 180.)

If the brain has been removed carefully, the ventral side
will resemble the cut on the following page. On the right
side of the cut the temporal lobe has been removed to show
the corpus geniculatum and several other parts that would
otherwise be covered.

By putting the brain of the rabbit in the same position
as the one shown in the cut the various parts may be found
and drawn.
THE RABBIT 209

Lepus cuniculus. The ventral surface of the brain of

the rabbit (2).—After MarsHALL.

   

 

BRM sd you 8

CC, crus cerebri. CG, corpus geniculatum. D, descending cornu
of left lateral ventrical. H, hippocampus major. LF, floccular lobe
of cerebellum. LL, lateral lobe of cerebellum. OC, optic chiasina.
OT, optic tract. P, pituitary body. PV, pons Varolli. T, temporal
lobe of cerebral hemisphere. I, olfactory lobe, with roots of olfac-
tory nerves. II, optic nerve. III, third nerve, or motor oculi. IV,
pathetic nerve. V, trigeminal nerve. VI, sixth or abducent nerve.
VII, facial nerve. VIII, auditory nerve. IX, glossopharyngeal
nerve. X, pneumogastric nerve. XI, spinal accessory nerve. XII,

hypoglosgal nerve.
STU. IN ZOOL.—1I4
210 VERTEBRATES

(4) Remove a nerve and dissect it as in the bird. See
page 189.) Find the parts and make a diagrammatic sketch

of a section running from cornea back through the optic
nerve.

IV. Tue Heap.—(1) Under the lower jaw find im-
bedded in the muscles the salivary glands, pink, roundish
bodies. Find four pairs, the parotid, the largest, just under
the ears; the submaxillary, just in front of the parotid;
the infra orbital, just below and in front of the eyes; and
the sublingual, under the tongue near the meeting of the
bones of the lower jaw. Of what value are the salivary
glands? Find their ducts leading to the mouth. Care-
fully remove the tongue. Note its connection with the
esophagus. At the base of the tongue find the triangular
bone, the hyoid, embedded in the muscles. Was it at-
tached to any other bone? Of what use is the hyoid?
Study the tongue. Note the muscular base, the furred
surface and the shape. Has the surface the same appear-
ance in different parts? Explain. Examine the surface
for evidences of taste bulbs, or papillae. A section of a por-
tion of top of tongue would perhaps show this latter. Draw
surface of tongue. Of what value to the rabbit is the
tongue?

(2) Remove the muscles from the jaws. Note their
thickness and mode of attachment. Explain the advantages
of such form and arrangement.

(3) Remove the lower jaw. Notice especially the nerves
which run into the jaw from the head. Find tube leading
from the mouth into the ear, the Eustachian tube. Note the
opening from the nasal passage into the mouth, the pharyny.
Notice the teeth of the upper and lower jaws. How many

®
THE RABBIT 2ir

in the back part? These are the jaw teeth or molars. Notice
how they articulate with each other: Note the front teeth,
incisors, above and below. Note how they articulate, and
how they are used. Do you think the rabbit is likely to
have toothache? Note the area without teeth. Is this an
advantage? Why? Study the roof of the mouth. Are
the corrugations of any value? Draw upper surface of
mouth, showing and naming the parts studied.

V. (1)—TuHeE SKELETON.—(a) Note the divisions of the
skeleton into skull, spinal column and appendages. Sever
the head from the cervical vertebrae, noting the method
of articulation of the condyles of the head and the atlas of
the spinal column.

(b) Replace the bone which was cut out to remove the
brain and study the bones of the skull. The following
bones may be easily seen: the occipital, through which the
spinal cord goes; the small interparietal, between the two
larger parietals, larger and curved; the frontals, the nasals
above the nostrils, and the premavillaries, from which the
incisor teeth grow. How are the bones of the skull connected?
Note the bones on the outer boundary of the eye orbit, the
eygomatic process. Draw upper view of the skull.

(c) View the skull from the lower side. The maxil-
lary bone is behind the premaxillary, and contains the molar
teeth. Then follow several small bones, which terminate
at the ear bone and unite with the squamosal, the larger
side bone which joins the occipital. Study the ear bone,
the tympanic; cut open the coil and note the winding bone,
the cochlea, through which sound is conveyed to the inner
part of the ear and finally to the auditory nerve. What is
the value of such a bone? Between the tympanic membrane
212 VERTEBRATES

and the cochlea find three articulating bones, the hammer,
anvil and stirrup which convey the sound from the outer
to the inner ear. Of what pecular value is the external
ear? In different parts of the skull note small openings
through which nerves pass from the brain. These are
foramen. A prominent one is seen on the inner surface
of the eye socket.

(2)—Tue Spinat Cotumn—(a) Identify the following
divisions of vertebrae: cervical (neck), the thoracic (rib-
bearing), the /umbar (without ribs), the sacral (united ver-
tebrae of pelvis), and caudal, or tail. Count the number
of vertebrae in each. Study the ribs in the thoracic region
and compare them with the projections or transverse pro-
cesses of the lumbar vertebrae. Of what value are the
ribs? The processes? Why would it not be better to have
ribs the entire distance?

(b) Remove the vertebra bearing the sixth pair of ribs
by cutting through the cartilaginous joints. Find the cen-
trum, the neural arch containing the spinal cord, the ribs,
and the cartilage which unites the ribs with the sternum.
Study the cartilaginous packing at each end of the ver-
tebra. Of what use is it? Does the rib grow out of the
vertebra? Is it movable? Explain the attachment: What
is the advantage or disadvantage of having movable ribs?
Study the attachment of the ribs to the sternum. What is
the nature of the sternum? Is it divided into segments?
How many ribs are attached to it? Sketch the sternum
with its attachments. Make drawing of the typical seg-
ment just studied (1).

(c) Remove the fifth vertebra of the lumbar region.
Study as before the centrum, neural arch, and the neural
THE RABBIT 213

spine above it, the transverse processes corresponding to
the ribs and the articular processes on the dorsal side.
Compare these parts in size and strength with the corre-
sponding parts of the first vertebra studied, and give rea-
sons for your conclusions. For what are the processes
used? Compare the cavities above and berieath the centrum
with the neural and haemal arches of the fish. (See page
159.) Draw the posterior end view of the vertebra under
consideration.

(d) With a scalpel carefully cut away the neural arch
and expose the spinal cord. Notice the openings, sinuses,
in the sides of the vertebrae where the spinal nerves leave
the cord. Remove the cord, noticing carefully which is
anterior and which posterior parts. Study the origin of
the spinal nerves in the anterior and posterior roots. Draw
the segment of cord thus studied.

(e) Remove the flesh and the hind limbs from the
pelvic arch and study the bones which compose it. How
many bones? How are they articulated? Are they ver-
tebrae? Could they have been specialized from the typical
vertebra just studied? Explain what changes have taken
place, and give reasons. Draw dorsal and ventral views
of the pelvic arch.

How many bones in the caudal region? Are they ver-
tebrae? Why?

(3)—Tue Limps.—(a) The bones of the limbs are easily
distinguished. In the front limbs the shoulder girdle can
be traced, consisting of scapula and clavicle, a small, almost
cartilaginous bone, extending through the flesh and uniting
with the sternum. Do you find the coracoid bone? What
office does it fill? (It is a process extending from the scap-
214 VERTEBRATES

ula over the end of the humerus). Other bones beginning
with the shoulder are the humerus, the radius, the smaller ;
and the ulna, the larger; below the elbow, the carpal, wrist
bones; the metacarpal, or palm bones; and the phalanges,
or toes. Study and describe the articulation in each of
these bones. Make a diagrammatic drawing of front limb.
Compare with wing of bird.

(b) In the hind limb the bones are equally easy to dis-
tinguish. Beginning with the pelvic girdle, find the femur,
with its deep ball and socket joint; the tibia and fibula, be-
low the knee joint, which is covered with a patella or knee
cap; the tarsus, the metatarsus and phalanges. Draw a dia-
gram of hind limb. Compare with leg of bird.

CrassiFication.—Adapted from Pacxarp.—The rabbit belongs to
the family Leporidae, order Glires, and class Mammals.

The class mammals contains the following orders which can be
fully worked out by reference to a larger Zodlogy.

Orders of Mammals.

Subclass I. With long toothless jaws like a duck’s bill, young
carried in a mammary pouch..............+000 Ornithodelphia.

Order 1. Monotremata. Duckbill.

Subclass II. Young born alive, but kept for awhile in a pouch.

Didelphia.

Order 2. Marsupialia. Opossum.

Subclass III. Young born of considerable size and perfect de-
velopment; nourished before birth through a placenta; brain
in most cases possessing convolutions............ Monodelphia.

Order 1. No incisor teeth; sometimes entirely toothless.

Bruta: Sloth.

Order 2. Rodents; with large incisor teeth...... Glires: Rat.

Order 3. Fore limbs often adapted for burrowing; teeth sharp;
feeding: on 1nSects mica cine ceri wswase Reman Insectivora: Mole.

Order 4. Fore limbs long, webbed, and adapted for flying.
THE RABBIT 215

Order 5. Cetaceans; body fishlike in shape; no hind limbs.
Cete: Whale.
Order 6. Body fishlike in shape; teeth like those of ruminants.
Sirenia: Manatee.
Order 7. Snout prolonged into a proboscis.
Proboscidea: Elephant.
Order 8. Long curved incisor teeth; feet with pads; toes hoofed.
Hyracoidea: Hyrax.
Order 9. Toes hoofed................05 Ungulata: Horse, Ox.
Order 10. Teeth pointed for tearing flesh; claws large.
Carnivora: Dog, Cat.
Order 11. Nails usually present; walking on all fours; or
using fore legs as hands; or erect and walking on the hind legs.
Primates: Monkey, Ape, Man.
SuMMary.—The rabbit is taken as a type of the class
mammals, or milk givers. It is a highly specialized ani-
mal. Make a list of the specializations you have observed,
and tell the advantages or disadvantages of each. Is it
solitary or gregarious? How does this benefit it? Has
the rabbit a good method of defense against enemies? What
method of escape does it select? What animals are ‘its ene-
mies? Since it is hunted by so many animals, and has such
a poor means of defense, why does it not become extinct?
(Reproduction.) What preparation does it make for its
young? Does it care for its young? What is its food in
summer? In winter? Is it injurious or beneficial to man?
Why ?
APPENDIX
I. THE COMPOUND MICROSCOPE

The foilowing simple outline is given for the use of
beginners with the microscope. It may be enlarged by the
teacher :

PARTS.
I Strawn,

a. Base: The part on-which the instrument rests.

2. Joint: Allows the upper part to move on a hinge.

3. Body: The part above the joint.

4. Adjustments :

a. Coarse, upward movement accomplished by
the rack and pinion.
b. Fine, accomplished by the thumbscrew usu-
ally at the top of the stand.
TI. Srace.

1. Floor: The surface of the stage bearing the clips
or holders.

2. Diaphragm: Contrivauce under the opening in
the stage, to regulate the amount of light trans-
mitted.

3. Mirror: A mounted adjustible mirror situated
below the stage to reflect the light through the
the object into the objective.

217
218 APPENDIX

III. Barren.

1. Eyepiece or Ocular: The lens at the top of the
draw tube.

2. Draw Tube: The tube capable of being with-
drawn, containing the eyepiece at the upper end
and the objective below.

3. Objective: The lenses at the lower end of the
draw tube, ordinarily ranging in focal distance
from 1 inch to 1-6 inch. They are named
from this focal distance.

4. The Revolving Nosepiece: A contrivance for hold-
ing two or three objectives for immediate use.

SUGGESTIONS ON THE USE OF THE MICROSCOPE.

1. Put the slide on the stage under the clips with the
object to be studied over the opening in the diaphragm.

2. See that the lens is in the proper position in the barrel
(always use the low power, 7. ¢., the longest focal distance
unless otherwise directed), and with the coarse adjustment
bring the objective close to the cover glass. Place the eye
over the eyepiece and look for the object; lift the barrel with
the coarse adjustment until the object on the slide appears
clearly defined. It is now said to be in focus.

3. After the object is in focus, use the fine adjustment
to clear up the different parts of the specimen. Move the
specimen until all the parts have passed the field of the mi-
croscope. It will be noticed that the image is inverted
as well as magnified. An explanation for this should be
sought from the teacher or from a good text on the micro-
scope.

4. The compound microscope is a delicate instrument,
APPENDIX 219

and should be handled with extreme care. It would be well
to memorize the following cautions and try to use them until
they beconie habitual :

Never touch the lens of the eyepiece or objective with
the hand. Cleanse them with a camel’s-hair brush or a
piece of soft silk.

Never move the lens downward while the eye is at the
eyepiece, always focus upward, especially if you are using
the coarse adjustment.

Before leaving a microscope, rub it dry and clean it with
a piece of flannel or chamois skin and put it in its proper
place. Never leave a microscope in the direct rays of the
sun or where dust may gather on it.

ll. HOW TO USE THE TABLES OF CLASSIFICATION.

To a student who has not used the Tables of Classifica-
tion, the following suggestions may be found helpful. It
will be easier to trace to its family the type specimen
which has been thoroughly studied as its characteristics are
fresh in the mind.

Some of the tables have the different divisions in figures,
and some have letters. The difference between these will
be apparent at a glance.

These tables do not carry the classification further than
the families; classification into genera and species can be
made by consulting specialists on the different classes of
animals.

Suppose that we have a beetle which we desire to trace
to its proper family. We proceed as follows:
220 APPENDIX

Look at the specimen carefully, noting its external fea-
tures.

Read the first line A (see page 59).

If your specimen agrees with this e.ractly, then its family
is found somewhere under A, the subdivisions of which are
set in farther to the right on the page.

If your specimen does not agree with A, then, omitting
all the subdivisions of A, go to AA on page 64, and com-
pare that description with your animal. If AA describes
the specimen correctly, then the family is under this group.

Suppose the specimen belongs under A.

Read B. If this is true, the proper family belongs under
this heading.

Read C. If this is true of your specimen in every particu-
lar, it belongs to the group Phytophaga, which contains
several families.

Read D. If this is correct the specimen belongs to the
family Spondylidae; if it is not true, look at DD, which is
coordinate with D and includes the families described in
E and EE.

Suppose your specimen does not belong under C, then
read CC at the bottom of the page. If this be true, trace
to the proper families in the manner above described.

In like manner, if B is not true of your specimen, turn to
BB on page 63. If this description be true, read C, D and
E to find one that is true. If you find nothing there which
fits your specimen, turn to CC on page 64 and follow
these descriptions in the same way.

In the tables where figures are used the same general
plan may be followed. Read the descriptions until you find
one that coincides exactly with the specimen in your hand.
APPENDIX 221

The difficulties in the way of using these tables, which
may at first seem great, will be easily overcome by tracing
three or four specimens through to their proper families.

Ill. REAGENTS IN COMMON USE.

Only the most common reagents are given, as it is sup-
posed that the teacher will have access to technical books
for all delicate experiments and tests.

ALcoHoL.—As commonly obtained for laboratory pur-
poses, alcohol is ninety-five per cent. pure. This may be
diluted to the required strength by calculating the amount
of water to be mixed with ninety-five per cent. alcohol to
produce the amount of liquid required. It may be obtained
for school purposes free of internal revenue by complying
with certain formalities required by law. Such alcohol
is of the best quality — ninety-five per cent. generally —
and can be obtained at a great reduction from the regular
retail price. For information address Secretary of the
Treasury, Washington, D. C.

Formattn.—This is a hardening agent, which has much
the same effect on hardening tissue that alcohol does, ex-
cept that it expands the tissue slightly. For all general
purposes it is equal to alcohol and has the adidtional ad-
vantage of being much cheaper. It is used in strength
from one to two per cent solution in water.

Osmic Acip.—One and one-half to two and one-half per
cent. solution used for killing microscopic animals. It
should be kept in the dark and should be diluted with water
when used.
222 APPENDIX

Borax CARMINE (Grenachcr’s).—Solution of powdered
carmine and borax in water and alcohol. The beginner
should order it in solution, and not dry. It is used for
staining, and is perhaps the most serviceable for general
use. It may be used cold or at a temperature of 50° C.

Macenta.—Solution of % grm, of roseine in 1 liter
of water, add 5 c.c. absolute alcohol. It is used io stain
fresh preparations for immediate and temporary use.

OL oF CiLoves.—A clearing agent. Used to clear a
specimen of alcohol before permanent mounting. Should
clear the object, but not stay on the slide too long, or it
will make the section brittle.

TURPENTINE.—May be used as a clearing agent. Also
used to remove paraffin from sections before mounting.

SaLt SotutTion.—Normal solution of 7.5 grms. common
salt in liter of water. Used for examining living or freshly
killed tissues.

GLYCERINE.—Used pure or diluted with water for mount-
ing objects for microscopic study.

CanapA BartsAm.—The common name for balsam fir
of commerce. May be used as bought from druggist or
evaporated to dryness, powdered and dissolved in alcohol
or turpentine. It is the most commonly used medium for
mounting stained sections for microscopic study.

ParaFFin.—Used for imbedding objects for permanent
mounting. Paraffin with melting point 56° C. may be used
alone or mixed with paraffin the melting point of which is
4o° C,

SHELL-LAC.—Dry shell-lac dissolved in absolute alcohol,
allowed to stand for some time is ready for use. Used to
fix the sections to the slide for mounting.
APPENDIX 223

CoLLopion.—Mixed with an equal part of oil of cloves.
Used for fixative in the same way as shell-lac and alcohol.

IV. METHODS OF PREPARING MATERIAL FOR MICRO-
SCOPIC EXAMINATION.

In fully equipped laboratories the teacher and student will
have at command special books on microscopical technique
and methods, but for the benefit of those who may not
have access to such books the following brief suggestions
are given:

The particular methods to be used depend upon the nature
of the tissue and the kind of observation to be done. Asa
tule, the softer tissues have to be hardened, and the harder
softened or cleaned, before making permanent mounts.

1. Kittinc: The method of killing depends upon the
animal, but as a rule that method should be used that will
leave the body in natiiral form with tissues uninjured.
Chloroform ‘for the crustaceans and vertebrates, potassium
cyanide for the insects, spiders, and centipedes, warm water
for the mollusks and earthworms, can in general be rec-
ommended; and for lower forms special methods may be
found by consulting books on histology.

2. Harpeninc: For ordinary purposes alcohol is the
best hardening agent. The specimen should be placed first
in weak solution, about sixty per cent., then in seventy per
cent. then eighty per cent. and ninety per cent. and finally,
before beginning the work of imbedding, it should be placed
in absolute or one hundred per cent. alcohol. Considerable
alcohol should be used each time, except the last, and the
224 APPENDIX

time for the entire process on ordinary tissue should ex-
tend over two or three days.

3. STAINING: lf the specimen is for temporary observa-
tion, the stains magenta or methylene blue may be used;
but for permanent mounts it is better to use alcoholic stains,
of which borax carmine (Grenacher’s) is perhaps the most
desirable. The object should be placed in the stain from
sixty per cent alcohol, and should remain in the stain
until saturated to the degree of color desired. The length
of time required for this will have to be determined by
trial and depends upon the size of the spcimen, as well as
its penetrability. After staining, the object should be run
up to ninety per cent. and then to absolute alcohol, as di-
rected in 2, on hardening. Alcohol is useful for removing
an excess of stain, used with hydrochloric acid (3 to 6 drops
to 100 c.c of seventy per cent. alcohol) it will give a better
result from staining with borax carmine. The stained ob-
ject should be left in the acid alcohol for a time varying
from one-half hour to three hours.. This staining may be
done if desired after the sections have been cut and mounted,

4. CrearinG: After staining, the alcohol must be re-
moved by oil of cloves or turpentine. A short time only will
be necessary for this, and the specimen is then ready for
imbedding.

5. ImpBepprwc: For this purpose paraffin, melting point
50° C., should be melted and kept in a water bath at not
above 60° C. A softer paraffin will be found better some-
times, especially in cold weather. Drop the specimen to be
imbedded in this paraffin, and allow it to remain until it
is thoroughly permeated with paraffin. The length of time
varies from thirty minutes to an hour.
APPENDIX 225

Make a small paper trough, considerably larger than the
object to be imbedded; fill it with the melted paraffin, and
drop the saturated object into it in the exact position de-
sired for cutting the sections. When this is done cool the
paraffin as quickly as posible by putting it in a basin of
cold water, being careful to keep the water away from the
paraffin until it is hard enough to prevent injury. When
it is thoroughly hardened, the paper may be removed and
the object is ready for cutting into sections. It has been
suggested that glass tray salt cellars will accomplish the
work of the paper trough.

6. Sectioninc: The paraffin block may be fixed on the
microtome by the method most convenient, and the sections
cut of the thickness desired. The particular method of
manipulating the microtome depends upon the structure of
the instrument.

MountTINnG: Prepare a glass slide as follows: The slide
should be free from flaws, and should be ground at the
edges. See that it is thoroughly dry, and has a temperature
of about 60° C. Spread on the center of it a thin layer of
cement, or a diluted alcoholic solution of shell-lac, and allow
the alcohol to evaporate almost to dryness. Next spread a
bit of oil of cloves or turpentine on the slide, and place the
section on the moist slide. Allow the slide to remain for a
while in a warm place free from dust, in an oven if con-
venient, until the section is thoroughly cemented to the
slide. Now put the slide in turpentine, or put turpentine
on the slide and allow it to remain until all the paraffin is
dissolved out of the tissue.

When this is done the slide should be taken out of the
turpentine, a drop or two of balsam let fall on it, the size

STU. IN ZOOL.—I5
226 APPENDIX

of the drop depending upon the size of the section, and
a thin clean cover glass placed lightly on top of the balsam.
Keep the slide in a warm place until the cover glass sinks
down flatly on the slide, and put the slide away for drying.
After drying for several days the balsam will become hard
and the slide may be cleaned with alcohol and the proper
label placed on the side. The label should contain the name
of the object, the thickness of the section, and the stain used
on one side of the cover glass; and the name of the prepara-
tion and the date, on the other. Then put the slide away ina
slide box, properly labelled.
GLOSSARY

Words that are clearly explained in the text are not defined here
but reference is made to the page where the explanation occurs.

Adduc’tor, 142,

A’erated, mixed with air. The
water is aerated before sup-
plying the gills.

Al'ulet, 74.

Ambula’cral, (Lat. Ambulare—
to walk). Pertaining to the
walking tube feet or their
areas,

A’nal. Situated near the anus
or in the posterior region.

Anal’ogous. Applied to organs
in animals that are put to
similar uses but are different
in origin and structure, as the
wings of a grasshopper and
bird.

Anas’tomosing.
the mixing of veins of differ-
ent directions.

Annel’ida. A group of animals
with bodies composed of simi-
lar segments without jointed
legs.

An'nulated.

Mixing as in

Surrounded by

bands or rings of different
colors,

An‘nulus, 126.

Ap’erture, 144.

Appendic’ulate.
appendages,

Apposi’tion. Placed side by side.

Ap’terous. Without wings.

Aquat’ic. Living in water.

Arach’nida, (Gr. Arachne—a
spider). A class of Arthro-
pods.

Arthrop’oda, (Gr. jointed feet).
A branch of animals distin-
guished by having segmented
appendages.

Having small

Asymmet’rical. Not symmetri-
cal.
Auditory. Pertaining to the

sense of hearing.

Bar’bules, 179.
Beak. The sucking tube of some
Hemiptera.

227
228

Bicus’pid. Composed of two
cusps or flaps.

Bi‘fid. Two divided or folded.

Bira’mous. Two branched.

Bi’valve. A mollusk having two
shells hinged together.

Blas’toderm, 120.

Boot’ed. Having an undivided,
horny, bootlike covering. Birds
sometimes have booted tarsi.

Bran’chia, pl. branchiae. Res-
piratory organs for breathing
air from water.

Branchios’tegal. Pertaining to
membrane covering the gills
of fishes,

Cae’cal. Pertaining to baglike
projections from alimentary
canal.

Cap’itate. Headlike in form.

Car’apace, 95.

Car’inate, Shaped like the keel
of a boat.

Carot’id. One of the principal
arteries of the neck.

Cau'dal. Pertaining to the tail.

Cephal’ic. Pertaining to the
head.

Cephalotho’rax, 88.

Cer’ci, 27.

Cerebellum. The posterior lobe
of the brain.

Cer’ebrum. The anterior por-
tion of the brain.
Chi’tin. The horny outside

skeleton of Arthropods.

GLOSSARY

Cho’roid, 158.

Cir'rus. A hairlike projection.
Cla’vate. Thicker toward the
top.

Cla'vicle, 174.

Cloa’ca, 166.

Coelentera’ta, (Gr. Hollow In-
testine). A branch of the ani-
man kingdom in which the
entire digestive canal is one
tube.

Co’'lon, 32.
Coleop’tera, (Gr. Sheath-wing-
ed). An order of insects

which have hard outer wings.

Columel’la, 145.

Com'missure. Nerve fibers con-
necting ganglia or other parts
of the nervous system.

Con’fluent. Uniting and running
together.

Coniros’tral. Pertaining to a
strong conical bill.

Con’nate. Growing from one
base.
Convolu’tion. Irregular folding

of the brain of vertebrates.
Cor’acoid, 174.
Cor’puscles, 169.

Cos’tal. Relating to the ribs or
sides.

Cranial. Relating to the skull.

Ctenid’'ia. Gills of mollusks.

Cu’bitus, 41.

Cul’men. The dorsal ridge of

the bill of a bird.
Cu’neus. A wedge-shaped part.
GLOSSARY

Decid’uous. Pertaining to being
shed or cast off, as the gills
of a frog.

Del’toid. Triangular in shape.

Diaphragm. Muscular partition
between chest and abdomen as
in mammals.

Dip’tera, (Gr. Two Wings). An
extensive order of insects that
have but two fully developed
wings.

Duode’num, 183.

Du'ra ma’ter, 171.

Ec’toderm, 120.

Ec’tosarc, 107.

El’ytron, pl. Elytra. The hard-
ened outer wings of some in-
sects,

En’doderm, 120.

En’dosarc, 107.

Envi‘ronment. The conditions
surrounding an animal which
influence its growth and de-
velopment,

Epim’eron, pl. epimera. The
part just outside of the basal
segment of an appendage in
Arthropods.

Esopha’geal.
esophagus.

Excre’tory. Having the power
to excrete or throw off.

Pertaining to the

Exten’sor. The muscle that
causes extension.
Ex’serted, Projecting beyond

some other part.

229

Fa‘cet, 28.

Fe'mur, pl. femora. The thigh
bone.

Filiform. Having the shape of
a thread or filament.

Fissiros’tral. Having the bill
cleft beyond the horny part.

Flabel'late. Fanlike in shape.

Fora’men. A small opening.

Gan’glion. A collection of nerve
cells through which nerve fib-
ers pass.

Gas’tric car’ca. Blind sacs ex-
tending from the stomach.
Genic’ulate. Bent abruptly at an

angle.

Go’nys. Under outline of a
bird’s bill from the tip to the
point of union of upper and
lower mandibles.

Grub, 57.

Gu’'la. The part of the neck
next to the chin. In insects
the plate under the submen-
tum.

Hae’mal. Pertaining to the
heart or blood vessels.

Ham'uli, 67.

Haustel'‘lum. The sucking tube
or proboscis of insects. It is
made of modified mouth parts.

Hemip’tera, (Gr. Half Wings).
An order of insects having
outer wings part hard and part
membraneous.,
230

Hepat’ic. Pertaining to the liver.

Heteroc’era. A group of Lepid-
optera having the antennae
variable in form.

Heterop’tera. A group of Hem-
iptera having base of front
wing thickened.

Hi’bernate, 85.

Homologous. Having similar
origin and structure but differ-
ent use, 96.

Homop’tera. A group of Hem-
iptera having wings of similar
texture.

Hymenop’tera, (Gr. Membran-
eous Wings). An order of
insects having both pairs of
wings membraneous.

In’fra.
Ima’go, 42.

Below or posterior to.

Keel. A projecting ridge on the
sternum of birds.

Lar’va, 42.

Lig’ament, 182.

Lepidop’tera, (Gr. Scale Wings).
An order of insects having
wings covered with scales.

Malpi’ghian Tubes, 32.

Mam’mary Glands. Milk-pro-
ducing glands of mammals.

Mantle, 140.

Medul’la oblonga’ta. Enlarge-
ment of the spinal cord below
the brain.

GLOSSARY

Mes’oderm, 120.

Mes’enteries. The thin mem-

branes holding the intestines
to the walls of the abdomen.
Mesoster’num. Middle segment

of the sternum of the thorax.
Met’amere. One of the similar
divisions of the body of an
animal, same as somite.
Metaster’num. Last segment of
the sternum of the thorax.
Metamor’phosis. In insects the
passing of the larva through
more or less complete changes
to the adult form.
Morphol’ogy. The study which
deals with the forms and
structure of animals.
Myriop’oda, (Gr. Thousand
Legs). A class of Arthropods
having many jointed legs borne
upon similar segments,

Nau’plius. The larval stage of
some of the crustaceans.

Nephrid’ia, 128.

Neu’ral. Pertaining to the
nerves or the nervous system.

Neurop’tera, (Gr. Nerve Wings).
An order of insects having
membraneous wings with nu-
merous veins,

Ni'ctitating Membrane, 178.

Noctur’nal. Active by night, as
many of the moths,
Nymph, 709.
GLOSSARY

Occip’ital condyle, 199.

Olfac’tory. Pertaining to the
organs of smell.

Op’tic. Pertaining to the organs
or nerves of sight.

Os’cines. The group of birds
that sing.
Orthop’tera, (Gr. Straight

Wings). An order of insects

which have straight outer
wings.

O'viduct, 33.

Ovipos’itor. An organ compos-

ed of several specialized parts
of the abdomen with which
many insects place their eggs.

Pal’lial, 140.

Papil’lae, 164.

Paraglos’sae, 55.

Pata’gia, 46.

Pec’tinate. . Shaped like a comb,
with toothed edges.

Pe’dal. Pertaining to the foot.
Ped’icel, 65.
Pelag’ic. Living in the sur-

face waters of the ocean.

Pericar’dial. Situated around
the heart.

Peritone’um, 153.

Phar’ynx, 165.

Pia mater, 171.

Pig’ment cells. Cells that give
coloring to the animals.

Pi’neal gland. A glandlike body
in the brain of vertebrate ani-

mals. It is sometimes con-

231

nected with a rudimentary eye

called the pineal eye.
Placen’ta. The vascular appen-

dage connecting the young to

the parent before birth.
Plas’ma, 169.

Pleu’ral. Relating to the pleu-
rum, 23.

Plex’us. A network of vessels,
nerves or fibers.

Plumose’. Feathery.

Porrect’ed. Extended horizon-
tally.

Preda’ceous. Living by prey.

Pri’maries, The long feathers
on the last joint of the bird’s
wing.

Probos’cis. In insects a hollow

sucking organ usually made by
the combining of several mouth
parts.

Prono’tum, 23.

Proster’‘num. The first division
of the sternum of the thorax
of insects.

Protrus‘ile. Capable of being
protruded or thrust out.

Pulvil’li, 75.

Pu’pa, 42.

Pygid’ium. The tail plate of
crustaceans and insects.

Pylo’ric caeca, 154.

Quad’rate bone. The small bone
between the lower jaw and
the base of the skull in most
vertebrates below mammals.
232

Rachiglos’sate. Having three
longitudinal rows of teeth on
the radula.

Ra’dius, 41.

Rad‘ula. Tongue of a gastero-
pod mollusk.

Re nal, 167.

Retic’ulate. Having veins or
fibers crossing like network.

Ret’ina, 158.

Retract’or, 142.

Rhopaloc’era. The group of
Lepidoptera having clubbed
antennae—butterflies.

Ric’'tal. Pertaining to the cor-
ners of the mouth.

Ros’trate. Beaklike.

Sclerot’ic, 158.

Scutel’lum, pl. scutella. Trans-
verse scales on the tarsi and
toes of the bird.

Sec’ondaries. The feathers on
the second section of the wing
of a bird.

Sep’tum, pl. septa. Radial par-
tition of a coral cup. A trans-
verse partition in worms.

Si’nus. A detached vessel or
canal. <A cavity.

So’mite, 26.

Sper’maries. The reproductive
glands of the male animal.

Spir’acle, 24.

Spurious quill. Outer primary
quill when much reduced.

Stridula’tion, The making of

GLOSSARY

sound by rubbing hard parts
together as in insects.
Su’bulate. Awl-shaped.

Taenioglos’sate. Relating to a
long narrow tongue of mol-
lusks bearing seven rows of
teeth.

Teg‘ula, pl. tegulae, 66.

Teg’men, pl. tegmina. The outer
wing of certain insects.

Ter’gum, 23.

Tertial feathers. Growing on
the innermost division of a
bird’s wing.

Thy’mus. A ductless gland in
the region of the throat of
many vertebrates.

Toxoglos’sate. Pertaining to
the tongue of gasteropods con-
taining poison fangs.

Tra'cheae. Tubes of the respi-
ratory systems of Arthropods.

The eardrum or

which

Tym’panum.
membrane through
sound is conveyed.

Um’'bo, pl. umbo’nes. The hump
above the hinge on a bivalve
shell.

Unira'mous.
branch.

Urinif’erous Tubules, 44.

U'rostyle, 174.

Consisting of one

Vas def’erens, 33.
Ver’miform, 201.
Outlines of Botany
FOR THE

HIGH SCHOOL LABORATORY AND CLASSROOM

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