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Books or REFERENCE . Sita oo Whe 5 at Sk ell ae tie SAS GEL ae, SLOPE

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| Presented to
The University of Coronto Library

from the Books of

Professor Belyien Etoart Henderson
MA., MB., F-B-SE-
(1877-1945)

Hor many years Chairman of
the Dibrary Committee of
the Faculty of Medicine

Digitized by the Internet Archive
in 2007 with funding from
Microsoft Corporation

http://www.archive.org/details/elementarycourseOOcoltuoft

AN

AN

ELEMENTARY COURSE

-PRACTICAL ZOOLOGY.

BY
x oo!

eT
BUEL P: COLTON, A.M.,

PROFESSOR OF NATURAL SCIENCE, ILuINorIs StaTE NoRMAL UNIVERSITY,

Normat, In.
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A
BOSTON:

D. C. HEATH & COMPANY.
1892.

PREFACE.

OO

In the entire absence of any handbook of zodlogy
adapted to the grade of work in which he was engaged,
the author began to draw up, for use in his own classes,
simple guides to the study of a few common. animals.
After repeated tests in the class-room, and under the —
advice of a number of eminent teachers of the subject, it
was decided to put the work into print.

The author takes this opportunity to thank those who
have so heartily aided him in this undertaking.

Prof. Alpheus Hyatt, of the Boston Society of Natural
History, has generously aided in preparing the book for
publication.

Pres. D. S. Jordan, of Indiana University, has read
most of the manuscript and proof-sheets, and has given
many valuable suggestions.

Especial thanks are due also to H. Garman, Assistant-
Professor of Zoélogy, University of Illinois, for corrections
and suggestions on the entire manuscript and on the proofs.

Mr. B. H. Van Vleck, Assistant, Boston Society of
Natural History, revised the manuscript on Echinoderms,
Celenterates, and Sponges.

As the proof-sheets appeared, from time to time,
they were critically read by Prof. N. S. Shaler, Harvard

iv PREFACE.

University; Mr. J. Y. Bergen, Jr., Peabody, Mass. ; Prof.
R. E. Call, Missouri Agricultural College and University,
Columbia, Mo.; Mr. E. P. Jackson, Boston Latin School;
Prof. L. M. Underwood, Syracuse University, Syracuse,
N.Y., and other well-known teachers. In the preparation
of the book, free use has been made of the works cited in
the text.

To aid in the study of the marine animals, arrangement
has been made by which schools may be supplied with
sets of material put up at the Seaside Laboratory, Annis-
quam, Mass. A list of these specimens will be found at
the end of this book. They may be obtained of Mr. B. H.
Van Vleck, Assistant, Boston Society of Natural History.

It is believed that with the assistance above acknowl-
edged, the book will be found fairly free from errors; but,
for any mistakes it may contain, the author alone should
be held responsible.

The author believes that he has encouraged only the
most merciful methods of handling live animals, and he
would strongly urge all teachers not to do anything that
might lead to cruelty to animals.

The only way to know animals, is to see and to handle
them ; and it is sincerely hoped that the day is near when
knowing an animal’s name will not pass for knowing the
animal itself. If this little book should do somewhat
toward the improvement of methods of teaching zodlogy,
the author will feel that he has not labored in vain.

Orrawa, Inu., Aug. 20, 1886.

.

INTRODUCTION.

Tuis work is designed to aid the student in getting a
clear idea of the animal kingdom, as a whole, by the care-
ful study of a few typical animals.

Most of the animals selected are abundant in the interior
States, and are easily collected.

These guides to the study of animals have been used
several years, and put into the hands of each pupil, together
with the specimens themselves.

The general plan of study is as follows: —

1. Directions are given for collecting and preserving the
specimens.

The live animal is studied.

The external features are noted.

The animal is dissected.

The development of a few forms is traced. .

After studying each animal, its relations to other animals
are considered (classification).

Senet Bo

The aim is, not to describe for the student, thus robbing
him of the opportunity to develop his own powers of
description, but to name the parts, telling merely enough
to enable him to recognize and apply the names to them.
This makes a real connection between words and things.

It is thought best for the student to make many of the
definitions for himself. A definition, thought out by the

vi INTRODUCTION.

student himself, imperfect though it be, is of more value
to him than a perfect definition learned from a book, which
often appeals to mere memory. Definitions made in the
way these pages require are good so far as they go: they
should be corrected and supplemented by the instructor.
It develops a boy more to earn a dime than to receive a
dollar as a gift.

If the main object of this study is the mere acquisition
of facts, full descriptions of most animals can be elsewhere
obtained ; but if the more important part in education is to
lead the pupil to see and think for himself, then some such
method as this should be used.

The underlying object in all our teaching is to make
seeing, thinking, self-reliant, honest men and women. All
branches of natural science, rightly pursued, are powerful
means to this end.

“The feeling is becoming general that practice must be
united with theory, in the education of young men, or the
best results of education are lost. The powers and faculties,
instead of being educated —drawn out and developed —
are crushed under a mass of merely memorized facts and
theory, and at the end of his educational course the young
man finds himself unfitted for the work of the actual world,
and has to unlearn, and learn again, before he can find the
path to success.

“This feeling has resulted, in Germany, in the object-
teaching of Freebel; in Russia, in that celebrated system
wherein practical work is united with the theoretical
teaching, which already shows such important results ; and
in the United States, in the building of workshops and
laboratories for the use of students in our higher schools
and colleges.”

INTRODUCTION. Vii

The order in which the animals are presented has been
determined by the following circumstances : —

The work in zodlogy has usually begun with the fall
term. At this time insects are abundant, and many kinds
may be easily collected; they therefore serve well to show
how animals are classified. The leading principles of
classification having been taken up in connection with
insects, no other group is so fully dwelt upon.

By beginning at this time, the transformations of the
butterfly may be followed through during the school
year.

Insects are attractive ; from insects the student passes on
to forms which, if taken up at first, would perhaps be
distasteful to him. Thus it is found that the most squeam-
ish pupils gradually become accustomed to the free handling
of all forms of animals. The subject need not be presented
in its least attractive form at first.

After devoting considerable time to insects, the student
takes up the crayfish, earthworm, clam, snail, a few proto-
zoans, a snake, a fish, a frog, a bird, anda mammal. This
order of study has been found convenient, but the order is
not a matter of great importance; the general principle
should be, —study what comes to hand. “He is a good
naturalist who knows his own parish thoroughly.”

Special stress is laid on devising cheap appliances for
’ collecting, preserving, and dissecting specimens.

These directions make no pretence of being complete
dissecting guides, but have been adapted to the ability of
ordinary pupils in the second year of a high school course,
and to the time allowed this study.

viii INTRODUCTION.

TO THE SCHOOL BOARD,

For practical work in natural history the teacher needs
a room in which is but the one class with which he is at
work. This room should be provided with plain tables
having drawers in which pupils may keep dissecting instru-
ments, drawing materials, and specimens for study.

This work is greatly aided by having a water supply in
the room where the work is done; this is not only a very
great convenience to the teacher, but the pupils are much
more ready to take hold of slimy specimens and the work
of dissecting, if they can wash their hands conveniently
before passing to recitation or study room.

The teacher cannot do justice to this kind of work if he
has recitation after recitation continuously through the day;
time is needed in which to prepare dissections which are too
difficult for the students to make, or for which they have
not the time; to arrange the material so as to save time
when the class has assembled, as well as to clear away
afterward, and be in readiness for another class. The fol-
lowing has proved a good arrangement: in a school having
three recitation periods in each half day the middle period
of each half day is “vacant,” z.e., no class comes to the
teacher of science at this hour; but this time has been very
far from vacant.

It is much better to buy several low-priced microscopes
than one expensive one.

TO THE TEACHER.

Do not set out with the intention of finishing this book
in a given time; zodlogy is the study of animals; study
animals as long as the time allows, trying to learn as much

INTRODUCTION. ix

as possible from a few typical forms; this will give a better
view of the animal kingdom than reading many books con-
cerning many animals.

Take the study of the grasshopper as an example. The
first day put the specimens into the hands of the pupil, or,
better, have him bring his own specimens; with the aid of
his dissecting guide he studies the whole hour; the teacher
goes about, helping those who need, giving directions as to
use of instruments, etc. Notes and drawings should be
made in a scratch-book; many a pupil says, “I cannot
- draw”; ask him to do his best; praise his work if you can;
suggest how he can do better. The next day question the
pupils on what they have seen; perhaps half the hour, or
less, will serve to bring out what has been discovered on
the preceding day. As soon as what has been seen is brought
out, go on with the study of the specimens.

After questioning on all the work, call for carefully made
drawings and descriptions in a permanent note-book, A
systematic arrangement of these notes should be insisted
on; but each pupil should be allowed to follow his own
plan as far as possible: encourage individuality.

The name of the study, and of the pupil, should be on a
white card, or paper, pasted on the outside of the cover.
An index of the notes should be made, as the work pro-
gresses, on the inside of the back cover.

If a rubber band be slipped over the front cover and
the pages already examined, much time will be saved in
looking over the books, as they are handed in from time to
time.

Urge the pupils to do as much as they will to procure
specimens for class work, but have ig reserve a good sup-
ply of material. The school should have a supply of alco

x INTRODUCTION.

hol. One boy may live near a creek where he can easily
get crayfishes or clams for the whole class; another may
happen on a lot of beetles. At the beginning of the work
ask them to carry boxes or bottles, and be on the lookout
for specimens ; in this way they will learn more, and lighten
your work. But do not neglect class excursions; go out
after school with as many as will accompany you; have
picnics on Saturdays with them.

Let each pupil be required to make a small collection of
insects; it is well to urge each pupil to select some order
or family of insects for special study. Written or oral
reports of such observations are helpful, and serve to vary
the work. If there be time, let the pupils select some of
the following subjects for investigation and reading: the
chinch bug, silk-worm, bark louse, army worm, cut-worm,
potato worm, mosquito, gall fly, ichneumon fly, Hessian fly,
cicada, locust, cochineal, May fly, June beetle, cockroach,
firefly, daddy-long-legs, plant louse, bed-bug, louse, tick,
jigger, flea, wasp, honey bee, ant, cabbage worm. Compare
these with the types studied. Ask the questions: What
insects are injurious to man? How can we get rid of
them? What insects are beneficial? How can we best
propagate them ?

Make blow-pipes for the students by drawing glass tubes
to a fine point, rounding the sharp edges in the flame, so
they will not cut. Tip with sealing wax a lot of bristles,
both black and white, for probing. Have a good supply of
cigar-boxes. At the beginning of the oyster season ask a
restaurant keeper to open oyster cans on the side and save
them for you; use these for dissecting pans, as described
under “the crayfish.”,

It may be better for the teacher to make the dissection

INTRODUCTION. xi

of the snake, turtle, and a few of the forms that cannot
usually be obtained in sufficient numbers to supply the
whole class, and to make some of the finer points clearer,
especially when the time is short; but each pupil should
do most of this work independently, with occasional sug-
gestions from his teacher.

If the school does not furnish a microscope, get one
yourself,

TO THE STUDENT.

For this work you need : —

1. A small pair of forceps.

2. A small pair of scissors.

3. A knife. ©

4, Two dissecting needles, made by thrusting the eye
end of a large needle into the end of a pen-holder.

5. A hard pencil for drawing.

6. A good pair of eyes.

Keep these all sharp, especially number 6.

7. A lens, such as the three-legged lens, or the linen-
tester.

8. A scratch-book in which to take notes while studying
the specimens. Keep this and number 5 in the
drawer of your work table.

9. A note-book, in which descriptions of the animals
studied should be carefully written in ink.

10. A bottle of mucilage (for every four students).
11. A quart fruit-jar.

In drawing, first trace the outlines; then if these-seem
correct when carefully compared with the object, make the
lines heavier. Avoid shading. See Morse’s “ First Book

xii INTRODUCTION.

of Zodlogy” for models of simple drawings. Draw ne
line that does not correspond, as closely as you can make
it correspond, to something in the object before you.
Look closely at the object before you put pencil to
paper.

In dissecting, follow the directions minutely; they are
made with care, so as to save time, labor, and material.

COLLECTING INSECTS.

Make an insect net as follows: get a light wooden han-
dle four feet long, and the same length of stout brass wire ;
bend the wire into a ring a foot in diameter, cut a notch
in the end of the handle, cross the ends of the wire in the
notch, and bend the ends so they will run close along the
handle for six inches; half an inch from the end of the wire,
bend it at a right angle, and drive into the handle; then
wrap tightly with fine wire.

The ring may be made of a barrel-hoop by steaming it
till flexible, and bending along the handle and nailing
firmly. Sew to this ring a bag of thin muslin, twenty
inches deep.

The net is used for capturing strong flying insects, such
as butterflies and dragon-flies, and for sweeping over the
tops of bushes and grass. When one of the strong fliers
is taken by the net, the handle should be instantly twisted
to throw the bag over the ring and prevent escape.

Butterflies may be killed by pinching the thorax between
the thumb and finger; fold a two-inch square of paper
cornerwise, put the butterfly in the fold, and again fold
the edges and corners. A better method of killing butter-
flies is as follows: Pack cotton two inches deep in the
bottom of a Mason fruit-jar; trim wire gauze to fit closely

INTRODUCTION. xiil

and press it down on the cotton; saturate, or nearly a»,
the cotton with chloroform just before starting out to
collect.

For killing most insects use a cyanide bottle, prepared
thus: get a wide-mouthed bottle with a glass stopper, or
tight cork; place in it two or three pieces, as large as
caramels, of cyanide of potassium; this is a very violent
poison, even its fumes being deadly; it should be handled
as little as possible, — pick the pieces up in paper, —and
should be labeled “Poison,” and kept away from children
and ignorant persons. Mix plaster of Paris and water to
a thin paste, and pour over the cyanide, covering the
lumps half an inch deep. Let the bottle stand uncorked
a day to dry;-.the plaster hardens, but, being porous,
allows the poisonous fumes to rise; after drying a day it
should be kept tightly corked.

When an insect is in the net, the bottle may be un-
corked, pushed into the net and over the insect, and the
insect pushed into the bottle by the cork, thus avoiding
stings, as well as injury to the insect.

Hard insects, as beetles, bugs, and grasshoppers, may .-
be put at once into alcohol. If not used soon, they will
thus be better kept.

Many insects, such as bees and beetles, may be taken
from flowers by quickly pushing them into the bottle with
the stopper.

An umbrella is very useful in collecting certain forms
of insects. Hold the umbrella spread and inverted
under the branches of trees and shrubs, and beat the
branches with a stick, or jerk with the handle, if it has
a hook.

A lamp, by an open window, has often been found too

Xiv INTRODUCTION,

good a means of attracting insects. Some of the most
beautiful moths fly only at night.

Look for beetles under logs, boards, and under the bark
of old logs and stumps. Look in ponds for insects and
their larvee. Treeless meadows and deep forests are not
as good places for insects as gardens, the edges of woods,
and the banks of streams and ponds. Collect cocoons and
larvee, as well as caterpillars, and keep them to see what
they become. It is well to carry several small boxes in
which to put such specimens, and insects that have been
killed in the cyanide bottle, that they may not become
bruised.

MOUNTING INSECTS.

For mounting insects get shallow cigar-boxes. Special
pins, called insect. pins, are made for this work, but com-
mon pins will serve. | In the bottom of the box tack small
pieces of cork, made by slicing an ordinary cork parallel
to its ends. Have the insects about two-thirds of the way
up the pin. Pin beetles through the right wing cover.
Pin butterflies with the wings spread, and pin through
the side of the body to show the position when at rest.
If the insect has dried, it may be softened by wrapping in
a wet cloth, in the case of hard insects as beetles and
grasshoppers; for softening butterflies, put a wad of soaked
paper into a fruit jar, cover this with dry paper, and put
in the butterflies still in their papers. Having softened
the insect in this way, it may be pinned to a piece of cork
or a pin cushion, and the wings having been stretched,
they may be pinned in this position, and so kept till dry.
For holding the wings in place cut small triangles of thick
paper, thrust the pins through these triangular papers; and

INTRODUCTION. XV

setting the pin so that the pin itself shall keep the wing from
moving forward or backward, so regulate the height of the
three-cornered papers that the wing may be held at the
proper height. A setting board may be made as follows:
two boards, sloping toward each other, and half an inch
apart, are fastened to a wide board as a base. The chan-
nel, or groove, between them should be half an inch deep,
and a strip of cork fastened to the bottom for holding the
pins. Pin through the body of the insect, and, the body
extending along the groove, let the wings rest on the
smooth, upward-sloping sides. Place the wings as desired,
lay narrow strips of paper over them and pin the strips
down. As the wings extend slightly upward, and dry in
this position, they will be less likely to droop after perma-
nent mounting. Draw the wings of butterflies forward,
in setting, till the hind margins of the fore wings form a
straight line. Let this rule apply to any spread insect.
Pin a beetle and a grasshopper side by side to show the
difference in the position of the wings, both folded and
expanded, and the different manner of folding the wings.
The name of the insect, date, and place of capture, should
be written on a small slip of paper and kept on the pin
below the insect.

In each box of insects place a piece of camphor to pro-
tect from injurious insects.

BREEDING CAGES.

Take a starch box or chalk box with a sliding cover;
cut off three inches from one end of the cover; slide this
short piece of cover into the farther end; set the box on
this end and put in three inches of soil; insert a sliding
glass cover which projects a little above the top of the

Xvi INTRODUCTION.

box. Put in this box some larva, say a potato worm; feed
it daily with the leaves on which it was found feeding ;
keep the soil moist, and, if no change takes place before
cold weather, remove to a cellar and keep till spring.
Any good-sized glass jar will serve as a breeding cage, as
a candy jar, fruit jar, or battery jar, with a piece of tin
laid on as a cover. A jelly glass makes an excellent
breeding case for eggs and young larve.

APPENDIX TO INTRODUCTION.

THE old-fashioned candy-jars serve admirably as aqua-
ria to be used in class work for the frog, minnows,
clams, snails, ete. It is very desirable to have one for
every student, or, at least, for every group of four at a
table.

For dissecting-pans, glass candy-trays with plain sides
and level tops are excellent. Some trays have knobs at
the corners; these prevent close covering of the tray with
a piece of glass, when a dissection is to be kept. For a
bottom, to which specimens may be pinned, use pieces
-of shingle weighted by lead strips wrapped around the
ends.

Instead of using mucilage, sew the parts of the grass-
hopper, crayfish, frog skeleton, etc., to cards. Many ani-
mals that are not to be dissected under water, such as the
pigeon, rabbit (or ground-squirrel, which serves well as a
type of mammals), may be most conveniently dissected on
ashingle. To it they can be pinned or tacked. If pin-

INTRODUCTION. XVli

ning out is unnecessary, brown paper may serve. Shingles
and papers can then be burned.

A METHOD OF KEEPING NOTES.

Instead of having students record their permanent
- notes in a bound note-book, the following plan is recom-
mended : —

Each student gets two pads,— one ruled, for descrip-
tions; the other unruled, for drawings. A good linen
paper serves well for the latter. The sheets are detached
and handed in to the teacher, with drawings and descrip-
tions as called for. If the pads are five inches by seven
inches, they can be conveniently carried between the leaves
of the Practical Zodlogy, but the most convenient way is
to have the book covered, and to carry the sheets in the
pockets of the cover inside the lids of the book. Each
student should have an envelope half an inch wider than
the pads, with the open end cut off an inch shorter than
the pads, and the student’s name and the name of the
study (zodlogy, in this case) on the envelope near the open
end. ‘This will keep the sheets together, and the project-
ing (top) ends will allow easy examination of the papers.
If several sheets are to be handed im at one time, the envel-
ope should be used. One hundred sheets in each pad will
probably be enough for a term’s work. This plan saves
time for teacher and pupil; lessens the risk of losing all
the work, or spoiling all by accident to one paper; allows
any arrangement of topics. At the end of the term the
notes can be arranged as desired, a table of contents made,
or perhaps even an index, and the whole bound at the
top. Thus the binding only takes the unused part of the

XV INTRODUCTION.

paper where the name of the student was written. Such
notes have been bound in manilla, with the name of the
school, of the study, date, and blank for student’s name,
printed on cover, at a cost of three cents each; giving
the student, at the end of his study, a clean, neat, well-
arranged, and indexed set of notes.

ad

=

PRACTICAL ZOOLOGY.

THE GRASSHOPPER.
THE PARTS OF THE BODY.

The foremost, or anterior, part is the head.
The middle part is the thorax.
The hinder, or posterior, ringed part is the abdomen.

THE HEAD.

Notice its shape and mode of attachment to the thorax.
Two slender projections, the feelers, or antenne.
Observe how and where they are attached to the
head. Use a lens to count the parts, or segments,
of which each antenna is composed.

Note the situation and shape of the eyes. Examine
one of the eyes under a microscope, using a one-inch
objective; make a drawing of what you see. These
eyes are compound, and each of the parts is called a
facet.

Just in front of the compound eyes look for a pair of
simple eyes, the ocelli. Find a third ocellus on the
head, using a lens if necessary.

At the lower part of the front of the head is a mov-
able flap, the upper lip, or labrum; raise it with the

10.

11.

12,

PRACTICAL ZOOLOGY.

dissecting needle. Observe how it is hinged; cut or

break it off.

This lays bare the true jaws, or mandibles. Examine

their black, toothed tips with a lens; find, by prying,

how they move. Study their action in the live grass-
hopper, raising the labrum. Study carefully the way
in which they move, and how they are hinged; then re-
move with the forceps, and again examine thoroughly.

Back of and between the mandibles is the brown

tongue.

Turn now to the back of the lower part of the head;

pry back the lower lip, labium; carefully remove it.

Attached to the base of the labium is a pair of short,

jointed appendages, the labial palpi. What is the

relation between the tongue and the labium?

If the above-named parts have been carefully removed,

there will remain one pair of appendages, smaller

jaws, called the maxille. Make out that each max-
illa consists of three parts : —

a. An outer, jointed part, the maxillary palpus.

6. A spoon-shaped piece covering ec.

e. The brown, in-curved maxilla proper. Examine
with a lens, then with forceps remove the whole
maxilla, being sure to get the basal part.

Cut the head off a fresh specimen; lay it on the table

and make a careful drawing of the face, naming all

the parts.

Draw the head as seen from the side.

THE THORAX.

The wide collar, or cape, back of the head is the
prothorax; make a drawing of it as seen from the side.

?

THE GRASSHOPPER. 8

The remainder of the thorax is formed by the union
of two parts, each bearing a pair of legs, the part to
which the middle pair of legs is attached being the
mesothorax, the hinder legs arising from the meta-
thorax. Look for the line separating these two parts
of the thorax.

Look just above the second pair of legs for a narrow
opening, guarded by a pair of lips, which, in the live
grasshopper, keep separating and coming together;
this is a breathing pore, or spiracle. Look for another
spiracle on the soft skin under the posterior edge of
the prothorax on each side.

Carefully compare the prothorax, mesothorax, and
metathorax.

THE WINGS.

Notice the position of the outer wings, and their mode
of overlapping.

With the forceps seize one of the Gusti wings by its
lower edge, near the anterior end, and draw it hori-
zontally forward, till it makes a right angle with the
body, and pin in this position. Seize the inner wing
by its lower edge near the posterior end, and pull
forward to its fullest extent, observing how it is
folded; pin this wing as expanded, and make a draw-
ing of both wings as thus seen. Cut a piece of paper
the same size and shape as the inner wing, and fold
it as the inner wing is folded.

The framework of the wings is composed of veins.
Compare the inner and outer wings in : —

a. Size.
b. Shape.

Ae Ae

PRACTICAL ZOOLOGY. .

Color.

Texture.

Position, both when at rest and in motion.
Use.

THE LEGS.

. Note their number, arrangement, and mode of attach:
ment.
Study carefully one of the hind legs.

a.

b.
C.
d

A short segment near the body, the coxa.

The big segment is the femur.

The slender segment is the tibia.

The remainder is the foot, or tarsus; count its
segments, and examine thoroughly, using a lens.
Remove a hind leg, and make a drawing show-
ing all these parts.

Examine the joint between the femur and tibia,
moving the parts back and forth. Note, also,
how these parts fit together when the leg is
drawn up.

In how many ways does the grasshopper travel?
In what order are the legs moved in crawling?
Grasshoppers make a shrill sound (stridulation)
by rubbing the inner surfaces of the hind legs
against the outer wings.

In what different ways does the grasshopper keep
from slipping when it jumps? Remove the legs
and wings; make drawings of the thorax as seen
from the side, from above, and from below.

>

te

6.

THE GRASSHOPPER. 5

THE ABDOMEN.

Count the abdominal rings.

Observe two grooves running along the under surface
of the abdomen. The under part of the abdomen,
included between these grooves, is the sternum, the
side of the abdomen is called the pleurum, and the
upper part is the tergum; the corresponding parts of
each separate ring are the sternite, pleurite, and
tergite.

Just above the groove which separates the sternum
from the pleurum is a row of small holes, the breath-
ing pores, or spiracles; count them.

In a live specimen, watch the movements of breathing.
All insects breathe by means of a complicated system
of air tubes, the trachez, which branch from the
spiracles throughout the body. Can the grasshopper
be drowned by holding its head under water? Connect-
ed with the air tubes, in grasshoppers and other strong
flying insects, as bees and flies, are large air sacs, which
fill with air, and are said to aid, like little balloons,
in keeping the insect in the air. By carefully cutting
away the roof of the abdomen, these air sacs may be
seen, marked by their white walls; the white air
tubes, or tracheze, may also be readily seen.

Under the bases of the wings, on the first abdominal
ring, is a pair of thin, shiny, oval membranes, the
tympana, or ear drums. The inner surface of each
tympanum is connected with a nerve; but several
investigators have denied the auditory nature of this
apparatus. *

The abdomen of the female ends in four points; in

6 PRACTICAL ZOOLOGY.

laying the egg these points are first pressed together,
then thrust into the ground, and then separated; this
process is repeated till a hole is made, sometimes as
deep as the abdomen is long, at the bottom of which the
eggs are deposited, passing out between the four points
of these egg guides, which together are called the
ovipositor; compare the inner and outer surfaces of
these egg guides. The males are smaller than the
females. Draw the abdomens, as seen from the side,
of both the male and the female. Take now an entire
specimen and draw a side view of it.

INTERNAL STRUCTURE OF THE GRASSHOPPER.

This work would better be done after the student has
dissected the crayfish. Dissect under water with the dis-
secting pan as described under the “ crayfish.” ;

1. Get a large female grasshopper, freshly killed. Cut
off the wings, and place the specimen, back upper-
most, in the dissecting pan; pin the hindermost ring
of the abdomen firmly to the bottom of the dissecting
pan; turn each hind leg outward and pin down.
With sharp, fine-pointed scissors, cut through each
side of the roof of the next to the last abdominal ring;
lift, with the forceps, the cover of this ring; continue
the cut forward, on each side of the abdomen, pulling
the tergum upward and forward as it is loosened.
Thus carefully unroof the whole abdomen.

2. The heart is a delicate tube, running along just
under the tergum, and probably was torn away with
the tergum.

8. On each side there should now be seen a row of air
sacs, with their white air tubes.

—_

—_—

THE GRASSHOPPER. 7

4. In the anterior part of the abdomen a mass of yellow
eggs is usually to be found; this mass may be easily
separated into two parts, right and left, from each of
which a tube, oviduct, leads to an opening between
the parts of the ovipositor.

5. Under the eggs is the dark intestine, running length-
wise.

6. Remove the roof of the thorax; more air sacs should
be found here. In the upper part of the thorax are
the white muscles which move the wings. Removy-
ing these muscles exposes more of the digestive tube;
as the food is swallowed, it passes upward in a brown
tube, which soon turns backward into the thorax; in
the prothorax, the enlargement is the crop, in which
is produced the dark liquid which the grasshopper
ejects from the mouth when held captive. The crop
may be removed, washed, split open and examined
under the microscope with a half-inch objective to show
the rows of hooked teeth with which it is provided.
A little further back the digestive tube is surrounded
by a set of double cone-shape pouches, which extend
parallel with the main channel of the digestive tube.
These are the gastric ceca. Behind them is the
stomach, followed by the intestine. The products of
digestion pass through the coatings of the digestive
canal, and mingle with the currents of blood which
pass along the ventral and lateral parts of the body.

7. The coloriess blood enters the heart through holes
along its sides; blood is sent from the heart into the
veins of the wings. These veins are hollow tubes,
and though they convey blood, are very different
from the veins in our bodies. Air tubes run along

8 PRACTICAL ZOOLOGY.

the centre of the larger veins, and give air to the
blood as it flows.

8. The nervous system of the grasshopper consists mainly
of a white cord extending along the floor of the whole
body cavity. In most of the abdominal rings the
nerve cord has enlargements called ganglia, from
which nerves branch to the surrounding parts.

THE DEVELOPMENT OF THE GRASSHOPPER.

The egg hatches out a little grasshopper, at first with-
out wings. As it grows, it sheds its skin (moults) several
times. In moulting, the skin splits along the back of the
head and thorax, and the insect works its way out. At
first the newly hatched insect is very soft; the writer has
seen a grasshopper bend its tibia double in the effort of
pulling out of the old skin; but the tibia soon straight-
ened and hardened, showing no signs of injury.

For descriptions of the grasshopper, see Packard’s “ Zodl-
ogy,” Packard’s “Guide to the Study of Insects,” Brooks’
“Handbook of Invertebrate Zodlogy,” “The Rocky Moun-
tain Locust,” in First Annual Report of U.S. Entomologi-
cal Commission, 1877 (issued 1878), Comstock’s “ Guide
to Practical Work in Elementary Entomology.”

GRASSHOPPER CARD.

Take a card six inches by four. Make a faint mark
lengthwise in the middle to aid in placing the parts sym-
metrically. Separate the parts of the grasshopper, and
paste them on the card in their proper order. Before be-
ginning, plan the whole arrangement. First, cut off the
head; leaving a central place for the head, remove the
mouth parts, pasting each to the card as it is removed.

THE CRICKET. 9

In separating the parts use the forceps, being careful to
get hold of the very base of each piece; then, holding
each part with the forceps, dip the side that is to go next
to the paper into the mucilage, and carefully place just
where it is to stay. This method avoids smearing the card.
Avoid getting too much mucilage. The mouth parts should
- surround the head; the wings should be opposite the parts
to which they were attached, as also the legs. The legs
should be separated to show all the segments; the thorax
should be separated into its parts, but the abdomen would
better be kept entire. As the parts become very brittle
when dry, it is well, if the card is to be kept, to make a
little bridge of a strip of paper, on which to string the
rings of the thorax and abdomen? The soft parts should,
of course, be removed.

THE CRICKET.

1. In what are the cricket and grasshopper alike?

2. In what respects do they differ ?

3. The female cricket has a long, slender ovipositor.
Compare its parts with the parts of the grasshopper’s
ovipositor, picking them apart with a dissecting
needle. Use a lens.

4, A pair of tapering, jointed projections from the abdo-
men are the stylets.

5. Compare the wings of the male and female. Look on
the under surface of the outer wings of the male for
a vein, running crosswise, near the anterior end, which
has on it a row of teeth. By rubbing this file on the

10 PRACTICAL ZOOLOGY.

veins of the other wing, the cricket makes its chirping
noise. Watch crickets to see how the wings are man-
aged during this process.

6. With a lens look for the so-called hearing organ on
the tibia of the fore leg.

7. Make a drawing showing all that can be seen from
above (dorsal view), and naming all the parts shown.

Grasshoppers and crickets both belong to the order of
insects called Orthoptera, or straight-winged insects.

e
THE BUMBLE BEE.

1. Find three ocelli on the top of the head. How are
they arranged ? .

Describe the antenne.

3. The mouth parts : —

bo

a. <A pair of true jaws.

b. The long, hairy tongue.

ce. Above the tongue the two blades of the maxille.
d. Below the tongue the thin, narrow labial palpi.

The last three form a proboscis; pick the parts asunder,
and make a drawing of the front of the head, showing all
these parts.

4. How does the bee take its food? Is the honey stored
by the bee the same as when taken from the flower?

5. Compare the segments of the legs with those of the
grasshopper. How does the bee get pollen? What
does the bee do with the pollen? .

er eee

10.

11.

THE BUTTERFLY. 11

Examine the wings; compare the front and hind
wings.

Get a bumble bees’ nest; examine the contents of the
cells, and note the different stages of development of
the young bees.

The sting is a modified form of ovipositor. Near its
base are poison glands, and a sac for storing the
poison. ,

How do bees compare with other insects in intelli-
gence ?

Read the account of the habits of bumble bees, and of
honey bees, in Packard’s “Guide to the Study of
Insects.” i

Ants, bees, and wasps belong to the order Hymenop-
tera, or membrane-winged insects.

THE BUTTERFLY.

The large, brown “milkweed butterfly,” with dark’
markings along the veins of the wings, is a good one to

study.

1. Notice the position of the eyes, and their relative size.

2. Where are the antenne attached? Compare with
those of the grasshopper.

3. The short projections in front of the head are the labial
palpi.

4. Between the palpi is the coiled sucking tube; uncoil
and examine it.

5. The wings :—

12

PRACTICAL ZOOLOGY.

Their shape and their mode of overlapping.

The dark, shiny veins; where are they strongest ?
Scrape some of the scales off a wing; examine
under a high power of the microscope, making
drawings.

d. Examine a piece of a wing, with the scales on it,
to see how they are attached and arranged. Look
at a part of the wing where the scales have been
removed.

= 8

Spread the wings of the butterfly, and draw them as
seen from above.

Examine the legs, and compare their use in this insect
and others. .

Make a drawing of the butterfly as seen when at rest,
naming all the parts visible.

Compare the colors and markings of the upper and
lower surfaces of the wings.

. Carefully compare a moth and a butterfly.
11.

Butterflies and moths belong to the order Lepidoptera,
or scaly-winged insects.

The orders of insects are divided into families; this
butterfly belongs to the family Nymphalidz.

Families are divided into genera; this butterfly belongs
to the genus Danais.

Genera are divided into species; this species is archip-
. pus.

So this butterfly belongs to the class, Insecta; order,

Lepidoptera; family, Nymphalide; genus, Danais; species,
archippus.
The males are distinguished by an elevated black spot
along one of the veins, near the middle of the hind wings.
Where is this butterfly found most abundantly ?

THE BUTTERFLY. 13

Consult French’s “ Butterflies of the Eastern United
States,” for finding the names of butterflies.

DEVELOPMENT OF THE CABBAGE BUTTERFLY.

The cabbage butterfly is small, yellowish beneath, paler
above, with black tips to the anterior wings. The male
has one round, black spot only on each upper wing, while
the female has two, and sometimes three.

1. Open the abdomen and look for eggs. They are yel-
low, oval bodies ribbed lengthwise, with cross mark-
ings on the ridges, resembling stunted ears of yellow
corn. Look also for these eggs on cabbage leaves, or
where these butterflies are seen hovering. Watch the
butterflies closely as they light on the cabbage leaves,
to see the egg deposited on the leaf; on which side of
the leaf are the eggs usually laid? How are they
fastened to the leaf? Make a drawing of the egg as
found attached to the leaf.

2. Get a chalk box with a sliding cover; substitute a
glass cover a little longer than the box. Cut windows
in the sides of the box and fasten wire gauze over
them. Keep the box on end, so that the door will keep
closed, yet may be easily opened. Put into this box
a cabbage leaf with eggs on it; examine several times
aday. What becomes of the egg? In another box,
similarly arranged, put some large cabbage worms ;
give them fresh leaves every day, and keep the box
in a light, well-ventilated room. Watch closely, and
keep record of the date of the beginning of the ex-
periment, and note the date of any change; describe
carefully all actions and changes in the worms.
Make careful drawings of each stage of growth: —

14 PRACTICAL ZOOLOGY.

=

The egg.

6. The larva, at different stages of growth; keep
one worm in a cage by itself, and make a draw-
ing every third day.

ce. The pupa, showing how it is suspended.

d. The perfect butterfly.

3. The cabbage butterfly belongs to the family Papilion-
idae, genus Pieris, species rape.

There are several species of the genus Pieris, just as
there may be several in one family among us; as in a
directory we read: “Smith, Charles,” “ Smith, Edmund” ;
so we read: Pieris rape; Pieris protodice.

What is the meaning of the word “rape” ?

For account of the cabbage butterfly, see “ Report of the
Entomologist” in the “Report of the Commissioner of
Agriculture for the year 1870.”

Occasionally a larva will fail to go through its proper
changes; this is generally caused by some parasite, the
most common of which is an ichneumon larva. The adult
of some kind of ichneumon fly stings the cabbage worm
and lays its eggs in its body; these eggs hatch out as
worms and live on the juices and tissues of the cabbage
worm, till it dies from exhaustion (though the cabbage
worm often lingers, and the parasitic larve complete their
transformation first), and the parasitic larvee become pupe,
and hatch out as perfect ichneumon flies.

Look for holes in pupe which fail to complete their
transformation; often holes may be found in them where
the ichneumon flies have made their escape. If a pupa
blacker than usual be found, put it in a vial, or pill box,
and catch the ichneumon flies as they emerge.

Se .

' THE HOUSE FLY. 15

THE HOUSE FLY.

THE PARTS OF THE BODY.

The head, the foremost, or anterior part.
The thorax, or middle portion.
The abdomen, the hinder, or posterior part.

THE HEAD.

Examine the eyes with a strong lens, and under a low
power of the microscope, to discern its parts or facets.
Such an eye is said to be compound, and in the fly is
composed of about 8000 parts; what shape have the
facets?

Cut off the head, lay it on a glass slide, and with a
one-inch objective examine the short antenne in front
of the head.

Look on the top of the head for simple eyes. :
With a lens examine the under part of the head to
see the tongue. How does it move? Remove it and
look at it with a one-inch objective. How is it used?

THE THORAX.

How many legsare there? To whatare they attached?
How many segments has each leg?

The wings; how manyare there? Back of each wing
find a short membrane, the winglet. Note the folded —
portion connecting the wing and the winglet.

A little further back are two slender knobs project-
ing on stalks like pins; these are the balancers, and
are considered as representing the hinder wings found

16 PRACTICAL ZOOLOGY.

in most insects. Note the effect of removing the
balancers. ;

4. The wings describe a figure 8 in flying, and make over
300 revolutions (7.e., go up 800 times and down 300
times) in a second.

5. On each side of the thorax, just back of the head, find
a narrow opening with yellow, lip-like border; ex-
amine closely with the aid of lens and microscope.
It is a breathing pore, or spiracle.

THE ABDOMEN.

Are there spiracles on the abdomen? How many rings
has the abdomen? Draw the fly as seen from above,
dorsal view.

The house fly lays its eggs about stables; after a day or
two the eggs hatch out as little worms, or maggots, which
eat voraciously and grow rapidly; in about a week they
cease eating, become dry and brown, resemble a seed, and
neither move nor grow; from this pupa the fly emerges.
The adult fly is short lived, though some live over winter.
Watch the development of the egg which the flesh fly lays
on meat and dead animals. How many kinds of flies do
you know? How do they differ? How does the fly walk
on the window pane? Examine the feet. In what order
does the fly move its feet in walking? For the study of
this point, take a fly that is sluggish from cold, or from
partial drowning. Do flies, on the whole, injure man, or
- benefit him? Flies belong to the order Diptera, or two-
winged insects. What other insects have but two wings?
Read:the Muscide in Packard’s “Guide to the Study of
Insects.”

SQUASH-BUG. — BEETLE. 17

THE SQUASH-BUG.

Find the sucking tube bent back under the thorax.
Are there both simple and compound eyes?

What peculiarities of the prothorax?

Draw a dorsal view, showing how the wings overlap.
Draw the squash-bug’s wings out at right angles to
the body, and make another drawing showing how
the outer wings appear when extended, and how the
inner wings are disposed.

6. Draw a ventral view.

SP eo SE

Look for eggs. Compare young and old squash-bugs.
Squash-bugs belong to the order Hemiptera, or half-winged
insects. What is the propriety of this name? Insects
belonging to this order are the only ones that are properly
ealled * bugs.”

See account of the squash-bug in Harris’ “Insects In-
jurious to Vegetation.”

THE BEETLE.

1. What are the characters that appear peculiar at first

sight?
2. Note the position, shape, and range of vision of the
eyes.
3. The antenne, their attachment, parts, and mode of
extension.

4. A small upper lip, the labrum.

18

10.

11.

12.

13.

PRACTICAL ZOOLOGY.

A pair of strong jaws, the mandibles, often very large,
and projecting forward as pinchers, or “horns.” How
do they move?

.. Back of these are two small jaws, the maxillz, bear-

ing a pair of jointed appendages, the maxillary palpi.
Back of (posterior to) the maxillary palpi is another
pair of similar appendages, the labial palpi.

The part of the body back of the head is the protho-
rax. Why not call it the thorax?

Pry up the hard outer wings. How do they meet
each other? The outer wings are called the wing
covers, or elytra. In what direction does the beetle
move the elytra in raising them? How are they held
during flight? Do they rise vertically?

How are the inner wings folded? Compare the inner
and outer wings in length and size. Cut a piece of
paper of the same shape as the inner wing, and fold it
as the inner wing is folded. How does the beetle
perform the act of folding the inner wings? Capture
live beetles and watch this process.

Make a drawing of the back, with the wings closed;
another drawing, with the wings fully expanded, as in
flight.

Count the segments of the legs. Examine each seg-
ment closely. Seize the foot of one of the hind legs
with the forceps, and pull it about in all directions,
to see how many joints the leg has, and what motions
are allowed by each joint. The segment nearest to the
body is the coxa. Then come in order, trochanter,
femur, tibia, and tarsus (foot).

What marks the line of division between the thorax
and abdomen ?

THE DRAGON-FLY. 19

14. Draw a ventral view on a large scale, showing

15.

16.

especially the parts of the legs, and the mouth parts.
Watch a crawling beetle, to see in what order the legs
are moved.

What can you tell of the habits of beetles? The -
different kinds of beetles, and their development?
What is a grub? Compare beetles with other insects
in strength. The large beetles are good insects for’
dissecting, to show the internal structure. Beetles be-
long to the order Coleoptera, or sheath-winged insects. '

See “Classification of the Coleoptera of North America”

by LeConte and Horn.

or

THE DRAGON-FLY.

Compare the shape and relative size of the parts of
body with those of other insects. In some dragon-
flies the eyes have as many as 12,500 facets each.
What kind of mouth parts has the dragon-fly ?

How does the dragon-fly compare with other insects
in power of flight? To what bird should the dragon-
fly be compared in its habits?

Has the dragon-fly a sting? Is it dangerous to man
in any way?

Watch the dragon-fly dipping the end of its abdomen
into the water to lay its eggs. Compare the oviposi-
tor with that of the grasshopper.

The larva of the dragon-fly may be found on the
bottoms of ponds and streams, and is very noticeable
on account of its wide head and prominent eyes, wide
abdomen, and short wings.

20 PRACTICAL ZOOLOGY.

7. When the larve are ready to transform, they crawl

up out of the water, their skins split along the back,

and the adult dragon-fly escapes, leaving its dry,

empty skin, which may be found clinging to the stems

of water plants, projecting logs, or rocks.

Draw a dorsal view.

9. The dragon-fly belongs to the order Neuroptera, or
nerve-winged insects.

oe

REVIEW OF INSECTS.

Take any insect not yet studied, and examine it thor-
oughly. Write a full description, and make drawings of
it. To which of the insects previously studied is this
most like? ‘To what order, then, does it probably belong?

Select two pages in your note-book that face each other.
On the left-hand page make a list of characters common
to all the insects you have studied, numbering the points;
on the right-hand page write briefly the characters peculiar
to each insect. The first list ought to be a very nearly
correct definition of an insect, so far as external features
are concerned. The second list should serve as a defini-
tion of each of the orders of insects.

All the orders of insects belong to the class Insecta.

Write now a list, in vertical series, of the orders of in-
sects studied, with the name of the insect representing
that order opposite it, and include all within a brace oppo-
site the word Insecta.

Read Hyatt’s “Insects” (No. VIII. in Guides for Science- -

teaching). See also “Standard Natural History,” Vol. II.,
and Saunders’ “ Insects Injurious to Fruits.”

THE SPIDER. . OF

THE SPIDER.

Spiders are best preserved in alcohol, as they shrink in

drying.

1. The anterior division of the body is the cephalo-
thorax, or united head and thorax.

2. The large posterior division is the abdomen,

3. How many legs are there? To what are they at-
tached? How many segments are there in each?
Examine the feet under a microscope. Make a draw-
ing of one of the feet. Can a spider climb out of a
tumbler? Compare it with the beetle in this respect.

4. With a dissecting needle pry apart the mandibles,
at the front of the head. Make out the fine, spine-
like, curved poison fang at the lower end of each
mandible.

5. Back of the mandibles find a pair of small jaws, the
maxilla. ;

6. To the maxille are attached a pair of jointed append-
ages, resembling a pair of legs, the maxillary palpi.

7. With a lens look for the simple eyes above the jaws.
How many are there, and how are they arranged ?

8 With a lens examine the spinnerets at the posterior

end of the abdomen. With a pair of forceps hold a
live spider by one leg, and watch the beginning of
spinning. Highly magnified, the spinnerets appear as
blunt protuberances arranged together in pairs, and
capable of being contracted or expanded. These
spinnerets are covered with hundreds of jointed hairs,
which are perforated and through which the web-
forming material issues. This material is fluid, and

22 PRACTICAL ZOOLOGY.

somewhat like the white of an egg. Escaping from
the body, through hundreds of these openings, the
strands of this fluid dry almost instantly, and uniting,
form the delicate, yet comparatively strong, thread of
the spider. ‘Thus it will be seen that the thread of
the spider is composed of hundreds of strands, which
may often be separated just as the fibres of a rope
may be pulled apart.

9. Besides trachez, spiders have a so-called lung, com-
posed of several leaves, into which blood flows, and is
thus aerated.

Place the description of the spider alongside the list of
characters common to insects, and note what features are
common to the spider and all the insects; also the points
wherein they differ.

Spiders belong to the class Arachnida. Is the young
spider, when first hatched, like the adult? Study the
habits of spiders, and their methods of spinning their webs
and capturing insects.

Read Emerton’s “Spiders, their Structure and Habits,”
and the chapters on spiders in Morse’s “First Book of
Zodlogy,” Packard’s “ Zodlogy,” and Packard’s “ Guide.”

THOUSAND LEGS.

One form of thousand legs, commonly found under the
bark of dead stumps and logs, is well known by its cylin-
drical body, by its numerous, short, hair-like feet, and by
its habit of coiling its body into a spiral when disturbed.

ee ee es

mf Po

THOUSAND LEGS. 23

How many segments has the body?

How many appendages has each segment?

Make a drawing of the thousand legs.

What are the chief differences between this animal
and insects ?

Another common form of thousand legs (Lithobius
americanus) is that called (wrongly) “centipede,” or
(also wrongly) “earwig.” It is, when full-grown, about
an inch long, with a broad, flat head, a brown, shiny back,
the segments being mostly of about the same size, with
one pair of jointed appendages to each segment. The
antenne are many jointed. It is found under boards, and.
about rubbish, and manure heaps, where it feeds on insects
and earthworms.

1:

2.
3.

4,

Examine the jaws and mouth parts carefully ; how
many pairs of jaws are there ?

With a lens examine the legs. How many are there?
What kind of eyes are there? How many, and how
placed ?

Arrange the legs. so they can be distinctly seen, and
make a drawing as seen from above.

Make an enlarged drawing of the mouth parts as seen
from below.

What are the differences between this form and the
thousand legs mentioned above ?

In what are the two alike? Both belong to the
class Myriapoda. Carefully compare them with the
insects, and make a list of points common to insects
and myriapods; also a list of the characters which
insects have and the myriapods do not have; anda
list of points peculiar to myriapods. |

\

24 PRACTICAL ZOOLOGY.

THE CRAYFISH.

Get a number of live crayfishes. They are usually to
be found hidden under stones in the shallow water of
creeks. Put into alcohol at least three for each student.
Keep some of them alive in an aquarium —a large pan
will serve, though the vertical sides of a regular aquarium
render it easier to watch the movements of these and
other aquatic animals. Let each student have a live cray-
fish in a fruit-jar. Examine from above, from the side,
and from beneath. How many legs does the crayfish yse
in walking? Frighten the crayfish by suddenly thrusting
a pencil at it; how does it effect such rapid locomotion?
Touch one of the eyes with the pencil; what follows?
Move the pencil slowly toward one of the large claws.
What does the crayfish eat, and how does it eat? What
are its habits?

The crayfish and lobster are so nearly alike that these
directions, though written for the crayfish, will serve
fairly well for the latter. Use crayfishes that have been
a short time in alcohol. If lobsters are used, get unboiled
specimens.

EXTERNAL PARTS OF THE CRAYFISH.

1. The united head and thorax are called the cephalo-
thorax.

2. The continuous covering of the two is the carapace.
The projection of the carapace, above and between
the eyes, is the rostrum.

3. The hinder, flexible part of the body is the abdomen.
Count its rings, or segments. Bend (flex) the ab-
domen, and straighten (extend) it repeatedly, obsery-

THE CRAYFISH. 25

ing how the segments are jointed together, and how
they move one upon another.

. Separate the third ring (counting from the front)
from the rings in front of and behind it. To do this
hold the cephalothorax and fore part of the abdomen
firmly between the thumb and forefinger of the left
hand, with the posterior end of the abdomen projecting
toward the right hand; then, grasping the dissecting
needle firmly 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
without breaking either; with scissors cut the mem-
brane between the under sides of the rings, and en-
tirely separate them. In like manner, detach the third
segment from the second. The ring has these parts: —

a. The upper part, the tergite.

6. The under part, the sternite.

ce. The side piece, the pleurite (projecting down-
ward).

d. Two appendages, the swimmerets.

Observe that each swimmeret has a main stalk and
two branches; examine these appendages thoroughly.
Lay the ring on its front side, make the branches of
the swimmerets diverge enough to appear distinct,
and make a drawing of the whole ring as seen from
behind.

Compare the other segments of the abdomen with
the third.

In the male the appendages of the first and second
rings are larger than in the female. Other organs as

26

PRACTICAL ZOOLOGY.

well as the generative apparatus present differences
in the two sexes, being modified for the performance
of special functions in the sexual life, such as the
differences in color and markings of male and female
butterflies, and the differences between the wings of
male and female crickets, already noticed. These
differences are known as secondary sexual characters.
Compare the male and female crayfish as regards the
width of the abdomen.

Study carefully the structure and action of the tail-
fin. Its middle piece is the telson, underneath which
is the external opening of the intestine, the anus.

Remove the telson, and without disturbing the side
parts of the tail-fin, separate the sixth abdominal ring
from the fifth. Now carefully compare this (sixth)
ring and its appendages with the third ring and its
appendages.

Are the appendages of the thorax borne upon rings
like those of the abdomen? If so, where are the
rings? With forceps seize the base of one of. the
hindmost pair of walking legs, and move it back-
wards and forwards; are these borne on a distinct
ting? Carefully clean the sternum between the other
walking legs, and look closely for indications of rings.
With the forceps break away one side of the carapace,
beginning at the lower edge. This lays bare the
white, feathery gills. Move the legs of this side
back and forth, watching the gills.

Study now the hindmost of the walking, or thoracic
legs. Count its segments. Observe how the first
segment is joined to the body. Flex the leg as far as
possible, in every direction, noting the number of

‘THE CRAYFISH. oT

joints, and the motions allowed by each. With the
forceps seize the squarish, basal segment of this leg,
and pull off the leg.

. Remove in like manner the leg in front of this, again

being careful to get a firm hold of the short, wide
segment next to the body. What is the relation
between the leg and the gill nearest to it? Lay this
leg on a paper in front of the one previously removed.
In this way pull off all the legs of one side, from the
hindmost to the foremost, laying them in order.
Compare them all with the one first taken. In the
legs bearing pinchers is there any really new part
added, or is the pinching apparatus produced by some
change in a part present in all the legs? How do
the legs which bear the big claws differ from the
walking legs? Compare them, segment with segment.

. In front of (anterior to) the big legs are several pairs

of appendages surrounding the mouth. Probe be-
tween them to find the mouth. These mouth parts
are numbered from the front, but on account of the
way in which they overlap, it is easier to remove and
study them in the reverse order.

The appendages just in front of the big claws are the
hindmost of three pairs of jaw-feet, or maxillipeds.
Gently raise them, to see how they cover the other
mouth parts. Note that these maxillipeds, or foot-
jaws, have an inner branch, which meets the corre-
sponding part of the opposite maxilliped, and an
outer branch. Observe that both these branches are
attached to one segment next to the body. Seize this
basal segment, and remove. the whole maxilliped.
Compare it with one of the swimmerets of the third

28

10.

11.

PRACTICAL ZOOLOGY.

ring of the abdomen. In the same way remove the
second and first maxillipeds of this side, keeping them
in order. Are there gills attached to the maxillipeds?
Is there more than one gill on each leg? Are there
other gills than those attached to the legs? Pick one
of the gills to pieces under water to determine its
structure. After removing the gills, ‘look in this
region for further traces of thoracic rings.

Anterior to the maxillipeds are two pairs of maxille.
These are very thin, and lie close to each other, so
that if great care be not taken, they are likely to be
pulled off together. Investigate closely, and then,
inserting the forceps well down, remove them, one at
atime, Attached to the base of the hinder maxilla
is a thin, double-spoon-shaped structure, the gill-
scoop. It lies in the front part of the cavity in
which the gills are, the gill-chamber. With the
forceps move back and forth the second maxilla of
the other side, to see how the gill-scoop is thereby
moved. The gill-scoop, swinging back and forth,
pushes the water out of the front end of the gill-
chamber. The water thus expelled is replaced by
fresh water, which comes up under the lower edge of
the carapace, about the bases of the legs; thus the
gills are constantly bathed with water containing
a fresh supply of oxygen.

The mandibles are short, hard, toothed, each bearing
a jointed appendage, which curves around the anterior
edge of the mandible in a groove. This is the mandib-
ular palpus. Move the mandible about to see how
it is hinged. Closely fitting against the posterior
surface of each mandible is a thin leaf-like structure,

12.

13.
14.

15.

THE CRAYFISH. 29

the metastoma. (The metastomata differ from the
maxille in pointing outward and in being undivided.)
Remove it and complete the series of mouth parts, —
mandible, first maxilla, second maxilla, first max-
illiped, second maxilliped, third maxilliped. Remove
the corresponding appendages of the other side, lay
them in a row facing those of the opposite side, as
before removal, but not now overlapping each other,
and make a drawing of the series, naming them.
The long projections in front of the head are the
antennez. Seize one of them with the forceps, and
pull about in all directions, to make out the large
segment, at its base, under the head. On this basal
segment find a small white cone, with a hole at its
summit. This is the aperture of the green gland,
in the head, which acts as a kidney in throwing off
certain waste products from the body. Remove the
antenna, with the whole of this big segment at its
base. What, probably, is the use of the blade-like
branch of the antenna just under the eye? Compare
the antenna and its branches with a swimmeret.
Above the antennze are the antennulea. Remove
one of them and compare it with a swimmeret.
In the base of each antennule, just underneath the
eye, is the ear-sac.
With the forceps pull the eye about to see its range
of motion. Pull it out by its stalk, and examine with
lens and microscope its black tip, or cornea. Is it
simple or compound ?

After removing the cephalothoracic appendages,
and the carapace, carefully clean and thoroughly
examine the framework of the cephalothorax, still

380

PRACTICAL ZOOLOGY.

looking for traces of thoracic rings. The number of
cephalothoracic segments can be determined only by
counting the pairs of appendages. All writers are
not agreed as to this number; some regard the eyes
as a distinct pair of appendages, comparable to any
pair of legs, and representing a distinct ring; but
the eyes seem to develop from the ring which bears
the antennule. Again, some regard the metastomata
as a distinct pair of appendages. ‘The line of division
between the head and thorax is also a matter of
dispute. Huxley places it between the second pair
of maxille and the first pair of maxillipeds. Hyatt
places the division between the first and second pairs
of maxille, as the space between these is membranous
entirely across the sternal region, while back of this
line the parts are hard and firmly soldered to-
gether.

The carapace is probably not a consolidation\of the
dorsal portions of all the cephalothoracic segments,
but a backward extension of the consolidated upper
parts of the rings of the head; the dorsal portions of
the thoracic rings, being thus covered, are conse-
quently no longer developed. In certain lower
crustacea the carapace is unquestionably a backward
extension of the head-shield (Hyatt). The groove
across the carapace has been generally regarded as
indicating the line of division between the head and
thorax. If this line be traced its extremities will be
found to lie between the antennze and mandibles.
Packard states that the carapace, or shield of the
head-thorax, may be seen, after close examination, to
represent the segments of the antenne and mandibles,

THE CRAYFISH. 81

and is so developed as to cover the other cephalotho-
racic segments.

16. Make, side by side, three drawings of the crayfish, —
a dorsal, a ventral, and a lateral view, — naming all
parts.

CRAYFISH CARD.

Take an entire crayfish; separate all its parts, and paste
them on a card, as in the case of the grasshopper; arrange
the eyes, antenn, antennules, mandibles, maxille, maxilli-
peds, and thoracic legs, symmetrically about the carapace.
Make a paper bridge on which to rest the carapace.
Separate the rings of the abdomen, string them on the
paper bridge, and place opposite each its appendages,
remembering that the side parts of the tail-fin are appen-
dages of the sixth ring. Draw in your note-book all the
parts as arranged on the card, with the name beside each
part. ;

INTERNAL STRUCTURE OF THE CRAYFISH.

The better dissecting pans have a thick layer of wax in
the bottom, or a sheet of cork weighted with lead, to
which specimens may be pinned, and dissected under
water. Very good cheap dissecting pans may be made
as follows: take oyster-cans that have been opened on one
side, and cut out this side, leaving a margin half an inch
wide. Bend this margin down inside. Cut a piece of
shingle or cigar-box cover for a false bottom, leaving it a
little long, se it will wedge in tightly and not float up
when water is poured in. (See Introduction, p. xvi.)

For this work use lobsters, or as large crayfishes as possi-
ble. Place the crayfish in the dissecting pan, and cover it

32 PRACTICAL ZOOLOGY.

with water. Pin it to the bottom, through the telson, and
through the big claws. Observe a groove, curving
lengthwise, on each side of the back of the carapace.
Insert the point of one blade of the scissors under the
hinder edge of the carapace at one side. Cut forward, a
little outside the above-noticed groove, to the groove
which separates the head from the thorax. Break away
the whole of the side of the carapace. Push the gills
downwards, and cut them off at their point of attach-
ment below.

Observe the thin wall separating the cavity in which
the gills were, the gill-chamber, from the body cavity.
Clear away the other side likewise. With the forceps
pick away the narrow cover of the body cavity carefully,
as the heart lies just under the carapace.

1. The heart is an oblong, whitish body. Look for holes
in its upper surface, and for small white tubes running
forward from it toward the head. With the forceps
gently lift the hinder end of the heart; note its
angularity.

There are two holes in the top of the heart, two
beneath, and one on each side. These holes are
guarded by lip-like valves on the inside, so that when
the heart contracts, the blood cannot flow out through
the holes, but is driven out through the arteries to the
various parts of the body. From the different parts
of the body the blood goes to the gills. Returning
from the gills, it enters the cavity in which the heart
lies, the pericardial cavity. As the valves at the
openings of the heart open inward, the blood readily
flows into the heart when it expands.

’

THE CRAYFISH. 38 .

. Under the heart, and projecting in front of it, are the
reproductive organs: in the female, the yellowish
ovaries, in which the spherical eggs may be distin-
guished; in the male, the whitish testis occupies a
corresponding position. The ovary on each side sends
downward a tube, the oviduct, or egg-tube, to the
first segment of the third thoracic leg, where it opens
externally. The testis has a much longer, coiled
white tube, which opens on the first segment of the
hindmost thoracic leg.

. Carefully cut away the roof of the head. The space
within the head is almost completely occupied by
the stomach, a roundish sac, with a thin wall, in
which is a hard framework. Gently scrape away
the soft tissues around the stomach, and examine it
closely. Observe the narrow gullet or esophagus
“leading from the mouth to the stomach.

. Along the sides of the posterior end of the stomach
and the anterior end of the intestine lie large reddish
masses, the liver. Pick one of these masses to pieces
to learn its structure. Find the duct leading from
each liver into the intestine.

Observe the white muscles which extend forward
from the abdomen along each side of the body
cavity.

. Beginning at the front end of the abdomen, cut with
scissors through the roof of the abdomen to the
telson, on each side. Seizing the fore part of this
roof with the forceps, carefully lift it and turn it
backward. A thin layer of white muscle may adhere
to it, or may remain connected with the organs in
the abdomen. ‘This is made up of the muscles that

-B4

PRACTICAL ZOOLOGY.

straighten (extend) the abdomen. Pick it away care-
fully with the forceps.

Running lengthwise, in the middle line, is the
intestine, a thin-walled tube, often of a dark color
from its contents. Trace it back to the anus, and
forward to the stomach. Carefully remove the in-
testine.

A large mass of muscle remains. ‘ This is composed
of the muscles that bend (flex) the abdomen. Draw
the point of a knife-blade or dissecting needle along
the middle line of this muscle, along the bottom of
the groove in which the intestine lay. After a thin
layer has been cut through, the whole muscle may be
easily separated into two rolls the whole length of
the abdomen. Pushing these carefully aside, find in
the middle line of the floor of the abdomen a slender
white nerve cord, with enlargements at intervals.
How many of these enlargements, ganglia, are there
in the abdomen? What relation do the ganglia have
to the segments? Observe the branches, nerves,
given off to the muscles on each side. Trace the
nerve cord forward to the thorax, where it disap-
pears in the hard framework of the floor of the
thorax. Break away as much of this framework as
is necessary to follow the cord to the head. Make
out that the cord is double. How many ganglia are
there in the thorax? Note the branches extend-
ing to the legs and other organs. From the large
ganglion back of the gullet trace two branches for-
ward, one on each side of the gullet, till they unite
in a large ganglion above the gullet, thus forming
the esophageal collar. From the ganglion above

THE CRAYFISH. 85

the gullet trace nerves to the eyes, antenne, and
antennule.

9. Cut open the stomach, wash it out with water, and
look on its inner walls for teeth.

10. Study the joint in one of the big pinchers. Pick out
the muscle from the end of the segment, and find the
thin, tough, white tendons. Seize these with the
forceps and pull alternately, to see how the claw is
shut and opened.

11. In what characters is the crayfish like the grass-
hopper? In what do these animals differ ?

12. Why should the name Crustacea be applied to such

~ animals as the crayfish?

THE DEVELOPMENT OF THE CRAYFISH.

The eggs are glued in masses to the swimmerets, under
the abdomen of the female, and thus carried till they are
hatched, and for some time afterward the young cling to the
swimmerets. In its growth the crayfish sheds its crust, or
moults, several times. In this process the carapace
separates from the abdomen above, and cracks along the
back. By a series of severe efforts the crayfish extricates
itself, at first soft, defenceless, and correspondingly
timid. Great difficulty is experienced in withdrawing the
legs; often they are broken off in the effort to withdraw
them. The legs are frequently broken off at other times,
but grow out again.

Read “The Crayfish,” Huxley; the chapter on “The
Fresh-water Crayfish” in “Practical Biology,” Huxley and
Martin,

36

PRACTICAL ZOOLOGY.

THE SOW-BUG.

Sow-bugs are usually to be found under boards and

stones, and in other damp places. Get the largest speci-
mens for this study.

POPP

ae

The first part is the head, or carapace.

Find and describe the eyes.

What are the peculiarities of the antenne ?

The jaws and maxille are closely pressed together,
forming a short, blunt projection under the head.
The tip of this blunt proboscis is usually black. A
longitudinal groove shows the line of union of the
hinder maxilla. By pinching the body of a live sow-
bug, the mouth is sometimes more clearly shown by
the exudation of a liquid, as in the case of a grass-
hopper.

Where is the line of division between the head and
thorax? Count the appendages which may be sup-
posed to belong to the head; how many rings do
these indicate ?

The line of division between the thorax and abdomen
is indicated by an abrupt change in the size of the
segments. How many segments has the thorax?
How many segments are there in the abdomen?

How many pairs of legs are there? How many seg-
ments has each leg? Do the legs all extend in the
same direction ?

A series of thin, over-lapping plates under the abdomen
are the gills. In the anterior plates observe the white
air-chambers. Beginning at the foremost of these
gills, pick them apart with a needle. Remove them

Ne a ee Le ee |

10.

CYCLOPS. 37

in this way, and with a lens make out their shape
and arrangement.

Under the thorax of the female there is a series
of thin membranes attached near the bases of the
legs. These are the egg-covers.* The eggs, after
being expelled from the body, undergo their develop-
ment in the space under the thorax enclosed by these
egg-covers. Look for specimens carrying eggs in this
manner.

In what respects are the sow-bug and crayfish alike?
In what respects do they differ from each other?

The crayfish and sow-bug both belong to the
Crustacea. The class Crustacea is divided into
several orders. The order to which the crayfish
belongs is the Decapoda, or ten-footed; the sow-bug
belongs to the order Tetradecapoda, or fourteen-
footed.

See Chapter X VIII of Morse’s “ First Book of Zodlogy.”

CYCLOPS.

Along the sides of aquaria, and sometimes in drink-
ing-water, there may be seen minute white animals
swimming with a jerky motion. Cyclops has a pear-shaped
body, and is just large enough to be seen readily with the
naked eye. The females carry two egg-masses attached-to

the sides of the abdomen. With a lens, watch these
animals through the side of the aquarium. Place a female
cyclops with a few drops of water in a watch-crystal, or

388 PRACTICAL ZOOLOGY.

on a piece of glass. Examine under a three-legged lens or
under a low power of the microscope.

1. The foremost division of the body is the carapace.
How many segments has the thorax ?

2. The egg-sacs are attached to the first ring of the
abdomen.

3. The eye; note its color, position, shape, and parts.

4. The antenne and other appendages.

5. How does cyclops swim ?

Make a careful drawing of cyclops as seen from above.

Cyclops belongs to the order Entomostraca (water-fleas).
Read “Anatomy and Metamorphosis of Cyclops,” in
Brooks’ “ Handbook of Invertebrate Zodlogy.”

OTHER CRUSTACEA.

The lobster is almost exactly like a crayfish, only larger.
If a lobster can be obtained, carefully compare it with the
crayfish. Shrimps are also very much like crayfishes.
Crabs have wide bodies and very short abdomens, folded
closely under the body. The structure of crabs, both
internal and external, is essentially the same as that of
crayfishes. The crab which is so much used for food has
the hinder pair of legs developed as paddles for swimming,
the outer segments being flattened. This crab swims
sideways. Just after moulting it is known as the “ soft-
shell crab.”

The little oyster crab, which often comes to us with our
oysters, is not a young crab, but is the female of one of
the smaller species of crabs.

a

——

OTHER CRUSTACEA. 39

The hermit crab backs into the empty shell of a sea-
snail, thus protecting the soft hinder parts of his body,
and with his head and anterior appendages projecting,
crawls about, dragging his house with him. When the
hermit outgrows his shell, he exchanges it for a larger
one. When first hatched it is like other crabs.

The sand crab runs rapidly on the beach, and when
pursued, and not near its hole, quickly buries itself in the
sand, leaving only the black tips of its eyes exposed. This
crab is nearly white.

The fiddler crab is small. The male has one large claw,
which it holds across the front of its body. The. other
claw is very small, the two suggesting the violin and
bow. It lives in holes between high and low tide
marks. The writer has seen these crabs covering the
beach for many rods, so thickly crowded as almost to
touch each other, making a loud rustling noise as they
shuffled away from their uninvited visitor.

Lobsters, crabs, and shrimps live in salt water.

Some small crustaceans, found in ponds, swim actively
about, enclosed in a bivalve shell, formed by the growth
of the carapace, which they can open and shut.

Collect a variety of the common small crustaceans, keep
them in a fruit jar, and study their habits.

Consult “Worms and Crustacea” in Hyatt’s “Guides
for Science Teaching,” “ Packard’s Zodélogy,” and Huxley’s
“ Anatomy of Invertebrated Animals.”

Look over the descriptions of the crayfish and sow-bug,
and make a list of the characters common to the two. Let
this list represent the characters of Crustacea generally.
Place side by side (1) the list of characters common to all

: . | |

40 PRACTICAL ZOOLOGY.

the insects studied, (2) the characters of spiders, (3) the
characters of myriapods, (4) the characters of crustaceans,
and by comparing these four lists make the following : —

1. A list of characters which they all have in common.

2. A list of characters which insects have, but which the |
others have not. |

3. A list of characters which spiders have, but which |
the others do not have. |

4. <A list of characters which myriapods have, but which |
the others do not have. |

5. A list of characters which crustaceans have, but which
the others do not have.

Which are more striking, the differences or the resem-
blances, in thus comparing these four groups?

The four classes, Insecta, Arachnida, Myriapoda, and
Crustacea, constitute the branch of the animal kingdom
called the Arthropoda.

List 1 ought to be an approximate definition of the
branch Arthropoda.

THE EARTHWORM.

Place a live earthworm on a newspaper on the table,
and watch its motions. How does it crawl? Is the same
end always foremost? Are the two ends alike? Near
the anterior end is the thick white girdle; is it a complete
girdle? Count the segments; are they all alike? Com-
pare the upper, dorsal, surface with the under, or ventral, |
surface. A dorsal vessel can usually be seen under the |
dorsal surface; watch for pulsations. With the forceps

THE EARTHWORM. 41

seize the worm near the posterior end and drag it back-
- ward; is there resistance? Repeat, and listen attentively.
Lay the worm over the tip of the forefinger, and drag it
backward and forward. Look for fine spines; how are
they arranged, and in what direction do they point? Note
_ the mouth opening at one end, and the anus at the other.
Draw as seen from above (dorsal view).

DISSECTION OF THE EARTHWORM.

Use the dissecting pan as for the crayfish. Half fill the
can with water, and renew if it becomes muddy during
dissection. Have in readiness two dozen pins.

Kill a large earthworm by putting it into a tumbler and
covering it with ether or alcohol.

1. Lay the specimen lengthwise in the middle of the dis-
secting pan, stretch it, and pin it firmly at each end.
With sharp, fine-pointed scissors cut through the skin
of the back, near the posterior end, continuing the cut
forward a little to one side of the middle line. Stretch
the edges of the skin out to the sides, and pin down,
slanting the pins so they will be out of the way.

2. If a milky liquid be found, place a drop of it on a

- glide, cover it with a cover-slip, and examine with a
high power of the microscope. White blood cor-
puscles should be seen.

3. As soon as the edges of the cut are separated, the
intestine, usually of a dark color, from its contents,
is seen.

4. Along the top of the intestine runs the dorsal vessel.
This is perhaps not a true “ blood-vessel,” for many
regard the milky liquid, above noted, as the real
blood. :

42

10.

4:

12.

PRACTICAL ZOOLOGY.

Observe the muscular ‘partitions between the seg-
ments; what is their relation to the intestine? Care-
fully compare the partitions with the external mark-
ings and the sets of spines. Are there as many seg-
ments as are indicated by the external appearance?
The brownish substance along the top of the intestine
constitutes the so-called “ liver.”

Continue the cut to the anterior end, being very
careful not to cut the intestine, especially in the part
anterior to the girdle. Pin well out. Cut the parti-
tions down at the sides, to free the inner structures.
In the region of the tenth segment are several roundish
white bodies, — reproductive organs.

Alternating with these are several red masses. These
are side branches of the dorsal blood-vessel, which
curve downward on each side of the gullet, to unite
with a ventral blood-vessel, thus forming rings around
the slender gullet. These rings have enlargements,
thus resembling necklaces.

Back of the reproductive organs are two enlargements
of the digestive tube, different from the intestine.
The foremost of these is the crop, the hinder is the
gizzard.

In the first six segments is a wide portion of the
digestive tube, the pharynx. Carefully dissect away
the thick muscular partitions, to see it more clearly.
This pharynx is used as a proboscis, being protruded
from the mouth and inverted.

The pharynx narrows behind into the gullet. Trace
this back under the reproductive organs to the crop.
The gullet is the narrowest part of the digestive tube,
and if the reproductive bodies have been sufficiently

13.

14.

15.

16.

THE EARTHWORM. -. 4d

studied, they may be dissected away, to disclose the
gullet more fully. Review now the whole digestive
tube, pharynx, gullet, crop, gizzard, intestine.

Under the intestine is a ventral vessel. Find its
side branches.

Cautiously dissect away the intestine and find under
it a slender white thread, the nerve cord, having
swellings, or ganglia, in each segment. Trace this
nerve cord to its posterior end. Then trace it for-
ward. Under the anterior part of the pharynx it
divides, sending a branch up on each side of the
pharynx. These branches unite in a large, double
ganglion above the anterior end of the pharynx.
This nerve collar is similar to that found in the
crayfish and in insects.

The thin outer skin, or cuticle, which easily peels
off in alcoholic specimens, was probably noticed in
cutting along the dorsal wall. Observe the pearly
lustre of the cuticle. Under the true skin is a layer
of muscle, with fibres running circularly. Under-
neath this is a second layer of muscle, whose fibres
run lengthwise. By the contraction of the circular
fibres the segments are made narrower and longer;
thus the body is extended. If the spines are held
pointing backward, the body will be pushed forward.
When the longitudinal fibres contract, the body is
shortened, and, owing to the direction of the spines,
is pulled ahead.

The reproductive organs are alike in all the individ-
uals of a given species of earthworms. All lay eggs.
There are no males, no females. They pair, each
fertilizing the eggs of the other. Animals of this

44

17.

18.

19.

20.

PRACTICAL ZOOLOGY.

kind, in which the sexes are united in the same
individual, are called hermaphrodites.

There are no lungs, no gills. Oxygen is taken by the
blood as it circulates, through the skin.

There are no eyes, but the first two segments seem to
be sensitive to light.

The worm, in digging a new hole, or deepening an old
one, swallows the soil, and passes it through its
intestine, the partly decayed vegetable matter in the
soil furnishing nourishment to the worm. The coiled
castings at the tops of the holes have probably been
noticed by all. In damp weather the worms come to
the surface to draw leaves, twigs, and seedling plants
into their holes. These holes are sometimes six feet
deep. It is found that the leaf is rolled together and
drawn into the hole with the stem pointing up.
Taken an inch or two below the surface, the leaves
soon become softened, and in a partly decayed condi-
tion are eaten. In this way, without the aid of teeth
or hard jaws, the worm obtains food solely by the
suctorial power of its proboscis.

Make a drawing showing the whole digestive canal as
seen from above. Draw a cross-section of the body
(i.e., what is seen if the body is cut across), and a
vertical longitudinal median section (as seen by
splitting lengthwise, from top to bottom, in the middle
line).

RANK OF EARTHWORMS AMONG ANIMALS.

Animals are ranked according to the number of things
they can do, and do well. The earthworm has many
parts, but they are all nearly alike, and do not enable it to

THE EARTHWORM. 45

do many different things. A part of an animal having a
special work to do is called an organ, and its work is its
function. The earthworm has many organs, but few
functions. Apply this principle to man and an ape. Each
has four limbs. The ape is called four-handed, but has no
good hands; he cannot handle things well. He has not
good feet; he cannot walk well. What is the one thing he
can do well with his four foot-hands? How many distinct
functions has man with his hands and feet? Multiplica-
tion of parts without corresponding variety of structure
and function mark an animal as low in rank.

Another respect in which the earthworm is low is this, —
the head end is not much better than the tail end. There
is no distinct head. At first glance there is not much
difference. Many worms similar to the earthworm may be
cut in two, and each part lives; the hind part developing a
new head, and the fore part a new tail. The part of the
nervous system in the head is not greatly different from
other parts. Just in proportion as the head rises in
importance, and the whole set of organs centre around it,
the animal rises in the scale. Apply this test to the earth-
worm and crayfish, crayfish and crab, bee and dragon-fly.

Compare insects with earthworms in rank from another
point of view. Most insects, before reaching the adult
state, pass through a worm-like stage. Crabs are at first
like crayfishes in having a well developed abdomen. As the
crab grows, the abdomen shortens, and the head becomes
more prominent. What would this indicate as to the
relative rank of worms and insects? of crayfishes and
crabs? Worms constitute one branch of the animal
kingdom. In this branch, Vermes, are the leech, trichina,
tapeworm, with many animals very unlike the earthworm

ee |

46 PRACTICAL ZOOLOGY. |

in appearance. In classifying animals, the more significant
characters are internal structure and mode of development
rather than mere outer form and general appearance. Most
worms have gills. Worms never have jointed appendages.
There is a group of slender worms called hair-worms.
“ They sometimes occur in horse-troughs, whence they are
supposed by the ignorant to be transformed horse-hairs.”
In what characters are worms like Arthropods? How
do worms differ from Arthropods ?
Read the life history of the tapeworm and the trichina.
Read Darwin’s “ Vegetable Mould and Earthworms,”
the description of the earthworm in Huxley’s “ Anatomy
of Invertebrated Animals,” “Anatomy of the Earthworm”
in Brooks’ “ Handbook of Invertebrate Zodlogy,” ‘“* Worms
and Crustacea,” No. VII in Hyatt’s “Guides for Science
Teaching.”

THE FRESH-WATER CLAM.

STUDY OF THE LIVE CLAM.

Look for fresh-water clams in the sandy bottoms of creeks
and rivers. They may be found nearly buried in the sand or
mud. If no better aquarium be at hand, take an old tub,
half fill it with water, and have two or three inches of
sand at the bottom. Drop several clams into the water,
and note carefully the place and position of each. On the
next day see if any of them have changed either place or
position. The part uppermost, in the natural position, is
the back. Look near one end, where the shell opens a
little, for two oval holes. These are the siphons; gently

THE FRESH-WATER CLAM. 47

touch the margin of one of them. What follows? The
water enters one of these openings and comes out of the
other. Prove the action of each by stirring up a little
mud, to show the currents; or take a small glass tube, dip
the lower end into ink, or finely divided indigo in water,
then placing a finger over the upper end of the tube, lift
out a little of the ink. Keeping the finger tightly on the
top of the tube, thrust the other end down to a point
just above the siphonal openings; then raise the finger
and release some of the ink. In some way prove the exist-
ence of these currents. Let each pupil have a clam in
a fruit-jar, with sand enough to support the clam. Keep
the clams alive for a week or more, and watch them daily.

THE CLAM-SHELL.

If a live clam is used, place it on a plate, or in the
oyster-can.

1. Notice the two parts of the shell, — the valves.

2. The edge along which the shell opens is the ventral
margin. |

3. The edge by which the two valves join each other is
the dorsal margin, or hinge margin.

4. The concentric lines parallel to the véntral margin
are the lines of growth.

5. The raised point around which these lines centre is
the beak, or umbo.

6. The umbones are nearer the front, or anterior, end of -
the clam.

7. Toward the posterior end, back of the umbones,
between the valves, and uniting them, is the hinge-
ligament. -

48 PRACTICAL ZOOLOGY.

8. Hold the closed shell with the umbones and hinge:
ligament uppermost, the latter nearer, and the former
pointing away from you. .

The end pointing from you is the anterior end.
The end pointing toward you is the posterior end.
The upper edge is the dorsal margin.

The lower edge is the ventral margin.

The half shell to your right is the right valve.
The half shell to your left is the left valve.

Fix these relations firmly in mind.

9. Make a drawing of the clam as seen from one e side,
naming all the parts.

10. Draw as seen from above, placing this drawing along-
side the side view.

11. Draw the clam as seen from the anterior end.

12. Observe the color, the degree of cleanness, and
general condition of the different parts of the shell,
and consider the relations between these facts and the
position of the clam when first found.

DISSECTION OF THE CLAM.

Put the live clam for a few minutes into water as warm
as the hand can well bear. This causes the muscles to
relax, so that the shell can be readily opened. If warm
water cannot be easily obtained, the clam may be opened
with a strong eee after reading the directions which
— follow.

Pry apart the two valves, and insert a small block to
keep them from shutting.

1. Observe a soft white membrane, the mantle, adhering
to the inner surface of the shell. Now hold the ciam

THE FRESH-WATER CLAM. 49

in the left hand, with the hinge-margin resting in
the palm of the hand, and the anterior end toward
you. Insert/the blade of a knife between the mantle
and the upper Cleft, if held as directed) valve, and
gently separate them by sliding the blade of the
knife along the inner surface of the shell. In this
way proceed backward, around the posterior end of
the’ shell, then forward along the dorsal margin.
Back of and below the hinge is a large white muscle,
which extends directly across from valve to valve.
Cut this off-close to the left valve. In like manner
loosen the mantle at the anterior end, and find
another muscle connecting the two valves near the
anterior dorsal margin. Sever as before, close to the
left valve, and loosen the mantle completely from the
upper valve, and turn this valve back like the lid of
a box. What makes the valve spring up after the
muscles are severed ?

. Lay the clam in a deep plate, or in the oyster-can,
and cover it with water. Renew the water as often
as it becomes turbid.

Observe that the left mantle lobe now covers the
body, and that the right lobe lines the right valve.
Notice the thicker margin of the mantle. Pinch this
thick edge; what follows? Observe a thin, dark-
colored membrane bordering the edge of the shell.
This is an extension of the outer covering, or epider-
mis, of the shell. Scrape off some of the epidermis
to see its relation to the limy shell. Carefully study
the relations of the epidermis to the mantle. Turn-
ing to the uninjured mantle lobe, pinch the edge of
the mantle, and observe the effect on this free border

50

PRACTICAL ZOOLOGY.

of the epidermis. Trace the right and left mantle
lobes to their points of union before and behind.

Examine the thick, dark-colored, hinder edge of the
mantle lobes, and see how by their manner of meeting
they form the two short tubes, the siphons, seen in
the live clam; prove the great sensitiveness of the

margins of these siphon tubes. Are the margins of

the two openings alike?

Examine the ends of the anterior and posterior ad-
ductor muscles where they were cut off in opening
the shell; scrape away any part of these muscles that
may remain attached to the left valve,and note the
marks or muscle scars which are shown.

Turn the mantle lobe back as far as it will go, and
observe the soft abdomen; its tough lower border is
the foot; prick it with the dissecting needle, and ob-
serve what follows.

Along each side of the abdomen and extending back
of it are two thin membranes, the gills, showing ver-
tical parallel markings (sometimes the outer gill is
thick, and of a dark color); study closely the rela-
tions of the gills to each other, to the body,.and to
the mantle. With a knife scrape off a little of the
surface of the gill and examine under the microscope

- to see the vibratory motion of the hair-like projec-

tions, or cilia, borne on the cells thus obtained.

In front of the gills, on each side of the body, are two
thin, triangular flaps, much smaller than the gills, the
labial palpi.

Raise the hind border of the left mantle lobe, and
observe that the gill next to the body unites with the
corresponding gill of the other side, thus forming a

z, Pe ae ae ea an = i iil aaa
2 : ah bel
~ ——s

10.

THE FRESH-WATER CLAM. 51

separate channel above the gills, into which the
upper siphon leads, while the lower siphon leads to
the lower cavity, outside of and below the gills.

With the thumb and all the fingers of the left hand
seize the left lobe of the mantle and pull it toward
the ventral margin, thus drawing the body away from
the dorsal margin. Just under the hinge a pale organ
may be seen, pulsating every few seconds; this is the
heart. .

Holding the mantle stretched, again examine the
upper siphonal opening; probe to see how it extends
forward above the united hinder portion of the gills.
In the upper part of this cavity find a tube running
back over the posterior adductor muscle, and ending
in a conical elevation; this tube is the intestine, and
the opening at its end is the anus; hence the siphon
leading from this cavity is called the anal siphon; the
lower siphon, which conducts water to the gills and
mouth, is called the branchial siphon or gill siphon.
Examine the gills from above, ¢.e., examine their
dorsal margins; observe that the two outer walls of
each gill are a short distance apart at this edge, while
below these walls unite, so that if the gill be cut
across, these walls, as seen at the cut, are like the
letter V. These diverging walls are connected by
cross partitions, thus forming a series of compart-

-ments within the gill, whereas if these partitions

were absent, each gill would be a deep, narrow, undi-
vided trough. The lateral walls of the gills are sieve-
like, and the surface of the gill and the edges of the
holes are covered with cilia. The vibrations of these
cilia drive the water which is around the gill through

52

PRACTICAL ZOOLOGY.

these holes into the cavities within the gill; the
water from each compartment of the gill passes up
into the chamber leading to the anal siphon.

Beginning at the upper edge of the anal siphon, in
the middle line, cut carefully forward just above the
intestine as far as the umbo. ‘This lays bare the cay-
ity in which the heart lies, the pericardial cavity.
Carefully cut away the thin covering of this cavity
and make out the following parts: —

a. The large yellowish ventricle in the anterior part
of the cavity; time its pulsations; observe that
the intestine runs directly through the ventricle,
though it has no more communication with the
ventricle than a stove pipe has with a room it
passes through; an artery runs forward from the
ventricle along the upper surface of the intestine;
another artery runs from the ventricle backward
under the intestine. Again pull the mantle ven-
tral-ward to show 6.

6. A thin sac, triangular as seen from the side, with
its apex joining the ventricle, and its base
attached just above the upper edge of the gills;
this is the left auricle. Each auricle receives
the blood from the gills of the corresponding side.

11. Just in front of the posterior adductor muscle is the

12.

dark kidney.

Above the kidney, and in front of the posterior
adductor, is a small muscle, which extends backward
from the side of the body to join the valve near the
posterior adductor. This muscle pulls the foot back-
ward. ;

oe

—-

OO
een =| “

13.

14.

15.

16.

17.

THE FRESH-WATER CLAM. 53

Look near the anterior adductor for similar mus-
cles; what work do they perform ?
To find the mouth, hold the clam, anterior end upper-

’ most, still. attached to the right valve, in the left

hand; press down the point of the foot, and find the
mouth opening below the anterior adductor; observe
that the two outer palpi unite above the mouth, and
the two inner palpi unite below the mouth. Back of
the anterior adductor a dark-colored mass may be
seen within the body; this is the liver, which sur-
rounds the stomach; the intestine has several coils in
the body before emerging on the dorsal surface a
short distance in front of. the heart. The intestine
can be traced much better in an alcoholie specimen.

Beginning at the posterior adductor, cut away all the

free flap of the left mantle lobe, following the upper

edge of the gills (being careful not to cut away the
labial palpi) to the upper edge of the anterior ad-
ductor. Make a drawing of all the parts above
named, as they lie in the right valve.

Remove the remaining soft parts in as good condition
as possible, and put into alcohol, for the dissection of
the nervous system.

Make a drawing of the inside of one of the valves,
showing the hinge, the muscle scars, and any other
markings that have any significance. Sometimes
there can be distinctly seen a line running near, and
parallel to, the ventral margin, along which the upper
edge of the thicker portion of the mantle was at-
tached; this is the mantle line, or pallial line.

Some clams have hinge teeth, by which the dorsal
edges of the valves are more firmly held together

18.

19.

20.

21.

22.

PRACTICAL ZOOLOGY.

when the shell is shut. The irregularly shaped teeth
near the umbones are the anterior, or cardinal teeth;
back of these are the long, narrow posterior,. or
lateral teeth.

Take an empty shell with the iairts still hinged
together; cut and fit into this shell a piece of paper
showing the shape of the whole mantle. Make also a
plaster of Paris cast of the inside of the shell.

Wipe dry a number of shells and weigh them. After
thoroughly roasting them in a fire, weigh them again.
If the shells are not burnt too long, some of the
animal matter may remain in the form of layers of
charcoal between the layers of lime.

Put a shell into dilute acid to dissolve out the lime.
Observe the animal matter remaining undissolved.
Compare the effect of acid on equal pieces of burnt
and unburnt shell.

Carefully pick to pieces a burnt shell and distinguish
an inner and an outer portion of the shell, the line of
division between which appears on the inner surface
of the shell along the mantle line. Make out the
successive layers of the outer part which were built
by the outer part of the mantle, and the layers formed
by the thinner, inner part of the mantle.

Break a burnt shell across from the umbo to the
ventral margin, and make a drawing of the edge thus
exposed, showing the arrangement of these sets of
layers. File a groove from the umbo to the ventral
margin of a fresh shell, and break it across. Compare
the edges of this with the corresponding part of the
burnt shell.

THE FRESH-WATER CLAM. ay)

THE NERVOUS SYSTEM OF THE CLAM.

This dissection requires the utmost care and patience.
Take a clam that has been hardened in alcohol, or by
boiling. Dissect under water; rinse the specimen often.

1. Immediately under the posterior: adductor muscle
find a double, yellowish body; this is composed of
the two parieto-splanchnic ganglia; dissect away
the thin membrane covering them.

2. From these ganglia trace nerves backward to the
gills and to the posterior borders of the mantle
lobes; trace also. two nerves forward, carefully dis-
secting away the soft parts that cover them ante-
riorly, and trace them to the sides of the mouth
where they join 3.

3. The cerebral ganglia: these lie near the surface at
the bases of the labial palpi. Trace a small nerve
which connects the two cerebral ganglia over the
mouth.

4, From each cerebral ganglion trace nerves backward
and downward to 5.

5. A pair of orange-colored pedal ganglia, lying to-
gether deeply imbedded between the foot and the
abdomen.

In the alcoholic specimen the stomach and intestine

may be traced. Cross-sections of alcoholic specimens

may be made with a razor, which show admirably the
relations of the different parts of the clam.

THE DEVELOPMENT OF THE CLAM.

If the outer gills be thick and dark-colored, open one
of them, remove some of its contents, and mix with water

56 PRACTICAL ZOOLOGY.

in a watch-crystal or on a slide. Examine with a one-
inch objective or a lens. Make a drawing of the young
clams. Compare the shapes of the young and adult.
Watch carefully for movements of the young clams.

The shell grows by additions deposited by the mantle
on the inner surface of the valves. Each new layer
projects beyond the others; so the shell grows in width
as well as thickness. Where is the thickest part of the
shell? If a thin piece of glass is slipped between the
mantle and its corresponding valve, and the clam be kept
alive, the shell substance is deposited over. the glass, and
the glass becomes buried in the nacreous matter of the
internal layer. Grains of sand become pearls by the
secretion of similar nacre around them.

Read “The Fresh-water Mussel” in Huxley and Mar.
tin’s “ Practical Biology”; “ The General Anatomy of a
Lamellibranch” in Brooks’ “ Handbook of Invertebrate
Zodlogy ”; No. VI of Hyatt’s “Guides for Science Teach-
ing”; Packard’s “ Zodlogy.”

THE SNAIL.

A dipper with a perforated bottom, attached to a
wooden handle, will be found convenient in scooping
up the sand and mud from the bottoms of ditches and
streams; the dirt being sifted out, the shells and other
objects will be left behind. Get a number of live snails,
and keep them in a fruit-jar.

1. The broad disk on which the snail creeps is the
foot.

Ov 92 bo pt

ote

THE SNAIL. 57

The “horns” are the feelers, or tentacles; touch
them; what would seem to be their use?

The dark spots at the bases of the tentacles are the
eyes; are they borne on a stalk in any common
snails ?

Watch the snail crawling on the glass; near the front
of the foot the mouth may be seen; observe its open-
ing and shutting as the snail gathers food from the
surface of the glass. Do snails clean the glass or
foul it?

Most snails have a ribbon-like tongue, fastened at
each end, and covered with teeth; as this tongue is
applied to an object, and drawn rapidly back and
forth, it acts like a rasp; in this way some marine
snails bore holes through the shells of other mollusks
and feed on them.

Many snails have gills; others breathe by a simple
lung. Watch the snails, to see if any of them come
to the surface to get air; how is this done?

THE SNAIL-SHELL.

The pointed end is the apex.

The opening at the large end is the aperture.

The outer edge of the aperture is the lip.

The lines parallel to the lip are the lines of growth.
The spiral groove on the outside is the suture.

The turns of the shell between the groove are the
whorls.

The whorls, taken together, make the spire.

The lid closing the aperture is the operculum; is this
present in all the snails you find?

58 PRACTICAL ZOOLOGY.

Make a drawing, naming all the parts, of the snail-shell
with the aperture toward you; with the aperture away
from you; with the apex toward you.

Lay the snail-shell beside a common screw; if the
whorls turn like the threads of the screw, it is a right-
hand shell; if they turn the other way, it is a left-hand
shell; the right-hand shells are sometimes called dextral,
and the left-hand, sinistral.

Clams, snails, and oysters belong to the branch of the
animal kingdom called Mollusca; the clam is a bivalve;
the snail is a univalve.

Read Morse’s “First Book of Zodlogy,” on snails and
clams.

PARAMECIUM.

In a tub, or aquarium, in which clams have been kept,
a thin white film may form on the surface of the water.
This is more likely to occur if some of the clams die and
the water gets “bad.” Place on a slide a drop of this
water with some of the white film, with a piece of paper
under the edge of the cover to keep from crushing the
animalcules. Examine first with a low, then with a high
power of the microscope.

Paramecium is somewhat slipper-shaped, swimming
actively by means of vibrating, hair-like projections, or
cilia; are these of the same size on all parts of the body?

Find, on one side of the body, a widely open, funnel-
shaped cavity, extending obliquely backward into the
body ; this is the vestibule; the narrower, inner part of
this funnel-shaped cavity is the gullet, or esophagus;

PARAMCECIUM. 59

observe that this whole cavity is lined with cilia, and that
they are in active operation, producing currents in the
water, by which food-particles are swept into the mouth;
the gullet does not lead by a continuous tube to a defi-
nite stomach, but any part of the body within acts as a
stomach. When a collection of food-particles has accu-
mulated at the lower end of the gullet, the mass, by a
contraction of the body, is forced further into the soft
substance of the body, leaving the blind end of the gullet
as it was before. By sifting some finely powdered indigo
into the water this process of taking food may be better
seen. ‘These animals seem to have little or no sense of
taste, as indigestible particles are readily taken in. There
is a regular place for ejecting such indigestible matter;
watch patiently to make out where this is.

Note the changes of shape which the body undergoes
as it forces its way through narrow places, between par-
ticles of sediment in the water.

If a specimen that is pretty quiet be carefully watched,
a large transparent space will be seen at some point in the
body; this, after remaining visible for some twenty or thirty
seconds, will suddenly disappear, and gradually reappear ;
this is the contractile vesicle. In some species there are
two contractile vesicles.

Watch closely the food-masses; do they retain their
original size? Do they maintain a fixed position ?

Place a drop of iodine solution on the slide at the edge
of the cover-slip. The cilia, thus stained, may be more
distinctly seen. Make a drawing showing —

1. The shape of the body. 4, The cilia.

2. The vestibule and gullet. 5. The contractile vesicle.

3. The food-masses.

60 PRACTICAL ZOOLOGY.

In swimming, is the same end always foremost?
Read “The Structure of Paramecium” in Brooks’
“ Handbook of ‘Invertebrate Zodlogy.”

THE BELL-ANIMALCULE (VORTICELLA).

Collect leaves and grasses that have fallen into water,
and the stems and leaves of water plants from ponds and
ditches; place some of these leaves in a plate of water,
and examine them closely; with the naked eye there
may sometimes be seen on them little patches resembling
mould; when observed more closely these appear to be in
the form of minute tufts, if these tufts shrink back when
touched, take a lens and examine, carefully ; cut out a part
of a leaf bearing these clusters, put on a slide with a drop
of water, cover with a cover-glass, and examine with a
one-inch objective.

Sometimes these tufts, which are colonies of Vorticelle,
may be attached to the sides of an aquarium, or jar, in
which clams have been kept.

Some kinds of Vorticelle are not in colonies, but are
borne singly on independent stalks.

When one is found, note, using a one-inch objective : —

1. The bell-shaped body.

2. The contractile stalk; suddenly jar the table, or
stage of the microscope, by tapping with a hard
object; what follows?

Put on a high power objective and make out the follow-

ing parts of the body : —

THE BELL-ANIMALCULE. 61

1. The projecting outer rim is the peristome.

2. The central disk, projecting above the peristome.

8. The short, hair-like cilia on the border of the disk
and peristome ; watch the motion of these cilia, and
the currents of water thus produced.

4, A depression between the peristome and disk, deep-
ening at one place to make the vestibule, or entrance
to the gullet, which extends a short way into the
body. : ‘

5. A clear space, just under the disk, is the contractile
vesicle; watch this closely for some time; what
changes occur?

6. At various points in the body may be seen rounded
masses, the food-balls; do they remain of the same
size, and keep the same place ?

7. Make drawings showing the above points.

Watch patiently to see the accumulation of particles at
the lower end of the gullet; after a time this mass may
be seen to be pushed into the body. This forms one of
the food-balls. These food-balls may be seen moving on
in a circle within the body. Ejection of undigested mat-
ter takes place near the mouth. Sometimes two vorti-
celle are found on one stalk; by watching it patiently it
may be found that the vorticella is dividing to form two
vorticelle ; this is one way these animals have of repro-
ducing. What powers and faculties have you and the
vorticella in common ?

Read “The Structure of Vorticella” in Brooks’ “ Hand-
book of Invertebrate Zodlogy.”

62 PRACTICAL ZOOLOGY.

AMCEBA.

One of the simplest forms of animal life is Ameeba. It
is found in standing water, where it lives on the leaves of
submerged plants or in the mud and ooze at the bottom.

Scrape up a thin layer of the ooze and allow it to stand
a few days.

Place a drop of such water, with a little of the sedi-
ment, on a clean slide, and cover with a clean cover-slip ;
if there be no solid matter in the drop of water, lay a
strip of paper on the slide before putting on the cover-
slip, letting one edge of the cover rest on it. Examine
with a high-power objective.

The ameba is like a minute drop of jelly, pale (nearly
colorless), with a more dotted central portion. Its most
noticeable characteristic is its slow, peculiar mode of
changing its form.

The following parts of the body should be made out: —

1. A clearer outer margin.

2. A dotted or granular inner portion.

3. A clearer, round body, in the granular part, called the
nucleus.

Study carefully the movements of the ameceba; first a
part of the clear outer portion bulges out, or is sometimes
thrown out as a long projection, called a pseudopodium ;
then the granular part flows into this, and by repeating
this process the amceba creeps along with a slow gliding
motion, though sometimes the pseudopodia are thrust out
and retracted without moving the body as a whole; care-
fully watch the beginning and the whole process of form-
ing a pseudopodium ; look for movements of the granules
in the central portion.

ae

AMCEBA. 63

The larger granules within are particles of matter that
have been taken in as food through that part of the body
with which they first came in contact; there is no mouth,
no stomach, but any place on the surface serves as a mouth
when a mouth is needed, and any place within serves as a
stomach when food is thus taken; neither is there a defi-
nite opening for ejecting indigestible matter, but by flow-
ing around the substances it meets, it in a way swallows
them, and, having digested and absorbed such parts as are
suitable for food, ejects, or rather flows away from the use-
less remnants.

Make a series of sketches of the outline, at as short
intervals as possible, to show the changes of form.

Make also a careful drawing, showing all the parts of
the body that have been made out.

The jelly-like substance of which the body of the ameba
is composed is protoplasm.

The ameeba reproduces its kind by simply dividing into
two parts, each of which becomes a perfect amceba.

** Thus the amceba lives, moves, eats, grows, reproduces
its kind, and after a time dies, having been during its
whole life hardly anything more than a minute lump of

protoplasm.”

The simplicity of the structure of the amceba and its
simple mode of reproduction show its low place in the
animal kingdom; with the Vorticella, Paramecium, and
myriads of other microscopic aquatic animals, the Amceba
represents the lowest branch of the animal kingdom, the
Protozoa. Most of the Protozoa are one-celled animals,
in distinction from some of the higher protozoa, which
some authors regard as many-celled, and all other animals
from sponges to man, which are undoubtedly many-celled.

64 PRACTICAL ZOOLOGY.

Thus the simpler Protozoa correspond to the eggs of the
higher animals, or the cells of which their bodies are
composed.

Many of the protozoans have no hard parts, others have
shells; chalk is composed of the shells of certain marine
protozoans, a cubic inch of chalk containing as many as
1,000,000 of these skeletons.

« Amcebe absorb oxygen and give out carbon dioxide and
water, and the presence of free oxygen is necessary to their
existence. When the medium in which they live is cooled
down to the freezing-point, their movements are arrested,
but they recover when the temperature is raised. At a
temperature of 95° F. their movements are arrested, and
they pass into a condition of “ heat-stiffening,” from which
they recover if that temperature is not continued too long;
at about 110° F. they are killed.

“Electric shocks of moderate strength cause amcebe to
assume a spherical form, but they recover after a while ;
strong shocks kill them.

“The amoeba is an animal, not because of its contractil-
ity or power of locomotion, but because it never becomes
enclosed in a cellulose sac, and because it is devoid of the
power of manufacturing protein from bodies of a compara-
tively simple chemical composition. The amcba has to
obtain its protein ready made, in which respect it resem-
bles all true animals, and therefore is, like them, in the
long run, dependent for its existence upon some form or
other of vegetable life.”

Since the amcba resembles one of the cells of the
higher animals, it is important to fix in mind these
properties and modes of life which are common both to
amcebe and the cells of the higher animals, as thus we

—_—— -_

AMCEBA. 65

have an explanation of many points in the physiology of
man: —

1. The amoeba moves; it has the power of contraction or
contractility, by means of which it accomplishes
motion and locomotion.

2. It feels; when any disturbance, such as contact with
a foreign body, is brought to bear on an ameeba at
rest, it moves; this is not because it is pushed or
pulled, but is due to its own activity, the contraction
of its protoplasm. Any living matter which, when
acted on by a stimulus, is excited to activity, is said
to be irritable (sensitive) in the sense of “susceptible
to impression from without.”

3. But the amceba does not always wait to be thus stim-
ulated by something external; it moves “of its own
accord,” as we would say; such action is called auto-
matic; the ameeba is an individual capable of spon-
taneous and independent activity.

4, The protoplasm of which the body of the ameba is
composed is constantly undergoing chemical change ;
this change is of two kinds: one a wearing out, de-
pending on the degree of activity, the other a building
up, to make good the loss. ‘The food is changed so
that it is ready to become part of the body; this
process is digestion. The building of this material
into the body is known by the name assimilation.
The waste products resulting from the breaking up of
the old protoplasm are called excretions, and are
thrown off into the same surrounding medium from
which food is taken. All these processes of taking
food, digesting and assimilating it, the decomposition

66

PRACTICAL ZOOLOGY.

of the body as an accompaniment of activity, and the
throwing off of the waste products, are included
under the term nutrition.

The ameba breathes; that is, takes in oxygen and
throws off carbon dioxide; this is really a part of
the process of nutrition, being most intimately con-
nected with the breaking down of the protoplasm
(which invariably accompanies any form of action),
during which not only motion, but also heat is
produced.

The amceba reproduces its kind by simple division
into two. Each individual of the higher, many-celled
animals develops from an egg, which is a cell, and is
essentially like an ameeba. As it develops, this cell
divides, forming two; each of these divides, and the
division continues till many cells are formed; these
cells are at first all alike, but soon they grow different
from one another, and are arranged in order, forming
the various parts of the body; thus one set of cells
form muscle, another set, developing in a different
way, produce the brain and nerves; other groups of
cells form bone, skin, cartilage, etc. Each of these
sets of different kinds of cells is called a tissue; thus
there is muscular tissue, nervous tissue, etc. The
process of “ growing unlike ” or “ growing different,”
which the cells undergo in their development, is called
differentiation ; thus, of the cells which were all es-
sentially alike, those of one set have taken one shape,
and have acquired certain peculiarities by which they
may be recognized, and we say they have become
differentiated into nervous tissue or muscular tissue,
ete.

AMGBA. 67

Now, in the development of higher animals, while all the
cells which result from the original cell (egg) are at first
essentially alike, not only in structure but in properties,
they grow unlike in this latter respect as well; that is,
while all the cells have at first in equal measure the proper-
ties of motion, sensation, digestion, respiration, assimi-
lation, and reproduction, each set (tissue) soon develops
in a special degree some one of these properties. Take, for
instance, the nervous tissue; the cells composing this tissue
are regarded as having had originally not only irritability
but contractility, and all the other characters enumerated
above in describing the amceba; but this kind of tissue has
developed, in a high degree, the property of irritability, and
has lost, in a large measure, the other properties; so the
muscular tissue, while it has not wholly lost its irritability,
has it feebly developed when compared with nervous tissue,
but has the power of contraction in a very high degree.
Thus each tissue has some one of the general properties in
a very marked degree, while the other properties are less
apparent, though seldom entirely wanting. All the tissues
work together for the common good of the whole animal;
all the tissues grow by the increase of the number of their

‘cells, and this is accomplished by the division of the cells ;
but that division of cells which gives rise to new individ-
uals is limited to the reproductive tissues.

Although one set of tissues (the organs of digestion)
has the chief work of preparing the food to be built into
the tissues of the body, yet each cell must take for itself
the food thus prepared for it, and, really, each cell leads an
independent life bathed in the liquid part of the blood,
which soaks through the walls of the blood-vessels and
surrounds every cell; from this liquid nourishment is

68 ; PRACTICAL ZOOLOGY.

taker. (or cell starvation follows), and into this surround-
ing luquid the cell throws its waste products.

In consequence of the complexity of structure, a compli-
cated set of organs is required to circulate this liquid to
all parts of the body, so that each cell may be supplied,
and to bring air into contact with this current in one part
of its course, where oxygen is absorbed for all the cells.

It now becomes evident why one can hold his breath
longer after taking several deep breaths, and why distress
for breath continues for some time after one has stopped
at the end of a foot-race.

The differentiation of cells in the formation of the vari-
ous tissues of the body may be compared with the division
of labor in a community. In a community of savages
there is little division of labor; each one, or at least each

family, gets and prepares his own food, makes his own
clothing, builds his own dwelling (if he has one), and in
general supplies all his own wants; in rude communities
of more enlightened people the same is very nearly the
case. But as time goes on, it is found more advantageous
to divide the labor, each devoting himself to one special
kind of work; thus each acquires skill in his special line,
better articles are produced, and time is saved for alls so,
in time, come tailors and butchers, teachers and tanners.

But just in proportion as each individual devotes him-
self exclusively to one pursuit, he neglects the others, and
consequently grows unable to do well in them; that is, by
becoming especially fit for one kind of labor, he propor-
tionally unfits himself for others. The grocer does not
make his own boots, clothes, hat, house, nor wagon.

« In the human body, also, the work is better done by
having a special set of cells devoted to a given kind of

THE WHEEL-ANIMALCULE. 69

work; and the cells of the different tissues, like the indi-
vidual members of society, by giving themselves entirely
to one kind of work, make themselves specially fit for this
work, and become almost completely unfitted for anything
else. s

This is what is meant by the physiological division of
labor.

Read the descriptions of Amceba in Brooks’ “ Handbook
of Invertebrate Zodlogy,” and in “ Practical Biology,” by
Huxley and Martin; the characters of Protozoa, in Pack-
ard’s “ Zodlogy”; the lecture “On a Piece of Chalk,” in
Huxley’s “ Lay Sermons, Addresses, and Reviews”; the

Introduction to Foster’s “ Physiology.”

THE WHEEL-ANIMALCULE (ROTIFER).

Rotifers are often found in the water of an aquarium
where clams and crayfishes have been kept; pick out
clusters of plant growth, found in the rubbish and sedi.
ment in the aquarium, or on the shells of clams; with a
‘lens look at the walls of the aquarium for small, white,
worm-like forms.

The body of the wheel-animalcule is tapering, ending
in a two-forked foot. At the larger end, when expanded,
are two circular disks, fringed with cilia; the disks are
retractile, as in Vorticella. Between the disks is the
mouth; this opens into the pharynx, lined with teeth;
back of the pharynx are the stomach and intestine.

Rotifers are classed with the worms; though small, the
presence of a distinct digestive tube, a distinct nervous

70 | PRACTICAL ZOOLOGY.

system, and organs of sight and hearing, show the rotifer
to be much more highly developed than the protozoans.
Rotifers have been dried and kept for years, and yet
when put into water they revived.
Study carefully —
The mode of locomotion.
The action of the disks and cilia.
The motions of the pharynx.
The contraction and expansion of the body as a
whole.

Fr

Make drawings showing the body both in the expanded
and in the contracted state.

Read the “General Characters of Rotifers” in Packard’s
“ Zodlogy”; “ Rotifera” in Claus and Sedgwick’s “ Text-
Book of Zodélogy.”

THE FISH.

Let each pupil have a live minnow in a fruit-jar.
Watch the movements of the mouth apd gill-covers at the
sides of the head. Observe the motions of the eyes. Can
a fish wink? Does a fish sleep? Study the action of
each fin, trying to discover what work is done by each.

What is the chief propelling power? Consider the fitness

of the shape of the body for locomotion in water.

THE EXTERNAL FEATURES OF THE FISH.

For this work, and the dissection which follows, the
perch is preferable, but bass or croppies serve very well.

as

me

THE FISH. 71

Use the dissecting-pan described under “The Crayfish,”
or put the fish on a large plate.

1. Notice the shape of the fish as a whole; hold the fish,
with the belly down and the tail toward you, and
observe that there is an anterior and a posterior
part, a dorsal and a ventral surface, and that it is
bilaterally symmetrical. A fish whose body is flat-
tened from side to side, is said to be “ compressed ” ;
the word “flat,” when used in describing a fish,
means flattened from above downward, and is applied
to such a fish as the flounder.

Close the mouth of the fish, and measure from the
foremost point of the head, the tip of the snout, to
the front edge, the base, of the tail-fin; this is the
length of the fish. Measure from the tip of the
snout to the hinder point of the hard part of the flap
which covers the side of the head; this is the length
of the head. How many times is the length of the
head contained in the length of the fish? Measure
from above downward at the deepest part; this is the
depth of the fish. How many times is it contained in
the length? Compare the width and depth of the fish.

2. The fins on the back are the dorsal fins ; spread them
out to their fullest extent, and study them thoroughly;
their framework consists of fin-rays; some of them
spinous rays, or spines (unjointed, or inarticu-
lated), others soft rays (jointed, or articulated) ;
study carefully one of the soft rays, using a lens;
count each kind of rays; observe the membrane
connecting the rays. ‘This membrane is double; the
fin is really a fold of the skin, with supporting parts
within the fold.

72

PRACTICAL ZOOLOGY.

Measure along the base of each fin; this is the
length of the fin; extend the fin fully, and measure
the length of its longest ray; this is the height of
the fin. Compare the length and height of the fin.
In some fishes the dorsal fin is single; in others it is
divided, forming two or more dorsal fins.

The tail-fin is the caudal fin; when this fin is sym-
metrical, or nearly so, the backbone apparently ending
at the centre of its base, the tail is said to be homo-
cercal, as in most fishes; if the backbone extends
into the upper lobe of the fin, making this lobe larger,
as in the sturgeon, the tail is called heterocercal.

The fin in front of and below the caudal, is the
anal (being just back of the external opening of the
intestine, the anus); compare this fin with the dorsal.

The fins above named, being in the middle line,
are called median, or vertical fins.

The remaining fins are called paired fins; the pair
back of the head are the pectoral fins, and are con-
sidered as representing the forelimbs of the higher
animals; the lower pair (usually farther back) are
the ventral fins, representing the hind limbs of
higher animals. Take the ventral fins between the
thumb and finger to feel their bony support; rest
the fish on its back, and press the thumb and fore-
finger of the other hand on the bony structures at
the bases of the pectoral fins; move the ventrals
about to determine, as far as possible by feeling, the
relations between the bones supporting the two pairs
of fins.

Open the mouth of the fish by pulling its lower jaw
down as far as possible; the bone which forms the

THE FISH. 73

border of each side of the upper lip is the pre-max-
illary; note its extension backward on the middle of
the snout; observe the fine teeth on it. Observe
their size, shape, arrangement, and the direction in
which they point.

The paddle-like bone back of the pre-maxillary is

the maxillary.
_ The bone on each side of the lower jaw is the
dentary. Which of these bones bear teeth? Open
and shut the mouth repeatedly, watching the move-
ments of these parts, and their relations to each
other.

Compare the perch or bass with the sucker in the
movements of the mouth parts.

Back of the pre-maxillary, in the front part of the
roof of the mouth, is a patch of teeth, borne on a
bone called the vomer; extending backward from
the vomer, on each side of the roof of the mouth, are —
rows of teeth on the palatine bones.

Examine the short tongue; feel its surface with
the tip of the finger, or scrape it with the head of a
pin; examine also the whole of the inside of the
mouth, to see if there are more teeth than those
mentioned. Can a fish taste?

. Note the shape and position of the eyes; with the
handle of the forceps press on the eye at various
points near its margin, to see its range of motion;
watch the roof of the mouth while pressing the eye,
also press outward on that part of the roof of the
mouth nearest to the eye. Compare the eyes with
human eyes. Are eyelids present? Observe a thin
bone imbedded in the skin immediately in front

4

PRACTICAL ZOOLOGY.

of the eyes; it is the ante-orbital bone. This and
several smaller bones just under the eye are known
as sub-orbital bones.

Examine the nostrils in front of the eyes. How
many are there? Probe them with a bristle tipped
with sealing wax; do they open into the mouth? do
any of them communicate with each other?

The flap at the side of the head is the gill-cover, and
the opening back of it is the gill-opening. The upper,
hinder piece of the gill-cover is the opercle; along its
lower posterior border, and rather closely attached to
it, is the sub-opercle; in front of the opercle, and
below and back of the eye, bordering the part known
as the cheek, is the pre-opercle. If the margin of
this be toothed, it is said to be serrate; under the
pre-opercle, and in front of the lower end of the sub-
opercle, is the inter-opercle.

The thin membrane below the gill-cover is the

branchiostegal membrane; the curved bones sup-
porting it are the branchiostegal rays; count them.
The narrow part of the body between the branchio-
stegal membranes is the isthmus.
Raise the gill-cover and examine the gills: each gill
has a central bony arch; on the hind and outer border
of this arch is a fringe of red gill-filaments; on the
front and inner border of the arch are the teeth-like
gill-rakers. Are these alike on all the gills? A red
streak along the arch, at the base of the filaments, is
made by the blood-vessels, which bring the blood to,
and carry it away from, them.

Thrust a finger into the mouth, and depress the
tongue. What effect has this on the gills? what

THE FISH. 75

effect on the gill-rakers? The slits between the gills,
which allow communication from the mouth to the
gill-opening, are the gill-clefts. How many gills are
there? How many gill-clefts? After this study of
the gills in their natural position, remove “the fore-
most gill, severing it at its upper and lower ends, and
note more fully the parts above named, especially the
structure and arrangement of the gill-filaments and
gill-rakers; tear away some of the filaments, and find
the groove along the posterior, outer border of the
bony arch in which run the blood-vessels. Look
on the inside of the gill-cover for a red spot —the
false gill.

. Observe the arrangement of the scales. Pull out a
scale and study its shape and markings, the radiat-
ing and concentric strie. Compare its inner and
outer surfaces, its anterior and posterior margins;
make a drawing of it, naming its parts; pull out a
scale from a black spot; compare that part of its sur-
face which was exposed with the part overlapped by
other scales; scrape the portion that was exposed;
. thrust one point of the forceps under the hind edge
of a scale, and watch closely this edge, while slowly
raising it, to see that a thin skin covers it and passes
on to the scale behind. This thin outer skin is
chiefly epidermis. In this epidermis lie the black
pigment cells which make the dark spots.

A scale with a smooth hinder border is a cycloid
scale; if the hinder portion is toothed or spiny, the
scale is ctenoid.

. A raised line along the side is the lateral line. Re-
move one of the scales on this line, and find what
makes the line. Is the line continuous?

76 PRACTICAL ZOOLOGY.

10. Make a drawing of the fish as seen from one side,
naming all the parts visible. Describe fully all the
parts above noted, including the general color and
markings. |

DISSECTION OF A FISH.

Hold the fish with its back in the palm of the left hand,
and the tail towards you; thrust the point of one blade
of the scissors obliquely forward through the body-wall,
just in front of the anus, and cut forward in the middle
line to the ventral fins. After observing the organs with-
in, cut upward, i.e., toward the dorsal region of the fish,
with scissors, from the beginning of the first cut as far as
possible without cutting anything but the body-wall, being
especially careful not to cut into the air-bladder which
occupies the upper part of the body-cavity; now cut for-
ward to a point a little above the pectoral fin; make the
same cut on the other side; turn forward the flaps thus
made, noting the silvery membrane, the peritoneum,
lining these flaps, and study the organs of the body-cavity.

1. In the front part of the body-cavity is a reddish or
brownish mass, the liver, lying chiefly on the left side
of the fish. Raise the hinder edge of the liver, and
observe how closely it fits the organs next to. it.
Press the liver backward, and observe the hepatic
veins passing forward from the liver through the
thin partition in front.

2. Lay the fish on the right side and turn the liver
downward, gently tearing away its thread-like attach-
ments. This uncovers a pinkish sac, the stomach.
Pass a probe back through the mouth and wide

a Se Ae

THE FISH. TT

gullet into the stomach, to determine its shape and
extent. When the stomach ends blindly behind, the
intestine arising from its front end, the stomach is
said to be cecal. Compare the stomachs of, the
perch and sucker. Observe a branch of the pneumo-
gastric nerve distributed over this side of the stomach.
Find a large tube arising from one side of the stomach,
the intestine. In many fishes there are at or near
this point several worm-like branches, often matted
together by fat. Rest the fish on its back, and turn
the liver to the left, to examine these. Clear away
this fat, separate these tubes and count them. They
are pyloric ceca. With scissors make a small hole
in the end of one cecum; insert the point of a blow-
pipe and inflate it.

Just beyond the ceca, on the posterior surface of the
liver, is a thin-walled sac, of a greenish or yellowish
color, the bile-sac. When empty, it has a worm-like
appearance. Snip it open with the scissors, or prick
it with a dissecting needle to see the bile.

Trace the intestine to the anus, observing that it is
held in place by a thin, transparent membrane, the
mesentery ; observe the blood-vessels in it; tear this
away in following the intestine; find a small, deep red
body near the intestine, the spleen. Compare the
length of the intestine in the perch or bass with that
of a sucker. The sucker eats vegetable matter, and
may be called herbivorous; while the perch and bass
feed chiefly on other fishes, and are carnivorous.

In the hinder part of the body-cavity are the repro-
ductive organs; the yellow ovary (varying greatly
in size, according to the season) in the female, the

78

10.

PRACTICAL ZOOLOGY.

two white testes in the male. In some fishes the
ovary is single, in others it is double. If double,
the two ovaries unite in one tube, which discharges
the eggs —the egg-tube, or oviduct. Trace the ovi-
duct; has it a separate outlet? Sometimes the eggs
in the ovary can be discerned.

Back of the oviduct or hinder part'of the testes is a
small pink sac, the urinary bladder. Look for its
external opening back of the anus.

In the upper part of the pode cavity is the air-
bladder.

Make now a drawing of the organs above noted
in their natural positions, as seen from below.

Look closely to see if there is any connection be-
tween the air-bladder and the stomach; gently scrape
away the thin outer covering, peritoneum, and note
its thin wall; examine the whole of this wall to see
if there are any blood-vessels in it. After thoroughly
examining, puncture and remove it.

Above the air-bladder, extending along the roof of the
body-cavity are slender, dark red bodies, the kidneys.
Look for an enlargement of the kidneys in front of
the air-bladder; trace one kidney to its posterior ter-
mination in the urinary bladder. Cut away all the
organs thus far studied, except the kidneys.

In front of the liver is a thin partition, the false dia-
phragm. If this is not already opened, cut carefully
through it to see the heart ; also cut from the anterior
end of the first slit in the walls of the abdomen for-
ward to one side of the ventrals, through the bones
of the pectoral arch and on through the thick mass
of muscle, in the middle line, to the isthmus, and pull

—

<A
i

11.

THE FISH. 79

the walls of this cavity, the pericardial cavity, out
to the sides.

The red, angular portion of the heart, which in the
natural position of the fish lies lowest and hindmost,
is the ventricle; the darker, more irregular portion
lying (in the natural position) above the ventricle, is
the auricle; the larger blood-cavity back of the auri-

cle, and extending across the body-cavity, above the

false diaphragm, is the venous sinus; in front of
the ventricle is the light-colored conical arterial bulb.
This narrows forward into an artery which gives off
branches on both sides, one to each gill. Make a
drawing of the heart and arterial bulb. After passing
through the gills, the blood-vessels re-unite to form
the dorsal aorta, which passes backward just under-
neath the spinal column. From above the gills
branches also run forward to the head.
Insert the finger into the fish’s mouth and depress the
tongue. Observe the thin membrane which forms
the floor of the mouth on each side of the tongue;
cut through this membrane close to the inner border
of the lower jaw on each side and across the band of
muscle which is attached to the point where the two
halves of the lower jaw unite; continue the cut back-
ward on each side between the gill-cover and the
branchiostegal membrane, and wholly separate them.
Turn back the whole flap thus loosened, and again
examine the gills; note the joints in the gills; with
the forceps seize the tongue, raise and lower it, to see
the action of these joints in the gill-arches.

Observe, where the gills unite above and below,
patches of closely set teeth, the superior and inferior

80

12.

13.

PRACTICAL ZOOLOGY.

pharyngeal teeth. The bones supporting these
teeth, above and below, are the pharyngeal bones;
they represent a fifth gill-arch. Again depress and
raise the lower ends of the gills, observing how the
pharyngeal teeth are brought together. What is
the probable use of these teeth, and what is the work
done by the teeth previously examined ?

Again examine the gill-rakers, and observe how
they are affected by bending and straightening the

gill-arches. Examine the bone which bears the

branchiostegal rays, and note with what bones it is
connected.

Examine the bones in the posterior border of the gill-
opening; these are together called the pectoral arch.
The largest of these bones is the clavicle; its upper
part forms a projection above the base of the pectoral
fin. Connected with the upper end of the clavicle is
the supra-clavicle, which, in turn, is connected with
the skull through the post-temporal. Cut away the
flaps of the body-wall bearing the fins.

Note also the bones supporting the ventral fins; these
are considered as representing the pelvis. In the
higher fishes the pelvis is fastened to the clavicle; in
the lower fishes it is separate from the rest of the
skeleton and imbedded in the flesh. How is it in
the specimen you are studying? Carefully remove
the ventrals, with the bones which support them; ex-

amine and describe them, after scraping away all

muscles and other soft tissues.

If the dissection of the muscles and the brain are
not to be made at this time, carefully cut away the
gills at their upper attachment, and remove them;

——————a

|

14.

15.

16.

Ji.

THE FISH. 81

wash the fish thoroughly, wipe it dry, and keep it in a
cool place.

Hold the fish in the left hand, with its back up and
its head away from you; insert the point of one blade
of the scissors at the base of the caudal fin and cut
the skin forward, passing to the left of the dorsal fin
and on to the head; remove the skin of this side,
carefully leaving the white muscles beneath undis-
turbed; scrape part of the skin clean on the inside;
note the arrangement of the scales as seen on each
side of the skin; look also for traces of the lateral line
on the inside of the skin. Hold the skin up and look
through it toward the light, alternately stretching and
shortening it, noting especially the lateral line. Roll
the skin lengthwise, with the scales outermost, to see
how the epidermis passes from one scale to another.
Observe the parallel, transverse markings on the mus-
cles along the body.

Cut and scrape away all the muscle of this side of the
body down to the bones, and make out the central
backbone, with its bony projections above and below.
Bend the dorsal and anal fins from side to side, to
show the bones which support these fins and the rela-
tion of these fin-supporters to the projections of the
backbone.

Break across the backbone under the centre of the
second dorsal fin, and remove one of the pieces, or
vertebrae, of the backbone; clear away all muscle and
other tissue, and make out the following parts : —

a. The central body, or centrum, shaped like an
hour-glass, and hollowed at each end.

82

18.

19.

20.

PRACTICAL ZOOLOGY,

b. Two projections extending upward, soon uniting
to form one spine, the neural spine.

e. The archway formed above the body of the ver-
tebra is the neural arch.

d. A similar arrangement below, forming the hemal
arch and hzmal spine.

Make a drawing of this vertebra as seen from the
side; as seen from the front.

In like manner remove and study a vertebra from a
point opposite the centre of the first dorsal fin, with
the ribs attached to it. What are the differences
between these two vertebra?

Thoroughly clean the last vertebra, and study care-
fully its relations to the caudal fin.

Observe.the white spinal cord in the canal formed by
the neural arches above the bodies of the vertebre.

_ This is the nerve-canal, or neural canal; note also

the blood-vessels in the corresponding blood-canal, or
hzmal canal, below.

THE BRAIN OF THE FISH.

Cut off the head; clear away the muscles at the back
of the head; carefully slice off the top of the skull with a
strong, sharp knife; with extreme care cut away the roof
of the brain-cavity ; a mass of loose, gray tissue covers the
brain, which is of a white or pinkish color; cautiously
pick away this loose tissue, using a small syringe to wash
away the loosened matter. Make out the following parts
of the brain, beginning at the posterior end: —

1.
2.

The cut-off end of the spinal cord.
The widened part of the spinal cord, where it passes

THE FISH. * 83

under the hinder part of the brain, is the medulla
oblongata.

. The hinder, undivided part of the brain is the cere-
bellum.

. In front of the cerebellum are the two large, rounded
optic lobes, forming the widest part of the brain.

. In front of the optic lobes are two oval masses which
meet in the middle line; these are the cerebral hemi-
spheres, and together they constitute the cerebrum.
Observe the olfactory lobes tapering forward in front
of the cerebral hemispheres; from these trace the
olfactory nerves to the nasal cavities.

Make a drawing of the brain as seen from above,
naming all these parts. Cut open one of the optic
lobes and note that it is hollow; push the eyes out-
ward and find a white cord extending inward and
backward from each. These are the optic nerves.

THE MUSCLES OF THE EYE,

. Cut away the upper part of the eye-sockets and find
in each a muscle extending outward and backward
from the anterior part of the socket to the top of the
eyeball. This is the superior oblique muscle.
. Another muscle coming from the posterior part of the
socket will be seen passing forward to be attached
under the oblique muscle. This is the superior
rectus. Make a drawing showing these muscles.
The other eye-muscles may be more easily examined
from beneath.

If the under surface of the skull of the specimen
previously studied be not injured, it may be used;
otherwise, cut off the head of another fish, and cut

84

yt

‘PRACTICAL ZOOLOGY.

away completely the lower jaw and the floor of the
mouth. Move the gill-covers in and out to show
more clearly the thin plates of cartilage between the
eyes and the roof of the mouth; with scissors slit in
the middle line the tough membrane lining the roof of
the mouth, and strip it out to the sides. Observe a
muscle running outward from each side of the base of
the skull to the corresponding gill-cover. Cut these
at their inner ends and turn them outward. With
scissors cut away the cartilages covering the under
surfaces of the eyes. ,
Observe a muscle passing outward from the front part
of the socket to the eyeball, the inferior oblique
muscle.

The muscle running forward close to the partition
between the eyes is the internal rectus.

On the under surface of the eye is the inferior rectus.
Attached to the hinder border of the eye is the larger
external rectus. Note carefully the origin of each
of these, their place of insertion on the eyeball, and
their change of shape in their course; consider the
effect of each on the eye.

Observe the thin-walled swellings at the sides of
the base of the hinder part of the skull;. cut into
these ear-capsules and find in each a membranous
sac, the vestibule of the ear. In this sac lies the
“ear-bone” or otolith. Find the white optic nerve
arising from the inner surface of the eyeball; with
a sharp knife cautiously cut away the base of the
skull and trace the optic nerves to the brain; de-
monstrate that they cross each other, the optic
nerve from the right eye entering the left half of
the brain, and vice versa.

—

a

THE FISH. 85

’ Make a drawing showing this view of the brain and
eyes; open one of the eyes and remove the spherical
crystalline lens.

The air-bladder (sometimes called the swim-bladder) is
believed to be of use to the fish in keeping its place in the
water. In many fishes the air-bladder is connected with
the cesophagus by a tube, and in many others there is a
circulation of blood in part of the wall of the air-bladder.
The air-bladder really corresponds to the lungs of the
higher animals.

Parts of animals having essentially the same structure,
or corresponding in origin, are said to be homologous.
Thus the air-bladder of the fish and the lung of the snake
are homologous. The pectoral fins are homologous with
the fore limbs of the higher animals, and the hind limbs
of the higher animals are the homologues of the ventral
fins of the fish. Parts which are alike in use are said to
be analogous. Thus the gill of a fish and the lung of a
man are analogous; both serve in getting oxygen into the
blood.

Analogy is correspondence in use or function.

Homology is correspondence in structure or origin.

In some fishes the air-bladder is actually used as a lung.
These fishes are in consequence called lung-fishes. Some
of our fishes which breathe by gills have the power of
living out of water for some time, and are said to crawl
from one body of water to another when the former
dries up. y

Fishes are the lowest of the vertebrates; they are also
the oldest of vertebrates, in the order of their appearance
on the earth.

86 PRACTICAL ZOOLOGY.

The young fishes of all kinds have heterocercal tails, but
as they grow older, the higher fishes develop homocercal
tails. The earliest fishes had heterocercal tails, as have
many of the lower fishes at the present day.

Again, the early fishes had cartilaginous instead of bony
skeletons. All young fishes have cartilaginous skeletons,
but the higher fishes develop bone in place of cartilage as
they grow older.

It will be seen then that the stages of development of
the higher fishes repeat the order of the geologic appear-
ance of fishes, and review the classification of fishes from
the lowest to the highest. What do these facts signify ?

Use Jordan’s “ Manual of the Vertebrates” (latest edi-
tion), or, better, Jordan and Gilbert’s “Synopsis of the
Fishes of North America,” for finding the names of fishes
as ‘ Gray’s Manual” is used for “analyzing” plants.

THE FROG,

In the spring frogs gather in ponds and streams to
breed. Later, they may be found in meadows and fields
near water. When seeking them in such places walk
rapidly along so as to frighten and make them jump so
they can be seen. When studying frogs it is well to get
a good supply and keep them alive in a box, which should
be shut securely, leaving a few holes. This box may be
kept in a cellar or in a watering-trough. Frogs will live
a long time without feeding. In capturing frogs observe
how they dive into the mud to escape.

THE FROG. 87

STUDY OF THE LIVE FROG.

1. Put a live frog into a tub of water and study carefully
its mode of swimming and floating.
Notice how the frog sits when at rest.
What has the frog in common with other animals that
jump well ?

4, Watch closely the frog’s breathing, paying especial
attention to the throat, nostrils, and sides.

5. Touch the eyeball with a pencil, and note what fol-
lows. .

6. Note the motions of the eyelids.

7. What does the frog eat, and how does it take its
food?

8. Look for slight pulsations near the end of the back-
bone on each side, near the anus. These are’ the
beatings of the lymph-hearts.

Make drawings of the live frog in the sitting pos-
ture.

go bs

EXTERNAL FEATURES OF THE FROG.

Kill a frog by wrapping it in a towel or piece of cloth of
any kind, and moistening the latter with chloroform; or
put a teaspoonful of ether in a fruit-jar nearly full of
water, immerse the frog in it, and cap the jar.

1. Has the frog a neck? Find the division between the
head and the body by bending the parts and feeling
for the joint. :

2. Back of and below each eye is an oval area, the mem-
brane of the ear-drum, or tympanum.

88

il yn

=

10.

i.
12.

13.

PRACTICAL ZOOLOGY.

The fore limb consists of the arm, forearm, and
hand. .

The hind limb consists of the thigh, leg, and foot.
Count the fingers and toes.

What differences are there between the fore and hind
limbs ?

Open the mouth, seize the tongue with the forceps
and draw it forward; observe that it is attached
in front, but free behind. How is such a tongue
used ?

Look closely for teeth. Where are they?

Pass a bristle tipped with sealing-wax into one of the
nostrils. Where does it enter the mouth?

Make a small opening in one of the tympanic mem-
branes, pass a bristle through this opening, and look for
its appearance in the mouth. The opening through
which it appears is the Eustachian tube.

The mouth narrows back into the gullet.

In the back part of the floor of the mouth is a small
slit, the glottis, leading to the lungs.

Compare the colors and markings of the upper and
lower surfaces of the frog; draw dorsal and ventral
views of the dead specimen, naming all visible parts.

INTERNAL STRUCTURE OF THE FROG.

Cut through the skin of the abdominal wall along the
middle line; turn the skin back on each side, noting
how loosely it is attached to the abdominal wall.
Cautiously avoiding any large blood-vessels, open the
abdomen lengthwise from the pelvis to the breast-
bone; from the hinder end of this slit cut outward on

Abebice

th.

12.

THE FROG. 89

each side and turn back the flaps so as to expose the
internal organs; with forceps raise the hinder part of
the breastbone ; observe the heart lying next it, and a
thin membrane extending from it to the breastbone ;
with scissors cut this membrane close to the breast-
bone; cut through the breastbone in the middle line,
and stretch its parts well out to the sides to dis.
close the heart and surrounding organs. Lay the
frog on its back; stretch the fore limbs out to their
fullest extent, and pin them down.

Insert the blowpipe into the mouth and inflate the
stomach. Study its shape.

Trace the intestine from the stomach to the anus,

An enlargement of the intestine near the anus is the
cloaca.

The thin membrane which attaches the intestine to
the back of the abdomen is the mesentery. In a
freshly killed specimen blood-vessels may be seen in
the mesentery. ‘Trace these blood-vessels.

The dark liver partly covers the stomach.

Between the lobes of the liver is the greenish bile-sac.
In the mesentery, near the stomach, is the pale pan-
creas. :
Further back in the mesentery is the small red spleen.
If the previous inflation did not reveal the large
urinary bladder, insert the blowpipe into the anus,
and inflate the bladder through the cloaca.

In the female, masses of dark, spherical eggs may be
seen. The eggs are in the ovary, which is very large
when full of eggs, and much folded and plaited.

The egg-tube, or oviduct, is a long, coiled tube running
back to open into the cloaca. Cut a small hole in the

90

138.

14.

15.

16.

17.

PRACTICAL ZOOLOGY.

oviduct near its anterior end and insert a bristle tipped
with sealing-wax to discover where the oviduct ter-
minates anteriorly, and with what it connects at this
end.

In the male, the yellowish testis corresponds to the
ovary.

Connected with the ovary or testis are usually found
slender masses of fat.

The kidneys are two long, deep red bodies alongside
the backbone, in the hind part of the body near the
cloaca.

Insert a blowpipe through the mouth into the glottis
and inflate the lungs; observe their shape, and that
they are nearly hollow sacs, not spongy all the way
through as in the lungs of the rabbit or man. When
a lung has but few cells, only a small quantity of blood
can come into contact with the air. Such a lung is
adapted to an animal of low temperature and sluggish
habits. Tie a thread around each lung while it is
inflated; cut the lungs out and hang them up to dry
thus expanded. When thoroughly dried, they may be
cut open and compared with the lungs of a turtle
similarly prepared.

The thin sac inclosing the heart is the pericardium.
Carefully cut it away; time the pulsations as seen in
a freshly killed specimen. What is the effect of
applying gentle heat to the heart, as by breathing

-on it? The hinder conical part of the heart is the

ventricle; farther forward and nearer the back are
the auricles; running forward from the ventricle is
the main artery. This divides into two branches,
each of which has three subdivisions: —

THE FROG. 91

a. To the head, the carotid.
b. To the body generally, the aorta. Trace the two
. aorte, right and left, to their point of union near
the spleen.
e. To the lungs and skin, the pulmo-cutaneous.

Part of the impure blood is sent to the skin, through
which it gets oxygen. In this way the frog gets
oxygen when under water for a long time, and during
the winter, when it hibernates deep down in the mud.
Remove the heart. Does it beat after removal from
the body? Note the effect of holding the heart in
the palm of the hand. Note the effect of pricking it
with a needle.

CIRCULATION OF BLOOD IN THE WEB OF A FROG’S FOOT.

Split a cigar-box cover or shingle in the middle, and cut
a V-shaped notch in one end; wrap the frog in a wet
cloth, with one leg projecting, and tie it thus wrapped to
the board; tie threads around two of the toes, and stretch
the web (but not too tightly) over the V-shaped notch;
place the board firmly on the stage of the microscope.
Examine first with a one-inch objective. The large ves-
sels which grow smaller by subdivision are the arteries.
The large vessels which are formed by the union of smaller
ones are the veins. ‘The finer vessels forming a network
are the capillaries; the black spots are pigment cells.
Where these are very abundant, they make dark spots, as
seen on the frog’s back. Take a triangular piece of cover-
glass a little smaller than the web under examination;
place a small drop of water on one side of it, and lay the
glass, with the water downwards, on the web. Put on a

.
92 PRACTICAL ZOOLOGY.

higher power, say a-quarter-inch objective, and study the
little bodies floating in the blood. ‘These are the cor- |
puscles.

1. The large, faintly colored oval corpuscles; do they
change their shape when pressed, as in turning a cor-
ner? What is the color of these corpuscles? Mould
a bit of clay into the shape of one of these bodies.

2. The smaller, rounded, paler corpuscles, fewer in num-
ber and moving with a slower and more unsteady
motion along the sides of the channel; what must
be the shape of these? Place a drop of frog’s blood
on a slide, cover with a cover-slip, and examine with
a high power. Make careful drawings of the two
kinds of corpuscles. (Take a small drop of blood for
this, and after covering it, run a little oil around the
edge of the cover to prevent drying.)

THE NERVOUS SYSTEM OF THE FROG.

The nervous system is better seen in alcoholic speci-
mens. Slit the skin along the back from the snout to the
anus; with a sharp knife cautiously cut away the top of
the skull, and find: —

1. Between the eyes, side by side, two elongated white
bodies, the two halves, or hemispheres, of the cere-
brum. Observe two small pear-shaped bodies, the
olfactory lobes, in front of the cerebral hemispheres.
These taper forward into nerves running to the nasal
region; these are the nerves of smell, or olfactory
nerves.

2. Back of the cerebral hemispheres are the optic lobes,
forming the widest part of the brain. Prove that a

THE FROG. 93

white cord, the optic nerve, connects each of these
lobes with one of the eyes; does the optic nerve
extend directly from each eye to the corresponding
optic lobe?

. Extending backward from the under side of the optic
lobes is the medulla oblongata.

. The medulla oblongata narrows and becomes the
spinal cord. Trace the spinal cord back into the
spinal column, cutting away the part of the backbone
that covers it.

. In the middle of the body-cavity find nerves emerging
from the sides of the spinal column, hence called the
spinal nerves. Find that several of these, after
running backward, unite to form one large nerve.
Trace the nerve down between the muscles of the
thigh; this is the sciatic nerve.

REFLEX ACTION OF THE FROG’S SPINAL CORD.

Take a live frog, and find, by bending the head, the joint
between the head and the backbone; lay the frog on a
board, and quickly thrust the blade of a knife through

_ the body at this joint, and completely sever the spinal
column and spinal cord. This destroys sensibility, and is
essentially the same as cutting off the head. After sever-
ing the cord back of the head, run a wire into the brain-
cavity and stir it about in order to entirely destroy the
brain. In a few minutes hang the frog by a hook through
the jaw.

1. Pinch the toes; what follows? Repeat the experi-
ment several times. Pinch the skin near the anus.
2. Slit the skin along the back side of the thigh; tear

a

94 PRACTICAL ZOOLOGY. ~

apart the muscles, and find the sciatic nerve; with a
sharp pair of svissors (while watching closely the foot)
sever this nerve; what takes place?

3. Hang up as before, and pinch the toes of each foot;
what difference is now observed?

4. With the forceps alternately pinch the two ends of
the severed sciatic nerve; what takes place as these
two ends are pinched ?

5. Run a wire down the spinal column, twisting it about
to destroy the spinal cord; what occurs while this is
doing ?

6. Pinch the toes as before; what results?

7. Again pinch the end of the sciatic nerve, still con-
nected with the parts below, being careful to pinch a
little lower than before.

THE FROG’S MUSCLES.

Make a circular cut through the skin at the top of the
thighs, and pull off the skin of the hind limbs like a pair
of hose. Notice the pale color of the muscles. The mus-
cles of the frog’s thigh are nearly the same in number and
arrangement as in man. Notice especially the calf-muscle ;
the end by which it is attached above, the less movable
end, is its origin. The muscle tapers into a strong, white
tendon below. The end of the muscle at its more
movable end (or its attachment by a tendon at its more
movable end) is its insertion.

Observe the thin, transparent membrane covering the
muscle, the muscle-sheath. Tear the muscle to pieces,
and note its fibrous structure. Puta bit of the muscle in
a drop of water on a slide, and cover with a cover-slip ;

THE FROG. 95

examine first with a low, and then with a high power, to
see the cross-markings of its finest fibres. This kind of
muscle is called striped or striated.

THE ACTION OF A FROG’S MUSCLE.

Entirely remove the skin from one of the frog’s hind
limbs; sever the limb from the body at the hip-joint; clear
away all the muscles of the thigh, carefully preserving the
sciatic nerve, still connected with the leg below; sever
the heel-cord below the heel, and separate the calf-muscle
from the other muscles of the leg, leaving undisturbed its
attachment above; just below the knee, cut away the
shin-bone, with all the muscles of the leg, except the calf-
muscle; there should now remain the thigh-bone, with the
lower part of the sciatic nerve running to the calf-muscle
suspended below; tie a string around the thigh-bone, and
suspend the whole; hang a slight weight, such as a door-
key or a pair of scissors, to the tendon at the lower end of
the muscle; now pinch the upper end of the sciatic nerve,
meanwhile closely watching the muscle.

THE FROG’S SKELETON.

Clean the skeleton of the frog after dissection. This
is easier after soaking it in water for a few days.

1. Note how open and light the skull is, and how easily
the bones are cut.

2. Count the parts of the spinal column; these are the
vertebrze. The long bone terminating the spinal
column is the urostyle.

8. Observe the long bones of the pelvis, parallel with
the urostyle. What makes the frog hump-backed ?

96 PRACTICAL ZOOLOGY.

4, The fore limb has, in the upper-arm, the humerus; in
the forearm the radius (same side as the thumb) and
the ulna; in the wrist are several small bones, the
whole collectively called the carpus; in the hand are
the digits.

5. The hind limb has, in the thigh, the femur; in the leg,
a bone which shows, by grooves near its ends, that it
is formed by the union of two bones corresponding to
the tibia and fibula of man; the several small bones
of the ankle are together called the tarsus; the
bones of the toes are the digits. .

6. Are there any ribs?

THE DEVELOPMENT OF THE FROG.

By wading into a pond where there are frogs, in the
spring, one can usually see how the eggs are laid. If these
eggs are watched, they will be seen to produce tadpoles;
the tadpoles may be reared; at first the form is fish-like,
not only in external form, but in the fact that the tadpole
has no lungs, but breathes by gills. An opening may be
seen on one side, through which water leaves the gills.
Later, the lungs develop, and the gills disappear. How do
the gills of a tadpole compare with those of a fish? Is the
tadpole a fish?

Put a small tadpole in a watch-crystal containing water ;
examine the gills under a one-inch objective to see the
2irculation of the blood through them. MHas the tadpole
teeth? Examine its mouth; what does the tadpole eat?
Open a large tadpole, and observe the long, coiled intestine.

— Se —

7
I

THE FROG. 97

THE FROG’S RELATIVES.

Frogs, with toads and salamanders, belong to that class
of vertebrates called Batrachia. What are the points of
difference between frogs and toads? “The toad is exceed-
ingly useful as a destroyer of noxious insects. It is noc
turnal in its habits, is harmless, and can be taken up with
impunity, though it gives out an acrid fluid from its skin,
which may poison the eyelids.”

How does a tree-toad differ from a common toad?
Should we say tree-toad, or tree-frog? Take a tree-toad
from green leaves, and put it into a white-lined box; cover
the box with a pane of glass. Is the tree-toad’s color
affected by this change of surroundings?

Salamanders are often found in cellars, and under rotten
logs, and in springs. They are often wrongly called
lizards. Lizards are scaly, and are true reptiles, and are
related more nearly to the snakes and turtles. Salaman-
ders have smooth bodies; they are harmless, as also are
lizards. If you find one, examine it carefully. Salaman-
ders also develop from a tadpole stage. Some salamanders
‘ are viviparous. If kept in the dark, they sometimes fail
to complete their development. ‘The mud-puppy, a large
salamander found in our rivers, retains its gills through
life.

The frogs and toads (tailless Batrachia) rank higher
than the salamanders (tailed Batrachia), having passed
through the salamander stage and gone on to a higher, in
which they have more perfect organs.

In studying insects, we observed that insects pass through
a worm-like stage, and that they rank higher than worms.

98 PRACTICAL ZOOLOGY.

Geology tells us, from the remains found in the rocks,
that most of the animals now living are different from
those of early ages.

The earlier Batrachians were tailed; they were sala-
mander-like; the frogs and toads appeared later. Thus
the different stages of development of the frog repeat the
order of appearance of Batrachia in geologic succession,
and review the classification of Batrachia from the lowest
to the highest.

EXTERNAL FEATURES OF THE SNAKE.

Examine the scales; observe their relation to each other
and to the skin. A scale having a ridge running length-
wise in the middle line is carinated; if there be no such
ridge, the scale is called smooth. How many rows of
scales are there, not counting the wide plates below?

These wide plates along the belly, as far back as the
anus, are the gastrosteges; count them. The plate im-
mediately in front of the anus is the anal plate; if it is
of one piece, it is called entire; if of two pieces, it is bifid.
The plates under the tail are the urosteges; how do they
differ from the gastrosteges? count them. Why should
there be these large plates below instead of the smaller
scales found on the upper surface? How does a snake
crawl?

Keep a live snake, and watch its breathing movements.
Does the interval of rest occur after breathing in or after
breathing out? Touch the eyeball with a stick; can the
snake wink? Watch the movements of the tongue.

THE SNAKE. 99

DISSECTION OF THE SNAKE.

For dissection get a large specimen ; a live one is better,
as after severing the spinal cord at the neck (which is
essentially the same as cutting off the head), the beating
of the heart may be seen, and the persistent vitality of the
nerves and muscles serve well to illustrate reflex action of
the spinal cord. Lay the snake’s head on a board, and
with a knife cut entirely through the spinal column, just
back of the head; but do not cut off the head. This
destroys its sensibility. Get a paper of tacks, and a board
as long as the snake. Lay the snake on its back, with the
head at one end of the board. Push the point of a tack
into the mouth at one side, and drive it through the upper
jaw, leaving the lower jaw free. Repeat with the other
side. Stretch the snake out straight, and tack through
the tail, just back of the vent. With the forceps pinch
up a fold of the skin of the throat, and cut through it
with the scissors; continue the cut back along the middle
line of the belly, being very careful not to cut anything
_ within. As the cut proceeds, stretch the skin out at the
sides, and tack it down every two or three inches. Cut
away the thin membrane which extends across from the
ribs on each side, avoiding blood-vessels.

1. With forceps seize the lower jaw and pull the mouth
open. Note how dilatable the mouth is, and how
loosely the lower jaw is hinged to the upper; note,
also, that the right and left halves of the jaws do not
unite in front. Examine closely the teeth, their
shape and arrangement.

L00

PRACTICAL ZOOLOGY.

Seize the tongue, and draw it forward from its sheath
in the floor of the mouth. Observe its black, forked
tip; tack it down. ;
Above the tongue find a small opening, the entrance
to the windpipe. It is called the glottis.

Insert a blowpipe (glass tube) into the throat through
the mouth; pinch the walls of the gullet closely
around the blowpipe, and inflate the wide gullet and
stomach. What does the snake eat, and how does
he eat?

For inflating the lung, a tube with a small point is
better; draw out a small glass tube, and connect with
a rubber tube; insert the point in the glottis, and in-
flate. This locates the pink lung, with its posterior,
thin walled extension, or air-sac.

Trace, from the glottis to the lung, the ringed wind-
pipe, or trachea. Only one lung is developed; look
for the rudiment of the other.

The heart will be noticed on account of its beating;
the part of it farthest from the head is the ventricle;
nearer the head find two parts, the right and left
auricles. These two contract at the same time, just
before the contraction of the ventricle. The heart is
in a thin sac, the pericardium; pinch up a fold of
this with the forceps, and cut through it, and remove
that part of it covering the heart, very carefully
avoiding blood-vessels.

Find a_-blood-vessel arising from the ventricle just
between the auricles, and passing forward between
them, curving around over the gullet to the posterior
part of the body. This is the main artery, or aorta;
look for its branches running to the head.

eo

14.

15.

16.

17.
we 1S.

THE SNAKE. 101

Look also for an artery running to the lung, the
pulmonary artery.

. Find several veins, of a darker color than the arteries,

leading to the heart.
Alongside the stomach is a dark red body, the liver;
a large vein runs along its surface.

. Back of the liver is the dark bile-sac, and near this

the spherical red spleen.

Clear away any masses of fat that may hide organs in
the posterior part of the body, and again inflate the
stomach and lung for a more perfect view of these
organs.

Trace the intestine from the hinder end of the
stomach to the opening, the anus, at its posterior end.
In the hinder part of the body-cavity may be found
the reproductive organs, ovaries in the female, testes
in the male. These both have long tubes, extending
backward to convey their contents to the posterior,
dilated portion, the cloaca, of the intestine.

Into the cloaca also open the ducts of the kidneys,
two reddish, elongated structures.

Count the ribs of one side.

Draw the points of the forceps quickly along the
muscles over the ribs; note the contraction of the
muscles that follows; such contraction of the muscles
is wholly involuntary (as the brain now has no con-
nection with the body), and is called reflex action of
the spinal cord. It is the same kind of action as that
seen in the case of a chicken with its head cut off.

Use “Jordan’s Manual of the Vertebrates” for findi
the names of snakes.

102

~ Pa

PRACTICAL ZOOLOGY.

THE TURTLE.

The upper part of the shell is the carapace.

The under part is the plastron.

Observe the large sections, or plates, marking the
shell. How many of these plates are there on the
carapace? how many on the plastron? how are they
arranged ?

Study the motions of the head, legs, and tail; observe
the scales on these parts.

Note the shape of the feet; for how many purposes
does the turtle use its feet? are the feet of all turtles
alike? Count the claws; compare the front and hind
feet.

With a strong pair of pinchers seize the héad, pull it
well out, and chop it off; examine the mouth; are
teeth present? Is there a tongue? Look for a third
eyelid. Compare with the pigeon in this point of
structure.

DISSECTION OF THE TURTLE.

Saw through, or cut with a strong chisel, the bridge
which connects the carapace and plastron on each side.
Carefully raise the plastron, and, keeping the blade of the
knife or scalpel close to its inner surface, cut away all its
attachments to the organs within, and remove it entirely.

2.
2.

In front are the bones supporting the fore limbs.
Behind are the bones of the pelvis, supporting the
hind limbs. Were these two sets of bones attached to
the plastron?

THE TURTLE. 103

A thin membrane covers the internal organs; through

it the heart may be seen beating. Cautiously avoid-

ing blood-vessels, cut away this thin covering, and

distinguish the following parts of the heart: —

a. The large, hinder part, the ventricle.

6. In front, on each side, the two auricles.

e. Between the auricles are blood-vessels, branching
toward the head. As in the frog, there are two
aorte, the right and left, which unite posteriorly.

Make out the following order of the heart’s beat: —

a. The contraction of the blood-vessels leading to the
auricles.

6. The contraction of the auricles.

ce. The contraction of the ventricle.

On each side of the heart appears the dark liver, con-
sisting of two main lobes, connected by a cross-band.
Search the liver to find the bile-sac.

Under the left lobe of the liver is the stomach.

From the stomach trace the intestine to the trans-
verse vent under the tail.

Masses of eggs may be found in the ovary (if a
female).

Find a large bladder near the pelvis.

. Raise the liver to find the lungs; pull forward the

neck, find the windpipe, and insert a blowpipe. By
inflating, the lungs may be better seen. When the
lungs are fully inflated, tie a string tightly around
the windpipe; carefully remove the lungs, and hang
them up to dry. When they are thoroughly dry and
firm, cut them across, and compare with the lungs of
the frog and rabbit. .

104

PRACTICAL ZOOLOGY.

How does the turtle draw in its head?
How long does the heart beat after the head is
cut off ?

THE SKELETON OF THE TURTLE.

Clean away the muscles and all soft parts. Boiling
loosens the outer plates; these are part of the skin,
and not of the skeleton proper; they aré called the
epidermal plates. .

When these plates are removed from the carapace,
there appears a series of bones extending outward on
each side; these are the ribs, very wide, and united
by their edges. How many of these flattened ribs
are there ?

On looking at the inner surface of the carapace, the
series of vertebrz will be found; and attached to the
sides of the bodies of these vertebre are the heads of
the ribs. :

Along the middle line of the outside of the carapace
between the ribs of the two sides, is found a series of
bony plates; these are the enlarged and flattened pro-
jections of the vertebre; they correspond to the
spines which make the sharp ridge along the backs of
most vertebrates.

Compare the bones of the pelvis and of the limbs
with those of the rabbit.

For a full account of the anatomy of a turtle, see “ How
to Dissect a Chelonian,” by Prof. H. N. Martin and
Dr. W. A. Moale.

For finding the names and classification of turtles, use
Jordan’s “ Manual of the Vertebrates.”

a od :

THE PIGEON. 105

THE PIGEON.

If possible, capture the pigeons alive and keep them fast-
ing a day, that their crops may become empty. Kill them
by putting them into a tight box, or jar, which has a
closely-fitting lid, with a sponge moistened with chloroform.
The “anesthetic box” described in Wilder and Gage’s
* Anatomical Technology” is very convenient for killing -
cats and rabbits as well as pigeons. Having glass sides,
this box possesses the further advantage of enabling the
student to watch the physiological effects of ether, chloro-
form, ete.

Note the shape of the body as a whole, and its adapta-
tion to rapid passage through the air.

THE HEAD,

1. The beak consists of the upper and lower mandibles ;
hold the pigeon’s head with one hand, and with the
other take hold of the tip of the upper mandible and
prove that it is movable.

2. Raise the upper eyelid, and look in the front angle of
the eye for the third eyelid; seize the edge of this
with the forceps, and pull it backward over the eye.
Watch the live bird, to see how it winks.

8. Brush forward the feathers below and back of the eye
to find the ear-opening; observe the peculiarities of
the feathers which cover this opening.

4, Examine the nostrils; open the mouth and insert the
head of a pin into the nostril, and probe, to discover
its place of appearance in the mouth.

106

PRACTICAL ZOOLOGY.

With the forceps pull forward the tongue for careful
examination.

Just back of the tongue is the opening, the glottis, of
the windpipe, or trachea.

The mouth continues backward to become the gullet.

THE WINGS.

Feel of the wing to make out the division into arm,
forearm, and hand.

The foremost angle of the wing is called the bend
of the wing. To what part of your arm does this
bend of the wing correspond? Just outside of the
bend of the wing find the false wing, a cluster of
short quills, borne on the thumb.

The long quills borne on the hand are the primaries ;
count them. The quills on the forearm are the sec-
ondaries; count them. When quills are found on
the arm, they are called tertiaries.

The shorter feathers which overlap these quills above
and below, are the upper and lower wing-coverts.
Extend the wing; compare its upper and lower sur-
faces; observe the shape of the quills, and the way
they overlap one another; put all these facts together
and consider their effect in the down-stroke of the
wing. What is the result of this arrangement when
the wing is moved quickly upward?

THE LEGS.

Feel of the parts, beginning close to the body, to be
sure to find the first division of the limb; this is the
thigh, or second joint.

3

5.

THE PIGEON. 107

Below this is the leg proper, or drumstick.

The next division is the tarsus; it is a consolidation
of several bones that were distinct in the young bird;
this part of the bird’s leg, then, really corresponds
to the tarsus and metatarsus of the human foot, or
that part between the ankle and the toes. Where,
then, is the true heel?

Bend and extend the toes to find how many bones
there are in each. |

The scales on the front of the tarsus are called
scutella; hence the tarsus of the pigeon is said to
be scutellate in front; the back of the tarsus of the
pigeon is reticulated.

THE TAIL.

Count the quills of the tail; spread the tail to see
their mode of overlapping; make a diagram to show
their mode of overlapping as seen from behind; com-
pare the middle and outer tail-feathers.

The feathers which lap over the base of the tail are
the upper and lower tail-coverts.

Raise the upper tail-coverts, to find the conical tip of
the outlet of the oil-gland; press the oil-gland to get
a drop of oil.

In front of the lower tail-coverts is the anus.

THE FEATHERS,

Pull out one of the large wing-quills and study its
parts; the central axis is the shaft; the expanded
part is the vane; the side branches of the shaft are
the barbs, and the side branches of the barbs are the

108 PRACTICAL ZOOLOGY.

barbules. With a lens examine the upper and lower
surfaces of the vane; then tear one of the barbs loose
from the barbs in front of and behind it, and study it
carefully ; again watch closely while tearing two barbs
apart, to see how the barbules are related to each
other; now examine the vane of the same quill at the
very beginning of the vane, near the end that was
attached to the wing. What is the difference between
the arrangement of the barbs in these two places?
Observe the hole in the tip of the shaft; run the
point of a dissecting-needle along the groove in the
under surface of the shaft toward the base of the shaft. |
This should lead the point of the needle into another
opening, communicating with the cavity of the shaft. .
Examine this region with a lens, and determine that |
the two sides of the vane meet at this point. Make |
drawings of a quill, as seen from above and below, |
showing all these points.

With sharp scissors cut across the middle of the
quill. Look at the cut end; observe that the vane is
attached to the upper edges of the shaft; compare
the place of attachment of the vane to the shaft,
with the place of attachment of the wing to the body.
Cut part of the wider side of the vane, at right angles
to the barbs; with a lens, or a low power of the
microscope, examine the edge of this cut. Make
drawings showing these arrangements of the parts of
the quill. What are the advantages of such arrange-
ment?

2. Take one of the body-feathers, and compare it with
the quill. In what lies the chief difference ?
3. Find a feather that is wholly composed of “down,” if

THE PIGEON. | 109

there be such; examine the “down” with a micro-
scope.

Pick a small part of the breast, and study one of the
pin-feathers. How does it differ from the feathers
already examined ?

Feathers correspond to the hairs of mammals; there
are muscles in the skin of the pigeon, by the action
of which the feathers may be raised, as when the
bird is angry, or when taking a dust-bath, just as
there are muscles in the skin of a dog or cat, or in
the human scalp, by which the hair is made to stand.
on end.

Study the arrangentent of the feathers; do feathers
grow on all parts of the body? a fledgling shows this
point well. Push aside the feathers along the line of
the ridge of the pigeon’s breastbone and examine the
skin; do feathers grow here? Look for other un-
feathered areas. Note how the feathers overlap.

Pick the feathers from one side of the pigeon, just to
the middle line; lay the bird on the feathered side,
and make a drawing, showing (1) the outline of the
feathers; and (2) the outline of the body within.

DISSECTION OF THE PIGEON.

Pluck the pigeon before dissecting it; dipping the bird

in hot water makes this easier.

19

Insert a tube into the mouth and inflate the crop,
compressing the neck to prevent the escape of the air.
Note the shape of the crop.

Beginning at the posterior end of the breastbone, cut

110 PRACTICAL ZOOLOGY.

through the skin along the line of the ridge, or keel, |
of this bone, and loosen the skin on each side, con- |
tinuing forward over the crop, being careful not to |
tear the crop; again inflate the crop, and examine it
more fully. Observe the fine lines running crosswise
and lengthwise in the walls of the crop; these are the
muscle-fibers, transverse and longitudinal. Glands in
the lining of the crop secrete a milky liquid, in the
breeding season, to act on the food and soften it; this
softened food is brought up from the crop and put —
into the mouths of the young pigeons.

8. Loosen the crop from the front of the breast and from
the neck.

4. Find the windpipe, or trachea, with its white rings of
cartilage.

5. On each side of the neck is a vein and a white cord,
the pneumogastric nerve; the vein is the jugular
vein. If it does not show distinctly, let the bird’s
head and neck hang over the edge of the table, and
the vein will soon fill with blood.

6. Insert the tube into the glottis, and inflate; observe
the swelling of the whole body, and the inflation of
the thin-walled air-sacs in the hollow in front of
the breastbone.

7. Break the bone of the upper-arm, the humerus,
cut through the skin and muscles, and push out
through this opening the end of the bone next to
the body; note that it is hollow; slip one end
of a rubber tube over the end of the bone, and
inflate; what is the result of this experiment ?
Keeping another tube connected with the windpipe,
determine whether air can be sent in through

— eo

i i

THE PIGEON. 111

the windpipe and out of the humerus, and vice
versa.

. Slit the skin back over the abdomen to the anus,

loosen it well back on each side, and cut through
the abdominal wall just behind the breastbone; in-
flate once more, and observe the abdominal air-sacs.

. Cut down into the muscle of the breast, close along-

side the ridge (keel) of the breastbone, and around
the outer border of the breastbone; thus loosen and
raise a great flap of muscle, the pectoralis major.
Note the nerve and blood-vessels entering its inner
surface; separate it from a smaller muscle lying under
it, which will be known by the glistening appearance
of the muscle-sheath; sever the attachment of the
pectoralis major to the breastbone, and all other
organs except at the extreme front end; here the
muscle narrows into a tough, white cord, or tendon;
trace this tendon to its attachment to the bone of the
arm; now lay the pigeon on its back in one hand, and
pull this muscle backward, noting the effect on the
wing. In like manner loosen all the posterior attach-
ments of the muscle which was covered by the pec-
toralis major, lying in the angle between the keel of
the breastbone and the body of the breastbone; prove
its action, this time holding the pigeon right side up.
Compare these two muscles in size, and in the amount
of work they have todo. The smaller muscle is the
pectoralis minor. The hinder attachment of each of
these muscles is called its origin; and the place of
attachment of the tendon to the wing-bone is the
insertion. Cut through the body-wall around the
margin of the breastbone, through the ribs, coracoid

112

10.

11.

12.

13.

14.

15.

16.

PRACTICAL ZOOLOGY.

bones, and wishbone, and entirely remove the breast-
bone.

Lift the liver and disclose, at the left of the body-
cavity, a hard mass, the gizzard. Slit the abdominal
wall in the middle line back to the anus, push aside
any fat that may cover the internal organs, and turn
the gizzard to the left of the bird to find where the
intestine arises from it; trace the intestine from the
gizzard backward.

The part of the intestine nearest to the gizzard is
the duodenum.

In a long loop formed by the duodenum is a pinkish
organ, the pancreas.

Trace the intestine, tearing away the fat and the thin
walls of the abdominal air-sacs, observing that it is
held in place by a thin, transparent membrane, the
mesentery.

Near its end the intestine has two short side branches,
the czeca.

Just before the intestine ends, it widens, forming the
cloaca.

Turn the gizzard to the right of the bird; entering
it from the front, find a mottled, bulging tube, the
glandular stomach; pull the crop forward, to show
the connection between it and the glandular stomach.
To the right of the glandular stomach is the small, red
spleen; seize the gizzard, pull it backward, and cut
off the glandular stomach as far forward as _possi-
ble; remove the gizzard and intestines. Note the
relations of the tubes which enter and leave the giz-
zard; open the gizzard, observing the thick outer
muscular coat, from which the gizzard is sometimes

———

17.

18.

19.

THE PIGEON. 113

called the muscular stomach. Note also its tough
lining; examine the contents of the gizzard; why
does the gizzard have such a thick coat of muscle?
do all birds have this kind of gizzard?

In front of the liver is the heart, in a thin sac, the
pericardium. Cut through its posterior wall, and
turn the heart forward, to see the dark vein, the
inferior vena cava, running to it from the liver; pull
the heart backward, to see the whitish arteries run-
ning forward from it. The main artery runs forward,
and turns to the right before going backward, while in
man the corresponding artery turns to the left. Prick
a hole in one of the large veins near the heart; insert
the point of a blowpipe, and inflate the heart; its red,
conical part is composed of the ventricles; the dark
base is made up of the two auricles. Tie a thread
around the veins at the anterior and posterior borders
of the liver, and cut this organ away.

On each side are the pink lungs. Pick away the thin
membranes bordering the outer hinder borders of the
lungs; look for holes through which the lungs com-
municate with the abdominal air-sacs; look for the
trachea. Remove the lungs, not failing to see how
closely they are attached to the back, being indented
by the ribs.

In the hinder part of the body-cavity are the dark-
colored, irregular kidneys. Tear them away, observ-
ing how they are composed of several lobes, which fit
into the hollows of the pelvis. After removing the
kidneys, observe the white nerves extending outward
from the sides of the spinal column to pass to the
thighs.

114 PRACTICAL ZOOLOGY.

20. In front of the kidneys are the reproductive organs;
the two white oval testes, in the male; in the female,
the ovary, often showing many eggs in different stages
of development. The kidneys and reproductive organs
send tubes to the cloaca: the tube which conveys the
eggs from the ovary to the cloaca is the oviduct.

21. Remove the heart, cut off the auricles, and look down
into the ventricles; cut across the middle of the ven-
tricles, and make a drawing of this cross-section.

22. Observe the fold of skin extending across the angle
between the arm and forearm; dissect away the skin,
and find a membrane within the skin-fold.

23. Observe the muscles connecting the hinder edge of
the breastbone and the pelvis (which were cut through
in opening the abdomen); these are the abdominal
muscles. How does the bird perform the act of
breathing? Compare the bird, snake, frog, and man
in their modes of breathing.

24. Bend the leg up close to the body, to the position of

perching; what effect does this bending of the leg
have on the toes? How does the bird stay securely
on the perch when asleep? Dissect the leg to find
the mechanism by which the toes are clenched as the
leg is bent.

25. Clean away as much as possible of the soft tissues, and
keep the skeleton for later study.

26. Dissect out the tongue, and compare it with the tongue
of the snake. The voice is produced in the lower part
of the windpipe, instead of in the upper part, as in
man.

5 ge

THE PIGEON. 115

THE BRAIN OF TH PIGEON.

Cut away the top of the skull with a sharp knife, using
great care not to injure the soft brain, and make out the
following parts : —

1. In front, the large cerebrum, consisting of two hemi-
spheres, which are separated by a deep groove.

2. Behind the cerebrum is the undivided cerebellum.

3. Running backward from the under side of the cere-
bellum is the spinal cord; trace it back into the
backbone. Make drawings of the brain, as seen from
above and as seen from the side.

THE SKELETON OF THE PIGEON.

Notice the lightness of the whole skeleton. What part
of the pigeon’s weight is bone? Compare the eye-cavity
with that of man. The lower jaw does not join the skull
directly, as in man, but is joined to an irregular bone,
which, in turn, joins the skull. This is the quadrate bone.

- The hole by which the spinal cord leaves the brain-cavity

is the occipital foramen; in front of this foramen is a
little rounded projection, the occipital condyle. Observe
how this condyle fits into a cavity in the first vertebra of
the neck. Count the vertebre of the neck, or cervical
vertebra. Observe the consolidation of the vertebra in
the back; note the joint in each rib, and the arrangement
for bracing the ribs together. Press the breastbone alter-
nately toward the back and away from it, meanwhile
watching the joints in the ribs.

116 PRACTICAL ZOOLOGY.

The “ wishbone” corresponds to the two “ collar-bones ”
of man. Alongside the two branches of the wishbone are
the coracoid bones; what especial need of such bones in
this place? In the wing find, in the arm, the humerus;
in the forearm, the ulna and radius. The hand has only
part of the fingers developed; a little bone, representing
the thumb, is present (which bore the feathers of the
“false wing”). In the thigh is the femur; in the leg is
the tibia; and alongside it, the small fibula. The bone
above the foot represents the consolidated bones of the
human ankle and foot as far as the toes. What evidence
is there of such consolidation ?

Read “The Anatomy of the Pigeon,” in Packard’s
“Zodlogy” and in Parker’s “ Zosdtomy”; also “Handbook
of Vertebrate Dissection. Part Il. How to Dissect a
Bird,” by Martin and Moale.

Trace the pigeon to its family by the aid of Jordan’s
“ Manual of the Vertebrates.” Use the same book, or
Coues’ “ Key,” for finding the name of any of our wild
birds.

THE HEN’S EGG.

So place a hen’s egg in a basin of water that it cannot
roll, mark the upper side plainly, and boil it hard; keep
track of the side that was uppermost.

1. Crack the shell, and pick it away; put a piece of it in
strong vinegar, or other acid. Of what is the shell
made?

oo

THE HEN’S EGG. 117

Note the thin membrane lining the shell.

Does the egg completely fill the shell? Where is the
air-space P Does the lining membrane, in this region,
adhere to the shell or to the “white”? How cana
fresh egg be distinguished, without breaking? Does
a fresh egg, in water, lie in the same position as when
ona table? What is the use of this air-space ?

How is the yolk situated in the white? how in refer-
ence to the position during boiling? Compare a num-
ber of eggs, to see if there is any regularity about this.
Note the round spot on the yolk, where it comes near-
est to the surface. This is the germ-spot, in which
the chick begins to form.

With a sharp knife, split the egg lengthwise. Is the
white alike throughout? is the yolk alike throughout ?
has the yolk a coat? Cut and tear these parts to make
out their structure, if they have any definite structure.
Boil an egg hard, as before; mark a line lengthwise
around the egg, passing through the point that was
uppermost while boiling; carefully break away the
shell on one side, and with a clean cut remove this
half of the white and yolk; place the other half in
the position it had while cooking ; make a drawing of
this section, using different colors to show the shell,
shell-membrane, air-space, white, yolk, germ-spot, etc.
Prop an egg on end, and boil in this position; is the
yolk in a different position in consequence? The
white of the egg has interlacing fibres and partitions
which keep the mass together; the white cannot be
mixed with water till these membranes are cut or
broken; hence an egg, to be eaten raw, should be
whipped to break these membranes, The white is not

118 PRACTICAL ZOOLOGY. |

a part of the true egg. In dissecting a bird, the eggs,

of various sizes, according to their stages of develop-

ment, may be found in the ovary. At this time the

egg consists of the yolk, with a thin coat; the white .
is deposited around this later during its descent

through the oviduct; the shell is last formed, and is

absent in the case of most animals.

In the development of birds all their nourishment,
before hatching, must be stored in the egg; hence its
large size. In the higher animals the egg is retained
in the body of the mother, and gets its nourishment
from her blood, which circulates through the placenta.

9. Set a hen on a dozen eggs; mark the date; open and
examine an egg each day; if the egg was fertilized,
the cells of the germ-spot multiply by division, and
soon take definite arrangement; at the end of twenty-
four hours the backbone is outlined; during the
second day the brain begins to develop, and the heart
appears; on the fourth day the legs and wings make
their appearance as flattened buds; until the sixth day
it would be impossible to say whether the embryo was
that of a bird, a reptile, or a mammal; after this, the
characters peculiar to birds become evident, the feath-
ers begin to develop, and, later, the particular kind of
bird may be recognized.

The development of the rabbit, guinea-pig, or any mam-
mal, including even man, follows nearly the same order as
in the chick, the chief differences arising from the fact that
the embryo mammal develops in a special portion of the
oviduct, the uterus, or womb,-and that the growing germ
is supplied with maternal blood.

The eggs of mammals are very minute. These eggs (if

THE RABBIT. 119

fertilized) go through the process of division, or segment-
ation, as described for the sea-urchin.

In the embryo of the dog it is twenty-five days before it
ean be told whether it is to be a mammal or not, and it
requires a much longer time to show the distinction be-
tween the human embryo and that of the dog. The human
embryo and the embryo of one of the higher apes are so .
closely alike that they are indistinguishable for a still
longer time than is necessary to distinguish between the
embryos of. dog and man.

The study of development is called embryology.

Egg-laying animals are called oviparous. If the young
develop within the body of the parent, receiving nourish-
ment from the blood of the parent, the animal is said to be
viviparous; “or, the young may complete its develop-
ment while the egg remains in the interior of the body of
the parent, but quite free and unconnected with it, as in
those vertebrates which are termed ovo-viviparous.”

THE RABBIT.

EXTERNAL FEATURES.

1. Note the shape of the body; the relative size of the
fore and hind limbs; the length of the ears. Compare
the soles of the feet with those of the cat. How
many toes has each foot, and how do the claws differ
from cat’s claws?

2. Make a series of dots showing the tracks made by a
running rabbit, indicating by which foot each track is

120 PRACTICAL ZOOLOGY.

made, and showing by an arrow the direction in
which the rabbit was going.
8. Observe the “whiskers” on the upper lip. Examine
the nostrils and the cleft in the upper lip.
4. Note the chisel-shaped front teeth, the incisors; ob-
serve the space between the incisors and the grinding
teeth, or molars.
Observe the hairiness of the inside of the cheek.
Find the third eyelid. How does it compare with
that of the pigeon?
7. Save a few of the hairs, and later examine them under
the microscope.

Or

INJECTION OF THE RABBIT.

Before beginning dissection it is well to have at least
one specimen injected for the sake of comparison. The
method of injecting recommended by Parker (“ Zodtomy ”}
has given good results. Kill a rabbit with chloroform;
as soon as it is dead, open the thorax by cutting through
the sternal ribs of both sides, sufficiently far from the
middle line not to injure the mammary arteries; cut
across the posterior end of the sternum, and turn it for-
ward ; slit open the pericardium, and make a large incision,
by a single cut with the scissors, in each ventricle; all this
should be done very rapidly, if possible before the heart
has ceased to beat, as it is desirable to get rid of as much
blood as possible; pass a ligature round the aorta close to
its exit from the heart, and give it a single loose tie; when
the bleeding has ceased, sponge the blood from the heart,
and pick away any clots that may have formed in the left
ventricle; pass a cannula through the incision in the left

THE RABBIT. 121

ventricle into'the aorta, tighten the ligature, and knot it
firmly. 7

If an injecting-syringe be not at hand, use as a cannula
a glass tube so drawn out as to have a notch in it that it
may be firmly tied; slip on the outer end of this a short
piece of rubber tubing, and insert into this the nozzle of
an ordinary syringe.

For the injection mass, fill an ordinary tumbler half full
of fine plaster of Paris, colored with a little carmine or
yellow ochre; fill the tumbler with water, stir well, and
immediately strain the liquid through coarse muslin into a
second tumbler. Fill the syringe and inject immediately,
as the plaster soon sets. Give a steady, even pressure.
On removing the syringe, the rubber tube should be
plugged to prevent escape of the liquid.

If the specimen be not injected, the veins can usually be
distinguished from the arteries by their greater diameter,
thinner walls, and by being of a darker color, retaining
the blood, while the arteries are usually empty or nearly
80.

ORGANS OF THE ABDOMINAL CAVITY.

_ 1. Slit the skin in the middle line from the breastbone
to the pelvis, and strip it well back to the sides.
Observe the thin abdominal muscles, which form
the ventral wall of the abdomen. Carefully slit the
abdominal wall in the middle line from the pelvis to
the breastbone; from the middle of this slit cut out-
ward on each side and turn back the flaps.

2. The lining of the abdomen is the peritoneum; what
does it tell the sense of touch?

8. Observe the coiled intestine, noting any variations in

122

PRACTICAL ZOOLOGY.

size, shape, or markings, but do not now move any
part from its natural position.

In the front part of the abdomen the dark-colored
liver may be seen, overlapping the stomach, and in
the hinder part of the abdomen there may be seen the
bladder, varying greatly in size and appearance ac-
cording to its state of distension.

Pull the intestine backward, and make out the shape,
size, position, and color of the stomach. Observe how
the liver and stomach fit together; push the liver
forward, and turn the stomach back to find a white
tube entering its anterior surface ; this is the gullet, or
esophagus. Just back of the stomach is a small red
body, the spleen.

Find now the connection between the stomach and
intestine. Make a drawing of the stomach showing its
shape and the connections with the gullet and intestine.
Trace the intestine; that part which forms a long
loop near the stomach is the duodenum. Within
this loop is an irregular, fatty-looking mass, the
pancreas. Find the pancreatic duct entering the
intestine. This is more easily found in the dog.
Observe that the intestine is held by a thin membrane
in which are branching blood-vessels; this is the
mesentery ; find its supporting attachment. In trac-
ing its course drag the intestine out of the abdominal
cavity, but do not tear the mesentery.

The large greenish side-branch of the intestine is the
cecum. All the intestine from the stomach to the
entrance of the cecum is the small intestine; that
part of the intestine posterior to the entrance of the
cecum is the large intestine.

10.

EI.

14.

THE RABBIT. 123

Turn the stomach and intestines over to the right (of
the animal), and observe a pink tube, the main artery,
or aorta, running along the middle of the dorsal wall
of the abdomen. Following this backward, find a
branch which subdivides and sends branches to the
stomach, liver, and spleen. Farther back a branch is
given off to the intestine; follow it as it branches
through the mesentery; this is the anterior mesen-
teric artery. Find a branch, the renal artery, of the
aorta running to the dark-colored, bean-shaped, left
kidney ; finally, the dorsal aorta divides into the two
common iliacs, extending toward the hind limbs.
Turn the stomach and intestines to the left, and
observe the two veins running forward from the hind
limbs; these are the external iliac veins, and by
their union they form the vena cava inferior.
Observe the branches derived from the right and
left kidneys, the renal veins. Compare the positions
of the right and left kidneys.

Trace the vena cava inferior to the liver. Observe .
the vein which gathers the blood from the intestines,
the mesenteric vein; the mesenteric vein is joined
by a vein coming from the spleen, the splenic vein,
and by the gastric vein, from the stomach; these
form the portal vein, running to the liver; this vein
distributes the blood through the liver; the blood is
re-collected and empties into the vena cava inferior
through the hepatic veins, which are almost wholly
concealed by the liver.

Turn the liver forward, and find on its posterior
surface the dark bile-sac. The bile-duct, by which
the bile is conveyed into the intestine, as also the

124

15.

16.

17.

PRACTICAL ZOOLOGY.

pancreatic duct, is more easily traced in the dog.
By probing with a bristle tipped with sealing-wax
these ducts may be traced.

Pull back the liver, and examine the thin muscular
partition, the diaphragm, which extends across the
body, separating the chest cavity, or thoracic cavity,
from the abdominal cavity. The thin, transparent
central part of the diaphragm is its tendon; through
this the pink lung, still distended, may be seen.
Keeping the eyes fixed on the lung, prick a hole
through one side of the diaphragm, and note the
collapse of the lung. Is the lung on the other side
affected by this operation?

Note the passage of the gullet, aorta, and vena cava
inferior through the diaphragm.

Tie the gullet in two places half an inch apart, and
cut through between them. Also double-ligature the
hinder part of the large intestine, the rectum, and
sever it. Remove the stomach and intestines, care-
fully cutting the mesentery along its whole attachment
to the intestine, and uncoil the latter. How many
times is the length of the body, including the head,
contained in the length of the intestine? Compare
the lengths of the small intestine, cecum, and large
intestine. Cut out about an inch of the small intes-
tine in the middle of its course, slit it open length-
wise, wash it thoroughly, and examine, under water,
its inner surface with a lens, to see the thread-like
projections, or villi. In the same way examine a
piece of the large intestine. These points may be
made out in the intestine of a dog, or from specimens
of the calf’s intestine obtained from the butcher.

THE RABBIT. 125

Preserve both specimens in alcohol. Ligature the
vena cava inferior just back of the diaphragm and
just back of the liver, and cut away all of the liver
but that part immediately surrounding the vena cava
inferior. To trace the lacteals and the thoracic duct,
feed a kitten or puppy on rich milk, and three hours
after place it in a box or under a bell-jar with a
sponge soaked with ether or chloroform. When it is
completely dead, cut off its head, open the abdomen,
spread out the mesentery, and observe in it the white
lymphatic vessels, known as lacteals, alongside the
veins, converging to form the thoracic duct. Trace
this along the aorta. Compare with a kitten that has
been fasting eight or ten hours.

THE KIDNEY.

The structure of the rabbit’s kidney may be made out

by the following directions, but the sheep’s kidney, being
larger and essentially similar, may be conveniently used.
If the sheep kidney be used, its dissection may be made
later.

vk

2.

Observe the depression in the inner border of the
kidney, the sinus.

From the sinus trace a slender white tube, the ureter,
back to the bladder. Find also the renal artery and
vein branching as they enter the kidney through the
sinus.

3. With a sharp knife split the kidney like a bean,

beginning at the outer border, stopping the cut when
a white membrane is reached near the sinus. With
forceps pry about to explore the cavity between this

126

PRACTICAL ZOOLOGY.

white membrane and the body of the kidney. Note
the branches of this cavity into the kidney. Note
also the extension of the white membrane into these
cavities. Make out that the blood-vessels extend
through these white branches to the outer parts of
the kidney. Count these branches.

In the center of the white membrane find the opening
of the ureter, through which the urine is conveyed to
the bladder. Pass a probe through this opening into
the ureter.

Note the difference in color of the outer and inner
parts of the kidney. At the line of change of color
find where the blood-vessels first branch into the real
kidney substance. Examine carefully the cut surface
of the kidney to see its markings.

Make a drawing of one-half of the kidney as seen
from the inside, showing all the above-named points.
Cut across the middle of the kidney at right angles to
its leigth, and make a drawing of this cross-section.
The projection of the kidney substance into the cavity
opposite the ureter is the urinary pyramid, and from
its apex, through many fine holes, issues the urine
which the kidney has secreted from the blood.

THE BRAIN AND SPINAL CORD.

Slit the skin along the middle of the back from the
nose to the tail, and strip it back well to the sides.
Dissect away the muscles from the back of the head
and the fore part of the neck; between the skull and
the first vertebra, or atlas, is a space covered by a
thin membrane, through which the white spinal cord

THE RABBIT. 127

may be seen. Insert the point of one blade of a pair
of strong scissors, or bone-forceps, at one side of the
spinal cord, and cut this side of the arch of the atlas;
repeat with the other side, and continue thus through
several vertebrae, raising and turning them back.
Observe the coat which covers the spinal cord and
lines this canal in the backbone, the neural canal.
Note the groove along the center of the cord.

Turn now to the head and insert one blade of the
bone-forceps at one side of the entrance of the spinal
cord into the skull. Cautiously cut and break away
the whole roof of the skull. This work may be done
with a strong knife, but the bone-forceps are best.
The tough membrane covering the brain and adher-
ing to the skull is the dura mater.

The fore part of the brain is the cerebrum; observe
the groove separating it into the right and left hemi-
spheres. Observe the shape of the cerebrum, and the
general character of its surface.

The prolongations of the cerebral hemispheres be-
tween the eyes are the olfactory lobes.

Back of the cerebrum is the cerebellum, The partial
bony partition between them was probably noticed in
removing the roof of the skull.

The part of the spinal cord within the skull is called
the medulla oblongata. Make a drawing of the
brain. If there be enough time, postpone 7 and 8 till
the completion of 9-17. Carefully cut away the
dura mater over the brain.

Cut through the olfactory lobes at the front of thee
cerebral hemispheres, and carefully pry up the front
end of the cerebrum. Running forward and outward

128

10.

ae.

12.

13.

PRACTICAL ZOOLOGY.

from the base of the brain will be seen the optic
nerves. Cut these close to the bone beneath.
Back of the optic nerves are the small third and
fourth pairs of nerves, then the larger fifth, the small
sixth, and close together the seventh, the facial, and
eighth, the auditory, and farther back four more
pairs. Cut these all where they leave the brain-case.
If 9-17 are not to be done the same day, the spinal
cord may now be cut an inch back of the brain, and
the brain be put into alcohol, supported on cotton to
prevent flattening.
Lay the rabbit on a narrow box, and let the head
hang over one end. Cut away as much as possible
of the muscle along the backbone. With the bone-
forceps unroof the whole length of the spinal cord in
the manner before described.
Note carefully the variations in the diameter of the
spinal cord in its course.
Observe the spinal nerves, passing off in pairs
through the spaces between the arches of the verte-
bre. Count the pairs of nerves, and compare them
in size in the different regions of the backbone.
Carefully cut away the bone and other tissue around
some of the nerves in the region of the shoulder, and
make out that each spinal nerve has two roots, an
upper, in the natural position of the animal, and a
lower. These get their names from human anatomy,
the former being the posterior root, and the latter
the anterior root. Trace them to their union in the
one spinal nerve.
On the posterior root, just before it joins the anterior,
find a swelling, the ganglion of the posterior root.

THE RABBIT. 129

14. In the region of the shoulder carefully trace several
nerves on each side as they unite to form the brachial
plexus, branches from which supply the fore limb.

15. In the region of the hips, in like manner trace sey-
eral large nerves to their union in the lumbo-sacral
plexus, the main nerve from which may be followed
down the back of the thigh, the sciatic nerve.

16. Compare the color of the brain with that of the spinal
cord.

17. Make a drawing of the brain and spinal cord. Re-
move the brain and cord with the plexuses, and put .
the whole into alcohol.

THE BRAIN OF THE RABBIT.

(Alcoholic Specimen.)

The brain of a cat or dog is better, being larger. Take
a brain well hardened in alcohol, or a strong solution of bi-
chromate of potash, and review the parts as named above.

1. Press down the cerebellum to see the deep groove
between it and the cerebrum, The thin membrane
covering the brain and dipping into the grooves is
the pia mater.

2. Press down the medulla oblongata, and tear away the
pia mater where it passes from the cerebellum to the
medulla oblongata. Note, between the medulla and
the cerebellum, a space covered by a thin membrane.
Cut through this membrane; the cavity is the fourth
ventricle of the brain. Observe the two ridges
bounding the sides of the fourth ventricle. At their
point of divergence, observe the opening of the central
canal of the spinal cord.

130
3.

PRACTICAL ZOOLOGY.

Gently separate the cerebral hemispheres, and note

_ the transverse band of white fibres connecting them.

4,

Examine the under surface of the brain and find the
roots of the cranial nerves.

The olfactory lobes (probably cut or broken off)
extend forward from the fore part of the cerebral
hemispheres.

Note that the optic nerves join each other before
reaching the brain. Only the first and second pairs
of cranial nerves directly enter the cerebrum.

Further back is the third pair of nerves.

The fourth pair extend up on each side into the
groove between the cerebrum and cerebellum.

Back of these is the larger fifth pair. This pair
supplies part of the face and sends branches to the
teeth. It is the nerve affected in neuralgia of the
face.

Back of, and inside of, the fifth pair is the smaller
sixth pair. The third, fourth, and sixth pairs control
the movements of the eyeballs.

The seventh pair are larger and are farther back
and outward. These are facial nerves, and control
the muscles of the face and the facial expression.

Close to the seventh is the eighth or auditory
nerve.

The ninth, tenth, and eleventh arise close together
further back, and well up on the side of the medulla
oblongata.

The ninth supplies the back of tongue and the
pharynx, and is called the glosso-pharyngeal nerve.

The tenth pair pass down out of the brain-cavity,
give off branches to the pharynx and larynx, and are

bo

THE RABBIT. 131

distributed to the heart, lungs, and stomach; hence
the name pneumogastric nerves.

The last pair of cranial nerves, the twelfth, arise
nearer the middle line of the medulla oblongata.
This pair supplies the muscles of the tongue and are
called the hypoglossal nerves.

Draw the brain as seen from below, showing all
these nerves. ,

Separate the cerebral hemispheres, and with a sharp
knife split the brain lengthwise in the middle line.
Make a drawing of the inner face of one-half. Note
the branching arbor vite, of the cerebellum. Trace
the cavities of the brain.

Trace the blood-vessels of the brain. For this the
brain of an injected rabbit or dog should be used.
Cut and examine cross-sections of the spinal cord
after it has been hardened in alcohol. Compare the
colors of the inside of the brain and spinal cord.

ORGANS OF THE THORACIC CAVITY.

Remove the skin from the throat and chest. With
scissors cut through the rib-cartilages along one side
of the breastbone, slightly separate the edges of the
cut, and note the position of the heart.

Cut along the other side of the breastbone and note
the thin partition, the mediastinum, attached to its
inner surface. Cut the hinder end of the breastbone
loose and raise it; sever its attachment within and
turn it forward. Observe the collapsed lungs on
either side. Examine the anterior surface of the
diaphragm,

132

PRACTICAL ZOOLOGY.

Note that the heart is, normally, in the plane of the
mediastinum, and that this membrane entirely sepa-
rates the two halves of the chest.

Take the heart between the thumb and finger to feel
how easily it slips about in its sac, the pericardium.
Cut away the mediastinum and the pericardium, and
note the appendages, auricles, at the large end, or
base, of the heart.

Cut away the breastbone entirely, press the ribs out
to the sides, and dissect away a thin layer of muscles
covering the windpipe, so that the blood-vessels which
run forward from the heart into the neck may be
traced. Carefully pick away a fatty-looking body,
the thymus gland, in front of the heart and trace the
following arteries.

The main artery, the aorta, is a whitish, thick-walled
tube. Springing forward from the centre of the base
of the heart, it soon arches over to the left (of the
animal) and runs along the middle of the dorsal wall
of the chest-cavity, piercing the diaphragm, as noted
in studying the abdominal cavity.

At the arch the aorta gives off two branches; the
first of these soon subdivides, giving off a branch to
the right fore limb, the right subclavian artery, a
branch running along each side of the windpipe, the
right and left common carotid arteries (called com-
mon because each as it nears the head divides into
the internal carotid and the external carotid). The
second branch from the arch is the left subclavian
artery.

Just outside of the common carotids on each side are
the white, thread-like pneumogastric nerves.

10.

11.

12.

138.

THE RABBIT. 133

Observe on each side of the neck the dark jugular
vein running back toward the heart; note that each
of these is formed by two main branches, the external
and internal jugular veins, which unite just back of
the head.

Just before each jugular vein enters the chest-cavity
it receives a branch from the corresponding fore
limb; these are the subclavian veins. The union of
the jugular and subclavian veins on each side forms
the vena-cava superior.

Trace the right vena cava superior straight back to
the right auricle. Turn the heart forward and follow
the course of the left vena cava superior in reaching
the same auricle.

The large vena cava inferior, coming forward through
the diaphragm to the right auricle, is easily seen.

The heart and lungs may now be removed, and the
pulmonary artery and veins traced, and the structure
and action of the heart made out by the following
directions ; but the heart and lungs of the pig, calf,
or sheep will show the same features much better on
account of their greater size.

THE HEAD OF THE RABBIT.

Remove the skin from the head.
1.

Below and back of the ear is an irregular pink mass,
the parotid salivary gland. The duct which con- —
veys its secretion runs forward and opens on the
inside of the cheek. It is hard to trace in the rabbit.
Find it in the dog, slit into it with fine scissors, and
push a bristle forward through it to find its opening
in the mouth.

134

=

10.

PRACTICAL ZOOLOGY.

Note the branches of the facial nerve running up.
ward over the cheek. Dissect away the parotid gland,
and find where the facial nerve emerges from the skull.
In the angle between the two branches of the lower
jaw observe two roundish bodies, the submaxillary
salivary glands. In the dog trace their ducts as in
the case of the parotid.

Observe the muscle which covers the outside of the
back part of each lower jaw. ‘This is the masseter
muscle. Place the fingers on the angle of your own
jaw and note the action of the masseter muscle in
shutting the teeth firmly together. In the rabbit
note the attachment of the masseter to the under edge
of the cheekbone. ‘Trim the muscle entirely away.
After removing the submaxillary glands, a muscle
will be found on each side having its origin on the
inside of each half-jaw near their junction. These
are the digastric muscles; they depress the lower
jaw. Cut away all the muscles and other connec-
tions and remove the whole of the lower jaw.
Carefully examine the tongue.

Thoroughly clean the lower jaw and examine the
teeth. How is the lower jaw hinged to the skull, and
what motion does this hinge allow? How does the
rabbit move its lower jaw? What is the relation
between this jaw-motion and the direction of the
ridges on the grinding teeth, or molars ?

Observe the opening on the inner surface of each
half-jaw where the nerve entered to supply the teeth.
Look at the side of the back part of the mouth for an
opening leading toward the ear, the Eustachian tube.
Trace the nasal passages.

THE RABBIT. 135

THE LEGS OF THE RABBIT.

Most of the following structures may be made out from

a shinbone of a sheep, readily obtained from the butcher.

1.

After removing the skin from the legs, observe the
muscles, covered by a thin glistening membrane, the
muscle-sheath. Study the shape of the muscles.
Note the white tendons which terminate the muscles.
Loosen the tendons from surrounding tissues and
separate the muscles from each other along their
sides without cutting them. Pull the different mus-
cles to determine the motion each produces.
A muscle which straightens a limb is an extensor.
A muscle which bends a limb is a flexor.
The large tendon running along the back side of the
shinbone is the tendo Achillis; it corresponds to
what part of our bodies? to what part of the horse?
By further dissection find how the different move-
ments of the toes are effected.
Cut into the knee-joint. Observe the liquid, the
synovia, which oils the joint. Rub a drop of it be-
tween the thumb and finger.
Observe the glistening bands which hold the ends of
the bones together. These are the ligaments. Care-
fully study their arrangement and uses.
Note the thin layer of cartilage over the ends of the
bones. Feel of it. Cutit. What are its properties,
and what its uses ?
With the forceps strip off a little of the muscle-
sheath from one of the muscles and note the color of

the latter. Cut one of the muscles across in its mid-

die and examine the cross-section. Each fibre has its

136

10.

' PRACTICAL ZOOLOGY.

own thin sheath, and the small bundles of fibres have
separate sheaths, which make the white markings seen
in chipped dried beef.

Tear off a few fine fibres of the muscle, mount on a
slide in water, or glycerine, cover with a cover-slip, and
examine first with a low and then with a high power.
The fine cross-markings of the fibres give to this kind
of muscle the name of striped, or striated, muscle.
The covering of the bones is the periosteum. Thor-
oughly clean one of the long bones and make a draw-
ing of it. Saw it in two lengthwise and make a
drawing of the surface thus exposed. Put a bone
into weak acid, and after a day or two compare it
with another that has been burned.

For a more complete guide to the study of the rabbit,
consult Parker’s “ Zoétomy”; and “ Practical Physi-
ology,” Foster and Langley.

THE HEART AND LUNGS
OF PIG, SHEEP, OR CALF.

Get the heart and lungs entire as first removed from the
body and “cut long,” the “ pluck,” as the butchers call it.

i.

Hold the mass up by the windpipe, with the heart
toward you; you now look at the front of the heart
as it hangs between the lungs.

Observe the windpipe, or trachea, with its stiff rings
of gristle, or cartilage.

Back of the windpipe is a soft red tube, the gullet;
find where it is cut off below, or cut across it, and note
its whitish lining, the mucous coat. The thick red

10.

oe
rt
a

HEART AND LUNGS OF MAMMAL. 137

coat is the muscular coat; try to make out an inner
layer of circularly arranged fibres and an outer longi-
tudinal layer.

Separate the gullet and windpipe and compare the
front and back surfaces of the latter; cut across the
windpipe and make out the shape of the rings of
cartilage.

Observe the smooth rounded dorsal surfaces of the
lungs which were fitted against the ribs on each side
of the spinal column.

Lay the lungs on the table, with their dorsal sur-
faces down, and with the point of the heart extending
away from you. The surface of the heart now upper-
most is its ventral surface, the side to your right is its
right side, and its left side is to your left. The point
of the heart is its apex, and the large end is its base.
If the sac which surrounds the heart, the pericardium,
be not already cut away, note how easily the heart
moves about in it, and then slit it along its anterior
surface. Observe the pericardial fluid.

Carefully compare the right and left sides of the
heart. Observe a groove running obliquely along the
anterior surface of the heart in which run blood-ves-
sels, often covered by fat. The part to the right of
this groove is the right ventricle; the part to its left
is the left ventricle. Press the two sides and note
the difference in firmness.

At the base of the heart, on each side, find an ear-like
appendage, with notched margins ; these are the right
and left auricles.

Seize the apex of the heart and tip it up toward you.
Compare the front and back surfaces of the heart.
Compare the thickness of the heart from right to left

138 PRACTICAL ZOOLOGY. | |
and from front to back. Hold the heart between the |
two hands, with its apex up, and again compare the
firmness of the two ventricles.

11. Turn the heart to the left and examine the right auri-
cle; find a large, red-walled tube entering it from the
front; this is the superior vena cava, which brings
the blood from the head, neck, and fore limbs to the
right auricle. Trace this vein forward to the point
where it was severed (or if this is not readily found,
prick a hole in it) ; insert the point of the blowpipe,
pinching the vein closely about it, and inflate the
vein. Meanwhile watch closely the posterior part of
the auricle ; there should be discovered another tube
entering the auricle from behind, the vena cava infe-
rior, which passes forward through the diaphragm ;
find where it was severed, and inflate the right auricle
through it, holding the vena cava superior if neces-
sary. By this inflation the outlines of the right auri-
cle and ventricle should be determined.

12. Turn the heart to the right and observe a large, light-
colored tube arising from the base of the right ventri-
cle between the two auricles; this is the pulmonary
artery ; again turn the heart to the left and raise the
right auricle ; find a second large artery arising from
the center of the base of the heart; this is the main
artery, or aorta. Carefully separate the aorta and
pulmonary artery above the base of the heart.

13. Trace the aorta as it arches over and runs down
between the two lungs behind, alongside the gullet ;
find where it was cut off. With knife and scissors
cautiously clear away the whole arch of the aorta
from the surrounding tissues.

14. From the arch of the aorta arise the branch or

etait ue

a

HEART AND LUNGS OF MAMMAL. 139

branches which supply the head and fore limbs.
Compare the branches, as here found, with those of
the rabbit’s aorta, and of the human aorta as shown
by the cuts in any text-book of human anatomy and

physiology.

. Now trace the pulmonary artery and its two branches

as they subdivide to the right and left lungs,

. Follow the branches, the bronchi, of the windpipe to

the lungs. Follow one bronchus as it is distributed
through the lung. Observe the structure of the lung.
Cut a lung in two, and on the cut surface find the
flabby ends of the blood-vessels and the stiff ends of
the branches of the bronchi. With a probe trace the
latter back to the trachea.

17. Try to distinguish the pulmonary veins; those roms

18.

the right lung run close along the tight auricle on
their way to the left auricle.

Cut the pulmonary arteries and veins near the lungs,
trim away the pericardium close to the heart, and
keep the heart in a cool place for further study.

THE STRUCTURE AND ACTION OF THE HEART.

Make three full-size drawings of the heart, front
view, back view, and side view, naming the parts and
blood-vessels as given above.

With scissors slit down the vena cava superior, and
continue the cut across the back of the right auricle,
and for a short distance along the back of the vena
cava inferior. Explore the cavity of the right auricle.
Opposite the entrance of the vena cava inferior ob-
serve, in the red inner wall of the auricle, a rounded
depression, the fossa ovalis, across the bottom of

140

PRACTICAL ZOOLOGY.

which is stretched a paler membrane; by slight pres- |

sure with the handle of the forceps, prove that this
membrane is thin and yielding. Below the fossa ova-
lis is the opening of the azygos vein. With a
syringe inject water into it and find whence it comes.
The projection between the entrance of this vein
and the fossa ovalis is the Eustachian valve. With
scissors slit open the azygos vein and find, entering
it, veins from the walls of the heart. Trace these
veins.
Cut away the whole of the right auricle; hold the
heart in the left hand, with the left ventricle resting
against the palm; pour water suddenly from a consid-
erable height into the right ventricle, watching closely
to see the valves float up and separate the auricle
from the ventricle. Pour in water again, and as soon
as the valves rise, press with the fingers on the outside
of the right ventricle; note the effect of this pressure.
Where does the water escape ?
Empty the heart and examine ‘the valves which have
been seen; they will now be found lying close against
the walls of the ventricle. Note the white cords
attached to the lower edges of these valves.
Push a finger past these valves to the very bottom of
the ventricle; from the outside cut through the wall
of the ventricle at this point, and cut cautiously
upward along the border of the cavity of the right
ventricle. Raise the outer wall of the ventricle and
more thoroughly study the valves; slip a blunt instru-
ment between the flaps of the valves and the walls
to which they adhere, and raise them so they can be
better seen. How many flaps are there, and how are

HEART AND LUNGS OF MAMMAL. 141

they arranged? How are they held in place? How
are they acted upon, and how do they act?

. Find the connection between the right ventricle and .
the pulmonary artery. Cut away the wall of the
right ventricle so that the beginning of the pulmo-
nary artery may be seen from below. Hold the heart
up by the pulmonary artery and force a stream of
water through the pulmonary artery toward the
heart. Look from beneath to see the filling and
bulging out of the valves at the beginning of the
artery. Note the number, shape, and arrangement of
these valves. What is the effect of the stream of
water on them, and what is their effect on the stream
of water? Slit the artery and examine the valves
from above. These are the semilunar valves.

. Examine the left auricle to find where the pulmonary
veins enter it; cut the auricle away from the ventri-
cle and examine it from the inside to see the openings
of the pulmonary veins. Pour water into this ventri-
cle as with the right. Compare the valves of this
and the right side of the heart.

Cut off the aorta near the heart; watch the open- ~

ing of the aorta when water is poured into the ven-
tricle, to see the action of the valves. In the pockets
of the valves of the aorta look for the openings of
the arteries which supply the walls of the heart with
blood.
. Cut open the left ventricle and compare its walls
with those of the right ventricle. Why are they dif-
ferent? Note the partition between the ventricles; is
there any direct communication between the right
and left halves of the heart?

142 PRACTICAL ZOOLOGY.

THE VALVES IN THE VEINS.

Dissect back the skin from the throat of the rabbit, cat,
or dog, till the jugular veins are well exposed. Let the
head of the animal hang over the edge of the table; note
that as the blood presses back toward the head it causes
marked bulging at certain points; with the handle of the
forceps slightly stroke the vein toward the head, watching
the bulgings. Dissect out the jugular vein from the head
to the shoulder; insert the nozzle of a syringe, first into
one end and then into the other, and show the effect of
forcing currents in each direction. Cut the vein open
along one side, pin inside out to a piece of a shingle and
examine the thin pocket-like valves. Test the elasticity
of the vein. Note the smoothness of its inner coat.
Remove a piece of an artery and experiment in the same
way with it.

DEMONSTRATION OF THE ACTION OF THE HEART.

Get the heart and lungs entire. Dissect out the aorta
as before. Clear the pulmonary artery and cut off both
branches close to the lungs. Carefully trim away the
pericardium and clean the venz cave inferior and supe-
rior. Turn the heart back and find one of the larger
pulmonary veins; cut a hole in it near the lung and slip a
glass tube into it toward the heart ; this tube should have
a groove, made by drawing it out in the flame; tie the
tube firmly in, and ligature the other pulmonary veins
without stopping to trace them. Tie any and all connect-
ions with the heart now remaining and cut beyond the
ligatures. Get a retort-stand and two large glass funnels.

HEART AND LUNGS OF MAMMAL. 1438

Place the funnels in the rings. Lay the heart, now
wholly severed from the lungs, on its front surface. Con-
nect one funnel, by rubber and glass tubing, with the left
auricle by the tube already in the pulmonary vein; con-
nect the other funnel with the right auricle through the
vena cava superior; ligature the vena cava inferior. Lay
the heart in a basin and pour water into the funnels ; hold
the heart with the two hands and compress it, repeatedly
adding water. In this way the clotted blood usually
present in the right ventricle may be washed out. If
this remain, it may interfere with later experiment. Con-
nect the aorta with the funnel which leads to the right
auricle, by means of a glass tube which bends over the
edge of the funnel, thus holding itself in place by the
hook, and emptying into this funnel any liquid which
escapes from the tube.

In like manner have a bent glass tube, from the pul-
monary artery, hooked over the edge of the funnel leading .
to the left auricle.

Pour water into one of the funnels and compress the
heart to imitate its natural contraction; observe where
the liquid next appears; add more water and follow it
around to its starting-point. A little ink may be poured
into one of the funnels and traced around, as the heart is
worked, to its starting-point.

That there is no direct connection between the two
halves of the heart may be shown by letting the liquid
from each artery empty into the auricle of the same side
of the heart. Different colored liquids may be used in the
two funnels.

144

PRACTICAL ZOOLOGY.

THE MUSCLES OF THE EYEBALL.

With bone-forceps, or a strong knife, cut away the bone

at the outer angle of the eye-socket of the rabbit (almost
any mammal will serve for this, though the bone is so
thick in the calf or sheep that it will be difficult work
without the aid of a good pair of bone-forceps).

1.

With scissors trim away the white membrane around
the front of the white of the eye; this was continuous
with the lining of the eyelid, and is the conjunc-
tiva.

Find a muscle running along the roof of the eye-
socket, which passes through a loop of tendon, near
the edge of the orbit, and turns outward to its attach-
ment to the top of the eyeball. This is the superior

oblique muscle.
Beneath the eye find a muscle, having its origin in

the inner front part of the socket, and passing out-
ward to be inserted in the lower surface of the eye-
ball; this is the inferior oblique muscle.

Four straight muscles, the inferior, superior, internal,
and external recti, are attached to the top, bottom,
and sides of the eyeball; find the origin of these, with
that of the superior oblique, at the posterior extrem-
ity of the eye-socket.

Dissect away the fat and other tissue around these
muscles, and find a cone-shaped muscle attached to
the back of the eye. Within this find the cylindrical
optic nerve.

THE EYE. 145

EXTERNAL PARTS OF THE EYE.

The eye of the rabbit may be used, but that of the ox is
better.

1.

Observe the clear front part of the eye, the cornea.
Note its shape. Its wider end was at the inner angle
of the eyelids.

Around the cornea find a whitish membrane, the
conjunctiva, which a short distance back from the
cornea separates from the eyeball to turn forward
and line the eyelid.

The severed muscles of the eyeball, a mass of fat
which forms a cushion for the eye, and other tissue,
should be trimmed away leaving the optic nerve,
which enters the eye below and outside of the centre
of its posterior surface; the place of entrance of the
optic nerve, together with the shape and natural
position of the cornea, will serve to distinguish the
right and left eyes.

Place the eye in its natural position, and make draw-
ings of it as seen from the front, from behind, being
still careful to have it right side up, and from one
side, naming the parts, and stating whether it be the
right or the left eye.

DISSECTION OF THE EYE.

Lay the eye on a plate with the cornea uppermost.
Hold the eye firmly with the thumb and fingers of
one hand; with the thumb and forefinger of the
other hand hold one blade of the scissors half an
inch from its tip; with a steady motion push the
blade horizontally through the cornea near its edge.

“146

PRACTICAL ZOOLOGS.

The liquid in the cavity back of oe cornea is the |

aqueous humor.

Cut around the margin of the cornea and remove it.
The dark membrane now exposed is the iris. Pinch —
the eye slightly at the sides to make the iris show
more distinctly. The hole in its centre is the pupil.
With the forceps raise the edge of the iris around
the margin of the pupil to see that it is here unat
tached to the structures underneath. Observe the
color and markings of the iris.

From one end of the pupil cut outward to the outer
margin of the iris, then cut around its outer margin
and remove it. Observe the color and markings of
its posterior surface.

The body now laid bare is the crystalline lens. Touch
it.

With a sharp knife make a quick light gash across
the surface of the lens to cut through the thin coat
which envelops it, the lens capsule. Enlarge the
opening thus made and carefully pry out the lens
with the handle of the forceps, noting closely, in so
doing, the difference between the front and back sur-
faces. Lay the lens on a piece of newspaper and look
through it at the letters. Make a drawing of the lens
as seen from the front, and as seen from one side,
naming the front and back surfaces.

With the forceps seize the lens capsule where it was
cut and pull it gently but firmly to one side; this
action will probably tear the mass within the eye
loose from the outer coats; repeat the pull in all
directions. With the scissors now cut outward about
one-fourth of an inch from the edge of the hole made

10.

11.

12.
13.
14.
15.

THE EYE. 147

in the front of the eye; then cut clear around the eye
and remove a strip of this width, thus enlarging the
opening before made. On the inside of the strip
removed there may be found radiating black ridges,
the ciliary processes. Note part of these ciliary
processes around the margin of the lens capsule.
Carefully pick away with the forceps and snip away
with the scissors everything on the surface of the
clear mass beneath.

The substance filling the remainder of the eye-cavity
is the vitreous humor.

Through the vitreous humor the entrance of the optic
nerve may be seen with the blood-vessels radiating
from it.

The tough outer coat of the eye is the sclerotic coat.
Inside the sclerotic is the dark choroid coat.

The inner, nearly transparent coat is the retina.
Drag out the vitreous humor and note the soft whit-
ish retina; observe that it is a continuation of the
optic nerve. Tear away the retina, noting its con-
sistency. Note the color and luster of the inner sur-
face of the choroid coat.

The reflection of light from this surface of the
choroid coat causes the color seen in the eyes of some
animals. Turn the remaining coats inside out and
tear the choroid coat from the sclerotic. Observe the
blood-vessels passing from one to the other.

THE LARYNX OF THE CALF.

The front of the larynx is readily distinguished by the
projection of cartilage known as the Adam’s apple.

148 PRACTICAL ZOOLOGY.

2. Along the back of the larynx runs a thick muscular
tube, the gullet, with a white lining membrane.

3. Trim away the muscles and other tissues from the
front and sides of the larynx. The large cartilage
forming the greater part of the front of the larynx is
the thyroid cartilage.

4. Observe the band of muscle attached to either side of
the thyroid cartilage and passing horizontally back
around the esophagus.

Cut away this muscle as completely as possible and
entirely remove the gullet. Note that the whitish or
yellowish mucous membrane which lines the gullet
is continuous with the lining of the larynx. Study
now more fully the shape of the thyroid cartilage.

5. Back of the upper part of the thyroid cartilage, cov-
ering the upper end of the larynx, is the arched
epiglottis. Feel of it to learn its consistency. Press
it upward and forward, then downward and _ back-
ward; observe that it now covers the entrance to the
larynx; note the position it takes when released.

6. Just back of the upper angle of the thyroid cartilage
find a muscle connected with the base of the epiglot-
tis; pull this muscle to determine what effect its
contraction produces on the epiglottis.

7. Under the thyroid cartilage in front observe a narrow
ring of cartilage not much wider than one of the rings
of the trachea. Move this up and down to prove that
it is distinct from the thyroid. This is the cricoid
cartilage.

8. Observe the sheet of muscle passing from the cricoid
to the thyroid. Again move the cricoid toward and
from the thyroid; what does this muscle do? Cut

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10.

11.

12.

THE LARYNX. ~ 149

away this muscle from one side and see that the cri-
coid cartilage widens as it passes backward. How are
the cricoid and thyroid hinged together ?
Projecting upward and backward from the top of the
larynx are two curved yellowish cartilages, the aryte-
noid cartilages. Move them about to see that they
are movable and that they rest on the upper edge of
the back part of the cricoid cartilage.
With one hand move the arytenoid cartilages back-
ward and forward, meanwhile watching the inside of
the larynx from its lower opening. The projecting
ridges, which meet just back of the Adam’s apple, are
the vocal cords. What effect is produced on the
vocal cords by the movements of the arytenoid carti-
lages ?

Observe the connection of the thyroid cartilage with

the cricoid by means of a downward projection of the

former. Cut away all of this half of the thyroid
cartilage. Notice the slender hyoid bone loosely
connected with the upper bone of the thyroid.

Examine now the muscles which move the arytenoid

cartilages.

a. On each side of the posterior surface of the cri-
coid is a muscle passing upward to be attached to
the corresponding arytenoid; this is the poste-
rior crico-arytenoid muscle. Dissect it loose
from the cricoid, at its origin below. By pulling,
determine its action on the arytenoid, and through
the arytenoid on the vocal cord.

b. Arising from the upper edge of the side of the
ericoid cartilage, and passing upward and back-
ward to the arytenoid, is the lateral crico-aryte-

150

13.

14.

15.

16.

PRACTICAL ZOOLOGY.

noid muscle; cut away at its origin close ta 7ne
cricoid and demonstrate its action on the aryte-
noid cartilage and vocal cord.

e. A broad muscle arising along the whole length of
the angle of the cricoid, whose fibers converge to
the arytenoid cartilage. This is the thyro-aryte-
noid muscle; cut it across near its origin, dis-
sect it loose, and by pulling it toward its origin
prove its action.

d. On the posterior surfaces of the arytenoids is the
small arytenoid muscle.

Cut between the arytenoid cartilages and remove one

of them. Examine the joint between the arytenoid

and cricoid. Note the synovia lubricating the joint.
Trim away the muscle from the arytenoid cartilage

and study the shape more fully. Fit it again to its

place and recall the motions given by each muscle.

Now examine the arytenoid cartilage and the vocal

cord of the opposite side; move the arytenoid back

and forth, watching the vocal cord.

Remove the epiglottis and cut into it to see its

structure.

Dissect away the parts of the other side from the

inside, reviewing the above points.

THE STARFISH.

For this work there is needed : —

1.

A set of dried specimens, one for each student; such
a set may be used with successive classes and will last
for years if carefully handled and kept in a dry place.

THE STARFISH. 151

2. Alcoholic specimens for dissection.

3. It is desirable to have a set of prepared slides:
showing cross-sections of a decalcified ray of a young
starfish, and a ground-down section of a calcareous
plate, etc.

4. An injected starfish and a number of injected rays.

The above and other desired material for work on ma-
rine animals may be obtained of Mr. B. H. Van Vleck,
Boston Society of Natural History, Boston, Mass.

DRIED SPECIMEN.

1. Observe, first, the shape of the body as-a whole. The

‘ central portion is the disk and its radiating extensions

> are the arms, orrays. Note that the rays are bilater-
ally symmetrical.

2. The mouth is at the center of a thin membrane in the
middle of the oral surface; the opposite surface is
called aboral.

3. Cut into one of the rays. Observe that the body
cavity is bounded by a leathery wall in which are im-
bedded hard plates. Compare a piece of a ray of an

_ aleoholic specimen with the dried one.

4. Test the flexibility of the integument of the alcoholic
specimen. By picking with forceps, prove that there
is soft matter, both on the outside and on the inside
of the hard plates. To show the real nature of the
plates and their relation to the integument, proceed
as follows: —

a. Handle a starfish which has been decalcified, 7.e.
has had its calcareous matter removed by very
weak (two per cent) nitric acid, chromic or other

152

PRACTICAL ZOOLOGY.

acid. Observe that the body wall is still present
but lacks the hard parts.

b. Examine a microscopic section of a decalcified ray

of a young starfish; in such section it should be
more clearly seen that the calcareous plates are
wholly within the integument.

To show still further the relation between the
plates and the integument, prepare a thin section
of a calcareous plate, as follows: select some pieces
of a starfish (left from previous dissection). Boil
a few of the larger plates in caustic potash in order
to remove all the organic matter; wash, and when
thoroughly dry, smooth down one side on a fine
file; polish on a perfectly clean oil-stone ; cement
this surface of the plate to a glass slide by means
of a drop of Canada balsam which has been boiled
on the slide, until on becoming cold it is with
difficulty indented by the thumb-nail. Proceed
then to plane off, by means of a file, and when
quite thin, scrape carefully with a sharp knife,
finally smoothing it on an oil-stone. The speci-
men should be examined from time to time under
the microscope, in order to ascertain when the
proper degree of thinness has been reached. Dis-
solve the balsam by means of turpentine, or better,
if properly managed, melt the balsam over a lamp
and carefully push the section into a watch-crys-
tal containing turpentine ; when thoroughly freed
from balsam, carefully brush it with a camel’s-
hair brush and mount in Canada balsam in the
ordinary manner.

5. Observe the arrangement of the plates and spines in

y
’
|

THE STARFISH. 153

different regions of the body wall. Along the middle
of the oral surface of each ray may be seen the
shrivelled remains of the tube feet, or ambulacra.
The region in which they lie is the ambulacral area.
The plates along this tract are the ambulacral plates.
One row of plates on each side of these ambulacral
plates are known as the inter-ambulacral plates. Ex-
amine these closely for comparison with the sea-urchin.

. The wart-like elevation on the aboral surface is the

madreporic body. Note that it is situated opposite
one of the inter-radial angles. Examine it with a lens.

. Make drawings of the oral and aboral surfaces of the

starfish.

ALCOHOLIC SPECIMEN.

. Briefly review the points noticed in examining the

dried specimen. Bend the rays; their flexibility is
now much less than in life.

. Compare the spines of different areas as to their shape,

size, and degree of mobility.

. Between the spines are soft, tapering projections, the

aboral tentacles.

. Observe a circle of projections surrounding the spines ;

delicately pinch them with the forceps to determine
their consistence; remove some of these bodies to
strong alcohol; mount temporarily in turpentine on a
slide, cover, and examine with a low power. ‘There
should be distinguished a short stalk bearing a pair of
pinchers; these bodies are the pedicellariz. In the
live starfish these pinchers may be seen continually
snapping; they are supposed to serve in removing
foreign matter from the body.

154 PRACTICAL ZOOLOGY.

5. The soft cylindrical projections along the median tract
of the oral surface of each ray, are the ambulacra or
tube feet. Remove one of them and examine it with
care. Note the arrangement of the series.

6. Press apart the tube feet and find running along the
median line of the ambulacral groove, a yellowish or
whitish ridge, the nerve of the ray. Trace it to the
soft membrane bordering the mouth, the peristome,
and find the nerve ring around the mouth.

7. Trace the nerves also to their outer ends and find a
reddish or yellowish elevation, the eye-spot, borne at
the base of a median terminal tentacle, resembling a
tube foot.

8. The eye-spot is borne on a distinct, but minute, plate.
Compare young and old specimens to see that what-
ever the size, this single ocular plate with its eye-spot
is always at the end of the ray. Count the ambula-
cral plates ina short andinalongray. Where do the
new plates develop?

DISSECTION OF THE STARFISH.

1. The ray opposite the madreporic body is the anterior
ray. Cut through its aboral wall near the outer end,
and from this point cut along the upper part of each
side of the ray, an inch or two toward the disk; raise
the flap thus freed, and, avoiding internal organs,
continue the cut on each side to the disk.

2. Attached to the aboral wall find a pair of elongated,
branched bodies, the hepatic czca. Note how each
cecum is held in place by the thin mesentery.

8. Along the middle line of the aboral wall, inside, is a
yellowish streak, the extensor muscle of the ray;
with forceps prove its general structure.

= ee

THE STARFISH. 155

Along each side of the ridge in the floor of the ray,
observe rows of thin-walled sacs, sometimes distended,
but more often collapsed in alcoholic specimens.
These are the ampullz, or ambulacral vesicles.
Watch the ampulle while pressing on the tube feet,
and vice versa. If a specimen injected with coloring
matter be at hand it should now be examined.

Near the base of the ray find, on each side, an elon-
gated body resembling a bunch of grapes, and of a
lighter color than the ceca; these are the reproduc-
tive bodies and are very much alike in appearance in
the two sexes, and only distinguishable by color or by
microscopic examination in the living specimens. Find
the point of attachment of one of them. The open-
ings in the inter-radial angle are not very evident.
Cut along the sides of the two rays lying on the right
and left of the anterior ray, connect the cuts at the
inter-radial angles, and turn back the cover of the
three rays and disk. Within the disk is the large,
thin-walled stomach. Examine this organ carefully.
Pass a blunt probe through the mouth and explore
its interior.

Observe the large lobes of the stomach extending a
short distance into the rays; lift one of these lobes
and trace the thin retractor muscles of the stomach
to the sides of the ridge in the ray.

In the live starfish the stomach is often found pro-
truded and surrounding a mussel or an oyster; after
digesting and absorbing its soft parts the stomach is
retracted.

Turning to the ceca of the anterior ray, trace them
toward the stomach; find the union of their tubes

156

10.

11.

12.

13.

14,

15.

PRACTICAL ZOOLOGY.

and the entrance of their common duct into the
stomach. Observe the place where this tube enters
the stomach, in reference to the corresponding lobe
of ‘the latter.

Carefully cut the mesentery along the aboral wall
and wholly free the czca of this ray from all attach-
ment above. Note that the mesentery is double.
Hold the starfish inverted and pour water through
the mouth into the stomach to show its shape.

In the other two rays which have been opened, cut
across the common ducts of the ceca close to the
stomach, and leave them attached to the aboral walls.
Find the extremely short intestine connecting the
stomach with the upper wall of the disk, near the
junction of the extensor muscles of the rays. Find,
also, some small branched appendages of the intestine.
The anal opening is minute.

Sever the intestine close to the aboral wall, cut across
the disk close to the madreporic body, and remove
entirely the roof of the disk and the three rays.

Make a drawing of the organs now exposed, show-
ing the ceca in one ray, the reproductive bodies in
another, and the ampulle in the third.

Thoroughly examine the stomach, and remove it after
cutting across the short esophagus.

The S-shaped stone canal may now be seen passing
downward from beneath the madreporic body.

Traced to its lower end, the stone canal may be found
to enter a membranous hollow ring, whose outer bor-
der rests against the inner surface of the hard parts
surrounding the mouth; this tube is the circum-oral
water-ring. Connected with its inner surface, find

18.

19.

16.

ele

THE STARFISH. 157

several pairs of pouches, which in the contracted
state are mere button-like projections. How many of
these are there, and are they all in pairs?

Observe also the pouches, like ampulle, connected

- with the upper part of the hard ring around the

mouth. Press on the water-ring at the level of the
peristome, and watch the effect of this action on these
last-named pouches or vesicles. Is there any connec-
tion between them and the water-ring ?

Enclosing the stone canal is a thin membrane, the
pericardium. Carefully tear it away. Alongside
the stone canal is a soft tube, the heart. In the live
starfish it may be seen to pulsate.

Cut across the middle of a ray in two places, about
an inch apart, and make a careful study of the part
included between the cuts. Remove the hepatic
ceca, observing again how they are suspended by the
mesenteries. Cut through the aboral wall in the
middle line and spread open the ring. Observe the
depressions in its inner surface; in the bottoms of
these depressions find small holes. What is the rela-
tion between these holes and the nearest structures
seen on the outside ?

Slowly peel away the thin membrane which lines the
interior of the ray, noting especially the connection
between this membrane and the depressions above
noticed. Also watch closely the aboral tentacles
while tearing away this lining membrane.
Turn now to the outside of the ray and gently scrape
the surface. A thin layer here may also be easily re-
moved. Thoroughly clean a small area, noting that
the aboral tentacles come away with this layer.

158

20.

21.

22.

24,

PRACTICAL ZOOLOGY.

There will now remain a tough white layer in which
are imbedded the calcareous plates which constitute
the skeleton. Bend this membrane to see the relations
of the calcareous plates to the membrane and to each
other.
By picking with the forceps prove that the membrane
is continuous over both the inner and outer surfaces
of the plates, as well as between them. This is an
important point, as the calcareous plates are devel-
oped in and by the membrane.

Part of the membrane, if not all, has the power of
contracting, by means of which motion is effected.
Note the perforations in the membrane in its thinner
portions between the plates where the aboral tenta-
cles passed out.

Reviewing what was noticed in the examination of
the inner and outer membranes, it will be evident
that the aboral tentacles are tubular extensions of the
body formed by the protrusion of the inner mem-
brane through the middle membrane, these tubes be-
ing covered by the outer membrane.

Turn now to the tube feet and their ampulle and
make out their relations to each other and to the ad-
jacent parts of the skeleton. The calcareous plates
which form the sides of the ambulacral groove are
the ambulacral plates.

. Pick away afew of the ampulle, and then the cor-

responding tube feet, comparing the arrangement of
the two. In this way clean the ambulacral plates
and examine them carefully.

Alternately press the ambulacral plates of the two
sides together and separate them to see the range of

20.

26.

THE STARFISH. 159

motion allowed by the joint. Observe the muscles
connecting the ambulacral plates of the opposite sides,
just inside of the nerve.

In the angle formed by the ambulacral plates, find the
cut-off end of the water-tube of the ray. Insert in
the end of this, the point of a drawn-out glass tube,
and inflate. When the ampulle are distended, press
on them with the finger and note the effect on the
tube feet; with a lens examine the distended ampulle.
In fresh specimens the ampulle may be injected with
a colored liquid or with gelatine to be kept as perma-
nent preparations. In such preparations and in a
microscopic section of a properly prepared ray, it may
be seen that the water-tube of the ray sends off side
branches to the tube feet, and also that the cavities of
the tube feet and ampulle are continuous. By the
contraction of the ampulle the tube feet are extended,
and by the muscles in their walls they are moved from
side to side and applied to-the surfaces on which the
starfish rests. The end is fixed by means of the sucker-
like disk at the tip of the foot to some foreign object;
then by the contraction of the tube feet, the starfish
pulls its body along.

The water finds its way through the madreporic

body into the stone canal, thence to the water-ring
around the mouth, and from this to the radial canals.
The water thus taken in probably serves for respira-
tion as well as for locomotion.
Make a drawing of a cross section of a ray, showing as
many as possible of the above noted points of structure.
A slide with a series of very small starfishes shows well
how the rays are formed as outgrowths of the disk.

160 — PRACTICAL ZOOLOGY.

For the anatomy and development of the starfish and
sea-urchin, see Brooks’ “ Handbook of Invertebrate Zodl-
ogy,’ Hyatt’s “Common Corals, Hydroids and Echino-
derms” (No. V. of “Guides for Science Teaching”),
“Seaside Studies in Natural History,” by E. C. and A.
Agassiz, Romanes’ “ Jellyfish, Starfish, and Sea-Urchins”
(Vol. XLIX. in the International Scientific Series).

THE SEA-URCHIN.

The requisites for this work are, cleaned skeletons, or
tests, alcoholic specimens, microscopic sections, etc., as in
the case of the starfish.

THE CLEANED TEST.

1. Observe the radial distribution: of the parts around an
axis, at one pole of which is a large opening.

At the opposite pole is a circular area composed of
several small plates, near the center of which is the
anal opening.

2. Note that the test is composed of distinct pieces or
plates. Put one of the plates into a little dilute acid
and note what occurs.

3. To make out the real nature of the skeleton, proceed
thus : —

a. Handle an entire decalcified specimen, 7.e., one
from which the calcareous matter has been re-
moved by chromic or other acid. Observe that
the body walls and.spines are still present.

THE SEA-URCHIN. 161

6. Examine a microscopic section of the decalcified
body wall to see that there was soft living matter,
both on the outside and on the inside of the cal-
careous plates.

e. Grind down and mount a thin section of a plate,
as in the case of the starfish, and see that not
only is the plate wholly enclosed in the body wall,
but that it forms a network whose meshes were
penetrated by the soft living substance of that
body-wall. It should now be clear that the plates
were formed by the deposition of calcareous mat-
ter within the living tissues of the body wall.
The joints, or sutures, between the plates are
formed by the absence of the deposit of calcare-
ous matter.

. Returning to the entire test, study the arrangement

of the plates, their variations in shape, size, etc.

Into how many similar areas may the surface of the
test be divided? ‘To make out these points, and the
shapes of the plates, pull apart a piece of a dried test
that was left over from previous dissection.

. At the aboral pole, observe a small distinctly marked-

off area, including numerous small plates. This is

the anal area, and the plates are the anal plates.

Unlike the other plates, these, in the living sea-urchin,

are movable. They surround the anus.

Surrounding the anal area are the five large genital

plates, each having a genital opening near its outer

angle.

. With a lens examine the largest of the genital plates;

its perforated portion serves as a madreporic body.

. Radiating from the apex of each genital plate, is the

162

10.

11.

PRACTICAL ZOOLOGY.

zigzag inter-radial suture. How many kinds of
plates are found within the area included by two
adjacent inter-radial sutures? The perforated plates
are the ambulacral plates, and the unperforated, the
inter-ambulacral plates. Compare these two sets of
plates with the corresponding parts of a starfish.

The ambulacral plates form the ambulacral areas.
Trace each of the ambulacral areas to its aboral end,
and find at its apex a small plate wedged in between
two adjacent genital plates. These smaller ones are
the ocular plates. Note the small opening from
which projects an unpaired tentacle, the end of the
radial water-tube.

Carefully compare the hard parts of the starfish and
sea-urchin. Wherein are they alike, and wherein do
they differ? What changes in growth would be
necessary to convert one of these forms into the
other? What part of a starfish is homologous with
the anal area of a sea-urchin ?

Make careful drawings of the oral surface, of the
aboral surface, and of the side of the test.

ALCOHOLIC SPECIMEN.

For the sake of review and comparison, it is well to
have the cleaned test before one in this study.

1.

Observe the soft membrane, the peristome, on the
oral surface and the teeth projecting from the
mouth.
At the aboral pole look for the anus and genital
plates.
Examine one of the largest spines; move it about to

ee a

THE SEA-URCHIN. 163

see its range of motion. Remove it and make out
how it is articulated to the test. The fleshy tube en-
sheathing the base is muscular tissue, by the contrac-
tion of which the spine is moved. Clean the spine
and make a drawing of it.

4, Note any variations in size and shape of the spines in
various regions.

5. Study carefully the arrangement of the spines, using
the cleaned test for comparison.

6. Between the spines in certain areas find soft tubular
projections, the tube feet or ambulacra. In life they
may be extended a considerable distance beyond the
spines, being used for locomotion as in the starfish;
carefully examine the tips of the tube feet to find
what is therein contained.

7. Find also among the spines and on the peristome,
slender flexible stalks, bearing three-pronged pinch-
ers. In life these pinchers keep opening and shutting.

8. Pick away the spines and other projections prepara-
tory to dissection.

DISSECTION OF THE SEA-URCHIN.

After removing the spines, cut, or better, saw with the
blade of a metal saw, through the equator of the test;
place under water and carefully raise the aboral portion
at one side.

1. Press on the tips of the teeth to show their connec-
tion with the complicated apparatus known as the
lantern; now open the test till the two halves are side
by side and complete the dissection under water.

2. Arising from the middle of the inner surface of the
lantern find the brown esophagus. ‘Trace this as it

164 PRACTICAL ZOOLOGY.

passes in festoons about the body walls, widening te
become the stomach. ‘Trace the intestine to the anus,
describing carefully its course.

3. Pick away the alimentary canal from the oral half of
the test. Note the five double rows of ampulle; be-
tween each of these double rows runs the radial
water-tube, and between the water-tube and the test,
is the radial nerve.

4, In the aboral half, note the reproductive bodies in the
loops of the intestine. Trace their ducts to the geni-
tal pores.

5. After cleaning away the intestine and reproductive
-bodies, trace the ampulle as they converge to the
ocular plate. Compare the inside and outside of the
test to see if the ampulle are really opposite the am-
bulacral pores noticed in the dry test.

6. Study the lantern, make out how it is supported, and
how its various parts are moved, and how they are
used.

Place in water the pieces of tests left after dissec-
tion and macerate till the spines are readily detached.
Then clean and keep them for the next class. They
will be useful for pulling to pieces to make out the
structure of the test. The sea-urchin and the star-
fish may be taken as convenient types of the branch
Echinodermata. ‘To this group also belong the Brit-
tle Stars, Holothurians, and Crinoids.

’ ’ o~

THE DEVELOPMENT OF THE SEA-URCHIN.

The reproductive bodies are very much alike in the
two sexes, distinguishable only by color or by microscopic
examination.

THE SEA-URCHIN. 165

In the dark-colored sea-urchin (Arbacia punctulata) the
ovaries are red, from the color of the contained eggs,
while the testes are white. Through the genital open-
ings already observed, there passes out into the water
from the female a multitude of red spherical eggs. From
the male there passes into the water a white liquid, which
on examination with a high power of the microscope is
seen to be composed of myriads of little bodies, the
spermatozoa, like slender tadpoles, and swimming by the
active vibration of their tails.

If these two elements meet in the water the egg may
be fertilized; otherwise, the egg does not develop, but
soon dies. This process of the fertilization and the
changes that the egg undergoes in consequence, have
been studied in the following manner :—

Live sea-urchins were opened, the ovaries and testes
removed, and torn open to let their contents escape. ‘The
ova and spermatozoa were mixed in a watch crystal of sea
water and watched under the microscope; the actively
swimming spermatozoa surround the ova; just how the
fertilization is accomplished is not fully known; it is
believed that a spermatozoon enters the ovum. After this
- the egg mass contracts, leaving a clear space around it
inside the outer coat, or cell wall; soon the egg mass
within divides into two equal parts, each of these halves
again divides into two, the four then become eight, six-
teen, thirty-two, and so on till the number can no longer
be counted and the egg lodks like a spherical mulberry.
This berry-like mass now becomes hollow, next one side is
pushed in like a rubber ball with one side punched in;
on the outside are little hair-like projections of the cells,
called cilia, which by their vibrations propel the body

166 PRACTICAL ZOOLOGY.

through the water. A set of needle-like rods develop
within, which soon make a skeleton shaped somewhat like
a common chair. This skeleton has a covering of soft
tissue, and the projections which correspond to the legs
of the chair are covered with strong cilia for locomotion.
The digestive tube has at first but one opening, that made
by the doubling-in of the outer wall, as above mentioned,
and the cavity of this depression forms the digestive
cavity. The mouth is formed later by a new opening
made through the outer wall into the first cavity and the
original opening becomes the anus. So far the young sea-
urchin is very unlike the adult; but after a time this larva
begins to transform into the real sea-urchin, and soon the
little sea-urchins, about the size of pins’ heads, are found
crawling up the sides of the glass vessels in which they
are kept.

The first of the changes here described should be care-
fully remembered, as this division, or segmentation, of
the egg is common to all but the very lowest animals,
though the manner of division may greatly vary.

THE FRESH-WATER HYDRA.

The fresh-water hydra has a cylindrical body, varying in
diameter from the size of a fine needle to that of a common
pin, and from one-fourth to one-half an inch in length. It
is found in fresh-water ponds and streams, usually attached
by one end to submerged stems, leaves, etc., frequently
on the under surface of a leaf. Surrounding the free end
of the hydra is a circle of thread-like appendages, the
tentacles, which often are longer than the body itself.

THE FRESH-WATER HYDRA. 167

Two species of hydras are found; one green, the other
brown or flesh-colored. Put the leaves and stems to
which the hydras are attached into shallow dishes, such as
fruit-dishes, and keep them in a light but shaded place;
watch their behavior when thus kept undisturbed. Cut
off a bit of leaf bearing a hydra, and transfer it to a deep
watch crystal half full of water. Without the aid of any
lens watch the hydra for several minutes. When it is
expanded, gently touch it with the tip of a pencil or other
blunt object.

Examine a hydra with a hand lens; are all parts colored
alike? Place the watch crystal on the stage of a micro-
scope and examine with a one-inch objective. The follow-
ing points of structure should now be made out: —

1. That the body is a hollow tube closed at one end and
open at the other. This opening, within the circle of
the tentacles, is the mouth.

2. That the tentacles are also hollow tubes, closed at
their outer ends, but at the inner communicating
freely with the body cavity.

3. That the body wall consists of two layers, which are
continuous with the corresponding layers of the ten-
tacles. How do these layers differ from each other? ©

The body is, then, a double-walled sac, and the ten-
tacles are simply extensions of this sac. Watch the
movements of the different parts of the body. Can
hydras move from place to place? If so, how is this
accomplished? Look in the body cavity for foreign
matter which has been taken in through the mouth
as food. Look also for minute particles obtained by
the digestion of such food matter. These particles
may often be seen in motion, caused by contractions

168 PRACTICAL ZOOLOGY.

of the body walls, or by the action of cilia lining the
body cavity. Look for knob-like extensions of the
side of the body. Buds are formed as outgrowths
of the body walls with a cavity continuous with the
body cavity. Place in a dish by itself with some
aquatic plants, a hydra bearing buds, and watch from
day to day the development of the bud into the form
of the parent. Observe the free circulation of food
material from the parent to the bud. Watch the
formation of tentacles. Look also for a thinning
away of the free end of the bud.
What is the greatest number of buds found on any
one specimen? Are buds borne on buds? By means
of a pipette transfer a hydra in a large drop of water
to aslide. Cut two strips of thick paper a quarter of
an inch long and one-sixteenth of an inch wide and
lay one on each side of the drop of water. Carefully
place the coverslip on the water, with its edges rest-
ing on the papers so as not to crush the specimen.
Examine now with a quarter or one-fifth inch
objective. Observe the cells of which the body walls —
are composed. Note the knotty appearance of the
tentacles. In these projections of the tentacles and ~
in the walls of the body are certain distinct oval
cells, the thread cells. Place a drop of acetic acid
on the slide at one edge of the coverslip, and touch |
the opposite edge of the coverslip with a piece of |
blotting paper, meanwhile watching the specimen |
closely. Examine carefully to see the thread-like
prolongations of the thread cells which have been
discharged as a result of the irritating acid. Small
animals coming in contact with the tentacles are

i-th

THE FRESH-WATER HYDRA. 169

paralyzed by means of these threads which are sud-

denly shot out; the tentacles then carry the victim

to the mouth, and it is swallowed.

Note the simplicity of the structure of hydra
—the absence of any distinct nervous system,
and all special organs of circulation and _ respira-
tion.

It is stated that hydras have been cut into
slices, lengthwise and crosswise, and each part not
only continued to live but grew into a_ perfect
hydra.

Besides multiplying by budding, hydra also pro-
duces ova and spermatozoa in projections of the body
walls. Both kinds of sexual elements are produced
in the same individual. Such an animal is called a
hermaphrodite.

There is a large group of animals, almost without
exception marine, constructed on essentially the same
plan as hydra, though often much more complicated.
Hence the hydra is the type of the group known as
the Hydroids. Many of them live in colonies, as
if the young hydras, instead of dropping off from
the parent and becoming distinct individuals, re-
mained attached with a free communication between
them all. At least two distinct forms of individuals
are commonly found: —

a. A hydra-like form, devoted to obtaining and pre-
paring nourishment for the colony, hence called
the nutritive zooid.

6. Modified forms, producing the generative ele
ments, the generative zooids.

oe

170

PRACTICAL ZOOLOGY.

c. Besides these two are often found forms modified
for protection, etc. |

If a stained and mounted specimen of a campanu-
larian or other hydroid be at hand, it will be found |
very useful in showing these points.

The different kinds of individuals, though often
greatly modified, still show the essential plan of the
hydra. Some hydroids have a tube of hard material
developed by the outer layer, and at the base of the
colony some kinds secrete a layer of this material
incrusting the object on which the colony is borne.
Some forms spread by runners like strawberries.
One form is common on the shells inhabited by her-
mit crabs. Others are attached to seaweed, while still
others are dredged up from great depths of the ocean.

Among certain forms of hydroids the generative
zooid becomes peculiarly modified in form, and ulti-
mately becoming detached, is known as a free gener-
ative zooid, jelly-fish, or medusa. These jelly-fishes,
or meduse are usually either bell-shaped or umbrella-
shaped, the part answering to the top being called the
bell or disk. Corresponding to a short handle is the
manubrium. This has at its free end an opening,
the mouth. The handle is hollow, and communi-
cates with tubes radiating through the disk, answer-
ing to the umbrella rays. These tubes are connected
by a circular tube, extending around the margin of
the disk. Along this margin are tentacles and organs
for receiving impressions of light or sound. Most
jelly-fishes swim by contracting the umbrella-like disk.

Along the radiating tubes, or in the manubrium,
are borne the generative elements; the eggs develop

THE SEA-ANEMONE. 171

into hydra-like forms, which, on becoming attached,
give rise by a process of budding, to a hydroid colony,
some members of which assume a medusa form, thus
completing the cycle. This mode of development
has been called, though inappropriately, an alterna-
tion of generations. All jelly-fishes do not, however,
develop in this way. Jelly-fishes are richly supplied
with lasso-cells, and the larger ones sting severely,
being dangerous to bathers.

Read the description of Cyanea and other jelly-
fishes in ‘“ Seaside Studies.”

THE SEA-ANEMONE.

In its general form the sea-anemone resembles a hydra,
having a cylindrical hollow body attached by one end to
some foreign object, and at the free end a mouth sur-
rounded by tentacles. In its internal structure, however,
the sea-anemone presents some new features. The mouth,
instead of opening directly into the body cavity, as in the
-hydra, opens into a stomach which hangs like a bag sus-
pended in this cavity; the stomach has no bottom, but at
its lower end communicates freely with the body cavity.

The body wall and stomach may be represented by a
glove-finger with its tip cut off and the open end turned
back part way into the larger part of the finger.

The cavity of the body is divided into a series of radial
compartments by fleshy vertical partitions, the mesente-
ries, which extend inward from the body wall, some reach-
ing the stomach and being attached to it, others not ex-

172 PRACTICAL ZOOLOGY.

tending so far inward as the stomach. Each tentacle
communicates with one of these radial compartments, and
is to be regarded as a mere extension of part of the body
cavity.

Alcoholic specimens should be sliced transversely and
longitudinally. In a transverse section of the lower part
of the body there will be seen the body wall with a series
of partitions extending inward and ending in a free edge.
The section across the upper part of the body shows an
outer circle, the body wall, an inner circle, the stomach
wall, and, connecting the two, the radially arranged parti-
tions, or mesenteries. Like the hydroids, the sea-anemone
is well provided with lasso cells.

Food is taken into the mouth, digested in the stomach,
then passed, mixed with sea water, into the body cavity,
through which it is made to circulate by the contractions
of the body walls. The indigestible portions of the food
are expelled from the stomach through the mouth.

The tentacles are often brilliant and variegated in color;
and when the sea-anemone is expanded, it well proves the
fitness of its name. For a very interesting description of
these beautiful animals read Mrs. Agassiz’s little book, “ A
First Lesson in Natural History” (No. IV. in “ Guides for
Science Teaching ’’).

CORAL POLYPS.

The coral polyps are similar to the sea-anemone in their
general structure. They usually grow in colonies with
their bases connected by a continuous layer of living
matter, from which the polyps grow by budding.

CORAL POLYPS. — STONY CORALS. 173

Through this common base the cavities of the polyps
communicate, more or less directly, so that food obtained
by one may nourish the whole colony. The coral polyps
also differ from the sea-anemone in forming a deposit of
hard matter. Representatives of the two kinds of coral
should now be examined.

STONY CORALS.
(Corals Proper.)

In a piece of stony coral, or compound skeleton of a
colony of coral polyps (Galazea is a good form to study),
make out the following points : —

1. The nature of the material itself; test by putting a
very small piece into weak acid, or by touching the
specimen with a drop of acid.

2. The cup, or theca, formed by an individual polyp,
often traceable as a long tube. Observe, —

a. The outer wall of the cup.
b. The partitions, or septa, extending inward from
the wall of the cup.

8. Between the cups, the porous limy secretion, which
was secreted by the common body substance, or cee-
nosarc, connecting the individual polyps.

Imagine the sea-anemone depositing limy matter in
the base of its body wall, forming a cup; fleshy radiai
ridges rising from the floor and wall of the cup be-
tween the mesenteries, and a similar deposit in these
ridges; thus it will be seen how the cup is formed by

174 PRACTICAL ZOOLOGY.

the individual polyp. By the continued growth of
the polyp, and the continuation of the limy deposit,
the cup becomes an elongated tube. By budding are
formed the branches of these tubes, increasing in size
and in the number of partitions as they grow.

4, Between the cups, a porous secretion of the same ma-
terial as that in the cups. This is deposited in the
common fleshy base, filling up, in some forms, the
spaces between the cups; and when one polyp dies, its
cup is covered over and buried out of sight by this
secretion of the common base.

5. Make a drawing of a mass of stony coral, showing
the general arrangement of the cups, their mode of
branching, and the common secretion between them.

6. Draw a cup as seen from its free end. Make also a .
drawing of a cross-section of the same cup toward
the smaller end.

In the stony corals the mesenteries are always in .
pairs, and the fleshy ridges, in which are secreted the
septa, arise between them. |

The tentacles are generally in multiples of six, and '
are not fringed. It is of this kind of coral that the ;
reefs are formed.

a

SEA-FEATHER, OR SEA-FAN.

In a sea-feather, e.g., Muricea, note : —

1. An outer bark-like layer; with the thumb-nail scrape
off a little of this layer and pulverize it between the
thumb and finger; mix this powder with water and
examine under a microscope. A better way to see

SEA-FEATHER, OR SEA-FAN. 175

the spicules is, to thoroughly clean them by boiling
some of the outer layer in caustic potash. In this
layer are holes from which the polyps protruded. In
this form, then, the secretion is wholly in the living
matter between the polyps, the bark-like layer being
composed of the dried flesh in which the spicules lie
imbedded.

Strip off a piece of the bark-like layer and note the
grooves on its inner surface. By examining the end
of this piece it may be seen that these grooves are
caused by a series of tubes running lengthwise near
the inner surface of this layer. Find the openings of
the tubes where they were broken; these tubes con-
nect the polyps of the colony.

. Thecentral axis of horn-like substance. Test its flexi-

bility and strength. Observe the grooves on its sur-
face, and the relation between them and the tubes
above noted. This horny axis is excreted by the
walls of these tubes, and is not penetrated by liv-
ing matter like the outer layer. In the precious red
coral the central axis is formed in the same way, but
is calcareous instead of horny, and the outer bark-like
layer has been removed.

. Note the mode of branching in a sea-fan, comparing
the margin with the central portion to see how the
meshes are formed. Remove some of the outer layer,
and compare with the sea-feather. In this group
(including sea-feathers, sea-fans, the precious red coral,
etc.) each polyp has eight fringed tentacles; also
eight mesenteries, which are never in pairs. An alco-
holic specimen, with the polyps expanded, should, if
possible, be examined.

176

PRACTICAL ZOOLOGY.

The hydroids, jelly-fishes, sea-anemones, and coral
polyps, with many other interesting forms, belong to
the branch Coelenterata. The celenterates are many-
celled, radially symmetrical animals, and never pos-
sess a digestive tube wholly cut off from the body
cavity.

SPONGES.

Each pupil should have a small specimen of a commer-

cial

sponge, showing large holes at the top, but not with

large holes running straight through.
The teacher will need several specimens of larger
sponges; one of the simple calcareous sponges, in alco-

hol;

a piece of a commercial sponge in alcohol, showing

the sponge-flesh still in place; a silicious sponge; and
slides showing sponge spicules.

The pupil should make out the following points from
his specimen : —

A;

Its elasticity; test first the specimen dry, and again
after wetting it. Compare the elasticity of different
kinds of sponges.

The fibrous structure; with forceps tear off a bit of

the sponge and examine with a lens. Then examine

under the microscope.

The sponge was attached by its basal surface to rock.
Find where it has been trimmed away with shears;
perhaps if this has not been thoroughly done, some
bits of rock may be found clinging to the base.
Examine now the different channels by which the
sponge is perforated.

SPONGES. 177

a. Large crater-like tubes, opening at the top of the
sponge. Looking into these, it may be seen that
they give off branches. If you can see right
through the sponge by looking into these open-
ings, you may know that too much of the base
has been cut away, and your specimen is not a
good one. With a razor or sharp knife, cut the
sponge in two down one of these large tubes, and
examine from the inside.

6. Trace the branches of the large tubes by gently
pushing into them a probe (a wire with a little
knob on one end). These lead, usually, to holes
seen on the outside.

e. Grooves on the surface of the sponge, some shal-
low, others already becoming enclosed by the
union of the tufts of fibres outside of them; in
this way is formed another set of tubes (d).

d. Tubes running parallel to the surface of the
sponge, whose cut-off ends may be seen near the
margins of the split sponge. Hold the half
sponge up to the light to see the radiating fibres
and the concentric series of holes indicating the
mode of growth of the sponge.

e. Minute branches of the above tubes penetrating
the sponge in all directions.

It must be borne in mind that the sponges we buy
are only the skeletons of sponges. In the living
sponge the skeleton is entirely imbedded in soft liv-
ing matter, and the skeleton cannot be seen on the
exterior; in fact, its fibres are not very evident in a
section of a fresh sponge. The outside of the sponges
whose skeletons we buy, when alive resembles, in color

178

“PRACTICAL ZOOLOGY.

and general appearance, the back of a kid glove, vary-
ing from dark reddish-brown to almost black. The
consistency of the living sponge is about the same as
that of beef liver. If one of these live sponges be
watched, a current of water is found to come out of
the larger holes at the top, and currents pass in
through the numerous smaller holes on the exterior.

If the sponge be handled, many of the smaller holes
close and entirely disappear.

In order to understand a little more clearly the
structure of the common sponge, and to see how the
currents of water are maintained, an examination of a
simple sponge will be useful. Our simplest sponges
have no elastic skeleton composed of horny fibres like
those of the commercial sponge, but have little needle-
shaped and three-pronged spicules of limy matter.

One form common on the northern Atlantic coast
is a simple or branched white tube, an inch or so in
height and sometimes as thick as a pigeon’s quill.
These are in clusters, attached by one end and open at
the other. Imbedded in the wall of each tube are the
spicules above mentioned, projecting both on the out-
side and on the inside. The inside of the tube is lined
with cells bearing cilia which, by their vibration, drive
the contained water out of the mouth of the tube; to
replace which, water enters through many holes which
pierce the wall of the tube. In sponges a little more
complicated, the cilia, instead of lining the main tube,
are limited to small pouches, or lateral branches of the
main tube, extending into the body wall and communi-
cating with the exterior through small pores. In others
the cilia are found only in certain enlarged portions

SPONGES. 179

of these radiating tubes. This represents the condi-
tion in the commercial sponges; certain cavities are
lined with cilia and are connected on the one hand
with the smaller tubes entering the whole surface of
the sponge, and on the other with the large tubes
opening at the top. These cilia cause the currents
above mentioned. Thus the sponge gets both food
and oxygen. cs

Sponges (including, besides those already men-
tioned, silicious sponges, whose spicules are flinty)
constitute the branch Porifera.

For a very interesting account of the gathering and
preparation of sponges for the market, read “Com-
mercial and Other Sponges” by Hyatt (No. III. in
“Guides for Science Teaching”).

180 PRACTICAL ZOOLOGY.

REVIEW OF ALL THE ANIMALS STUDIED.

1. How many different plans of structure have been shown by the
animals thus far examined ?

2. How many different ways of eating, and how do the digestive
organs differ?

3. What different arrangements for the circulation of the blood?
4. “Compare the various methods of breathing.

5. In what ways do animals effect motion and locomotion?

6

Describe the different sorts of organs of feeling, seeing, hearing,
smelling, and tasting.

7. Describe the methods of producing sounds.
8. What different kinds of coats do animals wear?
9. What weapons of attack and defence do they carry?
10. What different kinds of skeletons?
11. How many kinds of animals are native to your neighborhood?
12. The animals of a given region constitute its fauna. Thus, the
faune of North and South America are unlike; and North
America may be divided into regions having more or less dis-
tinct faune.
13. What characters are common to all the animals you have studied?
14. What is an animal?

BRANCHES OF THE ANIMAL KINGDOM.

(Packard.)

Vertebrata: Mammals, Birds, Reptiles, Batrachians, Fishes, ete.
Arthropoda: Crustaceans and Insects, Spiders, Myriapods, etc.
Mollusca: Bivalves, Snails, Cuttle-fishes, ete.

Vermes: Worms.

Echinodermata: Crinoids, Starfishes, Sea-urchins, etc.

et Fe ee

st at Sin aS

BOOKS OF REFERENCE. 181

3. Coelenterata: Hydroids, Jelly-fishes, Polyps, ete.
2. Porifera: Sponges.

1,

Protozoa: Amoeba, Paramcecium, Vorticella, ete.

BOOKS OF REFERENCE FOR THE ZOOLOGICAL

LABORATORY.

Of the following books, Nos. 1 to 9 are almost indis-
pensable. For general reference, at least, one of the first
three should be at hand, and every one of 4 to 9 gives
great aid in practical work.

1.

2.
3.
4,

Text-Book or ZodLocy. Claus & Sedgwick. Macmillan & Co.
2 vols. $8.00.

Zobiocy. Packard. Henry Holt & Co. $3.00.

Trext-Boox or ZoéLtocy. Nicholson. D. Appleton &Co. $1.50.

HaAnpBook OF INVERTEBRATE ZodLoGy. Brooks. Cassino.
$3.00.

PracticaAL Brotogy. Huxley & Martin. Macmillan & Co.
$1.50.

PracticaL Puysrotogy. Foster & Langley. Macmillan & Co.
$2.00.

Guipes ror Scrence Treacuinc. Hyatt and others. D. C.
Heath & Co. 10-40 cts. each.

First Boox or ZoéLocy. Morse. D. Appleton & Co. $1.00.

Zoébtomy. Parker. Macmillan & Co. $2.25.

Tue Crayrisn. Huxley. D. Appleton & Co. $1.75.

ANATOMY OF VERTEBRATED AND INVERTEBRATED ANIMALS.
Huxley. 2 vols. D. Appleton & Co. $2.50 each.

Guipe To THE Stupy or Insects. Packard. Henry Holt &
Co. $5.00.
Insects Insurrous TO VHGETATION. Harris. Cassino. $6.00,

182
14.
15.

16.
17.
18.

19.

20.
21.

22.

23.
24.

25.
26.
27.
28,

29.
30.

PRACTICAL ZOOLOGY.

Insects Insurious To Fruits. Saunders. J. B. Lippincott
& Co. $3.00.

VEGETABLE Movutp AND EArtHworms. Darwin. D. Apple-
ton & Co. $1.50.

Tue Naturatist’s Assistant. Kingsley. Cassino. $1.50.

CoMPARATIVE Zo6Loey. Orton. Harpers. $1.80.

SeasipE Strupres in Naturat History. Mrs. E. C. and
Alexander Agassiz. Houghton, Mifflin, & Co. $3.00.

SPIDERS, THEIR STRUCTURE AND Hasits. Emerton. Cas-
sino. $1.50.

Lire ON THE SEASHORE. Emerton. Cassino. $1.50.

MANUAL OF THE VERTEBRATES. Jordan. <A. C. McClurg &
Co. $2.50.

Synopsis OF THE Fisues oF Nort America. Jordan &
Gilbert.

Kry To THE Brrps or NortH America. Coues. $10.00.

THe BUTTERFLIES OF THE EASTERN UNITED STATES French.
J. B. Lippincott & Co. $2.00.

THE Cat. ANATOMICAL TECHNOLOGY. Wilder & Gage. Barnes.
$4.00.

Tae American Narurauist. Cope & Packard. Monthly.
$4.00 a year.

Tue Riversipe Natura History. Kingsley. 6 vols. Hough-
ton, Mifflin & Co. $30.00 to $42.00.

Practica ZobLecy. Marshall & Hurst. London: Smith,
Elder & Co.

DissECTION OF THE Dog. Howell. Henry Holt & Co.

Biotoey. Sedgwick & Wilson. Henry Holt & Co.

TYPES OF MARINE ANIMALS. 183

TYPES OF MARINE ANIMALS FOR LABORA-

TORY USE.
Protozoa.
Foraminiferal sand. Bahamas.
Sponges.
Commercial sponge. Small hand specimens for class use.
Florida Keys. . . B96 Shs le ais jain he el
Same. Section mounted on aide it age AE) :
Same. Alcoholic specimen eae fleshy Gatlant "Small
piece in vial . . oe v5 oy Gt es cen
Sea cap sponge. F aide Kove: 1
Calcareous sponge in vials. New iciand” 6
Microscopical prep. Showing spicules in place 1
Silicious sponge. New England . apa 1
Spicules of same. Mounted . . . . + »« « « 1
Chalinula. Pieces.
Ccelenterates.
HyproIps.

Tubularia. Invials. New England ........ 12
Tubularia. Exhibition cluster.

Clava on seaweed; clusters in vials. New England . . . 12
Hydractinia colonies on shells . . . . . «. « « « « «46
Campanularian. Invials . .. . i
Campanularian colony. Stained and tiounted. ‘Slide eA
Campanularian jelly-fish. Stained and mounted. New Eng-

land. « + « ‘s arf 1d ae oe
Sertularia on seaweed. Dry. Ne: ew England,
AOTINOIDS.

Sea-anemone. New England . 6
Sea-anemone. Section onslide . . ad wlea Jehlod ey Sea. Ue
Stony coral (Galaxea). Pacific. Small hand specimens. . 20
Alcyonarian coral (Muricea). Dry. Florida Keys. Ex. spec. 1
Same. Branches for class use . . . -) 20
Same. Branch in alcohol showing sobibe expanded 1
Same. Slide with spicules of skeleton . ‘ 1

184

PRACTICAL ZOOLOGY.

ACTINOIDS.

peayun. . Bahama "0s a5 oo. al eo ele esac «
Same. Horny axig. 35 wis Pgh a Be toe
Sane. Spicules: mounted. -.: 3.4503 a 6 “eee

Echinoderms.

Starfish for dissection. New England. ... .

DES RIES 6-5 Sete ey ae eee ge. Fa

Same. Prepared, showing skeleton .

Same. Decalcifed . .. . "4

Same. Injected rays showing waler Aaa ant

Section of plate showing microscopic structure. Mounted

Young starfish showing the budding out of rays. Stained
BIE MOUDGON 6 ween 4, Sg bp ey oey, Fem

Large W. I. Starfish (Oreaster) . . . . 2. « + » « «

Britiestars (Opianrens)s SEG. 6a ss 8 eR

Sea-urchins. Ale. For dissection. NewEngland .. .

Same. Tests. Dry... °°. eee, ers

Same. Alc. specimen dvalaitiea . . :

Same. Section of plate showing microscopic een Slide

Large W. I. Sea-urchin (Hipponoé). Test

Clypeastroid (Sand-dollar), with spines . Pr Bae,

Clypeastroid (Sand-dollar), without spines. . . . . .

Clypeastroid (Echinanthus). W.I.. . BOE det ne Se

Holothurian. Common sea-cucumber (Pentacta). New Eng-
land .

Synapta. Microscopical preparation showing plates in » body
walls. 2 4

Worms.

Nereis <i test=-webOs- SAICs es Sek a SOE

Polyzoan (Bugula). Dry.
Brachiopod (Terebratulina). Ale. . . . 2. «© «© « © «

Mollusks.
Clam killed with siphons extended . . . ....
nesses TW Adertie MRE MAPK PS alee see
Carnivorous sea-snail (Lunatia)
Carnivorous sea-snail (Purpura) .°. . . . .

Limpet. Alc. New England . i a a ce
Squid... New Tngiand. 958 ose a ee

bt to
an wor

ae oe a |

_

monwnwre ee

i
¥
i

ee err et ee Se

TYPES OF MARINE ANIMALS. 185

Arthropods.

Crustacea. New England.
Lobster. Small specimen. Dry . . . . . «6 « «
Shrimp. Ale . eee Sei icopes gat
Crab. Dry or ale. ‘
COIR CR BRS wg ee te Gea
Acorn barnacle. Dry.
King crab (Limulus). Small specimen. Ale. . . . .. 2
Gee rmoaum sie. “Dry. . . 4% se ale eo
Same. Moults. Smallspecimens ......... 8

wnond

INSECTS.
White ants (Termites). In vial. Bahamas.

Ascidians. :
Bana. New Ungland§. - 2 eo ON a ee ee
Bovebia: * Now England) 5.06 ee a ea a

Vertebrates. ;

Young shark (Acanthias). 6 inches. New England . . . 38

Small skate... New England. 6.0. i046 Be es
Kieunder. New England. << °s= 5, - «5. + ..+ 2-30: ee

_

_

The above collection, carefully prepared and designed
especially for class work, may be obtained from B. H.
Van Vueck, Boston Society of Natural History, Boston,
Mass.

Price (including packing), $25.00.

2 , SCIENCE.

The Elements of Inorganic Chemistry:

Descriptive and Qualitative. A Text-Book for Beginners, based on Experi
mental and Inductive Methods. By J. H. SHEPARD, Professor of Chemistry,
South Dakota Agricultural College, and Chemist to the U. S. Experimental Sta-
tion, S.D. 397 pages. Cloth. Price by mail, $1.25. Introduction price, $1.12.

T is a practical embodiment of the modern spirit of investi-
gation. It places the student in the position of an investigator,
and calls into play mental faculties that are too often wholly neg:
lected. It leads him ¢o experiment, to observe, to think, to originate.
Coming as it does from the working laboratory of a practical in-
structor, who has had the constant advice of fellow-teachers in all
parts of the country, this text may be fairly taken as an exponent of
the latest methods of teaching chemistry.

Its distinctive features are: experimental and inductive methods;
the union of descriptive and qualitative chemistry, thus allowing
these kindred branches to supplement and illustrate each other; a
practical course of laboratory work illustrating the general principles
and their application; a fair presentation of chemical theories, and a
conciseness which confines the work to the required limits.

The work closes with full and explicit directions for successfully
and economically equipping the laboratory, and preparing the needed
re-agents and solutions.

Our special circular on this book contains a list of over three hun-
dred and fifty Colleges and Schools into which it has made tts way by
merit alone, in a little more than a year’s time, and also gives a large
number of letters from teachers of the subject showing with what ease,
profit, and satisfaction it is used in the class-room.

C. A. Scheeffer, Prof. of Chemistry,
Cornell Univ.: Itis excellent. The plan
is well conceived, and embodies the method
by all means the best.

C.F. Chandler, Prof. of Chemistry,
Cotumbia Coll.:; An excellent book. A
great degree of accuracy characterizes the
entire work.

Otis C. Johnson, Prof. of Applied
Chemistry, Univ. of Michigan: 1 \ike
it so well I have nothing to criticise.

A

Ira Remsen, Prof. of Chemistry,
Johns Hopkins Univ.: The book teaches
that chemistry can only be learned in the
laboratory, and that the book is only a
guide to experimental work, —a lesson
which certainly needs to be taught above
all othecs in chemistry.

Herbert E. Smith, Prof. of Chem
istry, Yale Coll.: A class working
through it would gain an unusually good
knowledge of the subject.

SCIENCE. 3

L:lements of Chemistry. Briefer Course.

By JAMEs H. SHEPARD, Professor of Chemistry, South Dakota Agricultural Col-
lege, and Chemist to the United States Experiment Station, S. D.
Inorganic and Organic. 248 pages. Price, by mail, 90 cts. Introduction
price, 80 cts. Jnorganic. 183 pages. Cloth. Price, by mail, 7o cts. Introduc-
tion price, 60 cents. Organicalone. Paper. 65 pages. 25 cts.

HIS brief course is prepared on the same plan as the author’s Ele-
ments of Inorganic Chemistry, published some four years ago.
The book is not a fragmentary compilation, but gives the student a
concise and comprehensive view of the main formulas of chemical
science. The experiments are easily performed and bear directly upon
the subjects under consideration. The apparatus and chemicals re-
quired are as inexpensive as thorough work will permit. It is well
adapted to the needs of schools where the time is limited and
where the teacher aims to do most of the work, but it will find a warm
welcome in schools possessing working laboratories.

The Organic portion, although strictly elementary, includes some-
thing more than the detached and disconnected chemistry of a few
important compounds. Enough of the principles underlying organic
chemistry are introduced to enable the student to obtain a general
knowledge of how organic substances originated and how they are related.
At first a general view of the hydrocarbon series is given and then
one or two members belonging to the parraffin series are taken up at
sufficient length to illustrate the important classes of derivatives which,
in general, belong to each hydrocarbon series. After this only the
most important members of the remaining series are noticed.

Since the analytical features of organic chemistry present too many
difficulties for beginners with limited time, nothing of the kind has
been attempted. But the experimental work is sufficiently easy to af-
ford profitable work even in laboratories with limited facilities.

The following letters received soon after the publication of the book
are indicative of the favor with which it has been received.

C. E. Boynton, Senior Teacher,| D.L. Bardwell, Teacher of Sci-
Chicago Manual Training School: 1\ ences, State Normal School, Cortland,
think the bock in some ways an improve-| V. Y.; I am particularly struck with the
ment on the old, but for our course it is|simplicity of the apparatus generally

too brief, so we shall continue to use the | used,and above all, the suggestiveness of
larger book. the experiments, (Oct, 2, 1890.)

4 SCIENCE.

The Laboratory Note-Book.

For Students using any Chemistry. Board covers. Cloth back. 192 pages
Price by mail, 40 cents. Introduction price, 35 cents.

T contains blanks for experiments ; blank tables for the reactions of

the different metallic salts; pages for miscellaneous matter; and

an extra chart for the natural classification of the elements, similar to

that on page 221 of Shepard’s Chemistry, which may be rolled into a
cylinder by the student.

The advantages of using this note-book are, briefly, these: It
saves time for the student and gives the teacher control of his work;
its size is convenient; it is cheaper than an ordinary blank-book ; the
paper is such that it readily takes ink without blotting or smearing,
or it may be used with a lead pencil.

The value of systematic note-taking by the the student in chemis-
try can hardly be over-estimated.

Our Chemistry Circular contains fac-similes of three pages, pre-
pared by the students in the Ypsilanti high school for 1885-6, show-
ing how the book is to be used.

Geo. F. Sawyer, Deft. of Chemistry,| D. W. Batson, Pres. Ky. Wesleyan
Martha's Vineyard Summer School: \t\ Univ., Millersburg: It is answering our
is the best in plan I have seen. purpose excellently.

Chemical Problems :

Adapted to High Schools and Colleges. By JosEPH P. GRABFIELD and T. S, ©
Burns, Instructors in General Chemistry in the Mass. Inst. of Technology.
Cloth. 96pages. Price by mail, 55 cts. Introduction price, 50 cents.

HIS book comprises the principles of stoichiometry, with separate
chapters upon atomic and molecular weight, determinations and
specific gravity of gases, and upon the principles of thermo-chemistry
and its application to inorganic chemistry. The authors have added,
as a set of general questions, a series of problems and reactions and
the examination papers in general chemistry given at the Institute
of Technology during the last ten years. The book contains no
formulz, students being led to solve the problems from the principles
involved.

SCIENCE, 5

The Elements of Chemical Arithmetic,

with a Short System of Elementary Qualitative Analysis. By J. Mt1Lnor Coit,
Master in St. Paul’s School, Concord, N. H. 95 pages. Cloth. Price by mail,
55 cents. Introduction price, 50 cents.

HIS manual is divided into two parts. Part I. contains the more

important rules and principles of Stoichiometry, put in a very
simple way to suit the comprehension of the average student. These
rules and principles find application in a series of carefully selected
problems which follow. Part II. contains an elementary system of
qualitative analysis intended for beginners. The most available and
satisfactory tests for the more important metals and acids are given
with simple tables of separation. Besides these are some carefully
compiled tables for reference. The book will be found valuable as a
companion for some regular text of descriptive chemistry or where it
is desired to give an elementary course in practical chemistry. It
has just been carefully revised and some valuable tables added.

T. H. Norton, Prof. of Chemistry,| Robert Peter, Prof. of Chemistry,
Univ. of Cincinnati, O.: It is admirably | Kentucky State Univ., Lexington: I
written, and well adapted to supplement the | can recommend it as a good, compen-
ordinary descriptive text-book or series of | dious, and cheap guide for Laboratory
Jectures preparatory to scientific courses. | practice in Qualitative Analysis.

Modern Petrography.

An account of the Application of the Microscope to the Study of Geology, by
GEORGE HUNTINGTON WILLIAMS, of the Johns Hopkins University. Paper.
35 pages. Retail price, 25 cents.

IVES a charming account of the development and progress of

the new science; adds a description of the marvellous results
obtained by Fouqué and Michel Lévy in the artificial reproduction of
volcanic rocks; a consideration of the relation of microscopical
petrography to the allied sciences; a bibliography of petrographical
literature, and careful directions “on the preparation of rock-sections,
and on the manufacture of petrographical apparatus,” etc.

The Microscope: This book gives | American Microscopical Journal,
an excellent introduction to the study of | Washington: A satisfactory little book
microscopy. admirably presenting the subject.

ew

SCIENCE. 13

Elementary Practical Physics,

or Guide for the Physical Laboratory. By H. N. CHuTE, Instructor in Physics,
Ann Arbor High School, Mich. Cloth. 407 pages. Price by mail, $1.25. Intro-
duction price, $1.12.
| eas DED for students in high schools and colleges pursuing
the study of Physics experimentally. It consists of a series of
carefully selected excercises, both qualitative and quantitative in char-
acter, in which full directions are given regarding the preparation of
the apparatus, and the manner of conducting the experiments, to-
gether with numerous suggestions about methods of observing, note-
taking, making inferences from data, management of classes and
equipment of rooms. It aims tu place before the pupil an outline of
the method by which Physics has been developed; to teach him the
general laws of science in a way that will give them permanent lodg-
ment in his mind; to show him that such knowledge is gained only by
the study of natural occurrences ; to prove to him that physics is

more than a descriptive catalogue of interesting phenomena.

Our special circular on this book gives numerous and very emphatic
testimonials to tts value for school and college.

A.L. Kimball, Assoc. Prof. of Phy-
sics, Johns Hopkins Univ. : \ consider it a
very valuable handbook of laboratory work
for those beginning the subject, and I be-
lieve it will be found a most important aid
in teaching Physics in high schools and col-
leges. The suggestions as to the manage-

ment of a laboratory course and the con-
struction and use of simple apparatus are
most excellent and cannot but be exceed-
ingly helpful to teachers.

Arthur W. Wright, Prof. of Exper-
imental Physics, Yale Univ.:; It seems
to me well arranged for beginners in
practical physics, and a useful addition
to the resources of the teacher.

A.M. Mowry, Teacher of Physics,
High School, Salem, Mass. : It furnishes
for teachers and pupils alike just what
they need, —a comprehensive, accurate,
and well arranged list of experiments,
carefully prepared and clearly expressed,

A. C. Hale, Teacher of Nat. Hist.
and Physics, Brooklyn High School,
NV. Y.: I like it more and more and I am
becoming convinced that it is one of the
most valuable school books that have ever
been published in this country.

Edward P. Jackson, J/ustructor in
Physics, Boston Latin School: After very
careful examination I feel justified in pro-
nouncing a decided opinion in its favor,
I do not see how a student can use the
book, according to instructions, without
becoming thoroughly imbued with the
spirit of original investigation. That is
the highest compliment I can pay a text-
book on science.

J. M. Coit, Master in St. Pauls
School, Concord, N. H.: Ihave examined
it with great care, and think it superior to
any text-book of the kind I have yet seen.
I shall use it with my next class.

SCIENCE. :

Science Teaching in the Schools,

By Witt1AM NortTH Rick, Professor of Geology, Wesleyan University, Conn,
Paper. 46 pages. Retail price, 25 cents.
PLEA for the introduction of elementary science teaching in the
common schools, as ‘‘a valuable discipline for those who never
advance beyond such schools, and a valuable preparation for those
who do.” Also directions for a course of study in Elementary Science
for Primary and Grammar schools.

Guides for Science Teaching.

Published under the auspices of the Boston Society of Natural History.
NTENDED for the use of teachers who desire to practically instruct
their classes in Natural History, and designed to supply such in-
formation as they need in teaching and are not likely to get from any
other source.

No. L. About Pebbles.

By ALPHEus Hyatt, Professor of Zodlogy and Paleontology in the Massachu-
setts Institute of Technology. Paper. 26 pages. Price, 10 cents.

An illustration.of the way in which a few common objects may be
used to cultivate the powers of observation, and to teach interesting
lessons in elementary natural science. It contains all the suggestions
necessary to enable any teacher to make the lessons a complete suc-

' cess.

No. II. Concerning a Few Common Plants.

By GrorGE LiIncoLn GooDALE, Professor of Botany in Harvard University.
Paper. 61 pages. Price, 20 cents.

Gives a method by which a few of the more important and easily ob-
served facts can be taught respecting the structure, growth, and work
of plants. It calls attention to the manner of preparing the objects
selected for elementary study, and furnishes suggestions as to the way
in which they can be turned to good account. The appliances recom-
mended are of the most trifling cost.

——

8 SCIENCE.

No. III. Commercial and Other Sponges.

By ProFEssor ALPHEUS HyATT. Jilustrated by 7 plates. Paper. 43 pages.
Price, 20 cents.

Gives an account of the sponges in common use, and amply illus-
trates their processes of growth and the methods of obtaining them
and preparing them for the trade.

No. LV. A First Lesson in Natural History.

By Mrs. ELIzABETH AGAssiIz. Jilustrated by 40 woodcuts and 4 plates.
Paper. 64 pages. Price, 25 cents.

A general history of hydroids, corals, and echinoderms, written in
narrative form, for very young children, under the direction of Prof.
Louis Agassiz. .

No. V. Common HHydroids, Corals, and Echino-

derms. BY ALPHEUS HyaTT. Amply illustrated. Paper. 32 pages. Price,
30 cents.

Shows how the studies, or observations, are to be most satisfac-
torily made, and supplies such information as one needs in teaching
and is not likely to get from any other source.

No. VI, Mollusca. Oyster, Clam, and Other

Common Mollusks. By AtpHEuS Hyatt. J/lustrated with 17 plates, con-
taining 53 figures. Paper. 65 pages. Price, 3o cents,

This book holds in compact form all that need be taught begin.
ners about the oyster, clam, and other common mollusks, and is inval-
uable as illustrating in detail the natural method of teaching.

No. VIT. Worms and Crustacea.

By AtpHeus Hyatt. Jilustrated. Paper. 68 pages. Price, 3e cents.

The description of the lobster (and fresh-water crayfish) will, it is
hoped, incite teachers to occupy more time in dealing with some one
common animal, and thus to cultivate the habit of close observation,

SCIENCE. 9

No. VIIT. Jnsecta.

By AtpHeus Hyatr and J. M. Arms. 223 illustrations in the text and 13
plates. Cloth. 324 pages. Price, $1.25.

HIS Guide is a series of replies to questions which have arisen in
the minds of its authors while teaching. No attempt has been
made to prepare a treatise for scholars but to give a guide that will
enable instructors to give lessons with specimens, and dispense with
the use of books on the part of the pupil. The book is an original
work in many repects, but also describes in as compact form as possible
the elementary principles of insect anatomy, physiology, and classifi-
cation. The ‘synopsis” of chapters preceding the book will be found
valuable to the teacher. The plates and illustrations, which have been
prepared with unusual care, illustrate the prominent structural charac-
ters of each order of Insects.

No. XII. Common Minerals and Rocks.

By W. O. Crossy, Professor of Mineralogy in the Mass. Inst. of Technology '
Illustrated with 40 figures. 200 pages. Price, paper, 40 cents. Cloth, 60 cents.

HIS includes a brief and simple account of the principal geological

agencies, descriptions of all the more common and important

varieties of minerals and rocks, and an explanation of the leading
kinds of structure occurring in rocks, such as stratification, etc.

It is not merely a guide to teachers, but also a simple and logical
presentation of the leading facts and principles of structural geology.
It is well adapted for class use, and is already used in many schools.

Specimens to Illustrate, from 50 cents to $10.00.

No. XIVI. First Lessons in Minerals.

By ELLEN H. RICHARDs, Instructor in Mineralogy, Mass. Inst. of Technol-
ogy. Paper. 5opages. Price, 1o cents. A valuableintroduction to Guide No.
XII

HESE lessons were first worked out with three successive classes of
children, from six to eight years old, just out of the Kindergarten,
and then given to classes in two public schools in the city of Boston.

10 SCIENCE.

No. XIV. Hints for Teachers of Physiology.

By H. P. Bownitcu, M. D., Professor of Physiology, Harvard Medical School.
Paper. 58 pages. Price 20 cents.

‘o this little book an attempt has been made to show how a teacher

may supplement his text-book instruction by means of simple ob-
servations, and experiments on living bodies or on organic material,
thus imparting to his pupils a knowledge of the foundation on which
Physiology rests, and at the same time bringing the impressions made
on the senses to aid the memory in retaining the facts communicated
in a purely didactic way.

No. XV. Observation Lessons on Common Min-

erals. By HENRY LINCOLN CLAppP, Master of the George Putnam School,
Boston. Paper. 80 pages. Price, 30 cents.

HIS little book is not an epitome of any work on mineralogy, nor
simply a collection of suggestions, but a specific, practical guide
for the use of the ordinary teacher. It contains many transcripts of
the pupils’ records of their own personal observations, showing what
can be done by ordinary pupils under ordinary circumstances. The
lessons will icad the pupils to see the truth, state it, and at the same
time to become practically acquainted with common minerals, and to
make collections of their own. The errors in language, too, can be
detected and remedied by carrying out the design of these lessons.
They. can be given in forty weeks, by devoting one hour each week to
- the work.

A list of simple apparatus needed, names of reference books, infor-
mation on additional minerals, and a chapter on methods of forming a
mineralogical cabinet, are added.

Pupils’ Note Book to accompany No. XV., 10 cents.

Specimens to Illustrate, from 50 cents to $10.00.

Asa Gray, Late Prof. of Natural| Dr. Wm.T,Harris: I commend
History, Harvard Univ.: Those who | the series for the kind of work which I

have not had the advantage of the course iia ought to ‘be'done in the lower

of lectures should study these primers|” 4 jHert H Tuttle, Prof, of Zoology,
thoroughly, and follow the directions they | Qjz0 State Univ., Columbus: Ihave a
give, high esteem for the whole series.

SCIENCE.

Organic Chemistry : An Introduction to the Study of the Compounds of Carbon.

By Ira Remsen, Professor of Chemistry, Johns Hopkins University, Baltimore,
374 pages. Cloth. Price by mail, $1.30; Introduction price, $1.20.

The Elements of Inorganic Chemistry : Descriptive and Qualitative.

By James H. Sueparp, Professor of Chemistry in So. Dakota. Agricultural Col.
399 pages. Cloth. Price by mail, $1.25 ; Introduction price, $1.12.

The Element Ss of Chemistry < Descriptive and Qualitative. Briefer Course.

By James H. Sueparp, Professor of Chemistry in So. Dakota Agricultural College.
248 pages. Price by mail, go cts.; Introduction price, 80 cts.

Elementary Practical Physics. Or Guide for the Physical Laboratory.

By H._N. Cuute, Instructor in Physics, Ann Arbor High School, Mich. Cloth,
407 pages. Price by mail, $1.25 ; Introduction price, $1.12.

The Laboratory Note-Book. For Students using any Chemistry.

Giving printed forms for ‘‘ taking notes’ and working out formule. Board covers,
Cloth back. 192 pages. Price by mail, 4o cts.; Introduction price, 35 cts.

The Elements of Chemical Arithmetic : with a Short System of El

ementary Qualitative Analysis. By J. Mitnor Cort, M.A., Ph. D., Instructor in Chem-
istry, St.Paul’s School, Concord, N.H. 93 pp. Bymail, 55 cts. ; Introduction price, 50 cts.

Chemical Problems. Adapted to High Schools and Colleges.

By Joseru P. Grasriexp and T. S. Burns, Instructors in General Chemistry in the
Mass. Inst. of Technology. Cloth. 96 pages. Price by mail, 55c. Introduction price, soc.

Elementary Course in Practical Zoology.

By B. P. Corron, A.M., Professor of Science, Illinois Normal University. Cloth.
196 pages. Price by mail, 85 cts. ; Introduction price, 80 cts.

First Book of Geology.

By N. S. SHater, Professor of Paleontology, Harvard University. 272pages, with 130
figures in the text. Price by mail, $1.10; Sestendontion price, $1.00. fj

The Teaching of Geology.
By N.S. SHater, author of First Book in Geology. Paper. 74 pages. Price, 25 cents.
(Modern Petrography. An Account of the Application of the Microscope to the

Study of Geology. By Gsorcr HuntTincTon WI1ttrams, of the Johns Hopkins University.
Paper. 35 pages. Price, 25 cents.

Astronomical Lantern and How to Find the Stars.

By Rev. James FREEMAN CLARKE. Intended to familiarize students with the constel-
lations, by comparing them with fac-similes on the lantern face. Price of the Lantern, in
improved form, with seventeen slides and acopy of ‘‘ How to Finp THE STARs,” $4.50
“How To Finp THE Stars,” separately. Paper. 47 pages. Price rs cts.

D. C. HEATH & CO., Publishers.

BOSTON, NEW YORK, AND CHICAGO.

460944

al zoology.

An elementary course in practic

Colton, Buel Preston

: University of Toronto
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