Southern Branch
of the

University of California

Los Angeles

This book is DUE on the last date stamped below

OCT 1 5 lS2i.
NOV 1 31021
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MAR 19 1928

MAR 1 8 1.927
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NOV 5

1941

Form L-9-15»n-8,'24

OUTLINES OF

GENERAL BIOLOGY

AN INTRODUCTORY LABORATORY MANUAL

BY

CHARLES W. HARGITT

RESEARCH PROFESSOR OF ZOOLOGY IN SYRACUSE UNIVERSITY

AND

GEORGE T. HARGITT

PROFESSOR OF ZOOLOGY IN SYRACUSE UNIVERSITY

FOURTH EDITION

LEA & FEBIGER

PHILADELPHIA AND NEW YORK

641S6

COPYRIGHT

LEA & FEBIGER

1922

PRINTED IN U. S. A.

QM

3 1-7

USLO.

PEEP ACE TO THE FOURTH EDITION.

IN preparing the present edition little change has been
made; such errors as have been brought to notice have
been corrected, and some changes have been made in the
interest of greater clearness or more precise directions.

The ideal underlying the manual is, as it always has been,
to stimulate inquiry and develop the scientific habit of
work and thought. The order of presentation remains
unchanged, for both from practical and pedagogical reasons
such an arrangement has justified itself through years of
experience. The order of presentation of topics is, however,
of secondary importance, and the individual teacher will
make such choice of topics and order of study as best
meets his needs.

An elementary course in biology must of necessity be
limited to relatively few typical organisms, but the aim of
the manual is distinctly not the study of types as such.
In our own course the laboratory study is planned to illus-
trate general biological principles such as the following:
fundamental plans of animal structure; homology; adap-
tation; protoplasmic structure and behavior; development
of organisms; and other similar principles. In conducting
such a course it is necessary to make definite plans ahead
of time, and select from the manual those topics which cover
the desired ground. It is believed that there is sufficient
material included to make possible a considerable choice to
meet varied needs and desires.

vi PREFACE TO THE FOURTH EDITION

It is still a pleasure to acknowledge the cordial cooperation
among other members of the zoological staff in such sug-
gestions as their several experiences and observations have
prompted. Should others who use the book feel disposed to
offer suggestions touching either the matter or the method
of the manual they may be assured of the cordial thanks of
the authors.

C. W. H.

G. T. H.

SYBACUSE, 1922

CONTENTS.

INTRODUCTION:

LABORATORY AND APPARATUS 17

NOTES AND DRAWINGS 18

DISSECTION 21

THE MICROSCOPE 22

FROG 26

ORGANS, TISSUES AND CELLS 45

PROTOPLASM 47

CELL (CYTOLOGY) 50

AMCEBA 54

PARAMECIUM 57

VORTICELLA 62

QUESTIONS ON THE PROTOZOA IN GENERAL 64

PLEUROCOCCUS 66

COLONIAL PROTOZOA 68

SPIROGYRA 70

SPONGE 73

HYDRA 75

HYDROID:

PENNARIA 80

OBELLA 83

MEDUSA 85

EARTHWORM 87

SAND WORM 95

FERN . 98

YEAST 104

BACTERIA 107

CRAYFISH 110

GRASSHOPPER 116

HONEYBEE 121

CLAM 125

SNAIL 133

FISH 135

CLASSIFICATION . 140

ar

viii CONTENTS

. APPE- DIX:

OLLECTION AND PREPARATION OF MATERIAL 147

PREPARATION AND MOUNTING OF SLIDES 153

REAGENTS 155

TESTS FOR ORGANIC SUBSTANCES 161

GLOSSARY 163

INDEX . 179

GENERAL BIOLOGY.

INTRODUCTION

Laboratory and Apparatus

IN order to get the best results in a laboratory course
there should be cordial cooperation between students and
instructors. The laboratory should be orderly and attractive,
and its schedule regarded with the same promptness and
fidelity as that of the classroom. Certain apparatus is
assigned to each student who must be responsible for it
during use. Notebooks, dissecting instruments, pencils,
and the laboratory manual, are to be furnished by each
student. Each is expected to do his work independently,
faithfully, and to have his own outfit which should be kept
in the best possible condition for effective use.

Ample laboratory material is furnished for the work
required, but it should be used with reasonable economy.
This relates to reagents as well as specimens. Let there be
particular care in the handling of models or museum speci-
mens placed upon the demonstration table. These are not
to be removed from this table without express permission.
The same applies to demonstration materials and dissections.

At the close of the laboratory period, which may be ex-
tended to students desirous of doing extra work, let the
tables be cleared up, the instruments, dissecting pans and
2

18 GENERAL BIOLOGY

the like put in the proper places, all solid waste deposited
in receptacles for that purpose, and only water or liquid
waste thrown into the sinks.

Notes and Drawings

Experience has shown that it is necessary to make accurate
drawings and to write a definite and careful description of
an animal if one is to secure a satisfactory knowledge of it.
The drawings should be made (on one side only) on un-
ruled heavy paper, or cardboard, with a drawing pencil
(about 3H); the notes, written on separate sheets, should
accompany the drawings.

FIG. 1.

Figs. 1 to 3 are from drawings which are correct in form,
accurate in structure, and satisfactory from a scientific
point of view. The drawings made to accompany the work
of this course should be in outline like the figures, since
shading tends to obscure rather than clarify the details of
structure. The drawings shown in the figures demonstrate
the clearness with which details are shown, even when the
structure is rather complex. However, it is sometimes
desirable to represent the texture of a part and a shaded
drawing will occasionally be necessary. Fig. 4 is a drawing
of a group of cells characterized by thick walls of rather
definite appearance and structure. One side of the draw-

INTRODUCTION

10

ing is in outline and shows clearly the shape and arrange-
ment of the cells and the thickness of their walls. The

Fig. 2.

FIQ. 3.

20

GENERAL BIOLOGY

shaded portion illustrates the further detail of a certain
structure in the walls. Fig. 5, a cell in the process of divi-
sion, is shaded in a manner which will bring out the details
of cellular structure.

The following suggestion may be helpful: Make the
drawings large, leave considerable space between them and
have them symmetrically arranged on the page. In start-

FIG. 4.

FIG. 5.

ing a drawing make all lines very faint, and when the form,
proportions and arrangement of parts is satisfactory go over
the lines with a smooth continuous stroke, producing a line
of the desired strength. The drawing must represent the
actual specimen studied, should show the real structure
rather than the mere appearance, and should be finished
in the laboratory while the specimen is under observation.

INTRODUCTION 21

Give each preparation careful study before starting a draw-
ing.

The directions for laboratory study are merely suggestions
with regard to methods and order of work; the specimen is
the thing being studied. Do not be afraid to do some things,
or to make some drawings not asked for in the outlines, if
you can thereby get a clearer idea of the structure or add
further to your knowledge of the animal. Most of the
questions asked in the outlines can be answered from the
specimen if the search is made, but if help is necessary call
upon the instructor for aid.

Always give a clear and definite title to each drawing,
indicating what aspect of the specimen is shown; also clearly
name the parts shown in the drawing. Write labels parallel
to the bottom of the page and connect to the part desired by
faint continuous lines (these are better than dotted lines).
The title of the drawing should be followed by an indication
of the scale of the drawing, e. g. x | means one-half the
natural size, x 5 means five times natural size.

Dissection

The object of dissection is to separate the various organs
or parts in such a way as to show their form and relation
to each other. It consists largely in removing the con-
nective tissue which holds the parts together.

Fix the specimen firmly in a position that will be con-
venient for work, usually with the head away from you.
If pins are used stick them obliquely into the wax of the
dissecting pan. Large specimens should be moistened from
time to time to keep from drying, and small animals should
be dissected under water.

Before starting a dissection study the specimen care-

22 GENERAL BIOLOGY

fully and note where the cut may be made to expose the part
wanted with the least injury to the surrounding parts. Do
not grasp nerves or bloodvessels with the forceps, but hold
the tissue at one side of them. Do not allow scraps to
accumulate on the specimen; with a pipette wash away
the debris which gathers on the specimen under water, and
change the water frequently.

Instruments must be kept clean and sharp to accomplish
the best results, therefore do not use scissors or scalpel to
cut hard objects and do not allow the instruments to be-
come rusty.

Clean and dry the instruments, after using, and smear
them with a little oil or vaseline.

The scissors are used almost exclusively when cutting is
to be done. Each blade of the scissors holds the object for
the other blade, whereas the scalpel tends to push out of
the way the object to be cut, and also often leads to the
cutting of underlying tissues that should not be injured.
While cutting with one hand, whether with the scissors or
scalpel, always use the forceps in the other to steady the
object and to hold the edge of the cut.

The Microscope

Since the compound microscope is the instrument most
indispensable to the biological student some knowledge of
its construction and manipulation should precede its im-
mediate application to the work in which it is used. The
following study of its parts and their relations may there-
fore be made in the order indicated.

1. Parts, (a) The base, a heavy support bearing (6) the
column to which is fastened (c) the stage, a horizontal sup-
port for objects to be examined. In the center of the stage

INTRODUCTION 23

is an opening for the passage of light by which an object is
to be illuminated. It is provided with clips for firmly
holding the object in position during its study. Situated
just under the lower side of the stage is a mechanism, (d)
the diaphragm, for regulating the amount of light admitted
to the object. Note that these diaphragms may be of
different types, mere disks to be inserted in the stage, or a
circular disk to be rotated, or a shutter-like device known
as the iris diaphragm, (e) Attached to a movable arm
under the stage is the mirror by which light is reflected through
the object and lens to the eye of the observer. Note that
it is double, having on one side a plane, and on the other
a concave surface; the latter serves to concentrate more
light upon the object, and should be used chiefly with the
high power lenses.

Above the stage is (/) the tube supported on the arm of
the microscope. The tube is a means of attaching the
optical parts, i. e., the lenses, of which there are several;
those at the upper end being called the oculars or eye-pieces
since they relate directly to the eye of the observer; those
attached to the lower end known as the objectives, since
they relate to the object under observation. The wheel-
like parts working on the side of the arm, and a similar
smaller one at the top or side, have to do with focusing to
be explained later.

2. Adjustments. — These refer to the matter of so relating
the mirror, the object to be studied, the lenses employed,
the amount of light admitted, that clear and distinct images
are afforded. First in the process is that of light, and
practice will be required in order to learn its importance.
This will involve testing the effects of both plane and con-
cave mirrors, the use of the diaphragm in regulating the
amount of light, and finally that adjustment of the lenses

24 GENERAL BIOLOGY

known as focusing. In the last of these operations will be
involved learning the uses of the so-called coarse and fine
adjustments, the former effected by means of the rack motion
produced by the large milled heads at the side of the arm,
and the second by means of the small milled head at the top
or side. Try out all these operations in a general way and
finally under the directions of the next section.

3. Focusing. — The object to be examined must be thin,
since the light must pass through it. The object is placed
on a glass slide, with a drop of water or other liquid, and
covered with a thin glass cover. Place the slide on the stage
with the object directly over the center of the opening.
Move the low power objective rather close to the slide and,
while looking into the eyepiece, turn the coarse adjustment
so as to raise the tube until the object comes into view,
now using the fine adjustment focus carefully until the image
is perfectly sharp.

The high power, wyhen in focus, is so close to the cover
glass that great care must be used in adjusting it or it may
be injured. Turn the nose piece slowly to bring this ob-
jective into position, taking care to see that it does not
touch the cover glass. If it swings into position without
striking, a slight movement of the fine adjustment will usually
bring the image into sharp focus. If the high powrer can-
not be swung into position the same process of focusing
must be used as for the low power. Always focus upward,
since to do the contrary may result in the lens striking the
slide to the injury of both the slide and the lens.

Practice these points patiently and with care until every
phase is clearly understood and easily managed. This
practice in manipulation will be time wTell spent, since later
work will thereby be done easily and skilfully.

INTRODUCTION 25

4. Use and Care of the Microscope. — Having learned the
parts and adjustments of the instrument practice their
use until they become familiar. This is especially im-
portant in the adjustments relating to light. Test manip-
ulation of mirrors and diaphragms until able to obtain
and control just the amount and quality of light essential
to the best effects, doing so with eye constantly at the ocular.
The best light is that of the open sky (not sunlight direct)
or that reflected from bright clouds. Artificial light may
be used provided a screen of some sort be interposed, such
as a bluish, or ground glass. Begin every study with the
low power, nothing is gained by using a higher power than
serves the end in view.

To avoid eye fatigue while using the microscope practice
looking with both eyes open, which after a little practice
is not especially difficult. If not easily acquired, an artificial
shade or screen may be used as may be explained by the
instructor.

Proper care of the microscope is important if its efficiency
is to be at its best. Keep every part clean, do not allow
water, or dirt, or chemicals, to remain in contact with any
of its parts. This is especially important for the lenses.
Do not touch the lenses with the naked finger, and if they
should appear dirty cleanse with lens paper furnished by
the laboratory. This may be facilitated by breathing on
the lens and then gently wiping dry.

Never attempt to take lenses apart.

THE FROG.

RANA SP.

FROGS may be had at various times of the year, and are
easily kept in proper aquaria, so arranged that the animals
have range from water to dry or rocky support, provided
care is taken to guard against serious contamination of tank
or water. They may be secured in late summer or fall, or
even in spring, though in New York State there is now a
closed season in the spring as for other game animals. In
addition to living specimens kept during the year there
should also be an ample supply of preserved material for
the needs of classes. If specimens are to be injected for
study of the blood system this must be done immediately
after killing preparatory to preservation.

In the neighborhood of larger cities frogs may often be
secured through fish markets, provided attention is given
to the subject in ample time, and often at prices much lower
than those charged by professional supply departments.

I. External Characters.

What is the shape of the body as a whole? Are dorsal
and ventral surfaces well marked? How? Note the di-
vision of the animal into head, trunk, and limbs. Is there
a neck and tail? What is the character of the skin? In
the living animal is the skin moist or dry, warm or cold?
Are there scales or other protective structures in the skin?

1. Head.— Note its triangular shape. Observe the follow-
ing parts : mouth, nostrils, eyes, ear-drum or tympanic mem-

THE FROG 27

brane. Do the eyes have lids? How many? Which
moves in the living frog? Draw the head from the side.

2. Trunk.— Note the shape and the differences in the
dorsal and ventral sides.

3. Limbs.— Note the number and arrangement. In the
hand. How many digits or fingers? The hind limb is
fore limbs the following divisions occur: arm, forearm,
divided into thigh, leg, and foot. How many digits? - How
is the leg adapted for swimming? Compare with the fore
limb in length and number of digits. Draw both fore and
hind leg.

4. External Apertures.— Note the position, shape and size
of the following: mouth, anus, nostrils.

II. Mouth Cavity.

Open the mouth to its full extent, cutting the corners of
the jaw if necessary. Are there lips? Is there a tongue?
What is its shape, size and mode of attachment? Where,
are the teeth found? Teeth on the jaw bones are called
maxillary teeth, those on the roof of the mouth are vomerine
teeth. Pass a bristle through the outer nostrils and observe
the inner or posterior nostrils. Where are they found?
Pierce the tympanic membrane and pass a blunt probe into
the, ear; in the mouth cavity the place where the probe
appears is the opening of the Eustachian tube.

In the posterior floor of the mouth just at the end of the
tongue is a slit, the glottis, opening into the trachea and
lungs. Its margin is stiff and cartilaginous, and the opening
is closed except when air is passing. The esophagus lies
dorsal to the glottis. Compare with the latter.

Make a drawing of the mouth cavity, showing all the
points referred to.

28 ' GENERAL BIOLOGY

m. Internal Anatomy.

Fasten the frog in the dissecting pan on its back, and slit
the skin the entire length of the body in the median line.
Is the skin loosely or closely attached to the body? The
spaces that are found beneath the skin are lymph spaces.
Laying back the skin observe the walls of the abdomen,
made up of muscles. Determine the points of attachment
of these muscles. In what directions do the fibers of the
muscles extend on the ventral wall, and on the side wall?
The ventral muscles are the straight abdominal, and those
of the side walls are the oblique abdominal muscles. Also
observe the group of pectoral or breast muscles in the region
of the arm. Is this one muscle or a group of muscles ? What
is the probable function of these muscles?

Draw the ventral surface of the frog, showing the muscles
just studied. If time permits, the muscles of one of the
hind legs may be studied and a drawing made.

Cut through the body wall, taking care not to injure the
organs lying beneath. Notice that the internal organs lie
in a large cavity, the body cavity or ccelom. Pin back the
flaps and observe the following organs which are exposed:

1. Heart.— In the median line beneath the pectoral girdle.
It has two thin-walled auricles and a thicker-walled ven-
tricle, the whole being enclosed in a delicate sac, the peri-
cardium. If the heart is beating record the order of the
pulsations of the different chambers. From the ventricle
a large vessel, the truncus arteriosus, extends obliquely for-
ward over the auricles. On the dorsal side of the heart is
a thin, triangular sac, the sinus venosus, into which the blood
comes before entering the heart. Does the sinus com-
municate with the auricles or the ventricle?

Make drawings of the heart to show these points.

THE FROG 29

2. Liver.— A large, dark red mass, dorsal to the heart.
What is its size and shape? Of how many lobes is it com-
posed? Between the lobes is the bile sac, .or gall bladder.
The cystic ducts are tubes which lead from the liver to the
bile sac and the bile duct extends from the bile sac through
the pancreas to the digestive tube, which it enters about
half an inch posterior to the stomach. Turn the liver for-
ward and trace the bile duct to its opening into the intestine.

Make a drawing of this region.

(If the specimen is a female take up, at this point, the
study of the reproductive organs. Having shown their
position, size and structure in a drawing, remove them and
study further the other organs of the body cavity.)

3. Lungs.— Two thin-walled sacs dorsal to the liver and
at the sides of the esophagus. Note the texture pf the walls
and the character of the lining. The lungs may be expanded
by blowing air into them.

4. Stomach.— Note the shape, size and position. How7
is the stomach held in place? Slit the stomach longitudi-
nally, and determine the character of its walls and its lining.

5. Intestine.— Is it straight or coiled? How is it held in
position? Compare the walls with those of the stomach.
Near the posterior end note an enlargement, the large intestine.

6. Pancreas.— A pale mass lying in the loop made by
stomach and intestine. Show its position in the drawing
made of the liver.

7. Spleen.— A small round body lying in the posterior
part of the body. Does it appear to be joined to, or connected
with any other organ?

8. Bladder.— A thin walled sac in the extreme posterior
part of the body cavity. What is its shape? With what
organs does it communicate?

Make a drawing to show the organs so far studied.

30 GENERAL BIOLOGY

9. Ovaries.— Found in the female and composed of masses
of eggs, their size depending upon the maturity of the animal,
and the time of year. If the ovaries are mature they may
almost completely fill the body cavity crowding all the other
organs that are in the cavity. If the animal is immature
the small ovaries will be found near the dorsal part of the
body cavity hidden by the digestive organs. Long con-
voluted tubes along the dorsal wall of the body cavity are
the oviducts. Anteriorly these are held in place against
the esophagus, and open into the coelom by a funnel-shaped
mouth. Near the posterior end each oviduct enlarges to
form a sort of bladder, called the uterus.

Fastened near the anterior end of the ovaries are slender
yellowish fat bodies.

10. Testes.— These organs, the male reproductive organs,
are oval yellowish bodies near the dorsal body wall. Usually
connected to them are slender yellowish fat bodies. Ducts
from the testes pass into the kidneys and communicate
with the urinary duct or ureter. The ureter, therefore,
functions as a common urino-genital duct. Rudiments of
oviducts may occasionally be present along the sides of the
kidneys.

11. Kidneys.— To study the kidneys and their ducts,
remove the muscle and a portion of the bony pelvic girdle
which lie ventral to the intestine and cloaca. Place the
animal under water and displace the other organs to expose
the kidneys, a pair of elongated reddish organs situated
close to the vertebral column. A small tube, the ureter,
extends from the posterior end of each kidney to the cloaca.
On the ventral side of each kidney is a narrow yellowish
line, the adrenal body, a gland whose secretion is poured
into the blood.

THE FROG 31

12. Cloaca.— The cloaca is a continuation of the large
intestine, and opens to the outside on the dorsal side of the
animal. Expose the cloaca and note the connection of
the bladder, ureters, and oviducts with it.

A diagrammatic drawing made from the side will show
the relations of these ducts to each other and to the cloaca;
or a drawing on a large scale, from the ventral side will be
satisfactory if some parts are slightly displaced.

Observe the peritoneum, a pigmented membrane which
lines the ccelom. This also covers the organs, and makes
up the mesenteries which hold the various organs in position.

IV. Circulatory System.

This system must be worked out from specimens whose
vessels have been filled with a colored injection mass. Such
an injection expands the bloodvessels and causes them to
stand out clearly from surrounding tissues and organs. If
an injected animal is not used only a few of the larger vessels
will be found, and these can be followed for only a short
distance

1. Heart.— Observe again the shape and position of the
heart, and the chambers of which it is composed.

2. Arteries.— Leading from the ventricle is a single large
artery, the truncus arteriosus, which divides into tvtp parts,
one passing to the right, and the other to the left. Each
of these subdivides into three arteries called the aortic
arches. The most anterior of these is the carotid arch, which
supplies blood to the head. Following this is the systemic
arch which, with its branches, carries blood to the trunk
and appendages. The most posterior of the three arches is
the pulmo-cutaneous which conducts blood from the heart
to the lungs and skin.

32 GENERAL BIOLOGY

From each of these large vessels arise a number of smaller
arteries; their origin should be determined, and. their dis-
tribution carefully followed.

A. Carotid Arch. This arch divides into two arteries:
(a) External carotid or lingual which supplies blood to

the tongue and muscles of the lower jaw.
(6) Internal carotid, which passes around the lower jaw
to the roof of the mouth, the orbit of the eye, and the
brain.

At the junction o£ these two arteries is a swelling,
the carotid gland.

B. Pulmo-cutaneous Arch. This, the posterior of the
three arches, divides into twro arteries :

(a) The pulmonary extends to the lungs, in which it
divides into several smaller vessels.

(6) The cutaneous extends anteriorly to the shoulder
wrhere it passes dorsally, and, emerging behind the
ear, is distributed over the skin of the back and side.

C. The middle arch, the systemic, extends dorsally,
passes around the esophagus, and the two sides of
the arch unite into a single vessel, the dorsal aorta,
which proceeds posteriorly along the spinal column.
From each side of the arch several arteries arise.

(a) . The subclavian, a large artery which goes to the
shoulder, w-ill easily be found; it continues into the
arm where it is called the brachial.

(6) The occipito-vertebral arises just anterior to the sub-
clavian, passes dorsally through the body wall and
divides into two arteries. Branches from this artery
may extend into the esophagus.

(c) Laryngeal.— Along the systemic arch between the
occipito-vertebral artery and the heart is a small
artery, the laryngeal, which goes to the trachea and
larynx.

THE FROG 33

(rf) Esophageal. — This artery arises from the systemic

arch posterior to the subclavian, about half way

between it and the dorsal aorta. As a rule it comes

only from the arch of the left side.
(e) Dorsal Aorta.— If the stomach is pulled aside this

artery will be found along the spinal column; it is

formed by the union of the systemic arches of the

right and left sides.

Branching from the dorsal aorta are :

(I) Coeliaco-mesenteric.— This large artery extending
to stomach, intestine, pancreas, liver, and spleen
comes from the dorsal aorta just posterior to
the union of the two sides of the systemic arch;
but the blood is derived almost entirely from the
left side of the arch. The coeliac artery supplies
the stomach, the mesenteric the intestine, the
splenic the spleen.

(II) Urino-genital and lumbar arteries arise from the
ventral side of the dorsal aorta in pairs, and
extend to the kidneys, reproductive organs, fat
bodies, and dorsal body wall.

(Ill) Near the extreme posterior end of the dorsal
aorta a small posterior mesenteric artery passes
into the rectum.
(/) Common iliac arteries are formed by the division of

the dorsal aorta; they supply blood to the hind legs.

(J) A short distance from its origin each common
iliac gives off, on the outer side, one or more
epigastric arteries which extend to the ventral
abdominal wall.

(II) Slightly posterior to the epigastric a small artery,
the recto-vesical, comes out on the inner side of
the iliac and supplies blood to the bladder, cloaca,
and pelvic muscles.

34 GENERAL BIOLOGY

(g) The sciatic artery is the continuation of the iliac artery
in the leg. Soon after entering the leg the sciatic
gives off a large branch, the femoral artery, which
supplies blood to the thigh muscles. At the knee
the sciatic divides into two chief branches, the tibial
extending along the front of the leg into the foot, and
the peroneal which passes along the back of the leg
into the calf muscles.

Make a large drawing of the heart and arterial
system, carefully showing the origin and distribution
of the vessels studied.

3. Veins.— While the arteries have been under investi-
gation it will have been noticed that there were other vessels,
not injected, running parallel with the arteries. These were
some of the larger veins of the body. The veins make up a
system for the return of the blood to the heart, but their
further study will not be attempted here.

Before leaving the study of the circulatory system one
should see the circulation of blood in a living frog. This
may easily be done by examining with a microscope the
thin web in the foot of an anesthetized animal.

V. Nervous System.

The nervous system consists of three general divisions;
the central, composed of the brain and spinal cord; the
peripheral, which includes the nerves connecting the central
system with sense organs and muscles; the sympathetic, a
series of nerves extending to the internal organs.

1. The Central System.— Place the frog dorsal side upper-
most and slit the skin along the median line from the snout
to the anus. Lift up the cut edges and notice the pairs of
delicate thread-like nerves which run through the muscles

THE FROG 35

of the body wall to the skin. Next remove the skin of the
body, the roof of the cranial cavity, the muscles of the back,
and with sharp pointed scissors cut away the arches of the
vertebrae. This will expose the brain and spinal cord which
will be found to be covered with a delicate blackish membrane,
the pia mater. In addition to this inner covering there is
an outer one, the dura mater, which lies close to the skull
and vertebrae, and has been removed with the bone.

The following parts may now be identified, beginning
with the anterior end :

(a) Olfactory Lobes.— These are at the extreme anterior
end of the brain. They are not distinct lobes but
are separated by a shallow groove from the rest of
the brain. Are the two lobes separate or fused?
Olfactory nerves pass forward from these lobes to
the nostrils.

(6) Cerebral Hemispheres. —Two large ovoid bodies im-
mediately posterior to the olfactory lobes.

(c) Thalamencephalon, a narrow, cylindrical portion
connecting the cerebral hemispheres with the optic
lobes. Upon it, occupying a median position, is
a small body, the pineal gland.

(d) Optic Lobes, posterior to the thalamencephalon.
What is the size and shape of these parts as com-
pared with the cerebral hemispheres?

(e) The Cerebellum is a small transverse fold posterior
to the optic lobes.

(/) Medulla Oblongata, following the cerebellum. In it is
a triangular cavity, the fourth ventricle.

(</) Spinal Cord.— The medulla tapers gradually into the
cord without any sharp demarcation. Is the cord
as long as the body? Is it of equal width through-
out its length? If not, in what regions is it widest?

36 GENERAL BIOLOGY

A swelling in the region of the arm would constitute a

brachial enlargement, and one near the legs a sacral

or lumbar enlargement. How does the cord terminate ?

Make a large drawing of the brain and spinal cord from

the dorsal side. Use care in getting the dimensions and

proportions accurate, measuring the parts with a rule if

necessary.

Carefully remove the brain and cord from the body,

place in a watch glass of water, and construct an accurate

drawing of the ventral side of the brain. In addition to

the parts already observed the following should be identified:

(h) Optic Chiasma.— Formed by the crossing of the optic

nerves as they leave the optic lobes.
(i) Infundibulum.— A small shield-shaped body posterior

to the optic chiasma.

(j) Pituitary Body.— This lies in a little pocket of bone in
• the floor of the skull. It is usually torn from its
attachment to the infundibulum when the brain is
removed from the cranial cavity.

2. The Sympathetic System.— This is best seen by placing
the animal ventral side up, moving the viscera to one side
and looking for a very delicate thread-like nerve, the sym-
pathetic nerve, which runs along one side of the dorsal aorta;
a similar nerve is present in the same position on the other
side. When these are found the organs of the body and the
lower jaw should be removed, but the dorsal aorta left in
place. Place the animal under water and lift the dorsal
aorta to find the sympathetic nerves, their ganglia and con-
nections with the spinal nerves. Observe carefully the
relation of sympathetic and spinal nerves, the position and
number of sympathetic ganglia, and the delicate nerves con-
necting spinal and sympathetic nerves.

A single drawing should be made to show the sympathetic
and peripheral systems.

THE FROG 37

3. The Peripheral System.— This is composed of the nerves
which come from the brain and spinal cord; the former are
called cranial nerves, the later spinal nerves. There are ten
pairs of cranial nerves, but on account of their close relation
to the bone of the skull their origin and distribution will not
be worked out. If possible examine a demonstration prep-
aration showing these nerves.

The spinal nerves come out in pairs, and each single nerve

arises from the cord by a dorsal and a ventral root. Since

these roots pass through the bone of the vertebral column

their origin is difficult to determine, but the spinal nerves

themselves may easily be found along the dorsal wall of the

body cavity. Determine how many of these nerves there

are, and trace their course and distribution. Give especial

attention to networks or fusions of nerves called plexuses:

(a) The brachial, in the region of the fore limb. Of how

many nerves is the plexus composed? Is the fusion

of these nerves complete? Trace a large nerve, the

brachial, into the arm.

(6) The sciatic or lumbar plexus, is in the posterior part
of the body anterior to the place where the legs are
attached. Of how many nerves is the plexus com-
posed? What is the nature and the extent of the
union? Trace a large nerve, the sciatic, into the leg.
Follow it in its course through the leg and foot.
Construct a large drawing showing the spinal nerves, and
the sympathetic system so far as it has been studied.

VI. Sections of the Body.

Having studied the organs and the parts of the body
thoroughly, we should have a good idea of the relations of
one part to another. Make a drawing of an ideal cross-

64186

38 GENERAL BIOLOGY

section of the body of the frog showing all the organs and
parts in their proper relation and proportion.

VH. Microscopic Anatomy. (Histology.)

This involves the study of the tissues and cells of which
the various organs are composed. It will be found that
there are only a few kinds of fundamental tissues and these
are repeated over and over again in the various organs. The
relations of shape and position may differ somewhat in
different places, but the tissues have the same general ap-
pearance and function wherever they are found.

1. Tissues.

(a) Blood.— Mount a drop of the blood of a frog on a slide,
and cover with a cover glass. Observe the colorless
fluid or plasma in which are floating the corpuscles
or blood cells. How many kinds of cells do you find?
Observe their shape, color, relative size, and compar-
ative numbers. Are the cells nucleated? If the slide
is placed on a warm stage it may be possible to
demonstrate the movement of the white corpuscles.
Draw.

(b) Epithelium.— Epithelial tissues are those which cover'
the free surfaces of the body or line cavities. The
outer skin and the lining of the digestive tube are
examples. Epithelium is of different kinds according
to the shape, structure and arrangement of the cells.
(I) Squamous or Scaly.— Examine the epidermis of

the frog. What is the form of the cells? Are
nuclei present? Do the cells form a layer? Do
they overlap at the edges? If possible examine
sections made vertically through the entire skin.
In these sections only the outer layers of cells
make up the epithelium. Draw.

THE FROG 39

(II) Columnar.— Examine prepared slides which show
sections through the intestine of the frog. What
is the form of the cells lining the cavity? How
are they placed? What is the position of the
nuclei in the cells? Goblet cells, which contain
secretions of mucus, are often found in the
epithelium. Draw.

(Ill) Ciliated.— Examine the cells scraped from the
roof of the mouth of a freshly killed frog. Com-
pare the cells with those of squamous and colum-
nar epithelium in all points. In what are they
alike? In what different? Can you see the
movement of the cilia? Where on the cells are
the cilia located? Draw.

(c) Cartilage.— Examine prepared slides of cartilage, or
make a slide of fresh cartilage from the frog. Get a
very thin piece and observe the transparent matrix
in which are embedded the cartilage cells. Note
the shape and the size of the cells and the manner in
which they are grouped together. How does the
cartilage differ in appearance from the other tissues?
Are the cells nucleated ? Do you find cells with more
than one nucleus? Explain. To what does the
matrix correspond in the other tissues? Draw.

(d) Muscle.

(I) Striated.— The striated (voluntary) muscles are
those that are under the control of the will.
Examine the muscle of the leg of the frog, by
teasing it in salt solution. The fibers should be
well pulled apart. What is the shape of the
fibers? Do they tend to separate into smaller
fibrillae? Is there anything that suggests the
name "striated" muscle? If nuclei are present
where in the fiber are they located? Draw.

40 GENERAL BIOLOGY

(II) Smooth or unstriated muscles. —These are muscles
which are automatic in action, or at least not
under conscious control. The muscles of the
intestines, the bladder, etc., are examples. A
piece of muscle from the stomach when teased
should show the fibers. Observe the shape,
arrangement, and nuclei of the fibers. Draw7.
(e) Nerve Tissue.

(I) Fibers. — Tease the sciatic, or other large nerve,
in salt solution. In a single fiber look for a
place where it is torn or crushed and identify
the delicate sheath on the outside. Inside this
is the thicker medullary sheath. Making up
the center is the axis cylinder, axone, or nerve
proper. Draw.

(II) Cells.— Remove one of the spinal ganglia and
tease in a drop of salt solution containing some
stain, or study prepared slides showing the
nerve cells. Look for large cells and note the
relation of the cells to the fibers. Is there a
nucleus in the cell? Draw.

2. Organs.— Having studied several of the fundamental
tissues one should be able to recognize them in organs. In
the following study observe what tissues are present and
how they are arranged :

(a) Spinal Cord.— In prepared slides of sections of the
spinal cord note the following points: shape, size,
surrounding membrane (pia mater), nerve roots, dorsal
fissure, ventral fissure, central canal, position of the
white matter, shape and position of the gray matter.
In the white matter will be found nerve fibers, con-
nective tissue, bloodvessels and corpuscles. In the
gray matter the nerve cells will be rather prominent.

THE FROG 41

Make an outline drawing four inches in diameter showing
the relative position and proportion of these parts. Arrange
the drawing with the dorsal side of the cord toward the top
of the page. Fill in with care some of the details of structure
observed.

(6) Stomach.— With the low power observe the four
layers of the wall, as follows, from without inward:
(I) Serosa or Peritoneum.— (This is very delicate

and may be lacking.)
(II) Muscular coat, consisting of

(1) an outer longitudinal layer. Note the
shape of the cells. Do all contain nuclei ?
How do you account for this?

(2) an inner circular layer. What is the
shape of the cells? Are nuclei present?
What is the relative thickness of the two
layers?

(III) Submucosa. — Made up chiefly of connective
tissue and bloodvessels. Note the general
character of the tissue and the staining proper-
ties.

(IV) Mucosa or Mucous Membrane.— This is marked
off from the submucosa by a narrow band of
muscle cells (the muscularis mucosae). The sur-
face is covered with columnar epithelium which
dips down to form numerous pits into which the
gastric glands empty. The glands are sur-
rounded by connective tissue.

Make a drawing three inches in diameter of a segment
of the stomach wall as seen under low power.

Under high power study a portion of the mucosa and note
the following points: shape of the gastric glands; general
character of the epithelium lining the pits, the shape of the
cells and the position of the nuclei.

42 GENERAL BIOLOGY

Make a drawing of a gastric pit and of the glands empty-
ing into it, as seen with the high power.

Vm. Embryology.

It will be found necessary to have a complete series of
eggs and tadpoles preserved in formalin, especially in large
classes. It is also desirable to have the living material at
hand when undertaking this study.

1. The Egg.— Examine the eggs in a mass, also compare
the masses of the toad and other amphibia. How thick is
the surrounding jelly? Distinguish in it three layers, wTith
concentric layers in them. What is the color of the egg?
The darker side of the egg is the animal or protoplasmic pole,
the side opposite is the yolk or vegetative pole.

Make a drawing of the egg and its envelopes, also draw
each of the following stages as studied.

2. Early Cleavage Stages.— What evidence do you find
that the egg differs from the ones previously studied? Find
one with a single groove surrounding it. In what direction
does the groove extend? Are the resulting parts equal?
Find an egg with a second groove at right angles to the first.
The first one gives the two-cell stage, the second one the
four-cell stage. Are the cells equal in size? The third
groove passes in a horizontal or equatorial direction. How
many cells result ? What is their relative size ?

3. Later Cleavage Stages.— Study eggs in the sixteen-cell,
and thirty two-cell stages. How are these stages produced
from the earlier stages? Are the cells equal in size? Ex-
amine both poles of the eggs and explain the differences
found. Does the relative size of the pigmented and un-
pigmented areas remain unchanged in later cleavage stages?
How is this to be explained?

THE FROG 43

4. Blastopore.— The pigmented cells divide more rapidly
than the white cells and come to grow over the latter; at
the same time the pigmented cells become infolded and grow
into the egg itself. This continues until but a small mass of
white cells can be seen. The term blastopore is applied to
the opening, and the mass of white cells is spoken of as the
yolk plug. Later the blastopore closes and the yolk plug
is forced inside the egg.

5. Neural Groove.— On what is to become the dorsal side
of the body will be found an open groove with slightly
elevated margins. How far does it extend? Is. it open
throughout its length? Examine several specimens. What
distinguishes the part which is to form the brain from that
which will produce the spinal cord? The margins grow
together to form a tube and this subsequently develops into
the brain and spinal cord. How does the shape of the
embryo compare with the earlier stages? In eggs which
have elongated, is there any marked difference between
dorsal and ventral, anterior and posterior?

6. Gill Stage.— In a tadpole just hatched observe the be-
ginning of the formation of head, body and tail. There is no
mouth yet present, but on the ventral side of the head are
suckers by which the tadpole adheres temporarily to some
support. Nostrils and eyes are beginning to form, and gill
buds indicate the position of future gills. In a somewhat
later stage finger-like gills are produced upon the sides of
the head. At such a period mouth, eyes, nostrils and tail
are well formed, and the internal organs are undergoing
their development.

7. Tadpole.— Distinguish head, body and tail regions.
What has become of the external gills? The fold of skin
covering the internal gills is the operculum and the opening
to the gill chamber is the spiracle. On which side is the

44 GENERAL BIOLOGY

spiracle found? At this stage the eye, mouth, nostrils and
teeth are well developed. Also on the ventral surface the
heart, internal gills, and coiled intestine will show through
the body wall.

8. Metamorphosis.— The tadpole or fish-like stage con-
tinues for some time (it may be a year or two in frogs) be-
fore a metamorphosis into the adult form begins. This
metamorphosis is first shown by the formation of the hind
legs. Carefully study a tadpole with the hind legs present
and determine the character of sense organs and other ex-
ternal features. The forelegs start their formation within
the gill chamber and are not apparent externally until
they become rather large, when they break through the
skin covering the gills. In a specimen with both fore and
hind legs observe the changes in form of the body and head.
As the legs increase in size what becomes of the tail?

Dissect the ventral body wall from a large tadpole with-
out legs, and also from one with both pairs of legs present.
Determine what changes are taking place in the internal
organs during this time. When the tail is finally absorbed
and the toad or frog leaves the water, the animals are like
adults except for the reproductive organs, which require
a considerable time for their perfect development.

ORGANS, TISSUES AND CELLS.

THE term organism, as used in biology, designates in
general an individual animal or plant, and implies that they
are composed of organs. For example, the ears, eyes, legs
feet, of a dog are familiarly known as organs; and the same
is true of such internal structures as stomach and liver. It
is perhaps not so well known that organs are likewise
complex structures made up of simpler components, and
as in general these are composed of a network of similar
elements they are usually spoken of as tissues. To demon-
strate the organic structure of a frog it is only necessary to
critically observe its external features, or perhaps dissect
and lay open its interior. To demonstrate that organs are
composed of tissues will require the use of the microscope,
and in most cases some means of dissecting and preparing
them for study. This phase of biology is known as micro-
scopic anatomy, or histology. Finally, such a study will
reveal the fact that a given tissue is composed of still more
elemental .structures which are called cells. The following
outline of laboratory study will afford a direct introduction
to these phases of our subject.

1. Mount in water a small fragment of frog epidermis,
and examine with the high power. Make a careful drawing
of a group of cells, showing cell walls, and nuclei.

2. Strip the epidermis from the upper surface of the leaf
of Tradescantia, mount in water and examine. Compare
the shape, size, and general appearance of the cells with
those of the animal epidermis. Make a drawing of a group
of cells.

3. With a razor cut very thin transverse and longitudinal

46 GENERAL BIOLOGY

sections of the stem of Tradescantia, of geranium, begonia,
or other plants, mount these in water and examine. In the
cells near the center of the stem note the shape, arrange-
ment, and cell contents. Look especially for crystals in
these cells. The presence of crystals in the cells indicates
the presence of what kind of material?

4. Cut very thin sections of a potato tuber just beneath
the skin. Mount in water, study and make drawings of
the cells and their contents. Remove the cover glass, add
a drop of dilute iodine solution and allow it to remain for a
few minutes. Wash off the iodine, replace the cover glass
and examine the section again. Since the iodine solution
has the property of turning starch blue what do you con-
clude as to the cell contents in this case?

5. Stems of other plants may be sectioned and treated
in the same manner, and an idea obtained as to the abun-
dance of starch and its position in the plant. What is the
use of this starch? What explanation can you give as to
the differing amounts of starch and of the different places
of storing it in the plants examined?

6. Examine cartilage from a frog or other animal and
make drawings showing the cells and the intercellular sub-
stance. Mount a drop of blood from the frog and examine
with the high power, draw the various kinds of cells found
therein. If possible place this latter slide on a warm stage
and note the effect on the white corpuscles. In what ways
do these cartilage and blood cells differ from the other cells
already studied, and in what ways are they similar? Try
especially to determine what represents the cell walls in
the cartilage.

7. From the data obtained in the above studies write a
careful description of the cell as you understand it. Tell
particularly what you have found concerning the cell con-
tents, and their functions.

PROTOPLASM OR LIVING MATTER.

IN the preceding study it was found that the cells were
of various sizes, shapes, and uses. In some were found
such storage stuffs as starch, fats, and mineral substances,
in others, and indeed most, might have been noted a more
or less homogeneous or granular substance which has come
to be known as protoplasm, a substance which Professor
Huxley aptly called "the physical basis of life," since life is
only known to us in association with this physical material.
While a great deal of investigation has been devoted to the
study of protoplasm, its chemical nature and its physical
structure, and while much has been learned along these lines,
still that which is as yet unknown is much greater. An
elementary course wrould not be the place to undertake a
study of these properties of protoplasm, yet it is not beyond
the scope of even such a course to endeavor to observe some
of its more obvious characteristics, and some of the things
which it does. It will be interesting to study something of
its actual activities, its movements, its behavior under
varying conditions of cold or warmth, and to note perhaps
certain aspects of its structure. Since such study can only
be made with the high power of the microscope it will be
necessary to select living things whose structure is such as
to render them favorable for observation, i. e., those which
are sufficiently transparent to enable one to see through
them and note all that takes place within. Certain plant
cells are especially favorable subjects, as are also some of
the transparent animal organisms, like the common amoeba.

48 GENERAL BIOLOGY

The following types, among others also available, afford
good material for such study.

I. Protoplasmic Movement.

1. Mount some of the healthy, younger leaves of Elodea
in water and with the high power examine their structure.
In the cells look for rather large green bodies, the chlorophyll
bodies. What is their form and how are they arranged in
the cells? These bodies float in a liquid, the protoplasm,
which is so transparent it is exceedingly difficult to see.

Having noticed these features of structure look closely
for any signs of movement in the cell contents. The move-
ment is not rapid nor it is continuous, but you should observe
it in some of the cells of the young leaves. Make a draw-
ing of several cells, showing the chlorophyll bodies, and by
arrows indicate the direction of movement of the -proto-
plasm.

2. Mount a cluster of leaves from the tip of the stem of
the stonewort, Chara or Nitella. The younger, more trans-
parent cells in this cluster should show the circulation of the
protoplasm very clearly. It will be necessary to focus
through the outer layer of the protoplasm wyhich contains
the chlorophyll bodies, the latter being stationary in this
form. Note the direction in which the protoplasm moves,
and whether all the cell contents are involved. Make a
drawing of the cell as seen with the high power, and indicate
by arrows in what direction the protoplasm is moving. It
may be possible to see the nucleus wrhich is carried along by
the currents.

3. In the cultivated spiderwort (Tradescantia) the stream-
ing of protoplasm is beautifully shown. If the flower of
this plant is available take some of the hairs which are

PROTOPLASM OR LIVING MATTER 49

present around the stamens, mount in water and with the
high power observe the protoplasmic movements. Record
your observations in a drawing.

4. If amoeba is at hand observations should be made on
the streaming or flowing movements of the protoplasm.

II. Cib'ary Movement.

In certain cells, particularly of animals, the protoplasm
is extended beyond the free ends of the cells into very del-
icate vibratile filaments called cilia. Mount a small frag-
ment of the gill of a clam, or the cells scraped from the roof
of the frog's mouth, and look for these moving cilia. Possibly
the only sign will be in the currents of water caused by the
movement of the cilia, the latter moving so rapidly they
can scarcely be seen. In a place where the movement is
not so rapid observe the direction in which the cilia move
and whether they change the direction of movement. Make
a drawing.

THE CELL.

CYTOLOGY.

THE unfertilized egg of the starfish is a good example of
a typical cell or egg. Other eggs as those of Cerebratulus,
the large jellyfish Aurelia, or tissue cells, if large, may serve
equally well.

1. Form.— Are the cells alike in shape and size? The
shape of a 'cell, if unconfined, is usually spherical, but in
tissues this form is modified by the pressure of adjacent
cells, or as a result of adaptations for some particular function.

2. Structure.— The essential elements of every cell are
cell protoplasm or cytoplasm, and nucleus. Is there a mem-
brane about the cell? Note the general appearance of the
cytoplasm. Is it granular, fibrillar, or alveolar? Is the
cytoplasm alike in all parts? In some eggs spheres or
granules of yolk are scattered through the cytoplasm. In
what portion of the cell is the nucleus located? Is this
position constant? Is there a membrane about the nucleus?
What is the character of the contents of the nucleus? If
the cell is stained note the granules, or flakes, within the
nucleus which stain more densely. These are spoken of as
the chromatin, the faintly stained, or unstained, material is
achromatin. Is the chromatin arranged in any definite way
as though on a framework? Within the nucleus is often
a rather large, deeply, staining spot, the nucleolus. Is it
in any constant place in the nucleus?

3. Cell Division.— This fundamental feature of living things
presents two rather distinct and definite aspects, namely,

THE CELL 51

mitotic, or indirect division, and amitotic, or direct. The
latter, while apparently simpler, involving the direct di-
vision of nucleus and cytoplasm by a simple pinching into
two parts, is yet less common than the former, and no
attempt will be made to study the process in this connection.

Mitosis.— In sections of the root tip of the onion, or of
the testis of the grasshopper, study the cells which are in
the process of division. Find a stage in which the chromatin
of the nucleus is forming a long tangled thread, or else a
series of densely staining bodies. These bodies produced
from the chromatin of the nucleus are called chromosomes.
Find a cell in w^hich the nuclear membrane is disappearing.
What is the position of the chromosomes? Do you find
a spindle made up of delicate fibers to which the chromo-
somes are attached? In the cells of some organisms there
is a tiny spot, the centrosome, at the end of the spindle and
from this centrosome starlike rays, the aster, radiate into
the cytoplasm.

Next examine a stage where the chromosomes are grouped
into a mass, or plate, at the center of the spindle. At about
this stage each chromosome splits into two parts, and the
halves separate and are drawn toward the poles of the spindle.
In this position the chromosomes lose their distinctness,
form a new nucleus with a membrane, the body of the cell
divides into two parts and we have the division of the cell
completed.

The stage of the formation of the chromosomes and their
arrangement in the spindle is called the prophase of divi-
sion; the splitting of the chromosomes makes up the meta-
phase; the separation and the pulling apart of the chromo-
somes comprises the anaphase ; the formation of a new nucleus
and the division of the cell body is the end or telophase.

Make a drawing of a cell in each phase of division.

52 GENERAL BIOLOGY

It should be clearly understood that the nuclear changes
described above constitute an uninterrupted process. The
separation of the process into distinct -phases or stages is
made for convenience in description and analysis. The prep-
arations on the slides which show the distinct phases, there-
fore, represent cells which were killed in the midst of the
process, and which were permanently fixed in this condition.

4. Cleavage and Development.— In order that an egg may
develop and grow into a new organism several preparatory
processes are essential. First a ripening or maturation
process is necessary for both the female reproductive cells
(ova or eggs) and the male reproductive cells (spermatozoa).
After maturation fertilization must occur, and this consists
in the union of an ovum and a spermatozoon. The fertilized
egg is now capable of further development which is initiated
by a division into cells, a process called cleavage or segmen-
tation.

In dividing starfish eggs look for stages of 2-, 4-, 8- cells.
Are these cells enclosed within a membrane? Are they of
equal size? Each cell continues to divide until a large
number are present, and these are arranged in the form of
a hollow sphere, the blastula. Are all the cells of the blastula
of the same size? Look for other stages in which one side
of the blastula is flattened or pushed into the hollow of the
sphere. Such a stage is spoken of as the gastmla and is
really a double-walled sac or embryo, the outer wall mak-
ing up the ectoderm and the inner the entoderm. Later a
middle layer or mesoderm, is formed between the ectoderm
and the entoderm. These three layers are the germ layers
of the embryo from which are differentiated the organs of
the developing organism.

Study and draw several stages of cleavage, of the blastula
and gastrula formation.

THE CELL 53

In the development of any animal it may be stated that,
from the outer germ layer, or ectoderm are formed the cover-
ing of the body with its protective structures such as scales,
feathers and the like, the nervous system and the sense
organs. The entoderm or inner germ layer gives rise to the
lining of the digestive tube, the gland cells of liver, pan-
creas and stomach, the lining of lungs and trachea. From
the mesoderm are derived the muscle, bone, connective tissue,
blood, heart and bloodvessels, the kidney, reproductive
organs and their ducts.

AMOEBA

THE PROTEUS ANIMALCULE.

AMCEB.E are among the simplest of living things, they
look like tiny drops of clear jelly usually somewhat
granular within. The amoeba will be almost constantly
moving and changing its shape, whence it gets the name of
"proteus" animalcule. This habit of changing the shape
is one of the surest methods of identifying the animal.

Mount on a slide some of the sediment from the dish sup-
posed to contain amoebae, cover with a cover glass and search
for an amoeba with the low power. If one is not found
wait several minutes and examine again; in this time the
amoeba may have crawled out from the sediment. When
an amoeba is found examine with the high power. Be
careful not to move the slide enough to lose the animal.

I. Morphology.

1. Form.— Note the changing shape, and the root-like
prolongations of the body called pseudopodia. Are these
pseudopodia alike? How many are there? Is the number
constant? Can you discover their function? Make a series
of 10 outline drawings (each about an inch long) at intervals
of two or three minutes. By means of arrows indicate the
direction of movement of the protoplasm.

2. Structure.— The protoplasm which makes up the sub-
stance of the animal is composed of an inner part called the
entoplasm, and an outer ectoplasm. How are they dis-
tinguished? May these distinctions be traced into the

AMCEBA 55

pseudopodia? Is the boundary between the two parts a
sharp one? Which layer is the more fluid? Is there a
definite membrane about the animal ?

Within the entoplasm may be seen food vacuoles which
are usually rather small and spherical, though they may be
quite large and of irregular shape, depending upon the kind
of food which has been eaten. Do you find what might be
considered as lifeless material such as crystals, oil drops, and
the like? In the entoplasm may also be found the contractile
vacuole, a transparent, spherical body which disappears and
reappears at intervals. Its function appears to be excretory.

Sometimes the nucleus can be seen. This is a circular or
oval, denser body, usually granular in appearance. Does
it occupy a definite and constant position in the amoeba?
If it cannot be seen in the living animal examine one of the
stained and mounted specimens.

Make a drawing about two inches in diameter, fill in, and
label all the details mentioned above.

II. Physiology.

1. Movements.— Is motion continuous? Regular? How
is it produced? Is there any definiteness of direction?
Watch the formation of a pseudopodium and describe what
part the ectoplasm and entoplasm play in the process. Are
the currents in the entoplasm at all constant? Where are
they the swiftest, where slowest? Trace on paper the path
that an amoeba has taken in the time under observation.

2. Nutrition.— If opportunity oft'ers determine how an
amoeba eats, and how it gets rid of waste matter. From
an examination of the food vacuoles determine, if possible,
what the animal eats. Look especially for diatoms and
desmids and for small protozoa. Is there a definite course

56 GENERAL BIOLOGY

of food particles in the body? Where is the food digested?
How is it distributed ?

3. Sensation.— Does the amoeba ever appear to feel an
object against which it presses? Does it avoid obstacles?
Tap the cover with a needle, are there indications that the
animal has the sense of touch? If the slide is placed upon
a warm stage it may be possible to determine whether the
animal responds to temperature. If heated to 40° C. the
amoeba will be killed.

4. Reproduction.— Occasionally one meets some of the
stages that the animal undergoes in its life history, such as
encysted specimens and specimens undergoing division.
If any of these stages are found examine them with care
and make drawings of them.

Various kinds, or species, of amoebae may be found which
may differ in number, shape and position of the pseudopodia;
in size and abundance of granules in the entoplasm; and
in the presence of a shell about the animal.

PARAMECIUM.

THE SLIPPER ANIMALCULE.

PARAMECIUM is found in water containing decaying
organic matter, i. e., in infusions of organic matter hence
the name infusoria, the class to which the animal belongs.
In nature Paramecium will be found in almost any ditch
or pond which contains much organic matter. In a jar
containing an infusion of hay the paramecia are usually
found near the surface and often in a ring around the edge
of the dish. Mount a drop of water from this region of the
dish, first placing a thin layer of cotton on the slide to trap
the animals, or a solution of gum to lessen the activity.
Examine with the low power.

I. Morphology.

1. Form.— Are there individual differences in size? Can
the animals be seen with the naked eye? In outline the
animal is elliptical or oval, often rather slipper-shaped,
whence comes the name "slipper animalcule." Is the shape
constant under all conditions? Watch one while it is pass-
ing through a narrow space. Is the body rigid or flexible?
Are there definite anterior and posterior ends? If so, how
are they distinguished?

With a piece of clay make a model of the paramecium.
Be careful to get the right proportions and shape.

2. Structure.— Along one side of the animal is a groove
which leads to a mouth opening. The most satisfactory

58 GENERAL &IOLOGY

way to observe this groove, the buccal groove, is to watch
the animal as it rotates on the long axis (use the low power).
In the clay model already constructed indicate the position
and shape of this groove.

Examine with the high power. If the movements are
not sufficiently restricted to allow the examination of speci-
mens with the high power, place them in a rather thick
gelatin solution, which will retard their movements. Or one
may try the following scheme: on a slide without cotton place
a drop of the water containing the animals and cover with
the cover glass. With a piece of filter paper applied to the
edge of the cover glass slowly draw some of the water from
under the cover. Continue until the cover begins to touch
the animals and to flatten them slightly. At this point it
will be found that the paramecia do not have room to move
about and, being flattened somewhat, the internal structure
is more evident. The success depends upon the remova
of just the right amount of water. Remember the shape
of the animals under these conditions is considerably dis-
torted, and some of the structures are not normal.

Can you distinguish an ectoplasm and an entoplasm? In
what ways are these like, or unlike, the same parts of amoeba?
In a quiet specimen observe the ectoplasm carefully and
look for a delicate outer layer, the cuticle, which serves as
a cell wall. Fine, hair-like, protoplasmic processes, the
cilia, project from the surface of the body. Are these cilia
present on all parts of the body? Are they of uniform
length? In the deeper part of the ectoplasm are minute
oval sacs called trichocysts, arranged perpendicular to the
surface. Very often they look like short stiff rods rather than
sacs. The contents of these sacs may be forced out beyond
the cilia, or even entirely out of the body, and appear as
rather thick threads in the water. The tangle of threads

PARAMECIUM 59

so produced seems to serve as something of a protection to
Paramecium.

Within the entoplasm are food vacuoles, masses of food
forming little spheres or globules and surrounded by a little
liquid. Are these of the same size? Where in the body
are they most abundant? Do they resemble the food
vacuoles of amreba? Do you find contractile vacuoles?
How many? Where situated? Is the contraction or the
expansion more rapid? Just after the disappearance of
the vacuole look closely for radiating canals in the same
region. If more than one vacuole is present observe whether
they contract and expand together. What is the nature
of the contents of the contractile vacuoles? What function
might they serve?

The nucleus can rarely be seen in the living animal. In
order to render it. visible place a drop of methyl green near
the cover glass and draw it underneath by the -use of filter
paper. When the excess of stain is replaced by clean water,
the nucleus should be visible as a green spot. In what part
of the body is the nucleus? This nucleus is called the
macronucleus and is rather large; by its side is a smaller
nucleus, the micronucleus, which is difficult to demonstrate
except by special means of preparation.

A drawing about four inches long should be made and in
it should be represented all the details of structure mentioned
above. Also make a drawing of an ideal cross section of
the animal through the middle region of the body.

II. Physiology.

1. Movements.— In what directions may the animal move?
What are the means of locomotion? Run some powdered
carmine under the cover glass and observe the currents

60 GENERAL BIOLOGY

produced by the action of the cilia. What is the general
direction over the surface of the body? In the mouth
groove?

2. Defense.— Run some dilute picric acid under the cover
and observe the trichocysts which are thrown out. In a
drawing show the trichocysts and the cilia.

3. Nutrition.— (a) Ingestion of food.— Place some para-
mecia on a slide with a small amount of powdered carmine
in water and watch the formation of a food ball in the gullet,
and the way in which it is taken into the body. When it
gets into the body it becomes a food vacuole.

(6) Nature of the Food.— Study the contents of the food
vacuoles found naturally in the body and determine, if
possible, what the Paramecium feeds upon, especially
whether it is plant or animal food.

(c) Digestion.— Observe the changes in form, size and
amount which take place in the food as it passes through
the body. Are there changes in the food vacuole? What
do they mean?

4. Circulation of the Protoplasm. —Watch the food vacuoles,
especially after having added the carmine, and see whether
they change their position in the body. If there is any
movement make an outline drawing and show by arrows
the course of the circulation.

5. Irritability.— What reasons are there for believing that
Paramecium is sensitive to external influences? Do they
avoid objects? Do they collide with each other in motion?
Do they tend to collect in masses? Where? Why? Are
they as active at the end of the hour as at the beginning?
Why ? Is the animal sensitive to touch or pressure ?

6. Reproduction. — (a) .Fission.— This is the usual method of
reproduction and consists in the division of the animal into
two parts. At what part of the body and in what direction

PARAMECIUM 61

is the line of division? Can one speak of "parent" and
"offspring"? Stain the dividing animals with methyl green
and note what changes are taking place in the nucleus.

(6) Conjugation.— This is of less common occurrence
and depends in part upon the physiological condition of the
animals. Look for pairs of individuals which are joined
together by the buccal groove. This contact of the animals
is only temporary for they later separate; in the meantime,
however, portions of the nuclei have been exchanged. If
slides with stained specimens showing conjugation are at
hand examine them for the nuclear changes involved. Is
there any distinction of sex in these conjugating individuals?

VORTICELLA.

THE BELL ANIMALCULE.

MOUNT some of the scum from the top of the water in
a jar containing Vorticella, and look for tiny bell shaped
organisms borne on a stalk. They are much smaller than
Paramecium and are usually in groups or colonies. Be
sure that there is plenty of water and that the cover does
not press on the animals and distort them. It will not be
necessary to have a layer of cotton on the slide, since the
animals are fastened to a stalk and will not swim away.

I. Morphology.

1. The Stalk.— What is its shape? Its length as com-
pared with its width? Its shape when it is contracted and
when expanded? In the stalk there is present cuticle and
ectoplasm but no entoplasm. The central axis (ectoplasm)
is usually easily seen. Does it run through the exact center
of the stalk? With your highest power study the structure
of this stalk and make a drawing of it, very much magnified,
showing how it is constructed and how it connects with the
body of the animal. Can you give any explanation for the
coiling of the stalk when it contracts?

2. The Body.— What is the shape when seen from above?
from the side? When the animal is contracted? when
it is fully expanded? In a fully expanded individual note
the peristome or rounded edge of the bell. Does it extend
completely around the bell? The top of the animal is

VORTICELLA 63

raised in the form of a dome or plate, forming the disk.
Between the peristome and the disk is a gutter-like depres-
sion leading into a deep pit, the vestibule. Is there anything
in Paramecium which corresponds to this vestibule? From
the vestibule the esophagus extends downward. Trace its
direction and determine its shape. In Vorticella where
are the cilia located and how are they arranged?

In the body look for a transparent covering, the cuticle.
Is there ectoplasm and entoplasm as in Amoeba and Para-
mecium? Is the differentiation of these layers as marked
as in the other protozoa studied? Are food vacuoles present?
Are there contractile vacuoles ? How many? Where located?
The nucleus is an elongated horse shoe or "C" shaped mass
in the entoplasm. It may be more easily found if the animals
are stained with methyl green. A micronucleus is present,
but is so small as to be found only with great difficulty.

II. Physiology.

1. General Movements.— Observe the manner in which the
stalk contracts. What changes take place in the body
during this contraction? May the body contract without
a contraction of the stalk? Note the rapidity of the move-
ments in the contraction and in the expansion. How does
the animal assume the expanded condition? Which is the
part to first assume the expanded condition? Note that
in some cases there is no stalk attached to the animals. How
do they behave when this is the case? Vorticella may
separate from its stalk and become free-swimming for a time.
During this period a second row of cilia develops about the
base of the bell, to aid in locomotion. (In some cases this
separation from the stalk is not normal, but is due to pressure
from the cover glass or to some other unusual condition; in

64 GENERAL BIOLOGY

such instances the cilia are like those in the normal stalked
form.)

2. Ciliary Movements. —Add powdered carmine to the
water and observe the directions of the currents produced
and also the method of feeding. Watch the formation of
a food vacuole. If there is a movement of these in the body
indicate by arrows in a drawing the course taken.

3. Irritability.— Notice what happens when the slide or
cover is tapped, and when the animal is touched by some-
thing. Is Vorticella more or less sensitive than Paramecium ?
Does it always contract when it touches something? Ex-
plain.

4. Reproduction. — (a) Fission. Look for individuals un-
dergoing fission. Where does the division begin? In what
direction does the division take place? After the division
is completed one of the two new animals separates from the
stalk, swims away and later settles down, forming a new
stalk.

(6) Conjugation.— Individuals may rarely be found under-
going conjugation. In Vorticella this involves the per-
manent union and fusion of a small individual with one of
the normal stalked forms.

Questions on the Protozoa in General.

Tell something of the shape of protozoa, of their size. Is
the body symmetrical? Is the shape constant? Is there
any distinction of the animals into regions? What sorts
of motions have the animals? How are these movements
produced? Do all the protozoa examined have the same
motor apparatus? Does the body contain blood and is a
heart present? Is there anything corresponding to stomach,
lungs, or gills? Do the animals eat, digest food, breathe,

VORTICELLA 65

see, feel? Do they have nerves or brain? If the organs
needed for performing these functions in other animals are
absent in the protozoa, how can you account for the fact
that they do perform these functions?

Is the protoplasm protected in any way? What means
of defense have they? How can one account for their wide
distribution and abundance?

In what ways do these single celled animals differ from
the single cells of plants and of higher animals? In what
ways do they resemble each other? Could single cells from
the many-celled animals exist alone as do the Protozoa?

Write a brief paper answering the questions above and
discuss the points suggested.

PLEUROCOCCUS.

PLEUROCOCCUS is a unicellular plant, growing on damp
stones or ground, and is very common upon the trunks of
trees.

I. Morphology.

1. General Structure.— Note the appearance of Pleuro-
coccus in its natural growth on a piece of bark or damp wood.
Is it evenly distributed over the surface? Compare several
specimens of bark on this point. What is the color? Does
it vary in different specimens? Compare pieces of dry bark,
and those which have been in a moist place for several days.

2. Minute Structure.— Scrape bits of the plant from the
bark and mount on a slide with water. Examine first
with the low power, arid then with the high power of the
microscope. Note the form of the cells, and whether they
are single or associated in definite groups. Make drawings
of any different appearances found.

Is there a cell wall? What is its color? Can the proto-
plasm be seen? The green color of the plant is due to the
presence of chlorophyll; usually this is distributed through-
out the protoplasm, though it may be in several distinct
chloroplasts or chlorophyll bodies. Is there any nucleus
which can be seen in the living cells?

n. Reproduction.

Look for cells which are in the process of division to form
groups of two, three, four or more cells. This is the ordinary

PLEUROCOCCUS 67

mode of propagation by Pleurococcus. Is there any regular
order in the number of cells produced ?

In some unicellular plants similar to Pleurococcus an-
other sort of reproduction occurs, viz., by a division within
the cell there are formed a number of motile cells called
zoospores. These may be of two sizes, the larger ones called
macrozobspores, and the smaller ones microzoospores. Lo-
comotion of these spores is by means of flagella. Can you
suggest any advantage in having a zoospore stage? A
conjugation of macrozoospores and microzoospores may

COLONIAL PROTOZOA.

AMONG protozoa are to be found various species which,
instead of becoming independent and separating from their
fellows at once after division, remain for some time, or per-
manently, associated in colonies. The formation of groups
or companies was noted in Vorticella. Other vorticella-
like animals (Carchesium, Epistylis) may be grouped into
permanent, branching, tree-like masses. Gonium, Pandorina,
Volvox, are well-known examples of free-swimming colonies.
Such forms are especially interesting for they show the be-
ginning of differentiation and complexity in a phylum com-
prising the simplest organisms. They are further interesting,
(a) in suggesting a possible origin of multicellular organisms ;
(6) in that their animal or plant affinities are still open to
question.

As a type of these colonial forms Volvox is suggested for
study. It may often be collected in the spring or fall from
small lakes or ponds containing Riccia, duck-weed and other
plants. By stocking jars from the water of ponds where
the organisms are found, and maintaining conditions as
nearly normal as possible, they may be kept in the labora-
tory for several weeks.

I. Morphology.

1. Form of Colony. -What is the general shape? Color?
If living, note the movements of the colony and determine
how it is produced. Of how many kinds of cells is the

COLONIAL PROTOZOA 69

colony composed? How do they differ in size, position,
and shape?

2. Structure.— Note the size, shape, and large number of
cells which make up the body of the organism. How are
the cells connected with each other? Under high power
make out the flagella of the cells. How many has each cell?
With what part of the cell are they connected?

Make a careful drawing of a group of cells, their structure,
and connection to other cells.

n. Physiology.

1. Reproduction. — (a) Asexual. Certain cells, partheno-
gonidia, migrate from the outer wall into the interior of the
sphere and there, without fertilization, give rise to small
colonies by repeated divisions.

(6) Sexual.— Other cells which move into the interior of
the sphere are specialized reproductive cells. The egg
(macrogamete) is large, the spermatozoids (microgametes)
are small. These two kinds of cells fuse or conjugate and
the fertilized egg develops into a new colony.

Make drawings of different stages of reproduction, both
sexual and asexual.

Would you regard Volvox as a unicellular colony or as a
very simple multicellular organism? Give reasons for your
conclusion.

SPIBOGYRA.

POND SCUM.

SPIROGYRA is a filamentous alga common in ponds,
ditches, or sluggish streams during the summer months,
usually floating on the surface or adhering lightly to some
support. It is often called "pond scum," "frog-spittle,"
"brook-silk." The scientific name comes from the spiral
arrangement of the chlorophyll in the cells. The alga may
be collected late in the fall and kept in aquaria all winter,
usually in good condition.

I. Morphology.

1. General Characters.— Note the color, texture, slippery
feeling. Do different masses show variations in these
respects ? To what extent ?

2. Microscopic Characters.— Mount a few filaments in
water and examine with low, and with high powers.

(a) Shape of Filament.— Is it simple or branched? Is
it of uniform size? Are there signs of roots? Is there a
root end or a tip to the filament?

(6) Structure.— Is the filament composed of cells? If
so are they of uniform size? Note any variations. How
are the cells united? Is a cell wall clearly distinguishable?
Is it of uniform thickness over all portions of the cell? Stain
the filament by running a drop of iodine under the cover
glass and note effects on all parts of the cell. Are there
indications of starch?

SPIROGYRA 71

Mount fresh filaments and study the chlorophyll bands,
or chloroplasts. What is their general form? How many
in a cell? How many spirals of the chloroplast in a single
cell? Note the form of the margin of the band. What
relation has ;this to certain round bodies, the pyrenoids,
situated at regular intervals along the bands? Test for
starch in the pyrenoids and surrounding granules.

(c) Nucleus.— Examine the cells in both fresh and stained
condition for the nucleus. Does it occupy the same position
in all cells ? What is its shape ?

Make drawings to show the points observed.

II. Physiology.

1. Plasmolysis.— In fresh specimens look for a very deli-
cate film of protoplasm lining the cell wall. If it cannot
be found in fresh specimens try the following experiment of
plasmolyzing the cell: Run a few drops of a 10 per cent
solution of salt or sugar under the cover glass, and note
what happens to the protoplasm. Is there any change in
the cell wall? In the chloroplast? During the experiment,
and probably before, vacuoles will have been noted in the
cells. What effect had plasmolysis upon these? Explain.

2. Photosynthesis.— Study the effects of light on starch
making by examining specimens which have been kept in
the dark for twenty-four hours and testing for starch. Com-
pare with specimens which have been freely exposed to light.
What conclusions may be drawn?

3. Reproduction.— Occasionally during the summer or
fall Spirogyra may be found in the process of conjugation.
This consists in the union of cells of two parallel filaments
lying close together by outgrowths of tubular processes
from each cell, and their final fusion with those of the adjacent

72 GENERAL BIOLOGY

cell. In this way there is a fusion of the protoplasm of the
two cells.

If filaments are found in this condition note any differences
in color and size of the filaments and cells, as compared with
the ordinary condition. Are all the cells of the filaments
undergoing conjugation in the same stages of conjugation?
Does the chloroplast take part in the process?

The result of this conjugation is the formation of a zygo-
spore. What is its shape? Color? Size? Are zygospores
found in cells of both the conjugating filaments? Is there
any indication of sexual distinction in the two filaments?
In what condition are the old cells after conjugation is com-
plete?

SPONGE.

GRANTIA SP.

A FEW sponges are found in fresh water, but most are
marine; the latter are found in all parts of the world under a
great variety of conditions. Grantia is a solitary form,
not producing colonies as do many others, though buds at
its base may temporarily make a small colony. It is per-
manently attached to rocks, piles and sea-weed below low-
water mark.

I. External Anatomy.

Place a specimen in a watch glass in water or alcohol.
Observe the form of the animal, and its mode of attach-
ment. At the free end note the opening, the osculum,
partly covered and protected by a cluster of spicules. This
opening is not a mouth, but an excurrent opening for the
discharge of water from the animal. In the sides of the
animal are many minute openings, the incurrent pores or
ostia. Are these covered or protected by spicules like the
osculum?

Make a drawing of a specimen.

II. Internal Anatomy.

With a razor cut a dry specimen longitudinally and ex-
amine the section with a lens. Observe the central cavity
and the small pores, the apopyles, which pierce its wall. In
the walls find a series of canals arranged in radial fashion.

74 GENERAL BIOLOGY

These are of two sorts, incurrent canals open to the outside,
and radial canals or flagellated chambers which open into
the central cavity.
Draw the sectioned specimen.

III. Microscopic Sections.

Study stained sections made transversely through a
decalcified specimen. Make a careful study of the arrange-
ments of the parallel tubes in the walls, and their relation
to the central cavity. Are the tubes open at both ends?
Is it possible to distinguish the incurrent and the radial
canals? What structural features make this distinction
possible? Are there any openings, the prosopyles, between
the incurrent and radial canals?

With the highest power examine the cells. The central
cavity is lined by flat or pavement epithelium; the radial
canals are lined by peculiar cells, the gastral epithelium, or
choanocytes, which are elongated cells bearing flagella; the
incurrent canals and the outer surface of the body are cov-
ered with flattened cells, the dermal epithelium. Scattered
through the sections may be found germ cells, sperms or
eggs or segmenting eggs. Observe especially their location
with regard to the cellular layers.

Make a careful drawing of a portion of a transverse
section.

IV. Skeleton.

If a specimen is boiled in caustic' potash the fleshy matter
will be destroyed, leaving only the skeleton. The latter is
made up of a series of spicules embedded in the flesh. Mount
some of these loose spicules in water and examine with
the microscope. Draw the different kinds found.

HYDRA.

HYDRA is found in ponds and lakes which contain pond
weeds such as, Elodea, Sagittaria, water-lilies, duck weed,
and the like, usually being attached to these plants. Speci-
mens secured . from such localities and placed in aquaria
with aquatic plants will live indefinitely, if supplied with
food in the form of small Crustacea or "water-fleas."

From the aquaria in the laboratory remove hydra with
a clean pipette and place in a watch glass with water from
the aquarium. Place this dish on the stage of the dissecting
microscope and examine the specimens.

I. Morphology.

1. Form.— Describe the shape and color of the animal.
Is the body differentiated into regions as head and base?
Is it attached or free? Do the length and breadth remain
constant? At the free end of the body is a row of tentacles,
how many are there? Is the number the same in all speci-
mens? Compare notes with other students to determine
this. If both the green and the brown hydra are available
compare them in number of tentacles. Are the tentacles
smooth and even in contour? Compare the length and the
shape of the tentacles when expanded and when contracted.
Within the circle of tentacles is a small opening, the mouth,
often difficult to see in living animals.

On the larger, mature, animals will often be found pro-
cesses resembling the hydra. These are young hydras, or

76 GENERAL BIOLOGY

buds, and -this budding is the common method of repro-
duction. What become of the buds? Are colonies formed
by budding? Why?

Make an outline drawing of the animal in the expanded
condition, and one of the contracted animal.

2. Minute Structure.— Place the dish containing the hydra
on the stage of the compound microscope and examine with
the low power; or place the hydra on a slide and cover with
a cover glass, supporting the latter to prevent crushing the
animal. Is there a cavity (the enteron or digestive cavity)
in the animal? Does the cavity extend into the tentacles?
Sometimes small particles may be seen floating in the cavity
of the body or tentacles, or even passing from the enteron
into the tentacles. From this fact what inference may be
drawn as to the structure of the tentacles and their mode
of nutrition?

Observe that the body is composed of layers (tissues),
an outer ectoderm and an inner entoderm. Which of these
layers is thicker? Are the layers made up of cells? In
which layer is the coloring matter located? Is the color
evenly diffused or is it segregated into distinct bodies?

Draw a portion of the body enlarged to show the layers;
also show the cells if it is possible to determine their outlines.

With the high power observe an extended tentacle. Do
you find ectoderm and entoderm? Are cells present? Note
the knobs on the tentacles, composed of oval, transparent,
bladder-like bodies or cells. These are the stinging cells
(nematocysts or thread cells) which represent modified
ectoderm cells. Where are the nematocysts most abundant?
Is there any definite arrangement of these cells? From
the outer end of each of these cells projects a stiff hair-like
process, the trigger or cnidocil. Within the capsule of the
cell is a coiled thread which may sometimes be made out

HYDRA 77

with the high power. The nematocysts may be discharged
from the body and the thread thrown out, this serving to
secure prey or to protect the animal. The capsule of the
cell contains a fluid which escapes through the thread, and
kills or paralyzes small animals. By gently tapping on
the cover glass above the animal, or by introducing beneath
the cover some irritating fluid as dilute acetic acid or iodine,
one may cause a discharge of the nematocysts. Study
such discharged cells and observe the capsule, the thread
and the barbs.

Drawings should be made to show the structures worked
out.

H. Physiology.

1. Irritability. — Touch various regions of the body with
a needle and note results. Is hydra sensitive? Are the
several parts equally sensitive? Jar the table or the slide.
What does the hydra do?

2. Contractility. — Does the body of the animal show
spontaneous movements? Do the tentacles show the same
properties? Does the contraction of the tentacles and body,
or of all the tentacles, take place at the same time, or is
there independent movement and contraction? What
effects on the shape of the body do the various movements
produce? Do the movements seem to be definitely co-
ordinated or purposeful?

3. Locomotion.— Does the animal remain fastened in one
place in the aquarium or does it move about? On the out-
side of the aquarium make a mark to locate the position of
an individual. Make several observations after some hours
or days and determine whether the specimen has moved.

4. Heliotropism, or movements in response to light. Ex-
amine hydra in the aquarium. Are specimens arranged

78 GENERAL BIOLOGY

or distributed in any special relation to light? Note where
the specimens are most abundant, rotate the jar 90 to
180 degrees and observe again after several days. Have
the hydras retained the old position or are they in a new
part of the jar? Are they in the same position, relative
to the source of light, that they were before the jar was
moved?

5. Food Taking.— It is possible to artificially feed specimens
by suspending bits of raw beef within reach of the tentacles,
or by placing it in watch glasses with hydra. The method
of capturing prey may often be observed by placing water-
fleas in a jar or watch glass containing hydra.

6. Reproduction. — (a) Asexual. The presence of buds
has already been noted. How does the process take place?
In what ways does it differ from the process of fission in the
protozoa? What becomes of the bud? What parts of
the body are involved in the formation of the bud? DrawT.

(6) Sexual.— The same individual usually produces both
male and female reproductive products. The spermaries
(testes or male organs) will be found, if present, as small
conical elevations on the body just below the tentacles.
If these are mature the microscope may show active move-
ments on the inside; this is caused by the swimming of the
spermatozoa within the testis. If the testis is ruptured the
spermatozoa may be seen swimming about in the water.
Is there more than a single testis on one animal?

The ovaries (egg-producing or female organs) usually
develop later than the testes and will therefore not be found
on the same animal that shows the male organs. The ovaries
are larger than the testes, more spherical, and occur near
the base of the animal. Within the ovary may sometimes
be seen the single large egg or ovum. Is there more than a
single ovary on one animal?

HYDRA 79

Which of the layers of the body is involved in the form-
ation of the reproductive organs? Make drawings.

III. Sections of the Body.

On the slides are thin sections of the body cut transversely,
that is at right angles to the long axis of the body. These
sections have been colored to render them more distinct.
Distinguish the ectoderm and entoderm. How are they
separated ? How does the supporting layer which separates
them differ from the ectoderm and entoderm? Is the
ectoderm of uniform thickness? Note shape, size and con-
tents of the cells. At the inner ends of the cells may some-
times be found muscular prolongations of the ectoderm
cells. Between the bases of the ectoderm cells are smaller
cells not extending to the surface. These are interstitial
cells and from them arise the nematocysts and the repro-
ductive cells.

Compare the cells of the entoderm with those of the
ectoderm in shape, size and contents. Look for gland cells
in the entoderm. These will appear as more deeply stain-
ing cells between the ends of the cells which border on the
enteron ; they secrete digestive enzymes.

Draw a portion of the section much enlarged showing,
especially, the cell structure.

HYDROID.

PENNARIA TIARELLA.

PENNARIA is a colonial, marine animal growing on sea-
weed, on the piles of docks, and in similar places. It is
a relative of the fresh water polyp, which has already been
studied.

1. The Colony.— Examine a portion of the colony with a
lens, and note that it consists of a stem with branches, each
terminated by a flask-shaped body. This body is called
the hydranth or zob'id, and represents a single individual of
the colony comparable to an entire hydra. Are all hydranths
alike in form and size? What is the general form and char-
acter of the colony? Is there any definite order to the
branching? How is the colony attached? This basal
portion, the hydrorhiza, is really a creeping portion of the
stem. Do young stems arise from it? In the stem the
central axis, which is the fleshy part of the animal, is called
the cosnosarc, and it is surrounded by a horny, dark colored,
protective sheath, the perisarc. Does the perisarc cover
all parts of the colony?

Make a drawing of the colony about twice natural size,
showing its habit of growth.

2. Hydranth.— Place a portion of a colony in a watch
glass or on a slide and with the low power of the compound
microscope make out the form and shape of a single hydranth.
Are tentacles present? How many? How arranged? Are
the tentacles alike? If more than one kind is found note

HYDRO ID 81

the points of difference. A mouth is present at the tip of
the hydranth, but, unless open, will not readily be found.
Is there a cavity present as there was in hydra? Does it
extend into the stem and the tentacles?

Make an enlarged drawing of a single hydranth with a
portion of the adjacent stem.

With the high power examine the different tentacles of a
hydranth with care and make out the ectoderm and the
entoderm, and the boundaries of the cells. Are the tentacles
alike in the arrangement and relative size of the layers and
of the cells? Are they hollow as in Hydra? Look for
bladder-like, oval, transparent cells in the tentacles (the
nematocysts or stinging cells). Note their size and arrange-
ment.

Make drawings of portions of the different tentacles as
seen under the high power.

3. Reproduction.— Reproduction in, Pennaria, and in the
hydroids generally, is of two kinds, asexual and sexual.

(a) Asexual.— The entire colony is produced by budding.
Look for buds on the sides of the stem, just below the hy-
dranths. These buds produce new hydranths, and there-
by increase the size of the colony. Other buds are formed
on the sides of the hydranths, these are called medusae and
when they are full grown they separate from the hydranth
and float freely in the water. They have the power of
locomotion and swim about as distinct individuals. If
possible make out the structure of the larger ones.

(6) Sexual.— The medusae formed by budding from the
sides of the hydranths are sexual individuals, and they pro-
duce either. eggs or spermatozoa. The eggs and the sper-
matozoa are ripe when the medusae are liberated, and are
cast into the water where fertilization occurs. The fertilized
egg develops into a free swimming larva which after a time

82 GENERAL BIOLOGY

settles down, fastens itself to some body and grows into a
polyp or hydranth, which by budding produces a new
hydroid colony.

The life cycle of this animal is, therefore, somewhat com-
plicated and involves an alternation of generations. A
hydroid, we have seen, by asexual budding produces a
medusa, and this through sex cells gives rise to a hydroid
colony. There is, therefore, an alternation of the asexual
and the sexual methods of reproduction.

HYDROID.

OBELIA OR CAMPANULARIA.

THIS hydroid has about the same mode of life and lives
in the same places as Pennaria.

With a lens examine a colony making out the stem, branches
hydrorhiza, and hydranths. Compare with Pennaria on
these points. Make a drawing of the colony showing its
habit of growth.

With the compound microscope examine the colony more
carefully and discover whether there is a perisarc as in
Pennaria. Does it differ from that in the other hydroid?
In these hydroids the perisarc at the end of each branch
widens out to form a funnel-shaped enlargement (the hy-
drotheca) which may entirely enclose the hydranth. Why
are some hydranths entirely enclosed within hydrothecse,
while others extend beyond this? The perisarc around the
stem, and around the hydranth as well, is of a horny con-
sistency and has been secreted by the ectoderm cells of the
coenosarc. When this was taking place the ectoderm was
in contact with the perisarc. Examine the colony closely
and find different stages in the formation of a hydro theca.

Compare the hydranth with that of Pennaria in size,
shape and structure. How many tentacles are there? How
are they arranged? Are they alike? Note the mouth,
which is at the end of an enlargement, the proboscis or
hypostome. How is the hydranth supported in the hy-
drotheca?

84 GENERAL BIOLOGY

Make an enlarged drawing of an expanded and another
of a contracted hydranth.

Examine a tentacle with the high power and find the
ectoderm and the entoderra layers, and the outlines of the
cells of these layers. How does the tentacle differ from
that of hydra, and from that of Pennaria? Are nematocysts
present? Where are they located? Make a drawing of
the basal portion of a tentacle showing the cell outlines.

Look for branches which have an elongate, rather club-
shaped, enlargement of the perisarc. The ccenosarc within
will show no tentacles and no mouth. This is the gonangium,
or receptacle containing reproductive buds. The ccenosarc
forms a central core the blastostyle, which is a modified
hydranth body; from the sides of this are budded off small
medusae. . These medusae become free, escape from the
gonangium and swim away. Unlike Pennaria the medusae
of Obelia are not sexually mature at the time of escape, but
the eggs or spermatozoa are formed only after several weeks
of active life. The eggs -develop into new hydroids as in
Pennaria, the same alternation of generations being shown.

Draw a gonangium.

Campanularia differs from Obelia chiefly in its repro-
ductive process. In Campanularia no medusae are formed,
but within the gonangium eggs or sperms are produced.
Fertilization occurs within the gonangium and the egg
develops into a free swimming larva (planula) which escapes
from the gonangium. The planula fixes itself and trans-
forms directly into a polyp, which buds and produces a
colony.

THE MEDUSA.

GONIONEMUS MURBACHII.

THE medusae formed by the hydroids studied, Pennaria
and Obelia, are so small that their structure can be made
out only with some difficulty. Therefore, a larger medusa is
taken as a type for study. Although Gonionemus does not
belong to the same order as the hydroids described, and the
hydroid stage -is greatly reduced, it has about the same
structure as the medusae which are formed from these hy-
droids.

Place specimens in a watch glass with water and examine
with a lens. The umbrella or bell shape is rather character-
istic of all medusae. The external convex part is called the
exumbrella or aboral, and the concave part is the subumbrella
or oral side. The under part of the medusa is partly closed
by a membrane called the velum, or veil. Where are the
tentacles? Are they alike. How many are there? Are
they regularly arranged? Are nematocysts present? If
so note their arrangement. Near the tip of the tentacle is
an adhesive or muscular pad used by the medusa for hold-
ing against some object.

Within the subumbrellar space note the central hanging
sac, the manubrium or stomach. Is a mouth present? A
gastric cavity? How does the mouth differ from that of
the hydroids? Note the radial canals, delicate tubes which
extend outward from the center of the bell. How many
canals are there? Is the number the same in all specimens?

86 GENERAL BIOLOGY

Are they symmetrically arranged? Do they join the gastric
cavity? The canals extend to the periphery of the bell and
open into a marginal canal which extends completely around
the medusa and communicates with the hollow tentacles.
Why is there such a system of canals in the medusa and not
in the polyp?

Hanging from the under surface of the canals are large,
convoluted, ribbon-like organs, brownish in color. These
are the reproductive organs. The medusae are males or
females, but the reproductive organs look alike.

Draw the entire medusa from the side; also from the
oral aspect. Draw a portion of a tentacle showing the
arrangement of the nematocysts, and the adhesive organ.

EARTHWORM.

LUMBRICUS SP.

PLACE the worm in the dissecting pan with enough-
water to cover it. What is the form of the body? Does
it vary in any part? What is the color? Does it vary?
Has the body any protective covering? Are there append-
ages such as legs? Are there gills or other respiratory struc-
tures? Are there organs of hearing or sight?

I. External Anatomy.

1. General Features.— Notice the regular segmentation
of the body into a series of rings, somites or metameres.
How many? Compare with the number found on other
specimens and indicate whether it is constant. Are the
somites of the same size and form throughout? Notice
the prostomium projecting from the first somite, and the
clitellum or girdle about one-third of the way back from the
anterior end. Which segments make up the clitellum?
In what way does this part of the body differ from the rest?
The clitellum is composed of glands in the skin which secrete
a substance to form the cocoon or case in which the eggs
are deposited.

2. Regions of the Body. — Distinguish an anterior or head
end, and a posterior or tail end. Is there a definite head?
How are the dorsal and ventral sides differentiated? Are

88 GENERAL BIOLOGY

these distinctions equally marked in all parts of the body?
Are the two sides of the animal alike? If so, it is said to
be bilaterally symmetrical.

3. Setae are short, horny spines embedded in the body
wall but projecting a little. They aid in locomotion. They
may be felt by rubbing the finger over the ventral surface
of the body. If this region is examined with a lens the
seta? will be seen as tiny brown spots. How many are there
on each somite ? How are they arranged ?

4. Openings of the Body.— The mouth will be found on
the ventral side of the body at the first somite. What is
the position of the mouth relative to the prostomium? At
the end of the last segment of the body is the anus, the
posterior end of the digestive tube. On the ventral side
of the fifteenth somite are the openings of the testes, called
the sperm ducts, one on either side surrounded by swollen
lips. The ovaries open through the oviducts on the ventral
side of the fourteenth somite, but they are not surrounded
by swollen lips. The openings to the sperm receptacles,
of which there are two pairs, are situated in the grooves
between the ninth and tenth and the tenth and eleventh
somites, and are on the sides of the animal in the same line
as the lateral rows of setae.

The openings of the excretory organs are found in each
segment on the ventral surface a little anterior to the outer
seta of the ventral row. They are not very plain, but with
a lens will usually show well on some somites. The dorsal
pores, which communicate with the ccelomie cavity, are in
the middorsal line and open in the grooves between the
somites.

Draw the anterior and the posterior parts of the body
to show all that you have observed.

EARTHWORM 89

II. Internal Anatomy.

With the scissors cut through the body wall in the mid-
dorsal line from about the middle of the body to the third
somite, taking care not to cut the viscera lying beneath.
Carefully cut the membranous partitions, the septa, at the
points where they join the body wall and pin back the flaps
of the latter. Notice that the body wall forms a tube in
whose cavity, the body cavity or coelom, lies another tube,
the alimentary or digestive tube: also that the septa divide
the body cavity into smaller chambers. What relation is
there between the septa and the external segmentation?
Observe first the alimentary canal which extends through
the animal; also several pairs of conspicuous white bodies
near the anterior end. The latter are the sperm sacs.

1. Circulatory System.— This system is a series of closed
tubes consisting of several longitudinal vessels and many
circular vessels connecting them. The largest of the longitu-
dinal vessels, the dorsal vessel, is in the middorsal line
against the alimentary canal. Beneath the intestine is
the ventral vessel which will be seen later when the alimentary
canal is removed, and ventral to the nerve cord is a third
longitudinal vessel, the subneural vessel. The circular
vessels extend between the dorsal and the ventral vessels
and occur in pairs. Five pairs of these circular vessels in
the anterior region (somites seven to eleven) are very large,
and being contractile are called hearts; the dorsal vessel is
also contractile. Carefully dissect away the septa and
expose the hearts.

2. Reproductive System.— The earthworm is a hermaph-
rodite animal containing both the male and the female
organs in a single individual.

90 GENERAL BIOLOGY

(a) The Male Organs. —The sperm sacs, or seminal vesicles,
lying in somites ten to fourteen are large white organs, com-
posed of several lobes. In these the spermatozoa under-
go a portion of their development. There are two pairs of
spermaries or testes enclosed within the seminal vesicles,
but they are so minute as to render their dissection very
difficult.

(6) The Female Organs.— The sperm receptacles are two
pairs of spherical, whitish or yellowish sacs beneath the
sperm sacs, in the ninth and tenth somites. In these re-
ceptacles the spermatozoa received from another worm are
stored, and from them the sperms are passed into the egg
case in which the eggs are laid. The ovaries (one pair),
are small organs near the median line, attached to the
anterior septum of the thirteenth somite. They will be
rather hard to find. Posterior to them are funnel-shaped
openings which lead into the oviducts, and these in turn
open to the exterior at the fourteenth somite.

Earthworms meet and pair at night in May and June,
and the sperm receptacles of each are filled writh spermatozoa
from the other worm. They separate and later the girdle
secretes a fluid which hardens and forms a tough cylindrical
membrane or cocoon about the body. The cocoon is moved
forward and as it passes the fourteenth somite eggs pass
into it, and at somites ten and eleven spermatozoa enter
and the fertilization of the eggs takes place. The cocoon
passes over the anterior end of the animal and drops to the
ground, the ends close and within this free capsule the develop-
ment of the young worms takes place.

3. Digestive System.— Carefully remove the sperm sacs
and the septa in the anterior portion of the body, exposing
the tube-like esophagus. Find the following parts : pharynx
(somites twyo to five), esophagus (six to thirteen), crop (four-

EARTHWORM 91

teen to sixteen), gizzard (seventeen to ninteen), stomach-
intestine extending to the posterior end of the body. In
the walls of the esophagus in somites ten to twelve are
three pairs of small sacs or pouches, the calciferous glands,
which open into the esophagus.

Compare the several organs in size, color, thickness of
walls, the lining of each. • In the stomach-intestine note
the dorsal infolding, the typhlosole. Note also the delicate
muscle fibers wyhich extend from the body wall to the pharynx.
What possible function might these serve?

4. Excretory System.— This consists of paired segmental
organs, the kidneys or nephridia, which are made up of coiled
tubes held closely together and suspended close to the
ventral and lateral body wall. Remove one of the nephridia,
place on a slide, and examine with the compound micro-
scope.

Make a large drawing and in it show all the internal
structures that you have observed.

5. Nervous System.— Dissect and remove the anterior
end of the alimentary canal except the pharynx. This will
expose the white nerve cord, lying in the median ventral side
of the body cavity. Immediately over this is the ventral
bloodvessel, one of the main longitudinal trunks of the
circulatory system.

Examine with the lens and notice that there are small
swellings, the ganglia. How many in each somite? Are
there nerves coming out from the cord? How many in
each somite? Do they come from the ganglia, or from be-
tween the ganglia? Carefully expose the cord anteriorly,
pushing the pharynx to one side, and on the dorsal side of
the pharynx will be found the cerebral ganglia or brain.
How is this connected with the ventral cord? Make a
large drawing of the brain and several of the ganglia and
their nerves.

92 GENERAL ' BIOLOG Y

HI. Microscopic Anatomy. (Histology.)

On the slides furnished are sections across the body in the
region of the stomach-intestine, and these are stained in
drder that the various tissues may be more plainly seen.

1. Study the entire section and identify the following
structures: (a) body wall and its layers; (6) ccelom; (c)
intestine; (d) dorsal and ventral bloodvessels; (e) nerve
cord. Other organs likely to be found are setse, excretory
organs, septa.

Make a drawing of the entire section showing all the
parts mentioned, but not attempting to indicate the cells
which make up the tissues.

2. Body Wall.— With the high power study the body wall
and make out the cuticle, epidermis, circular muscles, longi-
tudinal muscles, and a delicate layer of cells lining the ccelomic
cavity, the peritoneum. Make out the cellular character
of the various layers and make a drawing of a small segment
of the body wall showing the layers and the cells which
compose them.

3. Intestine.— Are the walls of the same thickness through-
out? The dorsal infolding of the intestinal wall is called
the typhlosole. How much of the cavity of the intestine
does it occupy? Make a careful study of the tissues and
cells of the intestinal wall; from without inward these are
as follows: Chlorogogue, pear-shaped cells rather loosely
arranged; between the bases of the chlorogogue cells are
small scattered fibers, the longitudinal muscle; a definite
and clearly marked circular muscle layer; inside of this there
may be spaces, the bloodvessels of the intestine; lining the
intestine is a thick layer of ciliated, columnar epithelium.

Draw a portion of the wall as seen with the high power,
showing the cells of each layer.

EARTHWORM 93

4. Nerve Cord.— What is the shape of the cord as seen in
section? If nerves are present notice the place and the
manner in which they emerge from the cord. The cord is
enclosed within a connective tissue sheath, scattered through
which are many muscle fibers. Are these circular or longi-
tudinal muscles? Also within this sheath are located three
longitudinal bloodvessels, ventrally the subneural, at the
sides the lateral-neural vessels. The pear-shaped cells in
the cord are the nerve cells, and the delicate fibers that seem
to be prolongations of the cells are the nerves. Are nuclei
present in the nerve cells? Are the nerve cells abundant?
Where are they located? At the dorsal side of the cord are
three areas that are called giant fibers. Filling up the bulk
of the cord are connective tissue fibers.

Draw an enlarged section of the entire cord, showing the
points observed.

IV. Physiology.

Make the following study of the living worm.

1. Movements.— Place the worm on a damp, rough sur-
face, as filter paper, and observe the kinds of movements
and the way they are produced. By what means does the
worm move from place to place? Can it climb over ob-
structions? Place the worm on a moist, perfectly clean
glass. Explain the behavior observed.

2. Sensitiveness.— With a bristle or a blunt instrument,
touch the worm in different places. What regions are the
most sensitive? How is this indicated? Try the effect
of stimuli such as warmth of the breath, sunlight, vapor of
ammonia or chloroform, dilute acetic acid. Record the
results obtained.

3. Circulation.— If the body wall is not too thick, nor too
heavily pigmented, the pulsations of the dorsal bloodvessel

94 GENERAL BIOLOGY

may be seen through the wall. In what direction is the
blood flowing? Further observations on circulation may
be made upon a worm, anesthetized with chloroform, which
has been opened to expose the bloodvessels. Observe the
contraction of the dorsal vessel and the hearts, also note
the delicate bloodvessels upon the various organs.

SAND WORM.

NEREIS VIRENS.

THESE animals are found on the seashore in burrows of
sand and mud near low water mark.

I. External Anatomy.

1. General Features.— Is there a differentiation into dorsal
and ventral? Anterior and posterior? How are these
regions distinguished? Compare writh the earthworm.
How many somites? Is the number as variable as in the
earthworm? Are the somites alike in size and form? Is
the body divided into regions?

2. Head.— In the head there are the following parts:
A triangular prostomium which bears on its anterior margin
a pair of short tentacles. On each side there is a fleshy
palp. The four eyes are on the dorsal surface of the pros-
tomium, and are sometimes hard to find. The peristomium
is the ring around the mouth. Compare it with the first
body somite. It bears four lateral or peristomial tentacles
on either side. Note the large jaws which may be partly
extended from the pharynx.

Make a drawing showing the head and several of the
body somites.

3. Appendages.— On each side of most of the somites
there is an appendage called a parapodium. In each para-
podium there are the following parts: A dorsal blade, the
gill, which bears a short cirrus; and a ventral blade consist-

96 GENERAL BIOLOGY

ing of two fleshy lobes. There is also a ventral cirrus. From
each blade a number of setae arise in bundles. In each
blade there is embedded a short -stiff rod, the aciculum,
which serves to support the appendage. Examine the last
body somite and note any differences from the other somites.
Make an enlarged drawing of a single parapodium.

n. Internal Anatomy.

Open the worm in the same manner as the earthworm.
Note the body wall, the ccelom, the septa, and observe any
differences from the conditions present in the other worm.

The digestive system has a large muscular pharynx, in
which are the large jaws noted above, and also some small
teeth covering the walls. Can you account for the differences
in the pharynx of this worm and the earthworm? The
pharynx opens into a large crop, into which also empty
digestive glands. Was there anything corresponding to
the digestive glands in the earthworm? The rest of the
digestive tube is composed of the straight stomach-intestine.

The pharynx is protrusible and there are protractor and
retractor muscles to operate the proboscis and the jaws.

The circulatory and excretory systems are much like
those of the earthworm, though they are not so large nor
so easily worked out.

In the sand worm the sexes are separate and the repro-
ductive organs are present only at the breeding season.
A portion of the tissue lining the ccelom produces sperms
or eggs at this time. When the reproductive products are
ripe the body wall is ruptured and the germ cells escape
into the water where the fertilization takes place.. Unless
the worms were obtained during the breeding season the
reproductive organs will not be found.

SAND WORM 97

The digestive tube should be removed to expose the nerve
cord, which is present on the ventral body wall as in the
earthworm. Compare the cord with that of the earth-
worm. Are ganglia present? Describe the arrangement
and distribution of ganglia and nerves. Is there a com-
missure about the pharynx and a brain or cerebral ganglia
on the dorsal side?

On account of the numerous sense organs on the head
the brain is larger and there are more nerves coming from
it than in the earthworm. The brain lies very close to the
surface and is difficult to expose without injury.

Make drawings to represent the various internal systems.

THE FERN.

PTEBIS AQUTLINA.

THE common brake is widely distributed, growing in
nearly all damp, shady places. If the structure of the
entire plant is to be studied, they should be collected and
used fresh or else preserved in formalin. Early summer
is the best time for the collection, though the plants will be
in fairly good condition in the early fall. For the histological
study the rhizome must be sectioned in the usual way.
The sections may be stained, but some of the tissues will
show well without stain.

This organism is composed of organs which are partly
underground and partly above ground, the former com-
posed of the underground stem, or rhizome, and roots which
serve to absorb water and salts from the soil. From the
rhizome leaves, or fronds, extend into the air as the chlorophyll
bearing parts, with supporting and nutritive organs.

The leaf consists of a main stem or stalk divided into
leaflets, or pinnae and pinnules. It is in the leaf that the
food is elaborated from simple compounds and elements
.through the activity of the chlorophyll bodies, or chloro-
plasts, which are but modified masses of protoplasm. Here
are also found organs of reproduction.

The main object in the study here outlined is an insight
into the fundamental structure of a plant, its parts, their
relations and functions. A further aim is, by rough com-
parison, to discover any similarities of structure and organi-

THE FERN 99

zation, between plants and animals, as well as to demon-
strate the contrasts of structure and their relations to the
markedly different functions to be performed.

I. Leaf or Frond.

1. The stalk or stipe bears the expanded, foliaceous part
with its numerous lobes, pinnae, which are further subdivided
into ultimate leaflets, pinnules. Note whether there are,
on any part of the frond, hair-like elements, trichomes.

2. Midrib and veins are special structures forming a sort
of framework of the leaf. Are midrib and veins derived
from the stalk and connected with it? Do they sustain
any relation to the lobings of the leaf? Not only do these
form a structural framework, they are also paths for the
movements of liquids.

3. Histology of the Leaf.— From portions of the leaf re-
move bits of the epidermis and examine with both low and
high power and study the structure. Are cells present?
Observe the shape, structure, contents. Compare the
epidermis from both sides of a leaflet and note likenesses and
differences. Look for minute pores, stomata, and note upon
which side of the leaflet they occur. They are the so-
called breathing pores, and relate to the functions of trans-
piration and respiration. Sketch cells of the epidermis.

II. Rhizome.

Study sections of the rhizome and note the varied aspects
of different regions, which indicate the several tissues, or
tissue systems, of the rhizome. On the outside is the cortex,
made of an outer layer of epidermis, lifeless and protective,
and beneath this a subepidermis whose cell walls are hard
and woody, but which contain living protoplasm.

100 GENERAL BIOLOGY

Make a careful drawing of some of the cells of this region.

Within the cortex, and making up the greater part of
the rhizome, is the living tissue, called parenchyma or pith.
What is the shape of the cells? How are they joined to-
gether? Is there protoplasm within these cells? Are there
any bodies within the protoplasm which might be dead
substances as food? If fresh sections are available treat
with iodine solution and determine whether starch is present.

Make drawings of the parenchyma cells.

Scattered through the parenchyma are two large masses
and several smaller masses of brownish cells, the sclerenchyma.
Is there any definite arrangement to these masses? Com-
pare the shape and the grouping of the cells with that of
the parenchyma. Is it similar to the parenchyma? Is
the cell wall like that of the parenchyma cells? Is proto-
plasm present? Do these cells resemble more the paren-
chyma or the cortex? These cells are developed from the
parenchyma cells by the formation of lignin or wood, and
they serve to form a framework for rigidity and support.
Is the structure apparently adapted for this? Why would
the parenchyma not serve this purpose.

Make a drawing of the cells of this tissue.

Oval or circular patches are scattered through the rhizome
and are known as nbro-vascular bundles. These bundles
anastomose and form a sort of network through the rhizome
and frond, through which liquids are conducted from place
to place. Study one of the bundles carefully and make
out the following:

1. Bundle sheath, around the bundle.

2. Phloem sheath, parenchyma like cells containing proto-
plasm and starch.

3. Bast Fibers. Small cells with protoplasm.

4. Sieve Tubes. Large thin walled cells.

THE FERN 101

5. Tracheids. Very large thick walled, empty cells or
tubes.

6. Spiral Vessels. Smaller empty cells.

The functions of the different portions of the bundles
must be determined by reference to text-books.

Make drawings showing the different cells of the bundles.

If possible examine longitudinal sections and identify
the tissues observed in the transverse sections.

In a very general way compare the organization and
structure of the fern with that of the earthworm or other
animal. Are there similar functions in the two, if so what
are they, and what organs perform them? What organ
system has the animal that is lacking in the plant and vice
versa? In what are the tissues alike, in what different? In
what respects are the cells of these tissues alike, in what
different?

m. Reproduction.

Ferns present conspicuous sexual and asexual cycles, or
alternation of generations. Of these the ordinary fern plant
is the asexual generation or sporophyte, producing within
certain organs of the leaf numerous, non-sexual spores.
These germinating give rise to inconspicuous, sexual plants
forming the sexual generation or gametophyte, which form
the sex cells.

1. Sporophytic Organs. — Examine mature leaves for the
spore-producing structures, sporangia, which are borne along
the margins of the leaflets. Observe the membrane, indusium,
which encloses and protects the sporangia. With needles
carefully dissect off the coverings and observe the sporangia.
Describe the shape, color and size of these capsules. Can
you find any variations? If so, how do you account for
such?

102 GENERAL BIOLOGY

Examine some of the sporangia, and work out the follow-
ing parts, using the high power where necessary:

(a) The Stalk or Pedicle. —What is its shape and structure ?
(6) The Capsule which contains the spores. What is
its shape and structure? Note especially the annulus,
or crescent of thickened marginal cells forming a crest
or ridge. Is it continuous about the entire capsule?
Where is it most developed? Is the capsule more
fragile at one point than another? Examine several
capsules in demonstrating this point. Observe the
size, shape and arrangement of the lateral or parietal
cells of the capsule. i

(c) The Spores.— Rupture sporangia by pressure of the
cover glass and examine the spores. What is their
color and shape?

Make drawings which illustrate the various struc-
tures studied above.

2. The Prothallium (Gametophyte).— Study prothallia in
their normal growing condition if possible. What is their
general appearance, color and shape? Carefully isolate a
single specimen as directed by the instructor and proceed
to work out its distinctive morphological features. Is it
differentiated into an upper and a lower surface? If so,
what are the distinguishing characteristics? Has the plant
rootlike organs or rhizoids? \Vhere are they located and
what is then- probable function?

Carefully examine the lower surface of the prothallium
for the presence of the following organs:

(a) Antheridia.— These are small somewhat spherical
bodies usually located among the bases of the rhizoids.
They correspond to the male sexual organs and may
contain small coiled antherozoids, the male sex cells.

THE FERN 103

(b) Archegonia. — The archegonia, or female sex organs,
are small, finger-like projections in the region of the
sinus, or notch, of the prothallium. Compare care-
fully their shape and structure with that of the an-
theridia. When the archegonia are mature each
one contains a single egg cell.

Make drawings showing the location of the sex

organs on the prothallium, and also showing the

character of these organs as seen with higher power.

3. Development.— After fertilization, which takes place

within the archegonium, the fertilized egg cell undergoes a

cleavage and gradually develops into a young fern. It soon

develops its own roots and leaves and becomes a perfectly

independent plant. The plant produced in this way is the

sporophyte generation.

YEAST.

DISSOLVE a small piece of compressed yeast in water,
mount a drop on a slide and examine with the compound
microscope. Or better mount a drop of Pasteur's solution
in which yeast is growing vigorously.

I. Morphology.

1. Form.— What is the form of the yeast cells? Are all
cells of the same shape? Are they single or in groups?
Are the cells arranged similarly in different groups? Are
they uniform in size? Make drawings to show the points
observed.

2. Structure.— Is a cell wall present? Note its color and
thickness. Is protoplasm present within the cell? Does
it show any color? Look for vacuoles within the cell. Is
more than one present? Is the size of all vacuoles the same?
Is there any difference in size or number of vacuoles in single
cells and in groups of cells? Is there any difference in size
and number of vacuoles in growing yeast and yeast from a
compressed cake. How can this be accounted for? Small
glistening oil drops are often present near the vacuoles. A
nucleus is present in each cell but it can be demonstrated
only by special methods.

H Physiology.

1. Reproduction.— Examine cells from actively growing
yeast and from compressed yeast and note any differences

YEAST 105

in form, number and size of cells in a group. Explain the
differences.

The chief method of reproduction in yeast is by asexual
budding or gemmation. How does this method differ from
fission in protozoa?

2. Growth.— In the following experiments the amount
and rate of growth may be roughly estimated by the in-
crease in the turbidity of the liquids; fermentation may be
indicated by the rate and the amount of gas produced.

(a) Food Supply and Growth.— Fill four test tubes (if
fermentation tubes are at hand better results will be
obtained by their use) half full of the following fluids,
and into each place the same amount of yeast from
the same culture. Keep all the tubes under the same
conditions.
(I) Distilled water.
II) 10 per cent sugar solution.

(III) Pasteur's solution without sugar.

(IV) Pasteur's solution with sugar.

After several hours or a day observe the tubes and deter-
mine in which the growth and fermentation have been most
rapid and greatest.

(6) Other Conditions and Growth.— Prepare several tubes
with Pasteur's solution containing sugar, and to each
add the same amount of yeast. Place some of the
tubes in a warm place (about 35° C) ; some in a cold
place (on ice if possible) ; boil some and place with
the first ones; to some add a few drops of a poison like
mercuric chloride or formalin; place some tubes in
the sunlight and others in darkness. Into a similar
tube place some yeast filtrate. After several hours,
or on the next day observe the tubes and note all the
differences. Draw what conclusions you can as to

106 GENERAL BIOLOGY

the effect of the different conditions upon the growth
of yeast, and upon its power to cause fermentation,
(c) Fermentation.— Conduct some of the gas being formed
in a culture of vigorously growing yeast through lime-
water or baryta-water. What is the effect on the
lime-water? A milky appearance or a white pre-
cipitate indicates the presence of carbon dioxide.
Is this the gas which is being produced by the yeast?
Permit yeast to grow in a large flask of Pasteur's
solution until growth has ceased, i. e., until gas is no
longer evolved. Distill the contents of the flask at
a low temperature (about 80° C) and test the dis-
tillate for alcohol by odor, taste, and inflammability.
(The test will be more certain if a second distilla-
tion is made.) What conclusions can you draw from
the experiment?

From the experiments upon the life and activities of
yeast write a report clearly showing the nature of the experi-
ments, the results, and the conclusions which may logically
be drawn from them. Give a summary of the conditions
which are favorable and those which are unfavorable for
growth and ferment action of yeast.

BACTERIA.

BACTERIA flourish only in the presence of moisture, but
are found in soil and air; indeed hardly any condition where
life is possible is devoid of bacteria. Some are among the
most useful and important of organisms, and others are
among the most dreaded and dangerous of all living things.
Many of the most virulent of diseases which afflict mankind
have been traced directly to bacteria. Some study of their
peculiarities, conditions of activity, method of protection
from them may be of interest and importance economically
and biologically.

I. Morphology.

Mount a drop of water from a hay or other infusion of
organic matter, or from slime in aquaria, and examine under
the highest power of the microscope. Note the numbers of
very minute, almost transparent bodies present, some in
motion and others quiescent.

The forms of bacteria are very simple and comprise only
three principal types: the sphere- (coccus), the rod (bacillus),
and the spiral (spirillum). How many of these kinds are
distinguishable in your preparation? Is the size variable?
Which type is generally largest, and which smallest? Is
the movement which is taking place a locomotion or merely
a vibration or oscillation?

Make drawings to show the shape and relative size of the
types of bacteria found.

108 GENERAL BIOLOGY

II. Reproduction.

Bacteria reproduce chiefly by fission, hence the scientific
name of the order, Schizomycetes (Fission fungi). One
indication of this fission which may easily be observed is
the presence of chains or groups of bacteria. In what way
is this an evidence of division?

HI. Physiology.

Bacteria are plants but are not able to manufacture their
food as the green plants do. In order to grow they must
be in a medium which contains available food, and the
culture media used for their growth are so prepared as
to furnish the conditions necessary for their growth and
activity.

1. Distribution of Bacteria.— Methods of preparing the
nutritive media can be found in any of the manuals on bacter-
iology. With tubes or Petri dishes containing sterilized
gelatin make the following experiments :

(a) Keep some carefully closed and labeled "not exposed."

(6) Expose some to the air of the laboratory for three
minutes, and label accordingly.

(c) Expose some to the dust from laboratory tables or
floor, or dust from the outside.

(d) Let a drop of water from the laboratory tap flow over
another.

0) Capture a fly and let it walk over the gelatin.

Set these aside in a warm place and examine after a day
or two, noting what differences there are in the several
dishes. The small spots or patches probably present are
colonies of bacteria. Do they differ in form and color?
Examine the series still later. Have the colonies grown?

BACTERIA 109

How is this indicated? Do any of the colonies have any
effect on the gelatin?

2. Surrounding Conditions and Growth.— Into tubes of
bouillon introduce several drops of fluid from some culture
of bacteria and treat the tubes as follows :

(a) Close the tube with a plug of cotton.

(6) Close the tube with cotton and boil for five minutes.

(c) To a third tube add a small portion of a poisonous
substance, such as corrosive sublimate or formalin.

(d) Place some tubes in the bright sun and others in the
dark; place some on ice and others in a warm place.

Label all the tubes and set away for a day or more. Ob-
serve and note changes, if any, as indicated by the odor
and cloudy appearance of the culture fluid. Explain the
differences.

THE CRAYFISH.

CAMBARUS SP.

I. External Anatomy.

COMPARE with the earthworm with regard to regional
differences such as anterior and posterior ends, dorsal and
ventral sides, head and tail. Are these regions more or less
sharply marked? Is there perfect bilateral symmetry?

Distinguish an anterior region, the cephalothorax, and a
posterior, the abdomen. In what ways are they alike?
In what different? Is there a definite head? Note the
exoskeleton, is it present everywhere? Where is it thickest
and hardest, where thinnest? What explanation can you
give for these differences?

1. Abdomen.— Is it segmented? If so, how many seg-
ments? The last segment is called the telson. Does it
differ from other segments? Is free movement of the seg-
ments possible? Is it equal in all directions? How are
the segments joined together? Are appendages present?
Are they present on all segments ? Are they alike ?

2. Cephalothorax.— Is the form like that of the abdomen?
Are segments present? Is there any thing to suggest seg-
mentation? The shell-like exoskeleton in this region is
called the carapace. Are the edges of the carapace free or
fixed? To what extent? Are the appendages of this region
similar in form?

3. Sexes.— Distinguish the following characters:

THE CRAYFISH 111

(a) Male.— The first abdominal appendages are modified
into tube-like or spine-like organs; the abdomen is narrower
than the thorax; the genital openings are on the bases of
the hindmost legs.

(6) Female.— The abdomen is slightly broader than the
cephalothorax; the genital ducts open on the bases of the
third pair of legs. What is the character of the first abdom-
inal appendages?

4. External Openings.— (a) auditory, on the dorsal side
of the basal joint of the antennules; ('&) excretory, at the
base of the antennae on the ventral side; (c) mouth, on the
ventral side between the jaws; (d) genital ducts already
noted; (e) anus, on the ventral side of the last segment of
the body.

Draw the entire animal from the side, X 2.

II. Appendages.

1. Abdominal.— Carefully dissect the appendages from
one side of the abdomen and arrange them in order on a
piece of paper. Using the third appendage as a type notice
its biramous character ; there is a basal portion, the pro-
topodite, and two distal portions, the exopodite and the
endopodite. Compare the other appendages with this one
and determine whether they have the same structure. Are
there any variations from this structure? What are they?
Which appendages show the greatest modification? In
what way? Can you explain it? Draw the first, the third
and the last appendage.

2. Cephalothoracic.— In a similar manner dissect off the
walking appendages from the same side of the animal and
arrange them in order as before. Explain such differences
in structure as appear. Do these appendages bear any

112 GENERAL BIOLOGY

resemblance to the third abdominal? Are protopodite,
exopodite and endopodite present?

Draw the first, the third and the last walking appendages.
The first pair are called chelae.

Remove the mouth parts on the same side, and arrange
them in order. From the outside inward they are called:
3d pair of maxillipeds, 2d pair of maxillipeds, 1st pair of
maxillipeds, 2d pair of maxillae, 1st pair of maxillae, mandibles.
Compare each one of these with the third abdominal ap-
pendage and with the walking appendages. Are they bira-
mous, are the protopodite, the exopodite, and the endopodite
present? Are the appendages of this group alike? Might
they be considered as modifications of a common structure?
Do they have the same number of joints as the walking
appendages? In the 2d maxilla note the gill bailer which
lies in the gill chamber and whose movement creates a
current of water which passes over the gills.

Draw the 3d maxilliped, the 2d maxilla, and the mandible.

Remove the antenna and the antennule from the same
side of the body. Compare with the other appendages,
what are the likenesses and the differences? Draw.

Considering all the appendages, indicate whether there
is a common plan in their structure, and if so what it is.
Also indicate what the departures from this plan have been,
and suggest advantages of these variations. Parts having
the same fundamental structure are said to be homologous;
and in this animal there is represented a serial homology.

HE. Internal Anatomy.

1. Respiratory System.— Carefully cut away the carapace
from the side of the body and expose the gill chamber and
the gills contained therein. What is the form of the gills?

THE CRAYFISH 113

Of what advantage is this form? To what are the gills
fastened? How does the water get to the gills? Why are
they under the carapace?

2. Circulatory System.— Carefully remove the carapace
from the dorsal side of the body. The heart will be found
in the posterior portion of the cephalothorax, as a delicate
shield-shaped body. Notice any vessels which extend out
from the heart and examine an injected specimen, if one is
available. Note the small openings in the heart, these are
valves. In what direction do they permit the blood to flow?
Trace all the bloodvessels which can be found.

3. Reproductive System.— The ovaries are granular bodies
of considerable size located in the dorsal part of the thorax
and abdomen. Note the shape and extent of the organ
and trace the ducts to the openings already noted. The
testes are in a similar position but are smaller and are of a
whitish color; the sperm ducts are somewhat coiled and
longer than the oviducts.

4. Digestive System.— Remove the gills from one side of
the body and cut away the body wall of the same side. This
will expose the greenish liver and the other digestive organs.
Remove .the lobe of liver on this side and expose the stomach
and intestine.

In the extreme anterior part of the body cavity will be
found the large stomach composed of two parts, from which
the intestine leads backward to the anus. Between the
mouth and the stomach there is a short esophagus. Trace
the digestive tube from the mouth to the anus, observing
the shape and the size of the parts and their exact position.
Do the large digestive glands, or livers, open into the intestine
or the stomach?

Draw the animal from the side as opened and show all
the organs that are exposed or that can be seen by dissection.
8

114 GENERAL BIOLOGY

Open the stomach and observe the character of the lining.
Of what use are the teeth that are present in the walls ? How
do they operate? If food is present in the stomach try to
determine its character.

5. Excretory System.— The openings have been noted
as being on the basal joint of the antenna?. The excretory
organs themselves, the kidneys or green glands, lie just
dorsal to the bases of these antenna? and therefore in the
extreme anterior part of the body cavity.

6. Nervous System.— Dissect the muscle and other tissues
from the abdomen and expose the nerve cord. Be careful
not to break any of the nerves in cleaning away the muscle.
Expose the cord to the extreme posterior part of the abdo-
men, then trace it forward into the thorax, dissecting as
much as is necessary to expose it. In the anterior part of
the body the cord will be found to divide into two parts,
forming a commissure which passes around the esophagus
to the dorsal side. Here the two cords unite again to form
the cerebral ganglia or brain.

Notice the number, position, arrangement of the ganglia,
then* size, the distribution of the nerves which come from
them, and the termination of the nerves of the brain in the
sense organs of the head. Compare this nervous system
with that of the earthworm.

Make an enlarged drawing of the entire system.

IV. Physiology.

1. Locomotion.— In working on the living animals do
not excite or irritate them. Place the crayfish in a pan
with sufficient water to cover it and observe it while walk-
ing_or crawling. What appendages are used? Can it walk
backward as well as forward? Are the legs used in any

THE CRAYFISH 115

definite order? Place the animal on the table, does it
walk equally well out of water? While the animal is in the
water frighten it by thrusting a pencil at it; notice how it
swims, what parts are used and how? What advantage
comes from swimming in this direction?

2. Defense.— With a pencil make motions at an animal
to see how it defends itself. Allow it to grasp the pencil
to show the strength of the grasp.

3. Respiration.— While the animal is at rest in the water
place a little colored liquid near the bases of the legs. Where
is this liquid drawn into the animal and where does it re-
appear? Try dropping the colored liquid at various places
along the edge of the carapace. What causes the movement
of the liquid? What purpose do the currents serve? How
is it that a crayfish, while breathing by gills, can live for
some time out of water?

4. Sensitiveness.— Note the range of motion of the eyes.
Could an enemy approach the animal from any direction
without being seen? What are the advantages and what
the disadvantages of having the eyes on movable stalks?
In what ways are the eyes protected? Touch one of the
eyes and see what happens.

Test the sense of touch at various places on the body;
where is it most sensitive? Are all parts of the appendages
equally sensitive? Touch some of the hairs at different
places on the body; are they sensitive?

5. Feeding.— Small pieces of meat may be placed near
the animal to determine how it reacts, and also to show in
what way the food is grasped and how it is passed to the
mouth. If possible note the action of the different mouth
parts. If this sort of a test is made you should also deter-
mine whether the animal prefers fresh or decaying meat.

THE GRASSHOPPER.

THE following outline will apply to any of the common
grasshoppers, though the larger ones are, of course, pref-
erable for the study of the structure.

I. External Anatomy.

1. General Characters.— The body of the grasshopper is
made up of head, thorax and abdomen. Are these divisions
well marked ? Are they as well differentiated as in the crayfish
and earthworm? Are somites present ? Are they found in all
regions of the body? Is an exoskeleton present? Compare
with the crayfish in regard to exoskeleton. In what ways
do they differ? Are appendages present? Are they found
in all regions of the body?

2. The Head.— What is its shape? How is it attached
to the thorax? Study the position and structure of the
antennae. Observe the large compound eyes. With a lens
determine why these are called compound eyes. In addition
to these eyes there are three simple eyes or ocelli. One in
the center of the head, below the antenna?, and the others
near the dorsal, anterior border of the compound eyes.

About the mouth are several appendages: (a) labrum,
or upper lip; (6) mandibles, or jaws; (c) maxillae; (rf)
labium or lower lip. Observe the position each occupies
and the direction of movement. Remove the appendages,
note the structure of each one and make a drawing showing
this structure.

THE GRASSHOPPER 117

3. Thorax.— Distinguish the Following divisions: (a)
prothorax, (6) mesothorax, (c ) metathorax. These three parts
of the thorax represent somites. Are they sharply separated
from each other? Do they move? In what respects do
they correspond to typical segments of the crayfish? Ob-
serve the several plates of which each is composed. What
appendages are borne by each somite?

4. Appendages of the Thorax. — (a) Legs. How many?
Distinguish the following joints: coxa, a short segment
next to the body; trochanter, the second segment, which
may be fused with the first in the jumping legs; femur,
the middle segment; tibia; tarsus or foot. Is the tarsus
a single piece? Compare the several parts of each of the
legs with corresponding portions of the others. In what
are they alike ? In what different ?

(6) Wings.— How many? On which somites are they
borne? Note their size, color, and texture. What is their
relative position in repose? In flight? Spread the wings
and study the arrangement of the veins.

Make drawings of the first and third legs, and of both pairs
of wings. •

5. Abdomen.— Of how many somites is it composed?
Compare the male and female specimens carefully in shape,
size, number and relations of the somites. In what partic-
ulars do they differ? Compare the first somite with those
following and note any differences. In this somite there
is a membranous tympanum or ear drum.

Study the structure of a somite and observe a dorsal
portion, the tergum and a ventral sternum. Are these parts
well marked? Are they present in each somite? Are the
terga and sterna capable of movement?

In the side walls of the somites are small openings or
pores called spiracles. These are the external openings of

118 GENERAL BIOLOGY

the respiratory system, which is made up of a series of
branching tubes inside the body for carrying air to the
various organs and tissues. There are eight pah's of spiracles
in the abdomen, and two in the thorax; determine the
exact location of these.

At the end of the abdomen the somites are considerably
modified, to form spines, plates and the like. The hard
spines in the female comprise the ovipositor, or egg-laying
organ. Determine the number of spines and the relation
of these to the somites adjoining. In the male there are
smaller spines which function as genital organs during mating.
In both males and females the anal opening is dorsal,
beneath a chitinous plate, and the reproductive opening
is toward the ventral side.

Make a drawing of the entire animal from the side.

II. Internal Anatomy.

Remove the wings and cut along each side of the median
dorsal line. Remove the entire dorsal part of the body
wall and expose the internal organs.

1. Respiratory System.— Tracheae or air-tubes will be seen
as fine white tubes, much branched and extending to all
organs and tissues of the body. The tracheae open to the
outside through the spiracles. Demonstrate this connection.

2. Digestive System.— Distinguish the following parts:
(a) esophagus, leading from the mouth to the crop; (6)
crop, a large organ located in the prothorax; (c) gastric
caeca, a series of pouches surrounding the posterior end of
the crop; how many are there? Do they connect with
the cavity of the crop? (d) The stomach is an enlarged
part behind the cseca; (e) intestine the posterior portion

THE GRASSHOPPER 119

of the digestive tube ending at the anus. The intestine is
made up of three parts.

3. Excretory System.— This comprises a number of deli-
cate capillary tubes, the Malpighian tubules, which are
twisted together and may partly fill the body cavity. They
connect with the digestive canal at the point where the
stomach and intestine join.

4. Reproductive System.— The reproductive organs, testes
or ovaries, are present in the abdomen, dorsal to the digestive
tube. These organs are made up of tubules closely packed
together. They open to the exterior through the sperm
ducts or oviducts, whose openings are ventral to the anal
opening. The ovary in mature animals may be a mass of
eggs completely filling the body cavity.

Make a large drawing to show all the organs and systems
worked out.

5. Nervous System.— Remove the alimentary canal and
the reproductive organs. The nerve cord should now appear
along the median ventral line, covered over with a thin
sheet of fat tissue. Are ganglia present? How many
in the abdomen? In the thorax? Is there a ganglion to
each somite? Where are the ganglia largest? Trace the
general direction of the nerves which leave the ganglia.
In the head is a ventral inf ra-esophageal ganglion, and a dorsal
supra-esophageal ganglion or brain. These two large ganglia
are connected by circum-esophageal commissures. From the
brain nerves go to the ocelli, compound eyes, and antennae.

Make a large drawing showing the nervous system.

Compare the crayfish, the grasshopper and the earth-
worm in regard to: (a) The plan upon which the body is
constructed; (6) the organization of somites into well
defined regions; (c) the arrangement and structure of the
appendages; (d) the number, position and structure of

120 GENERAL BIOLOGY

the sense organs; (e) the structure of the circulatory,
digestive and nervous systems. Which of these animals is
the more highly specialized? Is one better adapted to its
modes of life than the others? Give reasons for your con-
clusions.

m. Physiology.

From a study in the field and in the laboratory work out
the following activities of the grasshopper.

1. Movements.— Describe the kinds and methods of
locomotion. What structural features of the legs are
adaptations for leaping? How many times the length of
the body may the grasshopper leap? What is the purpose
of the hooks on the legs? Are both pairs of wings used for
flight?

2. Sensitiveness.— With a bristle touch various parts of
the body, including the antennae . Which is the most sensitive
part? Does the grasshopper see? What evidence is there
of this? Is there any evidence that it hears?

3. Protection.— Has the grasshopper any means of de-
fense? Is it protected by color? How does it escape its
enemies?

4. Respiration.— Observe the respiratory movements of
the abdomen. Knowing the structure of the respiratory
system, which is characteristic of all insects, explain why
non-poisonous powders may often kill insects.

5. Nutrition. — Place animals in a cage with leaves of grass
and other plants. If possible observe the method of using
the different mouth parts. By using different kinds of
plants it may be possible to determine whether there is any
choice of food.

HONEY BEE.

APIS MELLIFICA.

THE honey bee belongs to the class Insecta and, there-
fore, has certain characteristics in common with the grass-
hopper and other insects. For example, there is the same
division into head, thorax and abdomen; a subdivision of
thorax and abdomen into segments; and a similar number
and disposition of antennae, eyes, legs and wings. The
grasshopper, however, is a relatively simple insect, wThile
the bee is one of the most complex. The bee is of interest
from its habit of community or social life, with different
castes or classes in the community. It is also of interest
in its highly specialized and adapted organs, as compared
with the more simple ones of the grasshopper.

External Anatomy.

1. General Characters.— Notice the division of the body
into regions, and compare with the grasshopper. Especially
note the covering of hairs over the body, is this present in
all parts or is it limited in distribution? Remove some
of the hairs, place on a slide and examine with the com-
pound microscope. The longer hairs of the body differ
in what way from the shorter hairs of the appendages?

2. Head.— Is the head freely movable? Is it more or
less so than in the grasshopper? The compound eyes are
quite similar to those of the grasshopper, but observe the
short spine-like hairs on their surface. Compare the com-

122 GENERAL BIOLOGY

pound eyes of a worker and of a drone bee; in what respects
do they differ? What explanation can you give for this
difference? The eyes of the queen are like those of the
workers. Three ocelli are present as in the grasshopper.
Observe the position and the structure of the antennae.

3. Mouth Parts.— The mouth parts of the bee are the same
in number as those of the grasshopper, but greatly modified
and adapted to different functions.

(a) Labrum.— This is a flap of skin forming an upper lip.
(6) Mandible.— There is a pair of mandibles or jaws be-
hind the labrum. Both the mandible and the labrum
are quite similar to those of the grasshopper, but
somewhat reduced in size. The mandibles of the
worker differ slightly from those of the queen and the
drone.

The remaining mouth parts, the maxillae and labium,
are much modified and together form a proboscis for
sucking liquid food.

(c) Maxilla.— The palp of the maxilla is reduced in size to

a mere rudiment. The remainder of the appendage
forms the hollow outer portion of the proboscis.

(d) Labium.— Of this appendage there are three chief

parts, the base, the labial palps, and the glossa or
" tongue. " The glossa forms the center of the pro-
boscis, is covered with long hairs, and ends in a spoon-
like lobe called the labellum.

To study the mouth parts straighten them out,
away from the head, cut off the entire tip of the head
and mount this on a slide in glycerin. It may be
necessary to separate these parts somewhat with
needles.
Make a drawing of the mouth parts.

HONEY BEE 123

4. Thoracic Appendages. — (a) Wings. — Remove the wings
from the body and mount on a slide. Study the
arrangement of the veins in each wing. With the
compound microscope observe the hooks on the an-
terior border of the hind wings which attach this to
the fore wing. What is there on the fore wing to hold
these hooks?
Make a drawing of the wings.

(6) Legs.— The legs are composed of five segments as
those of the grasshopper, but the basal joint of the
tarsus or foot is much enlarged and is sometimes
called the metatarsus. The legs of the bee serve not
only for locomotion, but also as tools for other com-
plex functions.

1. Prothoracic Leg.— Between the tibia and the first
tarsal segment is the antenna cleaner; on the outer
end of the tibia is a pollen brush, composed of stiff
hairs.

2. Mesothoracic Leg.— At the end of the tibia is a long
spine, the pollen spur.

3. Metathoracic Leg.— How do the tibia and first tarsal
joint compare in size with similar parts of the other
legs? The outer surface of the tibia is hollowed
out to form the pollen basket; the inner surface of
the first tarsal joint is covered with rows of stiff
spines, the pollen combs. Between the tibia and
the first tarsal joint are the so-called wax shears,
which, however, are used in gathering pollen and
have nothing to do with wax manipulation.

Compare these adaptive specializations of the legs of the
worker with the legs of the drone, and note what differences
occur. Is it possible to explain these differences?

Remove each of the legs from the body, study with a

124 GENERAL BIOLOGY

lens or low power, and make drawings to show the points
observed.

5. The Sting.— The sting is located in a cavity in the end
of the abdomen, which is formed by an infolding of some
of the posterior abdominal segments. The sting is homol-
ogous with the ovipositor of other insects.

Remove the dorsal wall of the end of the abdomen and
dissect out the sting apparatus. Mount this on a slide in
glycerin and study with low power. There is a shaft com-
posed of a dorsal sheath and two barbed lancets or darts.
The sheath and lancets form a hollow tube through which
the poison flows. At the sides is a pair of sting palps, soft
whitish projections, which serve as sense organs by which
the bee can tell when she is in contact with the object which
is to be stung. When the sting apparatus is removed one
or both of the poison glands will usually be present. Other
parts of the complicated apparatus will also be found.
Determine the character of the sting proper and the palps,
and make a drawing to show the structures observed.

As a portion of this study the different classes of the com-
munity, drones (males), queens (females), and workers
(neuters or imperfect females), should be compared. Es-
pecially should this comparison be made to determine the
differences in structure which are correlated with the speciali-
zations of parts for particular functions.

Field studies should be made, if possible, to observe the
habits of the bees, especially that of gathering nectar and
pollen. An interesting study of the activities within the
hive can be made if an observation hive of glass is available.

THE CLAM.

UNIO SP.

THE common fresh-water mussels or clams, of almost any
genus, are excellent for study. Those of some size are best.
The marine clam (Venus) while not so large nor so satis-
factory, is quite similar in most of its structural features.
Clams live partly buried in the sand or mud, writh the pos-
terior end of the body protruding. They may be collected
by digging. It is possible to keep them alive for some time
if placed in tanks of running water.

I. External Anatomy.

1. Shell.— Note the general form and relations of the shell.
Are the valves (the two parts of the shell) similar in size and
form? The dense horny hinge is the dorsal part, and the
knob or elevation on the shell (umbo) is nearer the anterior
end. Has the animal a right and a left side? Observe the
parallel, concentric lines extending from the umboes to the
margins of the valves; they indicate lines of growth, though
their number gives no evidence of the age of the clam.
Each line wras at one time the edge of the shell. Study
the action of the ligament or hinge in a recently opened shell ;
what function does it serve? The ligament is an uncal-
cified portion of the shell.

Make a drawing of the shell from the side, and one from
the anterior aspect.

126 GENERAL BIOLOGY

2. Interior Surface of the Shell.— Wedge the shell open
and then cut the muscles which are attached to the valves.
When this is done what happens to the valves? What
causes this? What is the function of the muscles? (If the
animal is preserved and the valves are already open, cut
the muscles and determine the functions of muscle and
ligament.) Cut the ligament and remove the left valve,
being careful not to remove any of the body within the
shell; a fold of skin which sticks to the shell must be care-
fully separated.

Compare the color and markings of the interior of the
shell with those on the outside. Are lines of growth present?
Are there any scars on the inside of the shell? What has
been the cause of these? Find the marks made by the
adductor, retractor, and protractor muscles. (In Venus there
is no protractor muscle.) How many of these muscles are
there? What is their function? When the clam was
smaller than it is now where were the muscles attached?
How do you know? Is there any evidence of growth over
any part of the muscle scars that now show? At the dorsal
side of the valve notice several teeth (not present in all
clams), the hinge teeth. WTiat is their function?

Draw the interior of the shell.

3. Structure of the Shell.— Break the valve that has been
removed and examine the broken surface. Notice the
thickness of the shell in different regions. Look for layers
in the shell, an outer very thin layer, the periostracum,
greenish or brownish in color. (This layer is not always
seen since it may have been worn off.) Next comes the
prismatic layer, and inside the nacreous or mother-of-pearl
layer. The periostracum and the prismatic layers are
formed by the thickened edge of the mantle. Once formed
they cannot be added to except at the edge of the shell.

THE CLAM 127

The nacreous layer is secreted by the surfaces of the body
and of the mantle in contact with the shell. It may con-
tinue to form throughout life. Is there any proof that this
has happened?

4. Body.— While working on the following external features
of the body remember that while the shell is properly a
part of the body, an exoskeleton, yet the fleshy part exposed
by the removal of the shell is still the external portion of
the body of the animal.

(a) Mantle. — This is the thin membrane lining the shell
and covering the rest of the body. How many lobes are
there? Are they attached to the shell? If so, where, and
to what extent? Are they joined to each other at any point?
In the posterior part of the body observe that the margins
of the mantle are hollowed out to form two oval openings,
a ventral incurrent, and a dorsal excurrent opening or siphon
(in Venus the mantle is fused to form two tubes). Deter-
mine the cavities into which the openings lead. All the
water that comes into the shell enters through the incurrent
and all leaves by the excurrent opening. The cavity be-
tween the mantle lobes is the mantle cavity and in it are
several organs.

(6) Gills.— Remove or turn back the mantle from one
side and expose the gills, which are thin membranes hang-
ing freely in the mantle cavity. How many on each side
of the body? Are they of similar size and form? How
and where are they attached to the body? In the female
the gill acts as a brood pouch during the breeding season
and is then greatly distended by the contained embryos.
A study of sections of the gill may be made to show the
layers of which the gill is composed, the water tubes, and
the bloodvessels.

128 GENERAL BIOLOGY

(c) Foot.— This is the large dense median part of the body;
it forms a muscular wedge or keel by means of which the
animal moves. Above the foot is the softer visceral mass
of the body.

(a) Muscles.— The adductor muscles, already noted, close
and hold the shell shut. There are protractor muscles for
pulling the foot and body ventrally, and extending it from
the shell. The retractor muscles draw these same parts back
into the shell. Note their position and the manner in which
they work. (In Venus there is no protractor muscle.)

(e) Labial Palps.— Small, thin, leaf-like organs behind
the anterior adductor muscle. They aid in passing the
food to the mouth.

(/) Mouth.— Between the palps and below the anterior
adductor muscle.

(</) Anus.— Opens into the excurrent or cloacal chamber
it will be found against the posterior border of the posterior
adductor muscle.

Make a drawing with the mantle removed.

II. Internal Anatomy.

1. Circulatory System.— The heart lies dorsally between the
ligament and the bases of the gills in an oval sac, the pericardial
cavity. Dissect the pericardium from the dorsal side and
expose the cavity and the heart. The latter is made up
of a central muscular portion, the ventricle, and two tri-
angular lateral portions, the auricles. Compare the auricles
and ventricles in thickness of walls. If a live clam is at
hand observe the pulsations of the heart. The ventricle
surrounds the posterior portion of the intestine. There are
two arteries leaving the ventricle, the anterior aorta and

THE CLAM 129

the posterior aorta, which carry blood to different regions.
Veins return the blood to kidneys, gills, and auricles.

2. Excretory System.— The kidney is a dark greenish
gland on either side of, and ventral to, the pericardial sac.
Each kidney is a wide thin-walled tube, doubled on itself
so that the two ends are close to each other. These ends
are anterior and about opposite, and ventral to, the anterior
end of the pericardium, while the loop is posterior and lies
against the posterior adductor muscle. One end of the
kidney opens into the pericardium, the other into the cavity
of the inner gill.

3. Nervous System.— This system is composed of three
pairs of ganglia connected by nerves. First locate the
visceral ganglion just under the posterior adductor muscle.
It will appear as a yellowish mass under the skin which
covers the muscle. How many nerves arise from this center?
To what regions or organs do they go? A small nerve on
either side extends forward from this mass to the brain.
The brain or cerebral ganglia will be found just under the
palps above the mouth, one on either side. From this nerves
extend to the adductor muscle, mantle and palps. Also
a nerve, the cerebral connective, connects the two ganglia.

The pedal ganglia are a fused pair in the foot and are
joined to the cerebral ganglia by connectives. These ganglia
will be found while working on the digestive system.

4. Digestive System.— With a razor split the foot and the
visceral mass vertically in the median line. Identify the
following parts: The mouth is immediately behind the
anterior adductor muscle. From this a short esophagus
leads to the stomach, which is in the dorsal part of the body.
Note the greenish digestive gland, or liver, surrounding the
stomach. The intestine extends from the ventral side of
the stomach to the ventral part of the foot, then poste-

130 GENERAL BIOLOGY

riorly through the foot. Here it turns on itself and extends
anteriorly again, then dorsally, passes through the ventricle
of the heart, goes dorsal to the posterior adductor muscle,
and ends at the anus in the cloacal chamber.

5. The Reproductive Organs.— The ovaries, or testes, are
present in the visceral mass .of the body. They are usually
light brown in color and entirely fill the spaces between the
folds of the intestine. The ducts empty near those of the
kidney in the supra-branchial chamber.

Make a large drawing to show all the organs studied.
• 6. Sections of the Body.— In order to show the relations
of the various organs of the body in a manner as clear as
possible a study of sections of the body is desirable. These
are sections across the entire body at different regions.
Make drawings of the sections and show the position and
arrangement of the organs that are in the section. Show the
plan of the organs by making the drawings rather diagram-
matic.

(a) Section through the stomach, shows the stomach,
mantle, palps, liver, reproductive organs, anterior aorta, foot.

(6) Section through the heart. Mantle folds, gills, supra-
branchial chamber, intestine (cut across several times),
pericardial cavity, ventricle, auricles, vena cava (a large vein
in the center of the body below the pericardial cavity),
kidney, ureters, reproductive organs.

(c) Section through the posterior adductor muscle. Ad-
ductor muscle, intestine, gills, supra-branchial cavities, mantle,

visceral ganglia of the nervous system.

•

m. Physiology.

1. Sensitiveness.— Place a clam in a dish of water and
allow it to remain until the shell opens and the foot and

THE CLAM 131

edges of the mantle are extended. Use a bristle or a delicate
glass rod to test the sensitiveness of the various parts ex-
posed. Determine whether foot or mantle, and which
portions of the mantle, are most sensitive; test especially
the edges of the siphons. What response is made to delicate
tactile stimuli? To stronger stimuli?

Sensitiveness to chemical substances may be tested by
directing gentle currents from a pipette against 'various
portions of the body.

Place a specimen in a very dim light, and when the shell
opens direct a beam of light against the body. Is there a
response to this stimulus? Place the animal in sunlight
or bright light from some artificial source, and interpose a
screen between the light and the animal, thus casting a
shadow upon the body. Note the character of such re-
sponses as occur.

2. Circulation of Water.— Introduce a few drops of a
colored fluid into the water near the posterior end of a clam
whose shell is open. If the water is drawn into the shell
observe the place where it enters. Does the colored fluid
pass out of the shell again? Where is the point of exit?
What service to the clam would there be in such incurrent
and excurrent movements of the water? Further light on
this advantage will be gained by observing a clam partly
buried in the sand in the normal manner.

3. Feeding. — Carefully insert a knife between the valves
of a living clam and cut the two adductor muscles where
they are attached to the shell. Loosen the mantle and
remove one valve entirely, thus exposing the body. Lay
back the mantle, or cut it loose, to expose gills and palps.
Drop some powdered carmine, chalk, or other small solid
particles upon the surface of the gills and note any movement
of these particles. In what direction is the movement?

132 GENERAL BIOLOGY

Are any of the particles carried far enough forward to reach
the mouth? In the clam it is by ciliary movements that
small organic particles are carried to the mouth, and the
entire food is composed of these particles.

4. Heart Beat.— In a specimen with one shell removed
observe carefully the region of the body dorsal to the gills
and in front of the posterior adductor muscle. This is the
position of the heart and its pulsations may be seen through
the delicate walls of the mantle. If care is used one may
remove the mantle and pericardial walls and expose the
heart itself. When the heart is exposed the pulsations of
auricle and ventricle may be easily observed.

SNAIL.

HELIX POMATIA.

FOR this study the French snail is suggested, but the
common pond snails, Physa, Planorbis, Limnsea can be
used.

1. The Living Animal.— How does the snail move? What
is the shape of the foot? What is the relation of the foot
to the rest of the body? What is its relation to the shell?
The anterior part of the foot is called the propodium, the
posterior portion the metapodium, and between these two
is the mesopodium. Are these regions sharply marked off?

2. Head.— At the anterior end note the position and form
of the mouth. Tentacles are present in this region. How
many? Size and form? Touch one with a needle. What
happens? On the tentacles are small, pigmented, glisten-
ing spots, the eyes. Note their position and number.

Locate the anal opening on the right side of the head. In
the air-breathing snails the respiratory opening is near the
anal opening.

3. Shell.— Is there a division into valves? How many
turns does the shell make? Do the shells vary in size?
Do the coils turn to the right, or to the left? Is the coiling
loose or close, flat or conical? The apex of the shell is the
oldest part, the opening of the shell is the newest part of the
shell. In some species one side of the mouth of the shell
is drawn out into a spout-like process. For what purpose
is this? In some snails there is an oval plate which closes

134 GENERAL BIOLOGY

the opening of the shell when the animal withdraws into
it. Is there such a plate, or operculum, in the form you are
studying?

The lines that run parallel to the mouth of the shell are
lines of growth. Are these uniformly spaced? Can you
explain any variations? The whorls or turns of the shell
run around a central axis, the columella. Observe the
columella and the spirals of the shell in a broken shell.
Describe the relations of the columella to the other parts
of the shell.

Make a drawing of the snail from the side, showing the
foot, head, shell.

THE FISH.

PERCH, SUCKER, GUNNER, OR OTHER BONY FISH.

WHILE the following directions have been made with
reference to the perch, the others named, or indeed almost
any species at hand may be employed. It will be especially
valuable to have a few living specimens, minnows or gold-
fish, in a laboratory aquarium for actual observations of
movements.

For dissection preserved specimens are quite as good as
those freshly killed or obtained from the market; the last
are likely to have been kept in storage for some time and
the internal organs are often worthless for study.*

I. General Features.

Note the shape of the body and its special differential
features— head, tail, body proper, fins. Are the body
features sharply marked? How do they compare with
those of the frog? Is the shape adapted to the life and
habits of the fish? Note the scales, their shape and arrange-
ment. Are they found on all parts of the body? How are
they attached to the body? What is their relation to the
skin? Examine a few quite critically and decide whether
they are entirely naked and whether the margin is smooth
or toothed. A scale with a smooth, rounded outline is
called cycloid, one with a toothed margin is called ctenoid;
to which of these does your specimen belong?

136 GENERAL BIOLOGY

U. External Anatomy.

1 . Fins. —How many are there ? Where are they located ?
Are they alike? Fins are said to be paired or single. The
paired are called pectoral, occupying a position similar to
the fore legs of the frog, and ventral, situated back of the
pectorals and on the ventral side of the body. How many
unpaired fins? The one just behind the vent is known
as the anal, one occupying the median dorsal position is
the dorsal. What others are present and how characterized ?
Study especially the structure of the paired fins and com-
pare with the others. In what alike, in what different?
Study also the ray-like structure of the supporting rods
of the fins, are they alike in all?

2. Mouth.— Note its shape and size. Open and close
the lower jaw and observe the movements of the several
parts. Are there lips? Identify the following bones of
the upper jaw: premaxillary, forming the anterior and lateral
portion and extending backward to unite with the maxillary.
Do both bear teeth? What is the shape of the teeth? The
lower jaw is composed of the dentary bones. Do they bear
teeth? Compare with those of the upper jaw. Within
the mouth cavity note the shape, size and position of the
tongue.

3. The Eyes.— Observe their location, size and shape.
Test the range of motion by pressing them with the forceps
or finger . Are there eyelids ?

4. Nostrils.— How many openings? What is their shape
and position? Do the nostrils communicate with the
mouth as in the frog? Are they of use in breathing? How
do they operate in smelling?

5. Gill Openings.— Observe that these openings are on
the side of the head and are covered by flaps, the opercles.

THE FISH 137

Can you identify the subopercle, preopercle, interopercle?
Under the opercles on the ventral side is the branchiostegal
membrane and the branchiostegal rays which support the
membrane. How many are there? Raise the operculum
and examine the gills, their number and arrangement and
method of support. On the anterior margin of the gill
arches are teeth called gill rakers. What function can you
suggest for them? Press down the tongue and observe
the effect upon gills and gill rakers. How does the fish
breathe? What motions are involved? Watch a fish in
the aquarium to find an answer to these questions.

6. Lateral Line.— A series of raised, dot-like markings
along the sides of the body. Examine one of the scales
which has on it one of the dots and see what it is like. The
lateral line has a sensory function.

7. Openings.— Just in front of the anal fin look for open-
ings of the anus and genital organs.

Make a drawing of the fish as seen from the side.

m. Internal Anatomy.

Make a median incision just in front of the anus and carry
it forward to the hinder border of the gills, being careful
not to injure the underlying organs. Make cuts at right
angles so that the flaps may be pressed to one side. Place
the fish on its side and work out the internal organs. Com-
pare the body cavity with that of the frog. Is there a
thoracic cavity distinct from an abdominal?

1. Liver.— This is a reddish organ of considerable size.
How is it held in place? Is there more than a single lobe
in it? Is a gall-bladder present as in the frog?

2. Stomach.— Raise the liver and push it to one side to
expose the stomach. From the stomach the esophagus

138 GENERAL BIOLOGY

leads to the mouth, and extending posteriorly to the anus
is the intestine. What is the shape and size of the stomach?
Are there pyloric coeca present? (These are small finger-
shaped filaments, not present in all fish.) Note the mesen-
tery which supports the stomach and intestine.

3. Spleen.— Observe its shape, color and position in the
mesentery.

4. Reproductive Organs.— The size of these organs will
depend upon the season, i. e., whether it be before or after
the breeding period. At this season they are large and may
fill up most of the body cavity. The testes are usually
whitish organs occupying a position similar to that in the
frog. The ovaries may vary in color and are often bright
yellow or orange. Determine the openings of these organs
in the posterior part of the body cavity.

5. Kidney.— Along the dorsal wall of the body cavity is
the large air bladder and just above are the twro kidneys.
The kidneys open into the urinary bladder in the posterior
part of the body, and this opens to the outside just back
of the anus.

6. Heart.— The heart is in the extreme anterior part of
the body. Is it in the same cavity as the other organs?
What is the shape, and of how many chambers is it com-
posed? If it is desired to trace the bloodvessels they should
be injected as in the frog.

Make a drawing in side view to show the internal organs.

7. Nervous System.— This system in the fish has much
in common with that of the frog. The brain and cord can
be more easily dissected in a specimen preserved in formalin.

8. Brain.— Dissect off the skin and muscle and finally
the bony skull thus exposing the brain, and note: (a) the
cerebral hemispheres; (6) olfactory lobes; (<?) optic lobes;
(<f) thalamencephalon, between (a) and (c), upon which

THE FISH 139

note the pineal body; (e) cerebellum; (/) medulla oblongata,
from which continues the cord.

9. Nerves.— The ten pairs of cranial nerves are very
similar to those of the frog and have the same names. The
spinal nerves may be exposed and their distribution studied
as may be directed by the instructor.

Make drawings to show the nervous system.

CLASSIFICATION OF LIVING THINGS.

BOTH as a convenience in the study of organisms, and as
in some degree indicative of their genetic relationships,
various efforts have been made to arrange them under such a
systematic classification as would serve these ends. The work
involved in the foregoing laboratory course, while dealing
with a few typical organisms, and devoted chiefly to their
morphology and physiology, has also revealed unmistakable
relationships of structure and function, which in turn have
afforded evidence of the larger relationships of descent.
That a given kind or species of animals has descended from
a common line of ancestry is of course universally recognized.
That differing, but closely similar, species have likewise
descended from a common ancestor slightly more remote
is also generally recognized as a fact. Out of the study of
large series of such facts has come the conception of evolution,
long known to students of biology, but first brought into
prominence by Lamarck and Darwin. All modern sys-
tems of classification have been attempts to express the
facts of such relationships of descent or evolution. The
following partial and abbreviated tabulation of the animal
kingdom may illustrate, in a general way, the main features
of the subject.

PHYLUM PROTOZOA.— Unicellular, microscopic animals,

or colonies of independent cells.

Class 1. Rhizopoda.— Protozoa possessing the power
of thrusting out pseudopodia. A shell is often
present. Amoeba, Arcella, Heliozoa.

CLASSIFICATION OF LIVING THINGS 141

Class 2. Mastigophora.— Protozoa, generally of small
size, provided with one or more flagella. Euglena,
Peranema, Pandorina, Volvox.

Class 3. Infusoria.— Protozoa bearing cilia, with mouth
and contractile vacuole always present. Para-
mecium, Vorticella, Stentor, Colpoda.

Class 4. Sporozoa.— Parasitic protozoa without motile
organs in the adult; reproduce by spore formation.
Plasmodium.

PHYLUM PORIFERA.— Radially symmetrical animals, the
body wall containing many pores for the entrance
of water, and usually supported by a skeleton of
spicules.

PHLYTJM CXELENTERATA.— Radially symmetrical animals
with mouth and gastro-vascular cavity, but with-
out ccelom. Stinging cells present.

Class 1. Hydrozoa.— Ccelenterates with solitary or
colonial polyps, and with an alternation of gen-
erations. The medusae have a velum. Hydra,
Pennaria, Obelia, Gonionemus.

Class 2. Scyphozoa.— Ccelenterates of considerable size,
the medusa prominent but the polyps much re-
duced or absent. The edge of the bell is lobed and
• a velum is not present. Aurelia, Cyanea.

Class 3. Actinozoa.— Polyps solitary or colonial, with
esophageal tube and mesenteric folds. A medusa
generation is entirely lacking. Sea anemones and
corals.

PHYLUM ECHINODERMATA.— Radially symmetrical ani-
mals usually with a pentamerous arrangement.
Mouth and anus present, ccelom well developed,
a water vascular system. The body wall con-
tains calcareous plates and usually bears spines.

142 GENERAL BIOLOGY

Class 1. Asteroidea.— Star-shaped forms, the arms not
sharply marked off from disc but with an am-
bulacral groove from which tube-feet project.
Starfish.

Class .2. Ophiuroidea.— Star-shaped forms, the arms
sharply marked off from disc and without am-
bulacral groove. Brittle stars, serpent stars.

Class 3. Echinoidea.— Spheroidal or discoidal forms with
a shell of closely fitting plates and with movable
spines. Tube feet project from five rows of pores
on the shell. Sea urchins.

Class 4. Holothuroidea.— Elongated worm-like echino-
derms with muscular body wall containing scattered
plates. Contractile tentacles about the mouth,
and tube feet in the form of papillae. Sea cu-
cumbers.

PHYLUM PLATYHELMINTHES.— Flattened, bilaterally sym-
metrical, worm-like animals with an excretory
system of branched canals containing flame cells.
Anus is not present, and coelom not developed.

Class 1. Turbellaria.— Free living Platyhelminthes with
a ciliated ectoderm and a centrally located muscular,
protrusible proboscis. Planaria.

Class 2. Trematoda.— Parasitic forms with unseg-
mented, flattened body. Anteriorly placed mouth
and one or more ventral suckers. Liver fluke.

Class 3. Cestoda.— Elongated, and usually segmented,
Platyhelminthes without mouth or digestive tube.
Suckers or hooks at one end, and a complete re-
productive system in each mature segment. Tape
worms.

PHYLUM NEMATHELMINTHES.— Elongated, cylindrical or
thread-like worms with unsegmented body. Ter-

CLASSIFICATION OF LIVING THINGS 143

minal mouth and anus, coelom present, appendages
wanting. Body covered with a heavy cuticle.
Free living or parasitic. Pork worm (Trichinella),
vinegar eel, thread worms,

PHYLUM ANNELIDA.— Segmented worms, usually with a
well marked coelom. Internal organs segmentally
arranged. As a rule chitinous setae are embedded
in the skin.

Class 1. Chaetopoda. — Annelida with conspicuous setae.
The well marked coelom divided by septa. Earth-
worm, Nereis.

Class 2. Hirudinea.— Elongated, flattened annelida with
anterior and posterior suckers, without seise and
with median genital openings. Coelom much
reduced. Leeches.

Class 3. Gephyrsea. Unsegmented worm-like animals
with a spacious ccelom not divided by septa, an
anterior anus and a single pair of nephridia. Setae
absent.

PHYLUM MOLLUSCA.— Bilaterally symmetrical, unseg-
mented animals, with a ventral foot, a mantle fold,
and usually a univalve or bivalve shell. The
central nervous system consists of a circum-eso-
phageal ring.

Class 1. Lamellibranchiata. — Symmetrical mollusca with-
out head; with bilobed mantle, bivalve shell, and
usually with lamellate gills. Clams, mussels,
oysters.

Class 2. Gastropoda.— Asymmetrical mollusca with a
distinct head usually bearing tentacles, a muscular
creeping foot, a continuous mantle fold and usually
a coiled shell of one piece. Snails.

144 GENERAL BIOLOGY

Class 3. Cephalopoda.— Mollusca with a well marked
head, a circle of arms bearing suckers around the
mouth, and well developed eyes. There is a heavy
muscular mantle fold; the nervous system is con-
centrated in the head. Squid, octopus.
PHYLUM ARTHROPODA.— Segmented animals with a
firm external skeleton and jointed appendages.

Class 1. Crustacea.— Aquatic arthropods breathing by
means of gills, with two pairs of antennae and
.numerous pairs of biramous appendages on thorax
and abdomen. Crayfish, lobster, crab, water flea,
barnacles.

Class 2. Myriapoda.— Worm-like arthropods with numer-
ous similar segments bearing similar appendages.
One pair of antennae, breathe by means of tracheae.
Millipeds, centipedes.

Class 3. Insecta.— Arthropoda with the adults usually
bearing three pairs of legs and two pairs of wings;
body divided into head, thorax and abdomen;
single pair of antennas; breathe by tracheae. A
metamorphosis is common in the life history. Fly,
mosquito, beetle, grasshopper, bee.

Class 4. Arachnida.— Arthropoda without antennae, with
four pairs of legs and two pairs of mouth parts.
Body divided into cephalothorax and abdomen.
Breathe by means of trachea? and book lungs.
Spiders, mites, scorpions.

PHYLUM VERTEBRATA.— Animals with dorsal brain and
cord, enclosed in an unsegmented skull and a seg-
mented vertebral column. Red blood; usually
with two pairs of appendages.

Class 1. Pisces.— Aquatic vertebrates breathing by
means of gills; typically with two paired and other
unpaired fins. Fishes.

CLASSIFICATION OF LIVING THINGS 145

Class 2. Amphibia.— Cold blooded vertebrates with
naked scaleless skin. Breathe by lungs in adult
life commonly, the larvse breathe by gills. Heart
with two auricles and a single ventricle. Frogs,
toads, salamanders.

Class 3. Reptilia.— Cold blooded scaly vertebrates.
Breathe by lungs; heart with auricles and two
imperfectly separated ventricles. Snakes, turtles,
alligators, lizards.

Class 4. Aves.— Warm blooded, oviparous, bipedal
vertebrates covered with feathers. The chambers
of the heart are completely separated. The an-
terior appendages have the form of wings. Birds.

Class 5. Mammalia.— Warm blooded, hairy vertebrates.
Viviparous; mammary glands with which they
suckle the young. Red blood corpuscles non-
nucleated. Mammals.

10

APPENDIX.

Collection and Preparation of Material.

Amoeba.— While amoeba has a wide distribution, -in no
place is it very abundant, nor are culture methods as success-
ful as with other protozoa. By putting Elodea, Cerato-
phyllum, or other water plants, into a shallow dish with a
small amount of water and allowing the plants to decay,
amoebae may often be found in some abundance in the slimy
sediment. The slime on lily pads often contains amoebae.
Occasionally amoebae will be extremely abundant in the
scum on a freshly started hay infusion, especially when
pond weeds have been present in the infusion.

Par amecium.— Into a hay infusion twenty-four hours old
(that made from dry timothy hay is best), place some water
and organic matter from almost any pond or swamp. After
about a week Paramecium will be found in abundance. Or
fill a jar half full of Elodea or other pond weeds, cover with
water and allow the plants to decay. Do not place the
jars in the direct sunlight.

To keep a culture in vigorous condition remove some of
the old hay and about one-third of the water, and add fresh
hay and water, every two or three days. If several cultures
are running and are changed on different days one may have
vigorous cultures of Paramecium constantly.

Conjugating paramecia are often obtained a few days or
a week after a fresh culture is started, if the culture has been
started by bringing in Paramecium from outside.

148 GENERAL BIOLOGY

Paramecium probably never encysts and a hay infusion
made as sometimes directed, but not inoculated from some
source containing the animals, will not give rise to para-
mecia. The culture must be inoculated from an old culture,
or the animals must be introduced from outside sources.

To kill Paramecium hot Worcester's fluid is probably the
best. A round bottomed vial is filled one-third full from a
good culture, with as many of the animals and as little fluid
as possible. Fill the vial to the top with hot Worcester's
fluid and allow to stand fifteen minutes, during which time
the animals will settle to the bottom. With a pipette draw
off as much of the killing fluid as possible and add water to
wash, using several changes and stirring up the mass of
paramecia as little as possible. Stain in hematoxylin
rather heavily, destain with weak acid, or acid alcohol, until
the color is very faint except in the nucleus. WTash in water,
dehydrate, clear and mount on a slide in balsam. Support
the cover glass to prevent crushing the animals.

Vorticella.— If sticks, leaves, and pond weeds are placed
in a jar and allowed to stand a day or two a scum will form
on the water, and in this scum Vorticella will often be abun-
dant. In such fresh cultures large specimens are usually
found. The methods used for continuing Paramecium
cultures will be fairly successful for Vorticella. Similar
metiiods of killing and staining may be used but are not
very successful, on account of the contraction which usually
takes place in Vorticella.

Hydra.— In ponds, swamps, and slow moving streams
covered with "duck-weed'"' (Lemna) green hydra will often
be abundant in spring and summer. Brown hydra is more
often found in larger ponds and lakes on Sagittaria and pond-
lily leaves. Place the plants, in both cases, in jars and set
in a bright place, but not in the direct sunlight. Within a

APPENDIX 149

few days hydra, if present, will be found on the side of the
jar toward the light. In the autumn secure leaves from
the bottom of the pond and some of the surface mud.

Hydra will nourish if the jar is kept supplied with an
abundance of "water-fleas," Daphnia, Cyclops, Cypris,
etc., and budding will be abundant on the hydras. If the
food supply is allowed to diminish reproductive organs will
often begin to appear.

To kill hydra expanded remove a single specimen from
the aquarium with a pipette and place in a perfectly clean
watch glass with only a small amount of water. When the
animal in the watch glass is well expanded dash hot Wor-
cester's fluid, or hot Bouin's fluid, over it and allow to stand
ten minutes. The animal may then be washed and treated
for further use by staining or embedding for sections. Handle
very carefully since the killing fluid makes them rather brittle.
If whole mounts are desired a light stain with hematoxylin
is good. When mounting support the cover glass to pre-
vent crushing.

Hydroids, Jelly-fish.— If these are collected the jelly-fish
should be preserved in formalin. Obelia should be nar-
cotized with magnesium sulphate before killing, to get the
hydranths expanded. It is well to have the hydroids killed
in some killing fluid and preserved in alcohol, though for
general external study preservation in formalin is satis-
factory. To make whole mounts of the hydroids proceed
as for hydra.

Earthworm.— In the spring and early summer after a
soaking rain large earthworms can easily be obtained at
night. With a light examine the ground, preferably in a
garden or where there is little grass. Place the worms in
a can with a little soil until morning.

To preserve put the worms in a dish or pan with enough

150 GENERAL BIOLOGY

water to just cover them and add a few drops of alcohol
every few minutes. After several hours they will be found
to be motionless and should not respond to tactile stimuli.
They should now be laid out straight and flat in a disk of
weak alcohol and allowed to remain for not more than four
hours. They are then to be placed in 80 per cent alcohol,
or better a mixture of alcohol and 10 per cent formalin for
preservation. The worms should be kept straight in the
preservative since they are much easier to study when in
this condition.

A somewhat clearer demonstration of setae and of external
openings can be made on worms killed (after narcotizing)
in 1 per cent chromic acid. After twenty-four hours in the
chromic acid, wash overnight in water and preserve in
alcohol. These are not so good for internal study.

For sectioning place worms in a dish with moist filter
paper and leave for several days until they void clean filter
paper instead of dirt. The digestive tract is now in con-
dition for sectioning. Narcotize with alcohol (or chloral
hydrate, or chloretone) and when motionless cut into small
pieces and fix in Bouin's fluid.

It is very easy to keep earthworms alive all winter with
little or no trouble. In a wooden box filled with moist
loamy soil place a number of worms and keep the box in
a cool place. Every few days leaves, pieces of apple, etc.,
should be spread on the surface for the worms to feed upon.
Cover the box with a heavy cloth (burlap) which is kept
moist and the soil will need very little attention. If the
soil should appear dry it must be sprinkled enough to
thoroughly moisten it.

Grasshopper.— The larger grasshoppers are best for study
on account of their size, and are necessary if much internal
study is to be made. But for the study of external features

APPENDIX 151

the small red-legged locust (Melanoplus femur-ntbrum)
will be satisfactory. Some of these should be alive in the
laboratory for study of the habits of living specimens.
Preserve insects in alcohol, rather than formalin.

Crayfish.— Crayfish may be purchased alive from dealers,
or collected. If they are collected in the autumn and placed
in a tank (or tub) with water and kept in a cool, rather dark
place, they will live for a long time. If running water is
not available the water in the tank should be changed
occasionally, especially if a scum appears on it.

For demonstrating water currents over the gills use
powdered carmine, India-ink, methylene blue, etc., and
drop along the edge of the carapace. A piece of the carapace
at the side of the mouth parts may be removed in the living
animal* if carefully done, and the movement of the gill
bailer demonstrated.

The heart and larger bloodvessels are easily injected with
a thin starch mass. Either remove a piece of the carapace
and with syringe gently inject the mass into the heart, or
if the position of the heart is determined the carapace and
heart may be pierced with the cannula of the syringe.

For preservation cut away a small piece of the carapace
on the dorsal side to permit the entrance of the preservative.
Alcohol is a better preservative than formalin since the acid
in the latter dissolves out some of the mineral matter of the
shell, and leaves an undesirable scum on the liquid and
about the animals.

Clam.— The fresh water clam is much easier and better
for study than the salt water forms. Use the larger forms.
If the valves are forced open and a wedge of wood, or a
pebble, is placed between to prevent closing, the animals
may be thrown directly into formalin for preservation. They
may be kept alive for some time in a cool place with running
water.

152 GENERAL BIOLOGY

To harden for making macroscopic sections across the
body., .wedge -the valves open, place in .1 per cent chromic
acid for a day or so. Wash in water and preserve in alcohol.
When ready, for sectioning remove the valves carefully,
place the body of the clam on a piece of cork or wax and
with a razor or brain knife make sections from | to \ inch
thick.

Snail.— If the edible snail (French or Roman snail) is used
it must be purchased from dealers.

Frog.— Any of the common frogs will do, though they
should be as large as possible. For the study of living
specimens in the winter, material must be obtained from
dealers unless it has been collected earlier and kept alive
in a tank. . If the animals are placed in a tank and kept in
a cool place in running water, or the water frequently changed,
and there is a platform or float on which they may rest, it
is possible to keep them alive all winter. During cold
weather food is not needed. To preserve, anesthetize with
ether or chloroform and place in 5 per cent formalin. Al-
cohol is not so good as a preservative for these forms.

For demonstration of circulation in the web, narcotize
the frog with chloretone, place on a plate of glass and cover
body with damp cloth. Hold the toes spread apart with
bent pins held in place against the glass with masses of
putty or wax.

To inject the bloodvessels for the study of the arterial
system proceed as follows: Anesthetize the frogs with
chloroform or ether (the latter leaves them in somewhat
better condition), remove a piece of the pectoral girdle from
over the heart, and remove the pericardium. With the
scissors cut a slit in the ventricle, insert the cannula through
the ventricle into the truncus arteriosus, and with a steady,
gentle pressure fill the arteries with the injection mass

APPENDIX 153

(formula for injection mass on page 159). No ligature will
be needed since the valves of the truncus prevent the back-
ward flow of the mass. During the injection of the arteries
the blood has been forced into the veins, and because of
this it is possible to follow the veins fairly well without in-
jecting them. After the injection is complete, the blood
and excess injection mass should be wrashed off, and the
frogs preserved in formalin.

For the study of the histology of the frog examine fresh
tissues in normal salt solution. For sections of the spinal
cord fix in 10 per cent formalin, embed in paraffin and make
rather thick sections. Borax carmine or hematoxylin are
good stains to show the general form and something of the
cells. For a sharp distinction of the white and gray sub-
stances Weigert's hematoxylin method for medullated
nerves gives beautiful results. (See directions in books on
technic. The mordant of copper acetate may be used after
the sections are on the slide.) For sections of the stomach
cut the organ into two parts, rinse in salt solution and fix
twTenty-four hours in Zenker's fluid. Hematoxylin and
Congo-red are good stains to differentiate the tissues.

In the spring get spawn from ponds and place small masses
in jars for the study of the development. Water plants in
the jars will help to aerate the water. If the water at any
time appears turbid, change. The tadpoles may be kept
for some time after hatching if the aquaria are kept supplied
with algae or other water plants.

Preparation and Mounting of Slides.

To get the best results in mounting small objects or
sections, the animal or tissue must be properly prepared.
It must be killed quickly so that the constituents of the

154 GENERAL BIOLOGY

cells are fixed in a normal condition. Usually some harden-
ing of the tissue takes place during the fixation, but if not
the alcohol used for preservation will also accomplish this
purpose.

Killing and fixing reagents are numerous; some are good
for a special purpose only and others have a wider use.
Those mentioned among the reagents are good, easily used,
and satisfactory for any of the work demanded in a begin-
ning course.

After fixation the tissue must be washed to remove the
excess of the reagent, and then preserved in 80 per cent
alcohol until wanted for use. Since this procedure has a
bleaching effect on the tissues, dyes are used to stain the
object to make it more easily seen. If sections are desired
it is necessary to embed the tissue or organ in paraffin or
other medium to support the softer mass while the sections
are being made. Directions for this must be had from books
on histological technic.

For examination of living tissues normal salt solution is
the medium used; for fresh water animals, if alive, water
is used; preserved animals are examined in the solution
in which they are preserved. Glycerin is used if it is desired
to render the objects somewhat transparent. They may
be placed in the glycerin from water, alcohol, or formalin
directly.

If a permanent mount is desired the object is usually
first stained, then dehydrated by placing for about an hour
in alcohol of various grades (35 per cent, 50 per cent, 70
per cent, 80 per cent, 95 per cent). If absolute alcohol is
at hand they should be placed in this for an hour to com-
plete the dehydration. To remove the alcohol some fluid,
usually an oil, is used which will mix with the alcohol and
also with the balsam which is used to complete the mounting.

APPENDIX 155

Cedar-wood oil, clove oil, creosote, xylol and benzol are some
of the common fluids used for this purpose. Not only do
they remove the alcohol but they also render the object
transparent and are therefore called clearing agents. Cedar-
wood oil and xylol are the most commonly used of the oils
mentioned. When the object has become transparent it
is placed on a slide, the excess of oil allowed to run off, or
removed with filter paper, then a drop of Canada balsam
placed on the object and this is covered with a thin cover
glass which is allowed to gently settle on the object. When
the balsam has hardened the object is permanently fixed.
If -absolute alcohol is not at hand for the final dehydration,
place the object from 95 per cent alcohol directly into a
mixture of one-third beechwood creosote and two-thirds
xylol, or into the same proportions of xylol and melted car-
bolic acid crystals. Cedar oil and oil of cloves will also clear
directly from 95 per cent alcohol. After the object has
been cleared proceed as directed in the previous paragraph.
Before a slide is laid away it should be labeled as to the
animal, or part, or tissue; how fixed; how stained; date
and name of person making the preparation.

Reagents.

Acetic Acid.— A solution of 0.2 per cent to 1 per cent
applied to fresh tissues will render the nuclei visible. %

Alcohol. —This is the most used reagent in the laboratory
and should be kept on hand in abundance, made up in
various strengths. Alcohol is rather expensive if bought in
small amounts from a druggist or ordinary dealer, but it
can be purchased, for scientific purposes, with the revenue
tax remitted. The collector of internal revenue of the
district, or the Federal Treasury Department can give

156 GENERAL BIOLOGY

directions for its purchase. Denatured alcohol may be
used and is cheaper, and about as satisfactory, as the regular
alcohol. Grain or ethyl, and not wood or methyl alcohol,
should be used ; the latter is poisonous.

Commercial alcohol is ordinarily about 95 per cent in
strength. To make various grades from the commercial
product, fill a graduate with 95 per cent to the mark which
indicates the desired strength, and then add water up to
95 cc (e. g., to make 70 per cent from 95 per cent take 70
cc of alcohol and add water up to 95 cc) . It is well to have
alcohol of the following grades prepared: 35 per cent, 50
per cent, 70 per cent, 80' per cent, 95 per cent. These will
be used in the preparation of slides. For preservation 70
per cent or 80 per cent is used.

Acid Alcohol.— Of 70 per cent alcohol take 99 cc and of
concentrated hydrochloric acid Ice. Used chiefly for
destaining tissues.

Anilin Dyes.— For staining, these may be dissolved in
water, or in alcohol of any grade. They, are most com-
monly used in aqueous solutions. It is better to stain for
some time with a weak solution, than for a brief period
with a strong mixture. Some of the stains will be removed
by alcohol, and experience, or reference to some book on
technic, must show the best methods of use. The com-
mon dyes used for the staining of the cytoplasm are: eosin,
congo-red, acid fuchsin, light green, orange G.

Benedict's Solution.— Used in the same way as Fehling's
solution for demonstrating the presence of grape sugar.
This solution is said not to deteriorate on long standing.

Sodium citrate 173 g.

Sodium carbonate 100 g.

Dissolve in 600 cc water, using heat. Filter and make up
to 850 cc with water. Dissolve 17.3 g. of copper sulphate

APPENDIX 157

in 100 cc water and make up to 150 cc with water. Add
the cupric sulphate solution to the carbonate-citrate solution
slowly, stirring. The mixed solution is ready for use.

Borax Carmine.— Dissolve 4 g. borax in 100 cc water. Add
1 g. carmine and dissolve it with heat. Cool and add to
the solution 100 cc of 70 per cent alcohol. Filter after
twenty-four hours. A good stain for large objects and for
tissues in bulk. Use the stain twenty-four hours, and
differentiate with acid alcohol.

Bouin's Fluid.

Saturated aqueous picric acid 75 cc

Commercial formalin 25 "

Glacial acetic acid • . 5 "

It is best to add the acetic acid just before using. Kill
the tissue four to twenty-four hours, wash in 50 per cent
alcohol, preserve in 80 per cent alcohol. This is one of the
best of the killing fluids for general use.

Chloretone.— Make a. saturated solution in water. Used
for narcotizing animals. In some cases it may be sprayed
on top of the water which contains the animals. For nar-
cotizing frogs for demonstrating the circulation of the blood
in the web the following method has proved satisfactory:
With a pipette inject about 2 cc into the stomach through
the esophagus. If after twenty minutes the animal is not
quiet repeat the dose. The animal will remain quiet for
hours, but will be recovered within twenty-four hours.

Chloriodide of Zinc.

Chloride of zinc 30 . 0 g.

Potassium iodide 5 . 0 g.

Iodine 0.89g.

Dissolve the above ingredients in about 15 to 20 cc distilled
water. The solution does not keep long, and should be
kept in the dark. Used as a test for cellulose.

158 GENERAL BIOLOGY

Fehling's Solution.

A. Copper sulphate 34.65 g. dissolved in ... 500 cc of water

B. Sodium or potassium hydroxide .... 125 g.
Sodio-potassium tartrate (Rochelle salts) . 173 g.

Dissolve in 500 cc of water.

Keep solutions separate until ready to use. Just before
using mix equal parts of A and B. This solution is used to
test for the presence of grape sugar.

Formalin.— Commercial formalin is a solution of formalde-
hyde gas in water (40 per cent). To use, this is considered
as absolute and a 5 or 10 per cent solution made (e. g., to
make 5 per cent formalin mix 5 cc of commercial formalin
and 95 cc of water). For practically all organisms, plant
and animal, used in the laboratory or in the museum 5 per-
cent formalin is an efficient preservative and for most things
as satisfactory as alcohol. If the tissues are very watery
the solution should be changed after twenty-four hours.

Glycerin.— Use pure or diluted with equal parts of water
or alcohol. Useful as a clearing agent and as a temporary
mounting medium.

Hematoxylin (Delafield's).— Hematoxylin crystals 1 g. di,s-
solved in 10 cc of strong alcohol. Add this slowly to 100 cc
of saturated aqueous solution of ammonium alum, stirring.
Expose this solution to the air for several weeks to ripen.
Filter and add 25 cc of glycerin and 25 cc of methyl
alcohol.

Hematoxylin is one of the most satisfactory stains for
tissues; it is a nuclear stain. To use, dilute the stain and
let it act until the tissue is dark and overstained. Destain
with acid alcohol or with very dilute aqueous hydrochloric
acid (1 per cent of acid or less, in water). The slides hold-
ing the sections must now be washed for at least five minutes
in running water, to remove the acid and restore the blue

APPENDIX 159

color. Now counterstain the sections, if desired, dehy-
drate, clear and mount.

Injection Mass.— The following is one of the best masses
for injecting bloodvessels.

Dry corn starch 1 Ib.

Chloral hydrate (2£ per cent) 600 cc

Alcohol (95 per cent) 150 "

Color 150 "

The chloral hydrate and alcohol of the above may be re-
placed by 750 cc of 5 per cent formalin; the resulting mass
appears to act as well as the one above. To make the
color take about 50 g. of dry insoluble color, such as chrome
yellow or vermilion, grind in a mortar with 50 cc of glycerin
and 50 cc of alcohol (95 per cent). Mix the color and the
liquid and slowly stir in the starch to make a homogeneous
mass. If the mass appears to be getting too thick use less
starch, if too thin add more starch. Before using the mass
should be strained through two thicknesses of cheesecloth,
to remove all particles which might clog the cannula or
artery. The injection mass does not spoil upon standing,
but must be well stirred before using.

Iodine Solution.— Dissolve potassium iodide in distilled
water to saturation, then saturate this solution with metallic
iodine. To use dilute with several volumes of water. May
be used as a stain for protoplasm, but chiefly used for starch
test.

Lime (or Baryta) Water.— Shake up a little quick lime
(or barium oxide for baryta water) in water and allow the
mixture to settle. Decant or filter the clear liquid. In the
presence of carbon dioxide this clear liquid will become
milky, or will show a white precipitate.

Lyons Blue.— This is one of the anilin dyes. An alcoholic
solution should be made. This is used as a contrast stain
with borax carmine.

160 GENERAL BIOLOGY

Methyl Green.— A strong aqueous solution (1 per .cent)
with 1 per cent of acetic acid. An excellent stain for fresh
tissues. Stains the nucleus only, stains rapidly and does
not overstain.

Methylene Blue.— Pure methylene blue added to water to
make a light blue tint will stain parts of the living animals
contained in the water. Several hours are usually neces-
sary. Does not affect the animals, but the stain should
be pure for this purpose.

Normal Salt Solution.— Dissolve 7 g. of common salt in
1000 cc of water. This solution is used as a medium for
the examination of fresh tissues. The concentration ap-
proaches that of the lymph, and tissues and cells in it are
not distorted as they would be in water.

Pasteur's Solution.

Ammonium tartrate .
Potassium phosphate
Calcium phosphate .
Magnesium sulphate
Cane sugar
Water to make

50 g.

10 g.

lg.

1 g.

750 g.

5000 cc

This solution is used as a culture medium for yeast, moulds
and bacteria. The Pasteur's solution without sugar is the
same wdth the sugar omitted.

Worcester's Fluid.— This fluid is a saturated solution of
corrosive sublimate (mercuric chloride) in 10 per cent
formalin. For small animals and small pieces of tissue kill
for fifteen minutes to an hour. Wash in water, preserve in
formalin or alcohol. Especially good for killing Paramecium
and Protozoa. If used hot Protozoa and hydra are killed
instantly.

Zenker's Fluid.

Corrosive sublimate (mercuric chloride) . , 5 g

Potassium bichromate ... 2 o'e

Water .'.".' l<X/cc

Just before using add glacial acetic acid ... 5 cc

APPENDIX 161

Fix for six to twenty-four hours, wash in running water for
twelve to twenty-four hours. Preserve in alcohol 80 per-
cent.

This is one of the standard killing mixtures, and for general
histological use it is excellent. It would be well to treat the
fixed tissue in alcohol with iodine for twenty-four hours to
remove all excess of the mercury salt. After this the iodine
must be thoroughly removed from the tissue by several
changes of alcohol.

Tests for Organic Substances.

Grape Sugar or Glucose.— Into a test tube place the sub-
stance to be tested, add Benedict's or Fehling's solution and
boil. The appearance of a yellowish or red color indicates
the presence of the grape sugar.

Starch.— If a substance containing starch is acted upon
by an iodine solution a blue color will result. The reaction
takes place more quickly if the substance has been boiled
and the starch grains swelled.

Cellulose.— This substance is common in plant tissues, in
the fibers and cell walls; cotton is almost pure cellulose.
The section, or material, to be tested for cellulose is treated
with a drop or two of chloriodide of zinc. Cellulose is
colored violet, lignified membranes a yellowish brown,
membranes containing cutin or cork from yellow to yellow-
ish-brown.

Fat.— Fats and oils are stained black by osmic acid. A
1 per cent solution acting on a thin piece of tissue will show
the reaction within a few minutes. Sudan III in aqueous
solution will stain fat or oil a yellowish color, and Scharlach
R will give a red color. These stains will also act upon fat
preserved in formalin. Ether or benzene may be mixed
11

162 GENERAL BIOLOGY

with the substance to be tested and allowed to remain for
a few minutes, then filtered and the filtrate evaporated in
a draft. The oil, if present, will be left behind in the dish.
Protein.— Place the substance to be tested in a test tube,
add a few drops of strong nitric acid and boil. Cool and
carefully add a few drops of ammonia. A yellow color
appearing when the nitric acid is boiled and becoming a
deep orange on the addition of the ammonia is an indication
of the presence of the protein. This is one of the best and
most easily made tests for protein.

GLOSSARY

abdomen.— In vertebrates that part of the trunk below or
behind the thorax; in invertebrates the posterior region
of the body.

aboral.— Opposite the oral or mouth region.

achromatin. — The material in the nucleus not colored by
certain dyes.

adaptation. —The condition of a portion of the body such
that it is adjusted or fitted to its functions.

adductor.— A muscle which draws some part toward the
middle line of the body.

alga.— Simple plants, one or many celled; without definite
leaves, stem or roots.

alternation of generations.— The alternation of sexual and
asexual forms in the life history of a plant or animal.

alveolar.— Resembling little cells or sacs, a common appear-
ance of protoplasm.

amitosis.— Simple or direct division of the nucleus, a mere
pinching into two parts. Opposed to mitosis or indirect
division.

analogous.— Similarity of function.

anaphase.— A stage in indirect division in which the chromo-
somes are pulled apart into two groups.

anastomosis.— The interjoining or fusing of nerves or blood-
vessels.

animalcule.— A microscopic animal.

164 GENERAL BIOLOGY

anterior. —At or toward the front or head end.

anus.— The posterior opening of the digestive tube.

aorta.— In invertebrates the chief artery of the body; in

vertebrates the large artery supplying the main organs

of the body,
aortic arch.— The arch or loop of the main arteries as they

leave the heart,
apopyle.— In the sponge the opening of a radial canal into

the central cavity.

appendage.— A subordinate part of an organ or body; es-
pecially an external organ or limb.

artery.— A bloodvessel carrying blood away from the heart,
asexual.— Non-sexual; reproduction by means other than

sexual, as by budding or fission,
aster.— Star. The star-like structure found at the end of

the spindle during mitotic division of the nucleus,
asymmetry.— Lack of symmetry, especially absence of bilateral

symmetry.

B

bacillus. —A little staff. A rod-shaped bacterium.

barb.— A hook or point extending backward, which pre-
vents the pulling out of the object.

bilateral symmetry.— Symmetrical with respect to the right
and left sides.

biramous.— Having two branches, as a typical crustacean
appendage.

bivalve.— Shell composed of two lateral valves or pieces -as
the shell of the clam.

blastopore.— The pore opening into the primitive gut of. a
developing animal.

blastostyle.— That portion of the fleshy axis which pro-
duces medusae in certain hydroids.

GLOSSARY 165

blastula. —A hollow sphere of cells produced by the develop-
ment of the egg.

body cavity.— Coelom; the cavity between the digestive
tube and the body wall.

brachial.— Pertaining to the arms.

branchial.— Pertaining to the gills.

buccal groove.— In infusoria the groove leading to the mouth.

caecum.— A tube or sac open at one end only; usually applied
to appendages of the digestive tract.

calcareous.— Composed of lime or calcium carbonate.

calciferous.— Esophageal glands in the earthworm contain-
ing calcium carbonate.

capsule.— A little case. In hydroids the cavity of a sting-
ing cell which contains the poison.

carapace. — A shell or shield covering the head and thorax
of Crustacea.

cell.— One of the structural units of a living body; a mass
of protoplasm containing a nucleus.

centrosome.— The central body or region of an aster in
mitosis.

cephalothorax. — The region of the body composed of the
fused head and thorax.

cerebral.— Pertaining to the cerebrum or brain; in inverte-
brates cerebral ganglia or brain.

chela.— The pincer-like claw of Crustacea and other arthro-
pods.

cbitin.— The horny material forming the covering of insects
and certain other animals.

chlorogog.— Gland cells surrounding the stomach-intestine
of the earthworm.

166 GENERAL BIOLOGY

chlorophyll.— The green coloring matter of plants.

chloroplast.— A chlorophyll body or granule.

chromatin.— The ingredients of the nucleus which stain
deeply with certain dyes.

chromosome.— A distinct body formed from the chromatin,
and present only at the time of nuclear division.

cilia.— Minute, vibratory, protoplasmic processes on a cell.

circum-esophageal.— About the esophagus. Refers to the
nerve connectives joining the ventral cord and cerebral
ganglia of invertebrates.

cleavage.— Splitting or division of the egg cell at the be-
ginning of development.

clitellum.— A thickened, glandular region of the earthworm
which secretes the egg case.

cloaca.— A chamber into which empty the intestine, kidneys,
and reproductive organs.

coccus.— A spherical bacterium.

ccelom.— The body cavity; the space between digestive
tube and body wall.

coenosarc.— The fleshy stalk or stem of hydroids, uniting the
various polyps.

colony.— A group of animals living or growing together, the
various individuals being connected.

commissure.— A band of nerves connecting ganglia in in-
vertebrates; tracts of nerve fibers within the central
nervous system of vertebrates.

conjugation.— A temporary or permanent fusion of cells in
reproduction.

contractile vacuole.— A pulsating vacuole in protozoa hav-
ing an excretory function.

corpuscle.— A cell of an animal body floating in a fluid or
separated by an intercellular matrix.

GLOSSARY 167

crop.— The pouch-like enlargement of the digestive tube
used to store food.

cuticle.— The outer skin. In protozoa the cell wall.

cytology. —The science of cell structure and function.

cytoplasm. —The protoplasm of the cell proper, as con-
trasted with the nucleoplasm, or protoplasm of the
nucleus.

D

desmid. ) _

Y Minute unicellular algse.

digit.— A terminal division of an appendage of vertebrates,

finger or toe.
distal.— Away from the point of attachment, opposed to

proximal,
dorsal.— The back or upper surface.

E

ectoderm. —The outermost layer of cells.

ectoplasm. —The outer, denser protoplasm in protozoa.

embryo. — The young of an animal before its parts are fully
developed, and before the commencement of inde-
pendent existence.

embryology. —The science of the development of animals
and plants.

encyst.— To enclose in a cyst or case, common in protozoa
and bacteria for protection.

endopodite.— In Crustacea the branch of a biramous append-
age toward the median line of me body.

enteron.— The digestive tube, especially the simple tract
of lower animals.

entoderm.— The inner tissue lining the enteron or digestive
tube.

168 GENERAL BIOLOGY

entoplasm. —The • inner, more fluid protoplasm of protozoa.

enzyme.— An active substance secreted by a living cell which
has the property, under certain conditions, of bring-
ing about changes in other substances without itself
entering into the composition of the substance which
results.

excretion.— Substances produced in the body as the result
of metabolism, which are of no further use to the body.

excurrent.— A pore or tube through which a current passes
outward.

exopodite. — The outer terminal segment of a biramous
crustacean appendage.

exoskeleton.— The external skeleton or shell.

ferment.— See Enzyme.

fertilization.— The union of a spermatozoon and an ovum.

fibrillar.— Composed of fibers.

nbro-vascular.— Bundles in a plant composed of fibers and

large vessels through which fluids or gases pass,
fission.— A division, usually into two parts; the common

method of reproduction in protozoa.

flagellum.— A long, whip-like, vibratory projection of a cell,
function.— The appropriate action of any special organ or

part.

« G

gamete.— A reproductive cell capable of union with another
gamete.

gametophyte.— A plant which produces gametes.

ganglion.— A group of nerve cells usually forming a swell-
ing in the course of a nerve.

GLOSSARY 169

gastro-vascular. — The inner cavity of hydra, hydroids and
medusae which performs both digestive and circulatory
functions.

genital.— Pertaining to reproduction or the reproductive
organs. .

germ layer.— Any one of the three embryonic tissues, ecto-
derm, entoderm or mesoderm.

giant fibers.— A group of large tubes in the dorsal portion
of the nerve cord of annelids. They may represent
degenerated nerve fibers or supporting structures.

gizzard.— A muscular stomach in which food is crushed and
ground.

gland.— A part or organ for secreting some substance to be
used in, or eliminated from, the body.

glottis.— The opening from the mouth into the trachea.

gonangium. — A reproductive individual in some hydroids,
covered by an enlargement of the perisarc.

granular. — Composed of granules or small grains.

II

hermaphrodite.— An animal containing both male and female

sex organs.
histology.— The science treating of the microscopic structure

of animal and plant tissues,
homology.— Similarity in structure and origin,
hydranth.— One of the individual polyps of a hydroid colony,
hydroid. —Resembling hydra ; marine, usually colonial animals

of the phylum Ccelenterata.
hydrotheca.— The vase-shaped expansion of the perisarc

which covers and protects the hydranth of certain

hydroids.

170 GENERAL BIOLOGY

I

incurrent.— A pore or tube through which water enters an
animal.

infusoria.— Protozoa found in infusions of organic matter;
ciliate protozoa.

interstitial cells.— Cells of hydra which fill the spaces be-
tween the bases of the ectodermal cells.

irritability.— Susceptibility of protoplasm to the influence
of stimuli.

labium.— One of the mouth parts of insects, the lower lip or
second maxilla.

labrum.— One of the mouth parts of insects, the upper lip.

lamella. —A thin plate or layer.

larva.— The free living young of an animal in which develop-
ment is accompanied by a metamorphosis.

lateral.— On or toward the side.

ligament.— A tough band which connects one part to an-
other; in the clam the elastic band which unites the
valves of the shell.

M

macronucleus.— The larger of the two nuclei present in

ciliated protozoa.

mandible. —The hard jaw of arthropods, one of a pair,
mantle.— The fold of skin covering the body and secreting

the shell in molluscs,
manubrium. — The proboscis or sac-like stomach of the

medusa,
matrix.— The intercellular ground substance which separates

the cells in such tissues as cartilage.

GLOSSARY 171

maturation.— Process of ripening; especially a stage in the
formation of spermatozoa and ova.

maxilla.— One of the mouth parts of arthropods; in verte-
brates the jaw bone.

maxilliped. — Foot jaws. Thoracic appendages of the cray-
fish modified as mouth parts.

medusa.— The free swimming, sexual individual in the life
history of hydroids.

mesentery.— A thin fold of tissue which holds the intestine
in place against the body wall.

mesodenn.— The middle one of the three germ layers formed
in the development of most embryos.

mesothorax.— The middle segment of the thorax of insects.

metamere.— One of the serially arranged body segments or
somites in animals such as Annelida and Arthropoda.

metamorphosis.— The striking changes in form undergone
by certain animals in the course of development after
the commencement of a free existence. For example,
the change from a caterpillar through a pupa into a
butterfly, the change of a tadpole into a frog.

metaphase.— The stage in mitosis during which the chromo-
somes are split.

metathorax. — The posterior somite of the thorax of insects.

micronucleus. — The small nucleus or nuclei found in certain
protozoa, always accompanied by a macronucleus.

mitosis.— Indirect division during which the nucleus under-
goes complicated changes, and the chromatin becomes
divided into equal halves.

morphology.— The science of the form and structure of
animals and plants.

mucosa.— Mucous membrane. An epithelial covering which
is kept moist by secretions of mucus, as in the stomach.

172 GENERAL BIOLOGY

N

nematocyst.— A stinging cell of Ccelenterates.

nephridium. — A much coiled tube serving as a kidney in

annelids and other invertebrates. Typically they are

paired segmental organs.

nucleolus.— A small dense spot within the nucleus,
nucleus.— The central, usually spherical, portion of the cell

which contains the chromatin.

ocellus.— A simple eye of an arthropod.

operculum.— A lid which closes the aperture of the shell of

some snails; the covering of the gills of a fish; the

skin which overgrows the gills of the tadpole,
oral.— Pertaining to the mouth, opposed to aboral.
organ.— A part of an organism capable of performing some

special action which is essential to the life of the whole,
organism.— An organized being or living body capable of

independent existence; often the organism is com-
posed of organs.
osculum.— The excurrent opening in the sponge through

which water passes to the exterior,
ostiura.— A mouth-like opening, as the pores on the outer

surface of the sponge, and the pores in the heart of

arthropods,
ovary.— The organ which produces the ova or female sex

cells,
oviduct.— The duct or passageway from the ovary to the

outside of the body,
ovipositor.— The organ by which many insects deposit their

eggs.
ovum.— The egg or female sex cell.

GLOSSARY 173

palp (palpus).— In arthropods a feeler, especially the jointed

palps on the mouth parts; in the clam soft, fleshy,

ciliated flaps near the mouth,
parapodium. — A fleshy unsegmented appendage of a somite

of annelids,
parenchyma. —The soft cellular tissue of plants and animals.

In the fern the pith; in flatworms the soft tissue which

fills the body cavity,
pectoral.— Of or pertaining to the breast or chest, as pectoral

muscles, pectoral girdle,
pelvic.— The girdle, in vertebrates, which attaches the hind

legs to the vertebral column.

pericardium.— The membrane which surrounds the heart,
perisarc.— The protective, horny, secreted sheath about

hydroids.
peristome.— A lip around the mouth in Vorticella and other

protozoa,
peritoneum. —A smooth serous membrane which lines the

body cavity and covers the viscera,
photosynthesis. —The process by which starch is manufactured

in green plants, in the presence of sunlight,
planula. — The larva of many Coelenterates; it is usually

oval in form and covered with cilia,
plasmolysis. —The separation of the protoplasm of a cell from

its enclosing cell wall,
plexus.— An aggregation of vessels or nerves forming an

intricate network,
polyp. —An organism or a part having a structure similar to

that of the fresh water hydra,
posterior.— At or toward the hind or tail end.
proboscis. —The long flexible sucking mouth parts of the bee.

174 GENERAL BIOLOGY

prophase. — The preparatory stage of mitosis; the period of

formation of chromosomes and spindle,
prosopyle.— In the sponge a pore connecting the incurrent

and radial canals,
prostomium. — The region which overhangs the mouth in

annelids.

prothorax.— The first somite of the thorax in insects,
protoplasm.— The living substance,
protopodite— The basal portion of a crustacean appendage

from which extend the two distal branches, exopodite

and endopodite.

protractor.— A muscle that draws forward,
pseudopodium.— A temporary and changing protoplasmic

projection in amoeba and similar protozoa,
pyrenoid.— Bright globules embedded in the chloroplasts

of green algae, which function to produce starch.

radial.— Diverging from a common center, as the radial

canals of a medusa.

retractor.— A muscle which draws parts back,
rhizome.— The underground stem of the fern.

S

sclerenchyma.— Woody or hard cells in plants which serve
to stiffen and support.

secretion.— A substance, made by parts or organs of an
animal, which is of use within the body.

septum.— A wall or partition, especially the partitions divid-
ing the ccelom of annelids.

serosa.— Serous membrane; a delicate tissue which lines
closed cavities and is bathed by lymph.

GLOSSARY 175

seta.— A chitinous spine or bristle in annelids used in lo-
comotion,
sexual.— Of or pertaining to sex. Sexual reproduction

involves the two sexes and the two kinds of sex cells,

spermatozoa and ova.

skeleton.— The bony framework which supports the verte-
brate body,
somite.— A metamere; one of the serial segments of which

an animal like the insect or annelid is composed,
spermatozoon. —The male sex cell,
spicule.— A small, spine-like skeletal body embedded in

the wall of sponges.
spindle.— The barrel-shaped structure of threads in a cell

at the time of the mitotic division of the nucleus,
spiracle.— One of the openings to the tracheae or air tubes

of insects.

spirillum.— A spiral-like bacterium,
spore.— An asexually produced body which gives rise to a

new organism,
sternum.— In vertebrates the breast bone; in arthropods

the ventral portion of the exoskeleton of a somite,
stomach-intestine.— The posterior portion of the digestive

tube in annelids, with the functions both of stomach

and intestine,
symmetry.— Orderly and similar distribution of parts in an

organism,
system.— An assemblage of parts or organs essential to the

performance of some particular function.

tarsus.— The jointed foot of an insect.

telophase.— The stage in mitosis in which the cell is divided,
and the nucleus reformed into a typical spherical form.

176 GENERAL BIOLOGY

tentacle.— A slender, unsegmented, tactile or prehensile

organ near the mouth,
tergum.— The dorsal portion of the exoskeleton of a somite

in arthropods.

testis.— The male reproductive organ,
thorax.— The middle of the three divisions of the body of

an insect.

tissue.— A group of similar cells having a similar function,
trachea.— The windpipe of vertebrates; a branching air

tube of insects.
trichocyst.— A sac or rod-like body in the ectoplasm of

Paramecium.
tubule.— A small tube,
tympanic membrane.— The ear drum or membrane of an

auditory organ,
typhlosole.— A longitudinal fold in the intestinal wall of

annelids, molluscs and certain other animals.

U

umbo.— One of the lateral prominences just above the hinge

of a bivalve mollusc shell,
ureter.— The duct of the kidney,
urino-genital.— Relating to the urinary and genital organs,

as urino-genital artery.

vacuole.— A globular space within a cell containing a gas

or liquid,
valve.— One of the pieces of the shell of a clam; a flap or

fold within a cavity which permits the passage of a

liquid in one direction only.

GLOSSARY 177

variation.— A modification, alteration, or deviation from the

typical or usual condition,
vein.— A vessel which carries blood to the heart; one of the

ribs in the wings of insects.
velum.— A circular membrane that partly incloses the space

beneath the umbrella in medusae.
ventral. —At or toward the under or belly surface,
viscera.— The internal organs taken as a whole.

yeast.— A unicellular, colorless plant which causes an alco-
holic fermentation of carbohydrates.

zob'id.— One of the single individuals in a colony of animals,
zobspore.— A spore provided with one or more flagella by

which it swims in the water,
zygospore.— A spore formed by the union of two zoospores,

or by union of protoplasm from two plants.

INDEX.

ABDOMEN, 110, 116

Acetic acid, 155

Achromatin, 50

Aciculum, 96

Actinozoa, 141

Adductor muscle, 126, 128

Adrenal gland, 30

Alcohol, 155, 156

Alimentary canal. See Digestive

System.
Alternation of generations, 82, 84,

101

Amitosis, 51
Amoeba, 54, 147
Amphibia, 145
Anaphase, 51
Anilin dye, 156
Animal pole, 42
Annelida, 143
Antenna, 112, 116, 122

cleaner, 123
Antheridium, 102
Antherozoids, 102
Anus, 88, 111, 128, 133, 137
Aorta, 32, 128
Aortic arch, 31
Apis, 121
Apopyle, 73 •
Appendage, 111, 116, 123
Appendix, 147
Arachnida, 144
Archegonium, 103
Artery, 31, 32, 128
Arthropoda, 144
Asexual, 69, 78, 81, 101
Aster, 51
Asteroidea, 142
Auricle, 28, 128
Aves, 145
Axone, 40

BACILLUS, 107

Bacteria, 107

Bast, 100

Bee, 121

Benedict's solution, 156

Bile duct, 29

sac, 29

Bladder, 29, 138
Blastopore, 43
Blastostyle, 84
Blastula, 52
Blood, 33

Borax carmine, 157
Bouin's fluid, 157
Brachial, 32, 36, 37
Brain, 35, 114, 119, 138
Branchiostegal, 137
Buccal groove, 58
Budding, 76, 81, 105

CAECUM, 118, 138

Calciferous gland, 91

Cambarus, 110

Campanularia, 83, 84

Carapace, 110

Carotid, 31, 32

Cartilage, 39

Cell, 45, 50

Cellulose, 161

Centrosome, 51

Cephalopoda, 144

Cephalo thorax, 110

Cerebellum, 35, 139

Cerebral ganglia, 91, 97, 114, 129

hemisphere, 35, 138
Cestoda, 142
Chsetopoda, 143

180

INDEX

Chloretone, 157

Chloriodide of zinc, 157

Chlorogogue, 92

Chlorophyll, 48, 66, 71, 98

Chloroplast, 66, 71, 98

Choanocyte, 74

Chromatin, 50

Chromosome, 51

Cilia, 49, 58

Ciliated epithelium, 39

Circulation of protoplasm, 48, 60

Circulatory system, 31, 89, 93, 113,

128

Cirrus, 95
Clam, 125, 151
Classification, 140
Clearing, 155
Cleavage, 42, 52
Clitellum, 87
Cloaca, 31
Cnidocil, 76
Coccus, 107
Cocoon, 87
Crelenterata, 141
Coeliaco-mesenteric, 33
Co3lom, 28, 89, 92, 96
Crenosarc, 80
Collection of material, 147
Colony, 68, 76, 80
Columella, 134
Columnar epithelium, 38, 41
Commissure, 97, 114, 129
Conjugation, 61, 64, 71, 147
Contractile vacuole, 55, 59, 63
Contractility, 77
Corpuscle, 38
Coxa, 117
Cranial nerve, 37
Crayfish 110, 151
Crop, 90, 96, 118
Crustacea, 144
Cutaneous, 32
Cuticle, 58, 62, 92
Cystic duct, 28
Cytology, 50
Cytoplasm, 50

DEHYDRATION, 154, 155
Dentary, 136
Development, 53, 103
Diaphragm, 23

Digestive system, 90, 113, 118, 129
Digit, 27
! Dissection, 21
Dorsal aorta, 32, 33

root, 37
Drawings, 18
Drone, 124
Dura mater, 35

EAR, 26

Earthworm, 87, 149

Echinodermata, 141

Echinoidea, 142

Ectoderm, 52, 76, 81, 84

Ectoplasm, 54, 58

Egg, 30, 42, 52, 74, 78, 81, 90, 96,

103

Embryo 52
Embryology, 42
Endopodite, 111
Enteron, 76

Entoderm, 52, 76, 81, 84
Entoplasm, 54, 58
Epidermis, 92, 99
Epigastric, 33
Epithelium, 38, 74, 92
Esophageal artery, 33
Esophagus, 27, 90, 113, 118, 129,

137

sEustachian tube, 27
: Excretory system, 88, 91, 114, 119,

129 '

jExcurrent, 73, 127
Exopodite, 111
Exoskeleton, 110, 116, 127
Eye, 26, 95, 116, 121, 133, 136

FAT, 161

body, 30
Feeding, 115, 131
Fehling's solution, 158
Femoral, 34
Femur, 117
Fermentation, 106
Fern, 98
Fertilization, 52
Fibrovascular, 100
Fins, 136

INDEX

181

Fish, 135

Hydroid, 80, 83, 149

Fission, 60, 64

LLydrorhiza, 80

Fixation, 154

Hydrotheca, 83

Flagellated chamber, 74
Flagellum, 69, 74

Hydrozoa, 141
Hypostome, 83

Focusing, 23, 24

Food vacuole, 55, 59, 63

Foot, 27, 117, 123, 128, 133

I

Formalin, 158

ILIAC, 33

Frog, 26, 152

Incurrent, 73, 127

Frond, 98, 99

Infundibulum, 36

Infusoria, 57, 141

G

Injection of frog, 152

mass, 159

GAMETE, 69

Insecta, 144

Gametophyte, 101

Interstitial, 79

Ganglion, 36, 91, 97, 114, 119, 129

Intestine, 29, 113, 118, 129, 138

Gastric, 41, 85, 118

Iodine, 159

Gastropoda, 143

Irritability, 60, 64, 77

Gastrula, 52

Germ layers, 52, 53

Gephyrsea, 143

K

Gill, 43, 95, 112, 127, 137
Gizzard, 91

KIDNEY, 30, 91, 114, 129, 138

Gland cell, 39, 79

Killing reagent, 154, 157, 158, 160

Glossa, 122

Glossary, 163

Glottis, 27

L

Glycerin, 158

Goblet cell, 39

LABIUM, 116, 122

Gonangium, 84

Labrum, 116, 122

Gonionemus, 85

Lamellibranchiata, 143

Grantia, 73

Laryngeal, 32

Grape sugar, 161

Lateral line, 137

Grasshopper, 116, 150

Lens of microscope, 23

Growth, 105, 109, 125

Ligament, 125

Lime water, 159

Liver, 29, 113, 129, 137

H

Locomotion, 77, 114

Lumbar, 33, 36, 37

HAY infusion, 147

Lumbricus, 87

Head, 26,, 95, 116, 121

Lung, 27, 29

Heart, 28, 89, 113, 120, 132, 133,

Lymph space, 28

138

Lyons Blue, 159

Heliotropism, 77

Helix, 133

Hematoxylin, 158

M

Hirudinea, 143

Histology, 38, 92, 99

MALPIGHIAN tubule, 119

Holothuroidea, 142

Mammalia, 145

Homology, 112 Mandible, 116, 122
Honev bee, 121 Mantle, 127

Hydra, 75, 148

Manubrium, 85

Hydranth, 80, 83

Mastigophora, 141

182

Maturation, 52
Maxilla, 112, 116, 122
Maxillary, 27, 136
Maxilliped, 112
Medulla, 35, 139
Medusa, 81, 84, 85
Mesentery, 31, 138
Mesoderm, 52
Mesothorax, 117
Metamorphosis, 44
Metaphase, 51
Metatarsus, 123
Metathorax, 117
Methyl green, 160
Methylen blue, 160
Microscope, 22, 25
Midrib, 99
Mitosis, 51
Mollusca, 143
Mounting, 153

INDEX

Mouth, 26, 27, 75, 85, 88, 111, 116, Parapodium, 95

Olfactory, 35, 138
Operculum (opercle), 43, 134, 137
Ophiuroidea, 142
Optic chiasma, 36
lobe, 35, 138
Organ, 45
Osculum, 73
Ostia, 73
Ovary, 29, 78, 90, 113, 119, 130,

Oviduct, 29, 88, 90, 119
Ovipositor, 118
Ovum. See Egg.

PALP, 95, 122, 124, 128
Pancreas, 29
Paramecium, 57, 147

118, 122, 128, 129, 136
Movement, 55, 59, 63, 93, 120
Mucosa, 41

Muscle, 39, 41, 92, 96, 126, 128
Myriapoda, 144

N

XACREOTJS, 126
Xemathelminthes, 142
Xematocyst, 76, 81, 84, 85
Xephridia, 91
Xereis, 95

Parenchyma, 100
Parthenogonidia, 69
Pasteur's solution, 105,1160
Pectoral, 28, 136
Pedal ganglion, 129
Pelvic, 30
Pennaria, 80
Pericardium, 28, 128
Periostracum, 126
Perisarc, 80, 83
Peristome, 62
Peritoneum, 31, 41, 92
Peroneal artery, 34
Pharynx, 90, 96

Xerve cord, 91, 92, 93, 97, 114, 119 Phloem, 100

tissue, 40 Photosynthesis, 71

Xervous system, 34, 91, 114, 119, Physiology, 55, 59, 63, 69, 71, 77,
129, 138 93, 104, 108, 114, 120, 130

Pia mater, 35
Pineal gland, 35, 139
Pinna, 98, 99
Pinnule, 98, 99

Xeural groove, 43
Xormal salt, 160
Xostrils, 26, 27, 136
Xotes and drawings, 18
Xucleolus, 50

, ,
^Pisces, 144

Xucleus, 50, 55, 59, 63, 66, 71, 104 Pituitary, 36
Xutrition, 55, 60, 78, 120, 131 |Planula, 84
; Plasma, 38
Plasmolysis, 71

OBELIA, 83 .
Objective, 23
Occipito-vertebral, 32
Ocellus, 116, 122
Ocular, '23

Platyhelminthes, 142
Pleurococcus, 66
Plexus, 37
Pollen basket, 123

brush, 123

comb, 123

INDEX

183

Pollen spur, 123
Pond scum, 70
Porifera, 141
Premaxillary, 136
Preparation of material, 147
Prismatic, 126
Proboscis, 83
Prophase, 51
Prosopyle, 74
Prostomium, 87, 95
Protein, 162
Prothallium, 102
Prothorax, 117
Protoplasm, 47, 66, 104
Protopodite, 111
Protozoa, 68, 140
Protractor muscle, 126, 128
Pseudopodium, 54
Pteris, 98
Pulmonary, 31, 32
Pyrenoid, 71

QUEEN, 124

RADIAL canal, 74, 85

Rana, 26

Reagent, 155

Recto-vesical, 33

Reproduction, 56, 60, 64, 66, 71,

78, 81, 89, 101, 113, 119, 130, 138
Reptilia, 145
Respiration, 29, 43, 112, 115, 118,

120, 127, 133, 137
Retractor muscle, 126, 128
Rhizome, 98, 99
Rhizopoda, 140

S

SALT solution, 160

Sand worm, 95

Sciatic, 34, 37

Sclerenchyma, 100

Scyphozoa, 141

Segmentation. See Cleavage.

Sensitiveness, 56, 93, 115, 120,

Septa, 89, 96

Seta, 88, 96

Sexual, 69, 78, 81, 101

Shell, 125, 126, 133

Sieve tube, 100

Simis venosus, 28

Siphon, 127, 131

Slides, mounting, 153

Snail, 133, 152

Somite, 87, 116

Sperm duct, 88

Spermatozoa, 52, 74, 78, 81, 90, 96

Spicule, 73

Spinal cord, 35, 40, 139

nerve, 37, 139
Spiracle, 43, 117
Spiral vessel, 101
Spirillum, 107
Spirogyra, 70
Spleen, 29, 138
Sponge, 73

Sporangium, 101, 102
Sporophyte, 101
Sporozoa, 141
Squamous epithelium, 38
Staining, 154, 156, 157, 158, 159,

160
Starch, 46, 70, 161

injection mass, 159
Starfish egg, 50, 52
Sternum, 117
Sting, 124
Stipe, 99
Stomata, 99

Stomach, 29, 41, 113, 118, 129, 137
Stomach-intestine, 91, 92, 96
Subclavian, 32
Submucosa, 41
Sugar, 156, 158, 160, 161
Sympathetic nerve, 36
Systemic arch, 31, 32

TADPOLE, 43

Tarsus, 117, 123

Teeth, 27, 96, 114, 126, 136

Telophase, 51

Telson, 110

Tentacle, 75, 80, 83, 85, 95, 133

Tergum, 117

Testis, 30, 78, 90, 113, 119, 130, 138

Tests for organic substances, 161

Thalamencephalon, 35, 138

Thorax, 116, 117

Tibia, 117

184

INDEX

Tibial artery, 34
Tissue, 38, 45
Tongue, 27, 122, 136
Trachea, 27, 118
Tracheid, 101
Trematoda, 142
Trichocyst, 58
Trichome, 99
Trochanter, 117
Trancus arteriosus, 28, 31
Trunk 27
Turbellaria, 142
Tympanum, 26, 117
Typhlosole, 91, 92

UMBO, 125
Unio, 125
Ureter, 30
Urino-genital, 30, 33

VACUOLE, 55, 59, 63, 104
Vegetative pole, 42
Vein, 34, 99, 117, 123, 129
Velum, 85

Ventral root, 37
Ventricle, 28, 35, 128
Venus, 125
Vertebrata, 144
Vestibule, 63
Visceral, 129
Volvox, 68
Vomerine, 27
Vorticella, 62, 148

WAX shears, 123
Wing, 117, 123
Worcester's fluid, 160
Worker, 124

YEAST, 104

Yolk, 42, 50

plug, 43

Z

ZENKER'S fluid, 160
Zinc chloriodide, 157
Zooid, 80
Zoospore, 67
^ygospore, 72

DC SOUTHERN REGIONAL LIBRARY FACILITY

AA 000480804 4

SOUTHERN

UNIVERSITY OF CALIFORN

LIBRARY,

COS ANGELES. CALIF