LABORATORY DIRECTIONS

IN

GENERAL BIOLOGY

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BY

EDWIN G. CONKLIN,

Professor of Biology
Princeton University

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LABORATORY DIRECTIONS

IN

GENERAL BIOLOGY

BY

EDWIN G. CONKLIN,

Professor of Biology
Princeton University

PRINCETON
UNIVERSITY
PRES

THE AIMS AND METHODS OF LABORATORY WORK IX

BIOLOGY.

The purpose of all laboratory work is to study nature at first
hand. Its educational value lies chiefly in the cultivation of ac-
curacy and independence both of observation and of judgment.
Each student is expected to make for himself the observations and
experiments hereafter indicated.

A record of every observation or experiment must be entered in
the prescribed note book, under numbers corresponding to those
in these Directions. This record should consist of drawings and
descriptive notes, and every page should bear the name of its
author and the date. The record for each topic must be inspected
and passed by an instructor before any new topic may be under-
taken.

To each student in the laboratory is assigned a locker containing
a microscope, reagents, glassware, etc., for the safe keeping of
which he is held responsible. The microscope is the most complex
and delicate instrument in this outfit and work with it should be
preceded by a study of the following description of its parts and
directions as to its use.

I. THE MICROSCOPE.

A.— DESCRIPTION. The body or tube bears the lenses and is
supported upon a stand which also carries a mirror to cast light upon
the object examined through a hole in the flat stage upon which the
object is placed. This hole can be made of various diameters by
means of diaphragms. A lens for concentrating light, and known
as a condenser may be placed between the mirror and the stage.
The lens at the upper end of the tube is the ocular or eye-piece;
there are two oculars, of different magnifying power. The combi-
nation of lenses at the lower end of the tube is the ob fee tire;
in this microscope there are two objectives of different magnifying
power, one marked 3, the other 6; the former ( low power objective)
is in focus, i. e., gives a clear image of the object examined when
its lower end is about 2/$ in. above the object, the latter (high power
objective) is in focus when it is about l/^ in. above the object. The
objectives are carried upon a nose-piece by revolving which either

one of them may be brought to lie at the lower end of the tube.
The tube is really double, one tube being telescoped within another.
By holding the body firmly in the left hand and taking hold of the
projecting brass ring just below the eye-piece with the right, the
inner tube may be drawn out some distance, thus lengthening the
body and increasing the magnification. The length of the tube
without lenses and nose-piece is 150 mm. and it can be drawn out
to 195 mm.; with the nose-piece the tube is 10 mm. longer. A table
of magnifications of the different lenses with a given tube length
is found on the inside of each case.

B. — USE. i. Reflect light, from white clouds if possible, upon
the object. \Yhere all the light is needed, use concave mirror;
where light is intense and a low magnification is required, use
plane mirror.

2. Use smaller diaphragms with higher powers.

3. To focus lenses upon an object, use first the coarse, then the
fine adjustment; the former movement is by means of a rack and
pinion. The rack is the toothed plate along the back of the tube,
the pinion is a small cog wheel which fits into the rack and is
turned by the two milled wheels on each side of the tube. The fine
adjustment is by means of a milled serein back of the pinion. If
the fine adjustment screw is turned in the direction in which a
clock's hands move the tube is lowered, turned in the reverse di-
rection it is raised. In using a high power turn the tube down
nearly to the object and, then, while looking through the microscope,
bring the object into focus by slowly turning the tube upward.
Never focus down upon the object, since by this method there is
danger of crushing the lens into the object. Keep one hand on the
fine adjustment when looking at an object and vary the focus con-
stantly to bring all the fine details of structure into view.

4. Do not use higher power objective without cover glass over
object examined.

5. Always use the lower power before the higher one ; and
always use the lowest possible power sufficient for distinct vision.

6. Do not touch lenses with fingers. If the field is blurred or
the object dim either the cover glass or the lenses are at fault. If
the cover glass is dirty remove it and clean it; if the fault is in
the eye-piece the particles of dirt revolve when the eye-piece is
rotated. If the field is still dim the objective is dirty and must be
removed and cleaned. In cleaning the lenses never use anything
but clean tissue paper supplied for that purpose. If necessary, the

lenses may be moistened by breathing upon them; if this is not
sufficient, consult the instructor.

7. Keep both eyes open, using either the right or the left. The
strain of microscopic work on the eyes is usually due to the
fatigue of constantly closing one eye. If you cannot see the object
with both eyes open use the eye-shade provided for that purpose.

8. Never leave the laboratory without first placing the micro-
scope in its case and locking it and all your apparatus in your
locker.

II. PREPARING OBJECTS.

The preparation of objects for examination under the microscope
is termed mounting. Objects are usually mounted on pieces of
glass 3 x i in., known as slides. Observe the following directions:

1. If the object to be studied is a mass of cells, separate it into
very small pieces by means of teasing needles; if it is a fluid use
only a very small drop. If too much fluid has been used it will run
out from under the cover glass and the excess must then be soaked
up with filter paper. Temporary preparations ure usually mounted
in water, permanent ones in balsam.

2. The lenses of the microscope, the upper side of the cover
glass and the lower surface of the slide m^st be perfectly clean
and dry.

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3. Having placed the object in a small drop of mounting fluid
take a cover glass in your left hand, rest me edge of the cover
on the slide near the drop and support the opposite edge on a
teasing needle ; lower the cover glass gradually over the drop, being
careful to inclose no air bubbles. Do not press upon the cover glass.

4. Before putting a permanent preparation away label it care-
fully w7ith the name of the object and the method of preparation.

5. Never use reagents hap-hazard but only when you have a
definite purpose in view. Reagents are used for fixing, hardening
preserving, staining, dehydrating, clearing, embedding and mount-
ing. Firing is the process of killing and hardening the living thing
so that it preserves as nearly as possible its natural form. Staining
is the dyeing of the object so that some parts are more deeply
colored than others. Dehydrating is the process of removing the
water from the object, usually by alcohol. Clearing usually consists
in substituting some oil for the alcohol which is in the object.
Embedding is the process of permeating and surrounding the ob-
ject with some substance such as paraffin, preparatory to cutting
sections of it.

III. NOTES AXD DRAWINGS.

1. Drawings should b'e made of every object studied; this is
necessary not only as a record of what has been seen, but also as
an aid to accurate observation. In general make outline drawings
only. Use hard pencils (/J.H-6H ), with very sharp points, and make
the drawings large enough so that all details can be represented with-
out confusion. Where certain structures occur in large numbers
it is sufficient to represent them in only a part of the drawing.
Label all important structures by means of reference lines and
marginal words.

2. To draw to scale : — Place paper at base of microscope and en-
deavor to trace outlines as seen with left eye while seeing point of
pencil at same time with right eye. The pencil point must appear
to coincide with the part of the object being drawn. Do not move
the eyes.

3. To make a scale : — Focus upon the lines drawn one-tenth
and one-hundredth of a millimeter apart upon a stage micrometer.
With a camera lucida draw several of the lines upon a card. Make
such a scale for each combination of lenses. Carefully label the
card with the lenses used and lay it away for future use.

IV. EXAMINATION OF COMMON OBJECTS.

1. Put a few fibres of wool, cotton, linen and silk in a drop of
water on a slide, cover with cover glass and examine first under a
low power, then under a high one. How do the fibres differ?
Sketch one of each and label them.

2. Examine a drop of oil emulsion (oil suspended in water) and
notice peculiar effects of refraction when lenses are focused upon
different portions of a drop.

3. Examine bubbles of air in water. These may be obtained by
running in water under a cover glass supported at one side by a
bit of paper and then tapping on the cover glass with a needle.
What differences can you see between these and oil drops?

PART I

GENERAL PHYSIOLOGY AND MORPHOLOGY

A. CHEMICAL AND PHYSICAL CHARACTERISTICS OF

LIVING THINGS.

The bodies of all living things are composed of about 15 chemical
elements and a great number of chemical compounds : 97 per cent
of the human body consists of carbon, hydrogen, oxygen and nitro-
gen, and 3 per cent of n other elements. Three-fourths of all the
hydrogen and nine-tenths of all the oxygen are combined to form
water. In addition to water and mineral salts living things con-
tain carbon compounds, or "organic compounds." Compounds of
carbon, hydrogen and oxygen form Carbohydrates or Hydrocarbons ;
compounds of carbon, hydrogen, oxygen and nitrogen form Protcids.

I. CARBOHYDRATES (Starches, Sugars).

Carbohydrates of physiological importance are :-

Polysaccharids ( Ct; H1(l O- )u -starch, dextrin.
Monosaccharids (C0 H12 O6) — dextrose.
Disaccharids (C12 H22 Oll ) — cane sugar.

i. a. POLYSACCHARIDS. Native starch. Mount a scraping of
potato in water and examine under microscope. Study and draw
structure of starch grains. Run a drop of iodine solution under
cover. What happens ?

b. Grind a little commercial starch in a mortar and shake with
cold water. Filter and test filtrate with iodine.

c. Test solubility in boiling water. Note character of resulting
solution. Dilute and add a drop or two of iodine solution. What
results? Heat and cool again noting result. Add (i) alkali, (2)
alcohol to the colored solution. What results ?

d. Cellulose (plant cell-walls). Cotton fiber is almost pure cel-
lulose. Note insolubility in water and alcohol. Is it insoluble in
acids? Alkalies? Does it react with iodine? Treat with 20 per
cent sulphuric acid and then add iodine. What results ? Treat with
Schultze's chlor-zinc-iodide. What results ? This is known as the
"cellulose test."

2. MONOSACCHARIDS (grape sugar, etc).

a. Dextrose. Make a one per cent solution in hot water. Test
solution as follows : —

(i). Add iodine. Result? Is starch present?

(2). Add }/4 its volume of strong potassium hydroxide and heat
gradually to boiling point. Xote color and odor (Moore's test).

(3). Add a few drops of copper sulphate solution, then ]/> its
volume of 10 per cent caustic potash and boil. Result? (Trommer's
test).

(4). Boil a little Fehling's solutions in a test tube. Result? Then
add some sugar solution and boil again. Result?

3. FERMENT ACTION : ENZYMES.

a. Salivary diastase ; Ptyalin. Collect a few cc. of saliva in a
test tube ; dilute with about five volumes of water and filter. Make
the following mixtures :

1. Equal volumes dilute starch paste and saliva solution.

2. The same using saliva that has been previously boiled. Place
tubes in incubator warmed to 40 C. After fifteen minutes, test each
mixture for starch (iodine) and sugar (Fehling's). What effect
does ptyalin have on starch ? What effect does boiling have on
ptyalin ?

II. HYDROCARBONS (Oils, Fats).

(i) Xote physical properties, differences in melting point, etc.,
of three fats, — olive oil, butter and tallow. Test solubilities of these
fats in water, alcohol, chloroform, ether. (2) Shake a few
drops of olive oil with water in a test tube. What happens? Set
tube aside for a few minutes. What happens? Shake up a few
drops of the oil with one per cent sodium carbonate instead of water,
examine with microscope, and note difference in results. (This is
an emulsion. ) (3) Place a small amount of butter on a slide, and
put on it a drop of 2 per cent osmic acid. Observe under microscope
what occurs.

2. CHEMICAL TESTS FOR FATS. The reaction with ether and
osmic acid are two well known tests for fats.

III. PROTEIDS (Albumens, etc.).

Use white of egg as type of proteid.

i. Carefully pour white of egg into a dish. This is approxi-
mately a 12 per cent solution of a proteid (albumen). Notice its
consistency; observe that it can be drawn out into threads. Test
its reaction with litmus paper ; is it acid, alkaline, or neutral ? Of

8

one half of the albumen make a 10 per cent solution. To do this,
place in an evaporating dish and cut the albumen up with scissors *
this frees it from membranes. Then mix with () times its volume
of distilled water, stirring thoroughly ; filter. Keep the undiluted
half for further use.

2. COAGULATION, (i) Coagulation by heat. Have a water
bath with water at the boiling temperature. Put some of the un-
diluted albumen in a test tube and place in the water bath. Does
it coagulate? Try a little of the 10 per cent solution in the same way.
Does it coagulate? What is the effect of dilution on coagulation by
heat? (2) Coagulation by chemicals. To 5 cc. of the 10 per cent
albumen add a few drops of 3 per cent copper sulphate. Try also
strong nitric acid and sulphuric acid, allowing a drop or two to run
down the side of the test tube. Try also 95 per cent alcohol.
(3) Manner in which coagulation takes place. Dip a thin thread of
silk in a 3 per cent solution of copper sulphate and lay the thread
on a glass slide beneath a cover glass. Allow some of the 10 per
cent solution of white of egg to run under the cover while observ-
ing the operation with high power of the microscope. The albumen
about the thread will be seen to form small granules appearing like
a fine cloud, and these later run together and form a network.

3. CHEMICAL TESTS FOR PROTEIDS. (i) Xanthoproteic Reaction.
Dilute some of the 10 per cent albumen till it is about 2 per cent ;
place a small quantity in a test tube. Add a few drops of nitric
acid. What occurs ? Boil. What occurs as to color and other
changes ? Cool the solution and add ammonia until saturated. Xote
color produced. (This is the essential feature of this reaction.)
Try in the same way a weak solution of gelatin (albuminoid) ; does
it give the xanthoproteic reaction? Try this reaction also with
water containing many infusoria ; first heat the water containing
the animals, then add the nitric acid and ammonia. What results?

4. ACTION OF ENZYMES ON PROTEIDS. Place thin pieces of boiled
white of egg in artificial gastric juice, made by adding pepsin to a
0.2 per cent solution of hydrochloric acid ; label and allow to stand
till next day. Place some of this digested albumen in one dialyzer
and some fresh, undiluted albumen in another ; after one hour test
the water below each dialvzer for albumen.

B. MORPHOLOGICAL AND PHYSIOLOGICAL CHARAC-
TERISTICS OF LIVING THINGS

Living matter, or protoplasm, is not a single chemical compound,
but is a combination of many albumen-like compounds. It exists
only in the form of cells, individual masses of protoplasm contain-
ing a denser body, the nucleus.

I. CELL STRUCTURES.

In sections through the root-tip of an onion observe the shape and
size of the cells. Having found one or more complete cells with
round nucleus observe and draw the following parts: I. Cell Mem-
brane. 2. Xucleus. 3. Cytoplasm (protoplasm surrounding nucleus).
In the nucleus observe : 4. Nuclear Membrane. 5. Chromatin
(stained part of nucleus). 6. Achromatin (unstained part of
nucleus ) .

II. CELL FUNCTIONS.

Each cell performs all the fundamental functions of life — it
nourishes and reproduces itself, is contractile and sensitive, though
some cells are devoted more exclusively to one of these functions
than to the others ( Specialization ) . In this place we study only
the functions of reproduction and movement.

i. CELL REPRODUCTION. All cells reproduce by division; the
nucleus first divides, in one of two ways, after which the cell body
constricts into two. Nuclear division occurs by the indirect process
(Mitosis), or bv the direct process (Amitosis).

(i). Indirect Nuclear Division (Mitosis). In prepared slides
of the root-tip of the onion observe nuclei in mitosis, and note (a)
the Spindle, (b) the Chromosomes (chromatic rods), (c) the
Equatorial Plate (stage in which the chromosomes surround the
equator of the spindle). The stages of division leading up to the
equatorial plate are ( d ) the Prophase ; the equatorial plate stage,
during which each chromosome splits longitudinally, is (e) the
Metaphase ; the stage after the equatorial plate during which the
halves of each chromosome separate, moving toward the poles of
the spindle, is ( f ) the Anaphase ; later stages in the division of
the cell body, and the formation of daughter nuclei are known as
(g) the Telophase. Draw cells in each of these phases of division.

(2). Direct Nuclear Division (Amitosis). In prepared slides
of the follicle cells surrounding the egg of the cricket observe

10

various stages in the direct division of the nucleus. Draw cells in
which (a) the nndeolns is dk'idiin/, but the nucleus is still spheri-
cal, (b) the nucleus is tin nib-bell shaped, (c) the nucleus is divided
into two.

2. PROTOPLASMIC MOYKMKXT. \Villi a pair of fine forceps pull
off some of the hairs which grow on the stamens of the flower of
the spiderwort (Tradescantia ) and mount them in water under a
cover glass. Observe: (i ) The hair is made up of a succession of
cells, with corrugated walls. (2) Just within the cell wall is the
granular protopasm, strands of which may be seen moving or
circulating. (3) \Yithin this protoplasm is a clear spherical or
ovoid body, the nucleus. (4) Most of the center of the cell is oc-
cupied by a purple, homogeneous fluid, the cell sap.

Alakc a drawing showing these structures, and indicate by ar-
rows the direction of the protoplasmic movement.

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CHIEF SUBDIVISIONS OF THE PLANT KINGDOM

SUBKINGDOM

DIVISION

SUBDIVISION

CLASS

A. Protophyta

B. Metaphyta

A'. Cryptogamia

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I. Thallophvta

II. Bryophyta

i. Flagellatae

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2. Schizophyta

3. Myxomycetes (Slime
moulds)

4. Eumycetes (Fungi, Moulds,
Mushrooms, Lichens)

5. Euphyceae (Algae, Sea
weeds, Flowerless fresh
water plants)

j 6. Hepaticae (Liverworts)
I 7. Musci (Mosses)

Photorlagellatae

(Euglena)
Schizomycetes

(Bacteria)
Cyanophyceae

(Blue-green

Algae)

8. Filicineae (Ferns)
III. Pteridophyta - 9. Equisetineae (Horsetail

B'. Phanerogamia IV. Spermaphvta

rushes)
. 10. Lycopodineae (Club moss)

11. Gymnospermae (Cycads,

Conifers)

12. Angiospermae (Flowering

plants)

The minor subdivisions of both animal and plant kingdoms are
very numerous and are known as Families, Genera, Species and
Varieties. The scientific name of any animal or plant consists
merely of the name of the genus and species to which it belongs.
This method of naming animals and plants is due to Linnaeus
(1707-1/78) and is known as binomial nomenclature.

Inspect the specimens in the Museum, Herbarium and Vivarium,
and become familiar with as many as possible of the classes named
above. Enter in your laboratory notes in the following manner
the scientific name (copied from the labels of specimens on exhi-
bition) of some one member of each class and phylum of the animal
kingdom, so far as represented in the exhibits :

PHYLUM

CLASS

GEXUS

SPECIES

Cnidaria
etc.

Hydrozoa

Gonionemus

murbachii

D. PROTOZOA AND PROTOPHYTA.

One-celled animals and plants in which the entire body consists
of a single cell, which may be independent or may be joined with
others to form a colony.

I. PARAMEC1UM CAUDATUM.

(A Ciliate Protozoon).

A. MORPHOLOGY.

Put a small drop of water containing Paramecia on a slide ; sur-
round it with gelatin to limit the movement of the animals, cover
and examine with the low power (of the microscope) and then with
the high power. Note :

I. Size : measure.

2 Shape: fusiform; rounded at the anterior end, bluntly pointed
at the posterior end.

3. Locomotion : due to cilia uniformly distributed over the whole
surface. Xote also movements of flexion.

4. Structure. The two layers: ectosarc (ectoplasm) and enclo-
sarc (endoplasm).

a. Ectosarc (Cortex) : the firm elastic outer layer; its deeper
part marked by oblique myophan striations, probably due to longi-
tudinal wrinkling of the inner surface of the ectosarc.

(i). The cuticle, a delicate superficial layer differentiated from
the underlying protoplasm.

(2). Cilia, delicate vibratile filaments arising from the ectosarc
and protruding through openings in the cuticle. These openings can
be seen on a specimen from which the water is allowed to evaporate.

(3). Trichocysts : minute oval sacs in deeper part of the ecto-
sarc arranged perpendicular to the surface ; when the animal is irri-
tated, e. g. by iodine, a stiff thread can be shot out and projected
beyond the cilia. They are probably defensive organs.

(4). Two contractile vacuoles in the ectosarc of the dorsal side
about 1/3 of the animals' length from each end. \Yhile dilating they
are nearly spherical, but at the moment of contraction separate
canals can be seen radiating from them.

(5). The buccal groove begins at the anterior end of the left
side and runs back to the mouth near the middle of the ventral
side. The cilia of the groove drive food particles into the mouth.
Run some Chinese ink in water under the cover glass and note that
some of it is carried into the groove.

(6). The mouth is an aperture in the ectosarc at the posterior

end of the groove through which food passes into the endosarc.
Watch the ink collect at the inner end of the gullet into a ball
which is suddenly passed into the endosarc. Watch the course of
the food ball around the body until it is finally ejected.

(7). The anus is a temporary aperture between the mouth and
the hinder end of the body — visible only at the moment of ejection
of fecal matter.

b. The Endosarc (Medulla) is the more fluid protoplasm filling
the central portion of the body.

( i ) . The food vacuoles are spherical spaces in the endosarc
filled with water containing food particles.

(2). The circulation of the endosarc is rendered obvious by the
food vacuoles and the granules, which are carried round in a
definite direction.

(3). The nucleus is an elongated oval body near the center of
the body of the animal. It is best seen with light reflected from the
slide, not from the mirror, or in stained specimens.

( 4 ) . The micronucleus is a much smaller body applied to one
side of the nucleus and resembling it in appearance.

J\Iakc one or two drawings of an animal to shoiv the above men-
tioned structures.

B. PHYSIOLOGY.
I. METABOLISM.

1. Ingestion of food. Place some Paramecia on a slide with
powdered Chinese ink and watch the formation of food balls in the
gullet and their ingestion. Study the formation of a food vacuole.

2. Circulation of Endosarc. Observe and sketch the changes of
position of the food vacuoles in the body and show by arrows the
course of circulation. Time the circulation by noting the time at
which the ink is added and that at which the first ink ball completes
the circuit.

3. Nature of food. Study the nature of the contents of the food
vacuoles of normal Paramecia and find, if possible, what they feed
upon. Is it animal or vegetable matter? Does Paramecium choose
its food? Stain with iodine and see if any starch is used as food.

4. Digestion. Observe the changes in color, etc., of food as it
passes through the body, also the changes in the vacuoles and their
fluid contents. What do these changes indicate?

5. Egestion. Observe, if possible, the egestion of ink from a

16

food vacuole, and from the body. SJww by a drawing where and
how this takes place.

6. Excretion. The contractile vacuoles are excretory organs for
getting rid of water and nitrogenous waste (urea). Study and
sketch a vacuole in various stages of contraction and expansion.
Time the contractions and expansions and record the results in your
notes. Place Paramecia in a thick solution of Chinese ink and ob-
serve the extrusion of a clear drop of fluid at the moment of con-
traction of the contractile vacuole.

7. Respiration. Place a number of the animals in a drop of
phenolpthalein ( which loses color in the presence of carbon
dioxide) ; also note the manner in which the animals collect at the
surface of a dish in which the water is very foul. What do these
observations teach ? Are there any organs of respiration ?

II. REPRODUCTION.

1. Fission. Observe and draw a Paramecium in the process of
division. In a stained preparation note what changes take place in
the nucleus and micronucleus during this process. Can you detect
any difference between the two daughter individuals? Howr do the
contractile vacuoles, the buccal grooves and the gullets arise in
the two ?

2. Conjugation. Study and draw living individuals in the act
of conjugation. What portions of the body are in contact? Is there
anv distinction of size or sex in the t\vo individuals? In stained

•/

preparations study the nuclear changes which take place during con-
jugation. Draw. Isolate an individual in a watch glass full of
water and note how many individuals are present on the next day.

III. IRRITABILITY.

1. Automaticity. Does the animal appear to act of its own
accord or only through the influence of external stimuli?

2. Movement. How many kinds of movement does the animal
exhibit? What are the organs of locomotion? With a dissecting
microscope observe the movements of an animal in a drop of water.
Does it move in straight lines ? Does it keep one side uppermost ?
How does it alter its course ? Can it move backwards ? By means
of lines and arrows plot the movements of an animal during one
minute. By means of powdered ink observe the direction of cur-
rents over the body. What is the direction of the currents in the

^

buccal groove ?

3. Sensitivity. Is the animal sensitive to touch or pressure ? How

does it behave when in contact with a solid body? Place a small
drop of salt solution colored with Chinese ink on a slide and note
whether the animals are sensitive to this substance. In similar man-
ner test them with i-io per cent and 1-2 per cent acetic acid, and also
with a bubble of carbon dioxide. Place animals on a slide heated at
one end and cooled at the other. What results ? In a similar man-
ner test them with the electric current and record your results.
Also test their sensitivity to light and gravity.

II. VORTICELLA SP.

(A Ciliate Protozoon).

A. MORPHOLOGY.

Examine filaments of algae, etc., for bell-shaped organisms borne
on a stalk. If a single individual is borne on a contractile stalk it
is some species of Yorticella ; if many individuals form a colony on
a common branched stalk it is some species of Carchesium or Zooth-
amnium (in Zoothamnium the stalk contains a common muscle
fibre which branches with the stalk) ; if the stalk is branched but
not contractile it is some form of Epistylis. Which genus are you
examining ?

Study under high power and note :

1. THE STALK, i. Shape; length compared with width. Shape,
when contracted and expanded. If branched, is there any regular
arrangement of the branches?

2. Structure. Is there any distinction in the stalk between ecto-
plasm and endoplasm? The central axial filament or contractile
fibre is easily seen. Does it run in the exact center of the stalk?
Does it join the ectoplasm or the endoplasm at its upper end?
With your highest power study the structure of the axial filament.

II. THE BODY. i. Shape, when seen from above ; from the side.
What is its shape when contracted ? When expanded ? In a fully
expanded individual observe: — (a) The peristome or rounded edge
of the bell. Does it extend completely around the disk? (b) The disk,
a lid-like structure within the peristome raised on one side, (c) Be-
tween the peristome and the disk a ciliated depression leading down
under the raised portion of the disk into a deep pit, the vestibule.
Is there anything corresponding to this in Paramecium?

2. Structure. Observe the following: (a) A transparent layer
covering the body, — the cuticle. ( b ) Within the cuticle a clear
cortical layer, the ectoplasm. Wrhere is it thickest? (c) A central

18

granular mass, the endoplasm, containing food vacuoles, etc. (d)
A contractile vacuole is present just below the disk. Note its shape,
(e) The nucleus, an elongated cylindrical body. Is it in the ecto-
plasm or endoplasm? (f ) The oesophagus or gullet, a ciliated tube
leading down from the vestibule, (g) Anus, an opening into the
side of the vestibule, to be seen only at the moment of egestion of
food remnants.

B. PHYSIOLOGY.

I. MOVEMENT.

a. General movements. Study the manner in which the stalk
contracts? What part of the stalk causes the contraction? What
change takes place in the body during contraction ? Note the rapid-
ity of the movements. How does the animal assume the expanded
condition? What causes it? What part is the first to assume the
expanded state? Compare the rate of contraction with that of
expansion. Note that the body sometimes separates from the stalk.
How does the body move after separation?

b. Ciliary movements. Add powdered Chinese ink to the water
and observe the direction of the currents produced and the method
of feeding. What is the significance of the animal's scientific name?
How many kinds of cilia does Yorticella have? To how many
uses are they put? How does it differ from Paramecium in this
respect ?

II. REPRODUCTION.

i. Fission. Look for animals undergoing fission. Where does
the division begin? By the aid of stains study the nuclear phenom-
ena of division. 2. Conjugation. Individuals may sometimes be
seen undergoing conjugation. Study the process and compare with
the conjugation of Paramecium.

Make drawings of all you have observed.

III. STYLONYCHIA MYTILUS.

(A Ciliate Protozoon).

In the same sort of material in which Paramecium is found look
for a broad, flattened infusorian, which moves swiftly about. This
is Stylonychia. Compare its size with that of Paramecium.

Notice two sorts of motion : a rapid swimming as in Paramecium,
and a crawling by means of the large ventral cilia.

STRUCTURE. Note the ectosarc and endosarc, the former contain-

19

ing no trichocysts, and less distinct than in Paramecium: two nuc-
lei about one third of the animal's length from either end : one con-
tractile vacuole : a buccal groove, much like that of Paramecium ;
along the left side of the groove a row of long powerful cilia. Three
groups of gigantic cilia on the ventral surface. The cilia of the
anterior and middle groups are hook-like, those of the posterior
group paddle-shaped. Along the margin of the ventral side is a
row of large cilia, three of which project posteriorly as long bristle-
like processes. Observe the method in which all three sorts of cilia
are used.

Make a drawing to show all the structural features of Stylonychia.

IV. AMOEBA PROTEUS.

(A Rhizopod Protozoon)

Place a small drop of sediment from a vessel containing Amoeba
on a slide with a drop of water ; cover with cover glass and search
for Amoeba with low power. If not easily found, prepare several
such slides and examine them after they have been standing for
some minutes, so that the Amoebae may crawl out of the sediment.
When an Amoeba is found examine with a high power and note :

A. MORPHOLOGY.

1. Size; is it visible to the naked eve?

J

2. Shape; is it regular? Constant? Are the pseudopodia of
the same size and shape ? Do they ever branch ? How many do
you find ? Sketch at intervals of one minute for five minutes.

3. Structure : An outer clear layer, the ectosarc, and an
inner granular more opaque substance, the endosarc (endoplasm). Is
the boundary between the two layers a sharp one ? \Yhere is the
ectosarc thinnest? Is there a membrane outside this layer? Are all
the granules of the endosarc of the same size? Which layer is
the more fluid ? In the ectosarc a clear vesicle may be found which
appears and disappears; this is the contractile vacuole. How long
does it take it to contract, how long to expand ? Are there any
visible contents ? Is there more than one contractile vacuole ?

In the endosarc a round, clear body may be found, which does
not change shape ; this is the nucleus. Is it more solid than the
surrounding protoplasm? What is its shape? Size? Is it always
in the same place? There are often also in the endosarc various
foreign bodies which serve as food, such as diatoms, desmids, green
cells, etc. Draw to show structure.

20

4. Life Cycle: Look for various stages in the life history;
encysted specimens, small individuals, large ones, etc. Also note
various kinds of Amoebae, some with short lobe-like pseudopodia,
others with longer slender ones; some large and coarsely granular,
others small and finely granular.

5. Stained Specimens : In a prepared specimen, stained and
mounted, observe nucleus, ectosarc, endosarc, etc. Draw.

B. PHYSIOLOGY.

1. Movements: Is motion continuous? Regular? How is it
produced? Watch process of formation of a pseudopodium. What
part does the ectosarc play in the process ? The endosarc ? Watch
an active Amoeba and trace on paper its path of motion. Are there
permanent anterior and posterior ends ? Does there seem to be
any difference in surface tension between the anterior and posterior
ends? Are the currents in the endosarc constant? Indicate in a
drawing the course of the currents bv arrows. Where are the

^J r'

currents swiftest? Where slowest? Are cilia present on any por-
tion of the body ?

2. Nutrition: If possible watch the process of taking in food
and of its egestion. What does the animal eat? How and where
does it take in food? Are food vacuoles formed? Is there a
definite course of circulation of food within the body? Where is
the food digested? How distributed? How are gaseous, liquid
and nitrogenous waste substances expelled from the body ."

3. Reproduction is difficult to observe and may be omitted from
notes.

4. Irritability : Are there any indications that Amoeba is sensi-
tive to mechanical stimuli? Is it sensitive to chemicals? To changes
in temperature? To electricity? To light?

Does Amoeba show any reflex movement? Is it behavior more
or less varied than that of Paramecium.

Make careful drawings and notes of all that you have observed.

V. EUGLENA VIRIDIS,

(A Flagellate ).

Place a drop of water containing Euglena on a slide and after
covering look with the low power for green spindle-shaped organ-
isms which swim swiftly. Having found them study with the high
power and note: (i) Size. (2) Color, due to chlorophyll. The
anterior end is colorless. X"ear the anterior end is a red pig-

21

ment spot, the stigma. (3) Shape, fusiform; the anterior end is
blunter than the posterior and bears a long flagellum which may be
lost in some specimens. The flagellum arises from the bottom of
the gullet, or mouth opening. Observe the contractile vacuole,
nucleus and the paramylum bodies near the center of the body.
What color do the paramylum bodies take when stained with iodine ?
What does this indicate? Is there any cell sac?

Look for animals in the encysted condition, showing stages in
division. Determine by the use of Schultze's solution whether or
not there is cellulose in the cyst.

Movements are of two kinds: (a) Rapid swimming movements
in which the flagellum is carried forwards, (b) Worm-like move-
ments, contractions and expansions by which the animal crawls
about. The latter movements are characteristic of Euglena and
are called "euglenoid" movements. Draw at intervals to show
changes in shape.

Make drawing to show all that you have observed.

VI. SPHAERELLA (HAEMATOCOCCUS)

(A Flagellate Protophyte).

A. RESTING STAGE.

( i ) . Spread out in water some sediment containing Sphaerella,
put on a cover glass and look with low power for red or green
spheres. Having found one examine with high power and note :
(a). Size, variable; draw several to scale.
( b ) . Form ; spheroidal.

(c). Structure; a sac surrounding the contents which con-
sist of protoplasm, chromatophores, a nucleus and
sometimes a vacuole.
(d ). Color; red, green or partly one and partly the other.

Where is the coloring matter always situated?
(2). Place a drop of iodine solution on the slide at the edge
of the cover glass, apply a bit of blotting paper at the other side,
thus drawing the iodine solution under the cover. What parts
stain ? How does it affect the nucleus and the chromatophores ?

(3). Look for individuals in the process of division, some elon-
gated with transverse lines of division, others divided into two or
more smaller portions often lying within the sac of the parent
Haematococcus. Draw various stages in this division b\ fission.

22

B. MOTILE STAGE.

(i). After dried, resting forms have been in water for twelve
hours examine for motile forms and note their movements,
(a). An active transition from place to place.
(b). A rotary motion around the long axis.
(2). Note the following kinds of motile forms:

(a). Large individuals, the macro-zoospores, of the same
size as the resting forms, each surrounded by a
thin colorless cell wall, separated from the contents
by a clear space.

(b). Much smaller motile forms, each surrounded by no
separate cell wall, but with two cilia or flagella at
the pointed end or "beak". These are the micro-
soospores.

(3). In the larger forms note: Color, structure, contents, sac
(cell wall), cilia, protoplasmic bridles. "Which end goes ahead in
swimming? How are the contents held in place within the sac?
In an individual which has nearly ceased movements study the suc-
cessive positions assumed by the flagella, and their mode of bend-
ing to and fro. Treat with iodine : the protoplasm is killed and the
cilia are rendered conspicuous.

Draw individuals in motile stages to sJww all of the above men-
tioned points.

VII. VOLVOX GLOBATOR.

(A Flagellate Protophyte).

Place a drop of alcohol containing Yolvox on a hollow-ground
slide cover and examine with low power. Having found a colony
as perfect as possible, observe with high power and draw the fol-
lowing :

1. Form; spherical when not disturbed.

2. Size ; variable depending upon age of colony.

3. Structure ; a hollow sphere surrounded by a single layer of
cells (zooids) each of which in life bears two flagella and contains
chlorophyll, a nucleus and a stigma or eye spot. The zooids are
connected together by a gelatinous substance, and each is connected
by strands of protoplasm to the zooids immediately surrounding it.

4. Life Cycle ; observe the cells which migrate into the cavity of
the sphere from the outer wall. These are the sex cells, which are
of two kinds: a. Parthenogonidia, which without fertilization give

23

rise to small colonies by repeated divisions; b. Ovaries, each of
which contains a single ovum surrounded by a spinous membrane;
c. Spermaries, each of which contains many spermatozoids. After
a spermatozoid has entered an ovum the latter undergoes re-
peated divisions and gives rise to a daughter colony.

Draiv various stages in the formation of the daughter colonies
from parthenogonidia and from fertilized ova.

VIII. SACCHAROMYCES CEREVISIAE

(A Fungus).

A. MORPHOLOGY.

Place some growing yeast in a drop of water on a slide and ex-
amine under a low power, then under the high one. Observe the
small oval bodies or yeast cells. Note : Size ; is it constant ?
Measure several. Shape; does it change? Nature of surface.
Mode of union. Is there any regular number or arrangement of
cells in the various groups ? How many cells in a complete yeast
plant? Structure; Observe the cell wall; contents. Is a vacuole
present? \Yhere is it found? Do you ever find more than one?
Is it contractile? A nucleus is present but it can be demonstrated
only by the most careful staining. Place a piece of blotting paper
over the cover glass and press firmly upon it ; in this way some of
the cells will be bursted and the sac and contents can be studied
separately, (a). What is the nature of the sac? Its color? Is the
color of the cell due to the cell wall or contents? Is there any open-
ing in the sac through which food can be ingested? Are there
any organs of locomotion? Is the wall elastic? (b). What is the
physical nature of the contents? Its color?

Draw several cells to show size, mode of union and structure.

B. CHEMICAL REACTION.

1. Run a drop of aceto-carmine under the cover glass and ob-
serve which individuals stain soonest and most deeply. Do the
crushed cells stain as readily as the entire ones ? Does the sac
stain ?

2. Treat another drop of yeast with dilute caustic potash. What
happens to the cells?

Kill some yeast cells by boiling them with water in a test
tube. Mount some of this dead yeast and stain with aceto-carmine.
Does it stain differently from the living yeast? What inferences
may be drawn ?

24

4. Mount a fresh drop of yeast on a slide and treat with a drop
of iodine. What is the effect on the cells? Is starch present in
the fluid? Is there any starch in the cells themselves?

Make drawinys of the yeast cells slura'iin/ the effect of the
reagents.

C. PHYSIOLOGY.

In the following experiments the amount of growth which has
taken place may be roughly measured by the increase of the tur-
bidity in the liquid. It may be tested microscopically by the number
of buds to which the cell has given rise.

1. Effect of food supply upon growth. Take five test tubes
each one-third full of the solution named: (a) distilled water;
(b) 10 per cent solution of sugar in water; (c) Pasteur's solution
without suger; (d) Pasteur's solution with sugar; (e) Mayer's
pepsin solution.

Carefully label each tube and put a drop of yeast into each ; shake
the tubes thoroughly and tightly plug the month of each with a
wad of clean absorbent cotton and set them in the incubator, heated
to 35 degrees C, for two or three days. Examine the tubes from
day to day and judge, from microscopic examination and the tur-
bidity, in which fluid the ,yeast grows best. In which are the most
bubbles of gas formed ? Does the formation of gas bear any re-
lation to the growth ?

2. Reproduction, (a) Budding. With the microscope examine
cells from each of the test tubes. In which have the cells the
largest number of buds ? In which the smallest ? How many buds
may a cell have ? Show by drawings the steps in the formation of
a mature bud. What is the difference between budding and fission ?
( b ) Endogenous Spore Formation may sometimes be observed
in yeast which has been kept for sometime under unfavorable con-
ditions, e. g. lack of food, moisture, etc.

3. The effect of growth of yeast upon food supply. ( a) Taste of
the 10 per cent sugar solution after yeast has been growing in it
for a day or two. Compare with a solution in which there is no
yeast. How do you explain the difference? (b) Examine the
distillate of a solution of sugar in which yeast has been growing
for a day or two. Notice that it has the taste and odor, and burns
with a pale blue flame, characteristic of alcohol, (c) Xature of the
gas given off. Take two test tubes, fill the first y$ full of clear
baryta water, fill the second about l/2 full of yeast which is actively
giving off bubbles of gas. Insert a cork in this second tube and

connect the two by a bent glass tube one end of which passes
through the cork into the air space above the yeast, the other end
of which dips below the surface of the baryta water. What
changes take place in the baryta water? This is a test for carbon
dioxide, (d) Chemical reaction of fluid yeast. Determine by the
use of litmus paper whether fluid yeast is acid or akaline in its
nature. What do you suppose the cause of this to be?

Prepare a written statement giving as far as possible an explana-
tion of all the facts yon have observed in these experiments.

IX. BACTERIA SP.

(Schizophytes).

A. BACTERIA OF HAY INFUSION.

Fill three test-tubes J/2 full of a fresh infusion of hay: (i) close
one tube with cotton wool carefully and boil a few minutes; (2) do
the same with a second tube and then boil it again after 24 hours
and repeat the boiling for several days if convenient; (3) leave a
third tube open and do not boil it ; set all three in a warm place
where they can be observed from time to time. Note the changes
which take place in each of the tubes. Does the infusion in any of
the tubes become turbid and in which one is this most marked? De-
termine by microscopic examination what the cause of the turbidity
is. How do you account for the differences between the tubes ? Keep
the tubes under examination for several days or weeks and observe
in what tubes a scum forms on the top of the liquid. Does the for-
mation of this scum have any influence on the turbidity of the fluid?
Study the scum under the microscope and determine what it consists
of and whether it differs in the different tubes. What ultimately
becomes of the scum ? What changes if any are there in the odor
of the fluid during the period of observation and how do you
account for them? Are different kinds of bacteria found in the
tubes? If so make sketches to show them. Do the bacteria in
the same tube differ in form from day to day? If so sketch
them in the order in which they appear. After one week
what is the condition of the fluid and the bacteria found in each of
the tubes? Write up an account of the phenomena yon Jiave observ-
ed and give your explanation of them.

B. BACTERIA OF THE AIR.

Clean a smooth potato with a stiff brush and water, removing with
a knife all injured portions as well as the "eyes'". Sterilize the

26

potato in boiling water for thirty minutes, then cut it in slices by
means of a knife sterilized in a Bunsen flame. Place the slices of
the potato on a sterilized glass plate and leave the clean cut surface
exposed to the air in the room for one hour. Cover with a sterilized
bell jar under which some distilled water is placed to maintain a
moist atmosphere and set aside for several days. If any organisms
develop on the potato they must have come from the air of the
room. Observe on the potato variously colored spots or "colonies".
Are all of these colonies bacteria? Are all the organisms in a colony
alike? \Yhat is the significance of this fact?

C. BACTERIA OF HYDRAXT WATER.

Take a sterilized gelatin culture plate in a Petrie dish (each locker
is supplied with one) open the dish and quickly allow a few drops
of hydrant water to run across the gelatin. Close the dish at once
and set it aside for several days. If bacteria were present in the
water one or more colonies of them will be found along the path of
the drop. Study these colonies as in the preceding experiments.

D. BACTERIA OF MILK.

Dilute i cc. of milk with 100 cc. of sterilized water. Add i cc. of
this dilution to a Petrie dish of "litmus agar", cover and place in
the incubator for 36 hours. Then by means of a "counting plate" de-
termine the approximate number of colonies present in the agar, and
calculate the number of bacteria present in i cc. of undiluted milk.
Colonies which have the form of minute footballs belong to the
group of "colon bacilli" and come from the intestinal tract of some
mammal. AYhat does the changed color of the litmus agar indicate?

E. BACTERIA FROM THE MOUTH.

Take some scrapings from the teeth, dilute with water, mount
and study the various forms under a high power. How many kinds
of bacteria can you find ?

F. MOTILE STAGES.

Study bacteria from various media, viz. : Pasteur's Solution, Beef
Tea, Infusions of Hay and Peas, Potato and Gelatin Cultures, Sew-
age, etc., and observe and draw the following forms:

1. Micrococcus; rounded forms occurring singly or in bead-like
TOWS ; without flagella.

2. Bacterium; short and thick rod-like forms.

3. Bacillus; long thread-like forms.

4. Vibrio; like Bacillus but with bent joints.

5. Spirillum; elongated threads rolled up into a more or less
perfect spiral.

6. Spirocliacta ; like Spirillum but longer and more closely rolled,
and without flagella. In these various forms observe the following
points :

First, size, measure.

Second, structure. Can you notice any change of form in an in-
dividual ? Any difference between the external and internal por-
tions? Any peculiarity of the ends in the longer forms?

Third, movements. Some vital, others purely physical (Brow man
movements}. The former progressive, the latter vibratory around
a stationary center. Study the Brownian movements in particles of
Chinese ink in water. Put a few drops of fluid containing
bacteria on a slide, hold the slide over a Bunsen flame and kill the
bacteria by boiling, cover and examine with high power. Can you
notice any movement of the dead bacteria ? Compare with move-
ments of living ones.

G. RESTING STAGES.

Examine the scum ("Zoogloea") from the surface of various-
liquids, especially the hay infusion ; it consists of myriads of bac-
teria in a resting condition imbedded in a gelatinous substance.

H. CHEMICAL TESTS.

Spread a small drop of liquid containing motile bacteria on a
clean cover glass and let it dry slowly ; then pass the glass through
a Bunsen flame two or three times to coagulate and fix the bacteria
upon the glass. Put a drop of Methylen Blue or Gentian Violet
upon the glass. After five minutes rinse with distilled water and
mount in a drop of water upon a slide. If a permanent mount is;
desired thoroughly dry the glass after rinsing and mount in Canada
Balsam.

Treat some of the Zoogloea in the same way and observe that the
bacteria stain more deeply than the substance in which they are
imbedded.

I. STUDY PREPARED SLIDES OF PATHOGENIC BAC-
TERIA.

J. DEMONSTRATION OF BACTERIA SEEN WITH "DARK
FIELD ILLUMINATION".

28

E. METAZOA.

Metazoa are many-celled animals in which there is a differentia-
tion into at least two body layers, the Ectoderm and the Endodcnn;
the former is the organ of relation, the latter the organ of nutrition ;
in addition all have heteromorphic sex cells, ova and spermatozoa.
In all metazoa the fertilized ovum undergoes repeated divisions
(Cleavage) which lead up to the formation of a hollow sphere of
cells ( Blastula ) and from the latter arises a two layered condition
(Gastrula) the outer layer being the Ectoderm, the inner the Endo-
dcnn; between these two a third layer, the Mesoderm, is usually
formed.

The cells of the different germinal layers differ from one
another, and in the course of further development differentiations
appear among the cells of the same layer. In this way arise Tis-
sues, differentiated groups of like cells and their products. From
the two primitive tissues, epithelium and mesenchyme, present in
the blastula and gastrula all other tissues are derived, as shown
herewith :

i. EPITHELIUM 2. MESENCHYME

a. Epithelial tissue a. Connective tissue

b. Muscular b. Skeletal

c. Nervous c. Vascular

d. Germinal d. Storage ( reserve) '
These different tissues will be studied in the laboratory in con-
nection with each animal considered.

The various functions of animal life, which in the Protozoa are
all performed by a single cell, are performed in the Metazoa not
only by many cells and tissues but also by groups of different
tissues united to form Organs, each with a specific function, and
by groups of organs united to form Systems, each having some
one general function, as shown in the following table :

29

FUNCTIONS

ORGANS

SYSTEMS

"Ingestion Mouth, Teeth
Digestion Stomach, Intestine Alimentary
Egestion Anus

Respiration Trachea, Lungs, etc. Respiratory

I. METABOLISM

Excretion Kidneys, Bladder, etc. Excretory

Circulation Heart, Arteries, Veins, etc. Circulatory

II. REPRODUCTION

III. IRRITABILITY

Assimilation
Growth
Dissimilation j

j Asexual
I Sexual

f Reception of

Stimuli
Transmission

of Stimuli
Coordination

Movement

Have no special organs or sys-
tems

Xo special organs or systems
Ovaries, Testes, Uterus Genital

Sense Organs ]

Nerves }

Gangalia, Brain j
Muscles

Nervous

Muscular

These various organs and systems will be considered in detail in
connection with each of the animals studied.

I. DEVELOPMENT OF OVUM.

In prepared slides of Echinoderm eggs observe the following
stages: — i. Cleavage; i-cell, 2-cells, 4-cells, 8-cells, [6-cells, 32- or
64-cells. Observe the appearance of a cleavage cavity after the
8-cell stage.

2. Blast nla : — Observe the hollow sphere composed of a single
layer of cells (Epithelium). Are there any indications that scattered
cells (Mesenchyme) migrate into the cavity of the blastula (Blas-
tocoel) as in Volvox?

3. Gastrula: — Note the flattening and ultimate infolding of the
blastula at one pole. Do the cells at this pole differ in appearance
from the others? The infolded cells constitute tin endoderm, the
outer layer the ectoderm. The infolded cavity is the Gastrocoel, or
digestive cavity ; the opening to the exterior is the Blastopore.

Draw and label the stages and structures named above.

II. HYDRA VIRIDIS OR FUSCA.

(Freshwater Hydrozoa).

A Metazoan which throughout life remains in a two layered con-
dition, like a gastrula. Observe with naked eye, or with pocket
lens, the hydras in a jar of water where they have been undis-
turbed for some time. Notice the general habitus of body, method
of obtaining food, etc. Transfer a hydra to a slide with plenty of
water, and observe with the dissecting microscope ; afterward cover,
supporting the cover glass so as not to crush the animal, and ex-
amine with the low power of the compound microscope.

I. FORM.

The body: \Yhat is the general shape? Do its length and
breadth vary? It is usually attached at one end, the foot, by a
kind of sucking disk and terminates at the other in a conical pro-
jection, the hypostome, with the mouth at its summit. The mouth
is a small aperture but it can be greatly dilated to take in food. It
opens into a central cavity, the enteron (digestive). The tentacles
are hollow processes of the body wall. How many are there? Com-
pare the number of tentacles in brown and in green hydras. Is there
more than one circle of tentacles? Observe the knob-like swellings
on the tentacles. Measure the length of the tentacles when expand-
ed; \vhen fully contracted. For what purpose are the tentacles
used? Buds :- -Young hydras of various sizes and stages of develop-
ment may be attached to the sides of the parent. Are colonies
formed by budding? AYhy?

Draw an entire animal, with all the parts named above.

II. STRUCTURE.

1. The body wall of the animal is composed of two layers of
cells, one within the other, (a) The Ectoderm is the outer layer.
What is its color? How much of the thickness of the body wall
does this layer form? (b) The Endoderm is the inner lining of
the body cavity (digestive cavity). In the green species (Hydra
viridis) it contains chlorophyll bodies; in the brown species, H.
fusca, it contains "sooty corpuscles". Which layer is the thicker?
(c) The supporting layer or Mesoglea is a thin gelatinous layer
between the ectoderm and the endoderm.

2. The tentacles. Examine a tentacle with the high power. Of
how many layers is it composed? Focus up and do\vn so as to
obtain views (optical sections) at various levels. Is the tentacle

31

hollow or solid ? The elements of the two layers c^a be most easily
seen in the tentacles. Observe the following :

(a) The ectoderm cells are large and conical with their apices
directed inward. The boundaries of the outer ends form a mosaic,
their inner ends rest directly on the supporting lamella. Do these
cells vary in shape \vhen the tentacle is extended or contracted ?

(b) The interstitial cells are small rounded cells placed between
the inner ends of the large ectodermal cells.

(c) The cnidoblasts or "thread cells" are modified interstitial
cells prolonged at the outer end into a cnidocil or "trigger" and con-
taining an oval, highly refractive capsule, the nematocyst. The cap-
sule is filled with fluid and contains a spirally wound filament formed
by the doubling in of the wrall of the capsule at one pole. The nema-
tocysts form knob-like swellings on the tentacles. They are of twro
kinds : ( i ) smaller, more numerous ones situated at the bases of
the longer cnidocils and containing short stout threads; (2) larger
ones lying near the middle of each knob-like swelling, globular in
shape when seen from the face, flask-shaped when seen from the
side ; they contain long slender filaments armed with barbs at the
basal end. Run in a little iodine and observe the ejection of the
threads of the nematocysts. Note that the threads are turned in-
side out in the process of discharge, the basal portion being dis-
charged first. AYhat is the use of the barbs? The hollow thread?
The fluid in the cysts ? Do nematocysts occur anywhere else than
on the tentacles ?

(d) The endoderm cells line the cavity of the tentacles. They
are large and some of them bear flagella by which currents are
caused. Focus on the middle of the thickness of a tentacle and
observe the flagella on the endoderm cells and the nutrient particles
streaming up and down the cavity of the tentacle. What difference
can you detect in the relative numbers of these elements (cells) in
the various parts of the body?

Make drawings to show the characteristic layers, and cellular
elements.

III. REPRODUCTION.

I. Asexual reproduction occurs by the formation of hollow out-
growths from the sides of the body wall. Each of these acquires a
mouth and tentacles at the distal end of its body and finally, con-
stricting at the base, separates from the parent animal. Look for
such buds in various stages of development.

32

2. Sexual reproduction : hydra is monoecious (hermaphroditic),
the same animal producing eggs and spermatozoa.

(a) The spermaries are swellings of the body wall produced by
the local multiplication of interstitial cells, and covered on the
outside by a cap formed of large ectodermal cells. The spermaries
are situated just below the tentacles. How many do you find? Is
the number constant? Find a ripe spermary and observe the move-
ment of the spermatozoa within the capsule. By gentle pressure
upon the cover glass break open the capsule and observe the swim-
ming of the spermatozoa and their size and shape.

(b). The ovaries usually develop later than the spermaries and
are formed near to the base of the animal. How many do you find?
Is the number the same in the brown and green species ? Single
cells of each ovary enlarge to form the ovum, while the other cells
nourish it and form a capsule about it.

Make drawings of buds and of the sc.rual organs.

IV. STUDY OF PREPARED SECTIONS.

Examine series of transverse and longitudinal sections of hydra
prepared by the paraffin method, and note the large central enteron
surrounded by a body wall of two layers of cells.

1. The ectoderm. Is it of uniform thickness? In it observe:
(a) Large squarish or conical cells. Do they contain nuclei and
vacuoles ? Their basal ends are continued into muscle fibres
(Klinenberg's Fibres) which are mainly longitudinal in direction,
and in cross-section appear as a row of refractive dots on the sur-
face of the supporting lamella. Over the outer surface of these
cells is a thin cuticle. At the foot the ectoderm cells are more
columnar and contain granules, (b) Interstitial cells are present over
the body and tentacles but absent in the foot ; they stain deeply,
(c) Nematocysts, abundant in the tentacles, less numerous on the
body and absent on the foot. Are they found in the endoderm?

2. The supporting lamella. A thin, deeply staining layer be-
tween the ectoderm and the endoderm. Is it composed of cells?

3. The endoderm cells ; variable in shape and size. They are
of two kinds: (a) Larger cells, irregular in shape and size, con-
taining A^acuoles, and with the nucleus flattened and near the basal
end. In H. viridis the basal part of each cell contains rounded
bodies, chloroplastids, coated with chlorophyll. In H. fusca similar
bodies are present, "sooty corpuscles", devoid of chlorophyll. The
basal ends of these cells are often prolonged into muscular processes
like those of the ectoderm cells, but transverse in direction, (b) The

33

smaller secretory cells, pear-shaped and lying between the bases of
the larger ones. These last mentioned cells are numerous in the
walls of the hypostome but fewer elsewhere. Their protoplasm is
granular and they stain deeper than the larger cells.
Make a drawing of each section.

V. STUDY OF ISOLATED CELLS.

Place living hydra on a slide, draw off the water and cover for a
few minutes with a drop of Mailer's Fluid. Cover and tap gently
upon the cover glass to separate the cells.

Select and draw good examples of the varieties of cells mentioned
above.

III. HYDRACTINIA OR PODOCORYNE SP.

(Marine Hydrozoa).

Examine with dissecting microscope a colony of Hydractinia on
a shell and note the way in which the shell is incrusted by the roots
or base ( hydro rhiza) of the colony, while the free portions, or stems
(hydrocaulis) arise from this base.

With the compound microscope examine mounted preparations
of Hydractinia, and observe the following : isolated polyps or zooids
which have been torn free from the base. Among these are (i)Hy-
dranths or nutritive zooids with mouth opening surrounded by
circle of tentacles. (2) Blastosyles or reproductive zooids, without
mouth opening, with rudimentary tentacles, and with sex buds
(gonophores) in which ova and spermatozoa are found. (3) Dae-
tylozooids, or fighting polyps, without mouth or tentacles, but with
long slender body beset with nettle cells.

Observe the cell layers characteristic of Coelenterates.

Make drawings of all that yon have observed.

IV. PENNARIA TIARELLA. (Marine Hydrozoa).

Observe the form and manner of branching of the colony. Which
is the oldest polyp in the colony ? Which branch is the oldest ? How
many kinds of zooids do you find?

In a stained and mounted specimen, observe the following :

(1) The stem (hydrocaulis) containing a central gastro-vascu-
lar cavity ; surrounded by two layers of cells characteristic of
coelenterates ; the perisarc or cuticular covering, with rigid con-
struction.

(2) The hydranth (nutritive zooid). How many circles of

34

tentacles? How many tentacles in each circle? Which are the
longest? Are the tentacles hollow as in Hydra?

(3) Medusoid buds, and medusae. Observe on sides of hy-
dranths various stages in formation of medusa buds. Where are
they attached ? Observe the structure of a fully formed bud, and
of a free medusa.

Record your observations in labelled drawings.

V. GONIONEMUS MURBACHII. (Hydro-Medusa).

The three typical layers of the Coelenterata (ectoderm, endoderm
and mesoglea ) are represented. The mesoglea, however, has become
very thick. The bell-shaped medusa bears a large number of ten-
tacles from its margin.

In the center of the bell is the manubrium, which bears on its
free end the mouth, the latter having tentacular folds. The opening
of the bell is partly closed by the velum.

The digestive system consists of a short oesophagus in the manu-
brium leading into the stomach ; from the latter extend four radial
canals to the margin of the bell. At the margin, these radial canals
open into a marginal or ring canal.

i he sexes are separate and the reproductive organs, both male and
female, are suspended from the radial canals. Fertilization takes
place in the water.

VI. PLANARIA SP. (Turbellarian Worm).

I. EXTERNAL ANATOMY.

In the living worm distinguish between the anterior and posterior
ends, and the dorsal and ventral sides. Place an animal on a
slide with a drop of blood and observe the manner in which the
blood is sucked up and fills the digestive tract. Then place a fresh
drop of water on the animal and cover with a heavy cover glass.
Observe that the animal is covered with cilia. In the following
description make out as much as possible in the living animal, and
supplement this with a study of stained and mounted specimens,
both entire mounts and sections.

II. THE DIGESTIVE SYSTEM.

The mouth will be found at the extremity of a movable proboscis
which hangs from the mid-ventral line. The cavity of the pharynx
leads into that of the red-colored, branched intestine. The intestine
is seen to be made up of three divisions (Triclad type). One divi-
sion extends anteriorly and nearly reaches the dark colored eye

35

spots, while the other two extend laterally and posteriorly. There
is no anus.

III. THE REPRODUCTIVE SYSTEM.

The two sexes are united in the same individual, the common
sexual opening being seen in the mid-ventral line a little posterior
to the proboscis. The ovaries lie in the anterior portion of the body,
one on either side. The ducts may be seen leading from them toward
the external opening. Yolk glands appear as tabulated structures
lying between the ramifications of the intestine. The testes are
rounded glands scattered along the sides of the body from the
anterior to the posterior ends. Do you find ducts leading from them?
Along each side of the proboscis sheath is a tubule, the ras dcfercns
which runs into the common sexual opening.

IV. NERVOUS SYSTEM.

In favorable specimens the nervous system can be easily followed
as a series of whitish lines and areas. The two eye spots mark
the situation of the cerebral ganglia, each ganglion appearing as an
irregular mass which sends a nerve posteriorly, and several smaller
ones anteriorly, and laterally. The right ganglion is connected with
the left by a commissure. Follow the lateral nerves posteriorly ;
they will be found to unite at the hinder end of the body. Are the
lateral nerves above or below the branches of the alimentary canal?
Study sections through the eye spots.

V. THE MUSCULAR SYSTEM.

The muscular system is especially developed in the region of the
pharynx. Muscle fibres also occur under the integument, the outer-
most layer consisting of circular fibres while there are two inner
layers of longitudinal fibres separated by a layer of parenchyma.
Many diagonal fibres are also found running from the dorsal to the
ventral side.

VI. EXCRETORY SYSTEM.

Along the sides of the body parallel to the longitudinal nerves is
a branched system of very small and clear tubules, the water vascu-
lar or excretory system. These tubules open to the exterior at many
points along the dorsal surface and are difficult to trace.

Study prepared sections and make drawings of all you hare ob-
served.

36

VII. DIPLODISCUS SP. (A Trematode Worm).

I. Crush and remove the shell from an infected snail (Gonio-
basis) and observe the multitudes of parasites in the liver. Place
the snail in a watch glass of water, and after puncturing the liver
with a needle observe the escape of the parasites into the water.
Among these the following stages may be observed: — (a) Sporo-
cysts ; irregular hollow sac-like structures containing germ cells
( eggs ) , germ balls ( many celled embryos ) , or rediae. ( b ) Rediae,
elongated sacks with mouth and rod-shaped intestine, beginning at a
pharynx in front and ending blindly behind. Xear the posterior
end of the body there are two processes extending out from the
sides of the body. ( c ) Cercariae, young trematodes with oval body
and a long tail. At the anterior end of the body is the anterior
sucker at the bottom of which is the mouth. The mouth opens
into the muscular pharynx, and this in turn into a bifurcated ( Y-
shaped) intestine. There is no anus. In the middle of the ventral
side is the ventral sucker. How are the suckers used ? How does
the cercaria swim ? Are there any cilia on the surface of the body ?
If possible observe the cercaria in the process of encystment. What
becomes of the tail? How is the cyst wall formed? (d) Encysted
worm: observe the little worms inside the cyst wall, (e) Mature
sexual forms (worms which have come out from the cyst and lived
for some time in the final vertebrate host ) . In mounted stained
specimens observe : the shape of the body as compared with that
of the cercaria, the posterior sucker (acetabulum), and the sexual
organs, — the testes two in number, one on either side of the body
about half way from the anterior to the posterior ends, the single
ovary in the median line some distance posterior to the testes, the
small lobulated shell gland near the ovary, and the large vitellaria,
one on either side, lying partly above and partly below the intestine.
The main trunks of the water vascular system will be seen along
the sides of the body lying in folds beside the intestine. The excre-
tory bladder is situated at the posterior ends of the body. It re-
ceives the posterior ends of the two lateral excretory trunks and
opens to the exterior on the dorsal side of the body.

Make drawings of all the stages observed.

VIII. CROSSOBOTHRIUM OR TAENIA SP.

(A Tapeworm).

i. Examine an adult worm and notice that the bodv is flat and

mf

jointed.

37

2. Study a mounted specimen and observe : the scolex or head,
its shape, size, the number and position of the suckers, the terminal
beak or rostellum provided with hooks. Are there any sense organs
on the scolex? The proglottides begin by faint constrictions just
posterior to the scolex. Observe how they increase in size toward
the posterior end of the worm. Along the sides of the body run-
ning through the whole series of proglottides, observe a clear tube
the main trunk of the water vascular system. Can you find any
connections between the trunks on the two sides? Does this trunk
reach the scolex? How does it end anteriorly and posteriorly? Can
you find any tubules emptying into the main tube ? The sexual open-
ing is found near the middle of each proglottis and in this worm
(Taenia) on both right and left sides. Trace the ducts which lead
from this opening toward the center of the body, and in the older
proglottides, notice the uterus, centrally placed and filled with eggs.
Each egg consists of a germ cell surrounded by yolk cells and all
enclosed in a cell membrane. Only in a very favorable specimen
can the glands which form each of these three constituents be seen.
Observe the vagina or tube leading from the uterus to the sexual
opening. The testes are rounded bodies on each side of the uterus
connected by fine tubules which convey the spermatozoa to the vas
defcrcus, and thence to the exterior. Study all of the above struct-
ures in prepared sections and observe in addition the body wall.

Make drawings of the entire worm, and of a single ripe proglottis
to sJiow all of the organs observed.

IX. ANGUILLULA ACETI (A Nematode Worm).

Place a drop of vinegar containing vinegar eels on a slide, cover
and examine with the low power of the microscope. Observe :-

1. Form; Fusiform, anterior end blunter than posterior, body
round in cross-section, unsegmented. Four longitudinal lines may
be seen on the surface of the body, one dorsal, one ventral, and two
lateral. Size ; Female about 2 mm. long ; male about I mm.

2. Cuticle ; smooth, forming a thick coat over whole body.

3. Alimentary canal ; mouth terminal in front ; anus on ven-
tral side in front of tip of tail; mouth cavity small; oesophagus 1/9
the length of body in female, 1/7 in male ; intestine, a straight tube
running from oesophagus to anus.

4. Reproductive system ; this consists of long, blind tubes which
lie in the body cavity, and open to the exterior behind the middle of
the body in the female, and through the anus in the male ; in the

38

latter the sexual opening is marked by two long slender spicules,
which may be protruded or retracted.

5. Nervous system, is difficult to see. It consists of a circum-
oesophageal ring from which a number of branches run forward,
and two principle trunks run backward in the mid-dorsal and ven-
tral lines.

6. Observe the manner of swimming. Run 50 per cent acetic
acid and then 50 per cent alcohol under the cover glass. How does
it affect the animals? Test in same way any other small animal.
How do you explain the results ?

X. LUMBRICUS TERRESTRIS (The Earthworm).

A. EXTERNAL CHARACTERS.

Place a preserved worm in a dissecting dish, cover with water, and
observe :-

1. General form, color, irridescence.

2. Anterior and posterior ends? How do they differ? Dorsal
and ventral sides ; how distinguished ? Right and left sides ; are they
symmetrical ?

3. Body divided into metameres, or somites by grooves around
it. Count the somites.

4. Between the 29th and 35th somites, a swollen light-colored
region, the clitclliim. How many somites does it cover?

5. The setae, stiff light-colored spines projecting from the sur-
face of each somite, and easily felt with the fingers. How many
are there on each somite, and how are they arranged? Do they all
point in the same direction? Remove a seta, mount it in a drop of
water, and examine it under the compound microscope. What is
its general shape? Do its ends differ?

6. The cuticle. Soak an alcoholic specimen in water for a few
minutes, and then strip off some of the cuticle. What is its color?
Texture? Examine some from the ventral surface and note the
cuticular sacs in which the setae are imbedded. What is their
shape? Arrangement? Examine the cuticle under the high power
and observe the striae crossing one another at right angles. At
some of the intersections are pores to allow the escape of secretions
of the epidermis.

/. Apertures, (a) The mouth, in front of the first somite, and
below a protuberant lobe, the prostomium, which runs across the
first somite on its dorsal surface, (b) The anus, a vertical slit at
the end of the last somite. The following apertures are not easily

39

seen, and must be looked for with a hand-lens, or a dissecting micro-
scope. They can often be seen by drying the surface of the worm,
and then gently squeezing it, when a small drop will come out of
the openings, (c) Sexual apertures, (i) Openings of spermaducts,
or vasa def erentia ; two openings surrounded by s\vollen areas on the
ventral surface of the I5th somite. From these openings, grooves
are often found passing back to the clitellum. (2) Openings of
oviducts; two small pores on ventral surface of the I4th somite.
(3) Openings of the seminal receptacles or spermatheca, two open-
ings on each side between the 9th and loth, and loth and nth
somites, in line with the outer row of setae and posterior to them,
(d) Nephropores ; openings of the segmental organs or nephridia ;
two openings in each somite, one on each side, just dorsal to the
ventral pair of setae. ( e ) Dorsal pores ; openings into the body
cavity at the anterior end of each somite on the median dorsal line.
Dnr^' the anterior and posterior portions of the body to illustrate
all that yon Jiave observed.

B. INTERNAL ANATOMY.

Extend the worm, ventral side down, in a dissecting pan, and
fasten firmly by a pin at each end (the anterior one through the
prostomium only ) ; cover with water, and cut open carefully with
fine scissors, making the incision along the dorsal side a little to one
side of the dorsal median line. Do not cut deep, but merely through
the body wall. Carefully cut through the partitions or septa along
each side, stretch out the body wall to right and left, and fasten
with pins.

Observe the following structures, dissecting as little as possible
to make them out :

I. GENERAL FEATURES.

1. Body wall, thick and firm and composed of three layers: (a)
A thin cuticle on the outside ; ( b ) a more or less colored layer, the
epidermis ; ( c ) a light-colored, and much thicker layer internal to
the epidermis, the muscular layer.

2. Body cavity or coelom, with the digestive cavity passing
through it from mouth to anus, and septa or transverse partitions
dividing it into as many chambers as there are somites. Each sep-
tum passes from the digestive tract to the body wall. \Yhat is the
relation of the septa to the external grooves ?

3. Seminal vesicles, large lobed bodies between the roth and
1 5th somites, partly covering the digestive tract.

40

4. Dorsal or supra-intestinal blood vessel, generally full of blood,
and seen on top of the digestive tract, along the dorsal median line.
In the 7th to nth somites it gives off laterally 5 large pulsatile ves-
sels, or "hearts", which pass around to the ventral side of the di-
gestive tract.

5. Nephridia ; or segmental organs, light-colored fluffy bodies
attached to the posterior side of the septum, right and left, in each
somite.

Make a sketch to show the above organs in place.

II. DIGESTIVE TRACT.

Make out the following parts in the order named.

1. Pharynx, thick and muscular, extending back into the 6th
somite and attached to the body wall by many radiating muscles.

2. Oesophagus, the narrow portion from the 6th to the i-].th
somites. On its sides in the nth and I2th somites are 3 pairs of
light colored swellings, the calciferous glands. Place one of the
glands in a watch glass of dilute hydrochloric acid ; explain results.

3. Crop. A large thin walled expansion in the I5th and i6th
somites.

4. Gizzard, immediately posterior to the crop in the i/th and
1 8th somites, and with thick muscular walls.

5. Stomach-intestine, extending from the gizzard to the anus.
It expands in each somite, and is contracted by each septum. Along
its dorsal surface is a dark colored body, the liver, or pancreas. Cut
open the intestine along one side and note the large ridge on its
dorsal internal surface, the typhlosole. Cut open the gizzard and
the crop, and note the lining of these structures and the character
of the food contained.

Alake a sketch of the digestive tract, showing the above men-
tioned structures.

III. VASCULAR SYSTEM.

The dorsal blood vessel and the "hearts" have been mentioned.
To observe the other principal vessels, remove the crop, gizzard, and
oesophagus. Cut the oesophagus away from the pharynx, pull it
gently back while cutting the septa which hold it is position, and
leaving all the other organs in place. This will lay bare the white
nerve cord on the median ventral line of the body cavity. Upon
it the supra-neural blood vessel may be seen. In removing these
parts of the digestive tract, the sub-intestinal vessel may be seen on
its ventral side.

41

IV. REPRODUCTIVE SYSTEM.

1. Seminal vesicles; composed of 3 pairs of white sacs arising
from a median portion below the oesophagus. This median portion
is subdivided into an anterior and a posterior part.

2. Seminal receptacles ; 2 light colored sacs on the ventral surface
of the body-wall, on each side of the median line and attached to
septa betwreen the 9th and loth and loth and nth somites.

3. Ovaries ; very small light colored bodies with pointed tips and
rounded bases on the anterior wall of the I3th somite, not very
far from the middle of the ventral surface, one on each side, right
and left.

4. Oviducts ; these are also not easily seen, but form what appear
as thickenings of the wall between I3th and I4th somites.

5. Cut off the lateral lobe of a seminal vesicle, cut open its
median part and carefully wash out its soft contents to show the
following structures ; great care in dissection and observation is
necessary, (a) Yasa Efferentia ; large folded or convoluted masses
which form the funnel-like openings, one on each side of the
median line in the loth and nth somites. From these, delicate thread-
like ducts pass back on each side to unite in somite 12 to form the
Vas Deferens, which passes along the body wall one on each side
of the median line, as far back as somite 15 where it opens to the
exterior. ( b ) Testes ; four small white bodies, a pair in each somite,
inside the seminal vesicles in part concealed by the funnels of the
vasa efferentia, and attached to the posterior surfaces of the septa
between somites 9 and 10, and 10 and n, two on the rght and two
on the left of the median line.

V. XKRVOUS SYSTEM.

1. The nerve cord; extending the whole length of body on the
median ventral line, lying in the body cavity but near the body wall.
In each somite it expands to form a ganglion and gives off three
pairs of nerves, (a ) Two large pairs arise from the ganglion, (b)
One smaller pair arises from the slender part of the cord (connec-
tive) near the anterior end of the somite.

2. Circum-oesophageal nerve ring. Raise the oesophagus and
trace the nerve cord anteriorly to its division into right and left
halves which pass around the digestive tract to form a ring which
unites with the brain on the dorsal side of the oesophagus.

3. Brain ; connected as above shown with the ventral nerve cord,

42

but lying dorsal to the pharynx. Note the nerves given off from

the brain and also from the connectives on the sides of the pharynx.

Make a diagram to show the reproductive and nervous systems.

VI. BODY WALL.

Pin out part of the body wall quite flat and note that the muscular
layer of the wall is interrupted along four longitudinal lines in which
are the setae in sacs or setigerous glands ; four of these occur in each
somite. Between somites 12 and 13 some of these glands are con-
spicuously large ; tease out one and note under the microscope the
color, shape and hardness of the setae.

C. ANATOMY AND PHYSIOLOGY OF LIVING SPECI-
MENS.

I. MOVEMENTS.

1. Place a worm upon moist filter paper and observe the direc-
tion and method of movements.

2. In small light-colored worms note the contraction of the
dorsal blood vessel and the movements of the blood toward the an-
terior.

3. Gently touch different parts of the body and note which are
the most sensitive.

4. Place the worm under a glass vessel with some cotton satur-
ated with chloroform, the vapor of which will render the animal
insensible ; when motion has ceased remove the worm and cut it
open as in the specimen previously dissected, but only in the anterior
region and a little to one side of the median line. Keep the specimen
wet with physiological salt solution.

II. VASCULAR SYSTEM.

If the specimen is not quite dead observe:

a. The contraction of the hearts, dorsal vessel, and sub-neural
vessel ; in the latter the wave of contraction passes backward.

b. Small blood vessels passing from the dorsal vessel to the
digestive tract, and from the ventral vessel to the body wall and to
the septa.

c. Fine vessels seen upon the septa, body walls and the nephridia.

III. COELOMIC FLUID.

Puncture the body where not yet opened and take out in a fine
pipette some of the fluid of the body cavity, examine under a high
power and note :-

i. \Yhite amoeboid corpuscles.

43

2. Yellow granules, from the cholorogogue cells (See D II. i).

3. Bacteria or other foreign bodies, especially Gregarina, which
are often present.

D. HISTOLOGY.

I. BODY \YALL.

Examine prepared transverse sections of the body ; observe body
wall, now seen to be made up of five layers :

1. Cuticle, a thin non-cellular layer (membrane) often torn off.

2. Deric epithelium or epidermis, a single layer of cells many
of which are swollen (gland cells).

3. A thin outer layer of circular muscle fibres with blood vessels
and connective tissue nuclei among them.

4. A thick layer of longitudinal muscle fibres or plates, arranged
in elongated groups of eliptical form.

5. Peritoneum or coelomic epithelium, a thin layer of granular
protoplasm containing nuclei, lining the body cavity.

Sketch a portion of the body wall to show the above parts.

II. DIGESTIVE TRACT.

In its wall four layers are to be seen.

1. Chlorogogue cells, large and more or less elongated and irreg-
ular.

2. An outer layer of longitudinal muscle fibres cut across.

3. A layer of circular muscle fibres and of blood vessels (not
easily made out ) .

4. Enteric epithelium ; a single layer of elongated cells with
stained nuclei and a thin cuticle over their central ends through
which fine cilia project into the lumen of the gut.

Sketch a small part of the digestive tract to show the above.

III. NERVOUS SYSTEM.

In a transverse section of the ventral cord, note :

1. An outer muscular sheath or coat.

2. Large ganglion cells in groups or clusters.

3. A mesh work of fine fibres.

4. Yery large clear "giant fibres" each in a definite sheath.

5. In some of the sections the nerves are to be seen as they pass
from ganglion cells to the body wall.

IY. BODY CAVITY.

Some of the sections will show the following structures :
i. The corpuscles of the coelomic fluid.

44

2. Blood vessels cut across and tilled with coagulated blood.

3. Mesenteries or dorsal and ventral membranes connecting the
digestive tract with the body wall on the median line.

4. Septa and nephridia cut at various angles.

Make drawings to show the histology of the nervous system and
bod\ cavity.

XI. CAMBARUS SP. (The Crayfish).

A. GENERAL CHARACTERS.

I. BODY.

Note that the animal has a body proper and a series of paired
appendages. The body is bilaterally symmetrical and divided into
a posterior jointed abdomen and an anterior portion the ccphalo-
thora.r. The entire body is covered by a hard calcarious shell the
e.roskeleton which is flexible at the joints where movement may take
place.

II. APPENDAGES.

Note that all of the appendages are jointed, that they are attached
in pairs to the ventral surface of the body and that they vary much
in size and form.

Make a drawing of the crayfish as seen from the dorsal side.

III. APERTURES.

Make out the following apertures in the body wall:

1. The mouth seen under the anterior part of the cephalothorax
after separating from one another the crowded appendages.

2. Anus, a much elongated slit upon the lower side of the ter-
minal piece of the abdomen, the telson.

3. Genital openings on the basal joints of the legs: (a) In the
male on the delicate papilla on the last appendage of the cephalo-
thorax (one on the right and one on the left ) ; (b ) in the female an
opening with a valve-like edge on the antepenultimate appendage of
the cephalothorax (one on the right and one on the left).

4. Auditory organs : A small opening on the appendage (anten-
nule ) just under each eye stalk.

5. Green glands : A large opening on the first joint of the next
following appendage (antenna) on each side.

B. ABDOMEN.

This is made up of six segments or somites bearing appendages
and a terminal, seventh piece, the telson, which is subdivided

45

by a transverse hinge and bears the anus. Carefully examine the
third abdominal somite. The following surfaces are found upon it :
(a) T erg um } the dorsal arched portion overlapped anteriorly by the
preceding tergum. (b) Sternum, the ventral portion between the
appendages, composed of a transverse bar and a more calcined
cuticle where movements take place in bending the abdomen, (c)
Pleuron, the downward projecting portion on each side, overlapped
in front by the pleuron of the preceeding segment. The appendages
are attached to the body by soft flexible cuticular parts of the exo-
skeleton.

Each abdominal appendage consists of the following parts :

a. Protopodite : This is the proximal part of the appendage and
is divided into a long joint, and a small ring-like piece by which it
is attached. It bears distally two parts.

b. Endopodite : This is the part nearer the middle line.

c. E.ropoditc: The portion farther from the middle line.

C. CEPHALOTHORAX.

a. The large shield-like part of the exoskeleton covering the
cephalothorax above and on the sides is the carapace, which is pro-
longed in front into the frontal spine or rostrum.

b. A groove, the cerrical saturc runs across the carapace and
marks off the head from the thorax.

c. On the ventral side the region between the appendages is very
narrow; the anterior appendages project forward and not downward
as do the more posterior ones.

d. The locomotor appendages are attached to the thorax; the
posterior pair are upon a movable somite while all the others arise
from a fused single mass continuous with the head.

e. The free lateral part of the carapace, above the appendages,
is the branchiostegite. Raise its edge and see that it covers the
gills.

f . Respiratory organs : Remove one of the branchiostegites,
study the gills under water and observe : Six of them are attached
to the appendages, prodobrauchiae ; eleven of them are attached to
the soft cuticle joining the appendages to 'the body arthrobraiichiae.
At the anterior end of the branchial cavity a canal leads forward
toward the mouth and in this lies the flat part of the second maxilla
called the scaphognathite.

D. APPENDAGES.

Carefully remove all of the appendages from one side with all

46

the basal parts of each, see which are alike and then draw one of
each kind or set, keeping all of the small ones in water in watch
glasses.

I. ABDOMINAL APPENDAGES OR SWIMMERETS.

Composed of a two joined protopodite, and an exopodite and an
endopodite each with many joints ; found on all but the first and
sixth somites (and the second also in the male) where the appen-
dages are more or less modified.

II. THORACIC APPENDAGES.

There are five pairs of ambulatory, and three pairs of masticatory
appendages (the maxillipedes).

a. The posterior pairs of ambulatory appendages have the fol-
lowing seven joints: (i) Coxopodite, the short and very thick basal
joint. (2) Basipodite, a very small and conical joint. (3) Ischio-
poditc, cylindrical and with a groove around it. 14) Meropodite,
very much longer than the last. (5) Carpopodite, about half as long
as the last. (6) Propoditc, slender and long. (7) Dactylopodite,
the short, pointed terminal piece. (Of these (i) and (2) probably
correspond to the protopodite of the abdominal appendages, and the
other five to the endopodite, as may be seen by comparing all of the
other appendages with the third maxilliped.

b. The next pair of appendages have in addition a branch-id and
epipodite upon the coxopodite and extending up into the branchial
chamber.

c. The third and fourth appendages (counting forward) differ in
having the propodite produced opposite the dactylopodite to form
a pair of forceps.

d. In the large anterior pair of ambulatory appendages, the
chelae, the forceps is greatly enlarged and the basipodite and
ischiopodite are united into one piece.

e. The third or posterior maxilliped should be carefully studied.
Note: d) The large basal part, protopodite, bears a long five
jointed endopodite and a slender many jointed external exopodite,
besides a curved lamella, epipodite, lying in the branchial chamber
and bearing a branchia. (2) The protopodites and endopodites
make up together a seven jointed organ like the ambulatory ap-
pendages.

f. The second maxilliped differs from the last mentioned,
chiefly in the size of the endopodite.

g. In the first maxilliped the endopodite is short and flat, the
protopodite two jointed and foliaceous, the epipodite has no gill.

47

III. CEPHALIC APPENDAGES.

These are the maxillae, mandibles and antennae.

(a ) Second or post maxillae; the endopodite is not jointed, while
the two parts of the protopodite are subdivided or cleft ; the large
oval plate, seaphognathite, acting to bail water out of the branchial
chamber, represents the epipodite and probably also the exopodite.
(b) First maxilla ; this is very small and lies close to the mandible.
It is divided into three parts representing the coxopodite, basipodite
and endopodite. ( c ) Mandibles ; each has a strong basal part
bearing a two jointed palp or endopodite. ( d ) Post antenna ( antenna
proper); each has a two jointed protopodite with the opening of
the green glands on a tubercle on the proximal joint, the scale-like
plate is the exopodite and the long, filiform, many jointed part is
the endopodite. (e) First antenna (antennula); here the pro-
topodite has three joints and bears a long many jointed endopodite,
and a similar exopodite, while upon its large proximal joint is the
opening of the auditory organ, surrounded by hairs.

Compare your drawings of the different kinds of appendages,
labelling similar parts with the same name: the IQ pairs may be
regarded as modifications of such a one as the third maxillipede.

E. INTERNAL ORGANS.

Pin the crayfish down under water, dorsal side up, and carefully
remove the carapace bit by bit with strong forceps, commencing at
the free posterior border.

I. HEART.

Posterior to the cervical suture, a median chamber is laid bare,
the pericardia! sinus, within which lies the polygonal, fiat heart
which has six openings into the pericardinal sinus, two on the
dorsal surface, two on the lateral surfaces, and two on the ventral
surface.

II. REPRODUCTIVE ORGANS.

Carefully remove the heart to expose the reproductive organs.
fa) Testes ; in the male, these form a Y-shaped mass with the
smallest of the three lobes passing back along the median line.

(b) Vas deferens. Cut away the thoracic wall on one side and
trace the much convoluted tube from the union of the posterior
and anterior lobes of the testes down to the external genital
opening on the posterior ambulatory appendage on that side.

(c) Ovary. In a female specimen the larger reddish ovaries have

48

the same general form and position as the testes in the male, (d)
Oviducts. These are short and go directly down from the ovary to
the openings on the third, or middle, ambulatory appendages.

Make a drawing of your dissection, showing all these organs in
place.

III. DIGESTIVE TRACT.

(a) Carefully remove the anterior part of the carapace and
notice the very large sac-like stomach anterior to the heart. Pass a
probe into it through the mouth and short oesophagus, (b) Dis-
sect away the exoskeleton and muscles and follow the intestine from
the stomach to the anus. Immediately posterior to the stomach is the
"mid gut" having a short dorsal diverticulum on it. ( The remainder
of the intestine is short and simple.) (c) The digestive gland (the
so-called "liver") forms a yellow mass opening by a duct on each
side of the mid gut. Wash away its contents if the duct cannot
otherwise be found, (d) Remove the intestine and cut open the
stomach along one side (under water) and note a large round
(cardiac), and a narrow posterior (pyloric) portion. The chitinous
lining forms in the cardiac portion three conspicuous tooth-like
thickenings. In the pyloric region ridges, set with hairs, reduce the
lumen of the stomach to a narrow slit.

Draw a side view of the digestive tract.

IV. XERVOUS SYSTEM.

Remove the muscles of the abdomen until the nerve cord is seen
along the ventral wall of the body, (a) Note the relation of the
ganglionic swellings to the somites. (b) Follow the cord into
the thorax; here it enters a canal, the roof of which must be
broken off bit by bit with forceps to show the nerve cord. Note the
number of ganglia in the thorax, (c) The cord divides at the
oesophagus into a right and left half which meet again at the brain.
The brain, or supraoesophageal ganglion, lies just posterior to the eye
stalks, close to the exoskeleton, and sends a large nerve into each
of the eye stalks.

Make a drawing of the nervous system.

XII. VENUS MERCENARIA. (A Pelecypod Mollusk).

I. PHYSIOLOGY.

If living speciments are available, allow powdered carmine to settle
slowly past the openings of the siphons and determine the direction
of the current of water for each. Observe if possible the method of

49

locomotion. Touch portions of the animal and find what parts are
the most sensitive.

II. SHELL ; EXTERIOR.

Note its general shape, and that it is composed of two symmetrical
parts, the valves. For each valve notice:

1 i ) The outline.

(2) A swelling, the \imbo, ending in a point, the beak, from
which growth has proceeded.

( 3 ) The lines of growth. Were the valves cut off along one
of these lines, the shape would not be changed. Why are the
lines arranged in this manner? How were they formed? The
two valves are joined by the ligament. The margin bearing the
ligament is dorsal, and that toward which the beak points is an-
terior. Which valve is right and which is left?

Drazv a valve showing the points observed.

Pry the two valves apart and insert a knife blade between the
mantle and one valve of the shell. Notice that the lobes of the
mantle are loosely attached to the shell at their margins, and more
firmly attached at a point a half inch or more back from the margin.

III. SHELL; INTERIOR.

Separate the mantle from one valve and cut the adductor
muscles where they are attached to this valve. Why do the valves
gape now ? Press them together and notice that they stay closed
only when held. Remove a valve and study its interior.

( i ) Find the large scars where the anterior and posterior ad-
ductor muscles were attached.

2. Find smaller scars where the anterior and posterior foot
muscles were attached. The anterior scar is dorsal and a little
posterior to the corresponding adductor muscle scar. The posterior
scar connects with the dorsal portion of the corresponding adductor
muscle scar.

3. The ventral borders of the adductor muscle scars are con-
nected by a distinct line, the pallal line. What forms it? The
posterior end of this line is indented to form the pa-Hal sinus. What
is the meaning of this sinus ?

4. Along the dorsal margin of the valve notice prominences,
the teeth. There are two kinds of teeth. The anterior, cardinal,
consist of short elevations. The posterior, lateral, are not very
prominent, but extend for some distance along the dorsal margin.

50

Notice that the teeth on the two valves interlock. What is their
function ?

Draw a 1'ali'c as seen from the inside.

5. By examining a shell of Mytilus, or Unio, near its margin,
the typical three layers of which it is composed can be seen. How
is it possible for all three layers to be secreted by the mantle, which
lines the inside of the shell ? Can you rind any reason for more
than one layer?

IV. MANTLE.

This consists of two lobes (one of which is normally applied
to the inner surface of each valve of the shell ) , that are united
do rally.

1. The free border of each lobe is thickened and contains muscles
which are attached along the palial line. What function do these
muscles perform?

2. The posterior portions of the lobes of the mantle are thickened
and united to each other so as to form two tubes (in Unio the
ventral tube is formed by contact only), the siphons, through which
water passes into and out of the shell.

3. See how the muscles of the siphons are arranged and attached.
Does the attachment bear any relation to the palial sinus?

V. VISCERAL MASS AND FOOT.

These portions form the large median mass. The viscera are
contained in the dorsal portion. The ventral portion is hard and
muscular and forms the foot.

VI. GILLS.

These consist of two thin, striated lamellae (gills) on each side
of the foot. The inner and outer gills of each side are attached
to each other along their dorsal borders, and the outer gill is also
attached to the mantle ; the inner one is attached to the visceral
mass anteriorly, while posteriorly the inner gills of the two sides are
united, thus partially separating an upper cavity, the cloacal cham-
ber, from a lower one, the branchial chamber. These attachments
occur only at the dorsal borders of the gills, which otherwise hang
free in the branchial chamber. The ventral siphon opens into the
branchial chamber, while the dorsal siphon opens out from the
cloacal chamber. Labial Palps : A pair of small triangular flaps
on each side of the visceral mass. The outer palps are united
above the mouth, which is situated just posterior to the ventral

border of the anterior adductor muscle, to form a kind of upper
lip. The inner palps unite to form a fold corresponding in position
to a lower lip.

Make a drawing showing the arrangement of the soft parts.

Cut off a bit of a gill with scissors and examine it in sea water
under a low power of the microscope. Observe :

a. The surface is marked by a series of parallel ridges, the
gill filaments, which are united together, side by side, by inter-
filamentar junctions, to form a lamella; the spaces between the
interfilamentar junctions are the ostia. Each gill is composed of
two such lamellae, which are united together at intervals by inter-
lamellar junctions ; the spaces between these latter junctions form
water tubes, which open dorsally into the cloacal chamber. With a
high power observe :

b. The movements of the cilia which cover the filaments. Place
a little powdered carmine on the surface of a gill submerged in sea
water and see what happens.

Draw a surface view of a portion of a gill as seen under the loiv
power.

VII. CIRCULATORY SYSTEM.

Anterior to the posterior adductor muscle on the dorsal side is a
clear space, the pericardium, in which the heart lies. Open the
pericardium and observe the beating of the heart. The heart con-
sists of three parts :

1. A central ventricle, which surrounds the intestine and gives
rise to a blood vessel at each end.

2. Two triangular auricles, which receive blood from the gills
and open into the sides of the ventricle.

Draw the lie art.

VIII. EXCRETORY AND GENITAL SYSTEMS.

Beneath the pericardium is a pair of dark colored excretory
organs. Each communicates with the pericardium by a small open-
ing and with the cloacal chamber by another small opening. The
genital glands are light colored organs that, during the breeding
season, extend through the principal part of the visceral mass.

IX. NERVOUS SYSTEM.

i. Cerebral ganglia; carefully remove the body-wall by the
side of the oesophagus and observe a rounded, slightly yellow or-
gan, about the size of a pin-head, lying just posterior to the dorsal

52

border of the anterior adductor muscle. The ganglia of the two
sides are united by a commisure which passes anterior to the
oesophagus.

2. The Visceral ganglia lie on the ventral side 'of the posterior
adductor muscle and may be exposed by separating the united
lamellae of the inner gills. The two are connected by a short com-
missure with each other and are connected with the cerebral ganglia
by connectives that may be traced forward a short distance with-
out dissection. A large nerve leaves the posterior end of each
ganglion and supplies the posterior margin of the mantle and the
siphons.

3. The Pedal ganglia lie in the substance of the foot, dorsal to
the muscular part and in front of a loop of the intestine. With
a sharp scalpel make a median section of the foot extending it
some distance into the visceral mass ; this will expose these gang-
lia. They are connected together by a broad commissure, and with
the cerebral ganglia by connectives.

Draw the nervous system, showing the ganglia, connectives and
commissures.

X. DIGESTIVE SYSTEM.

1. The mouth lies ventral to the anterior adductor muscle. Is
it provided with teeth or any organs of prehension ? AYhat is the
nature of the food and how is it brought to the mouth?

2. The oesophagus leads from the mouth to the stomach, which
is an enlarged portion of the digestive tract surrounded by a
brownish gland commonly called the "liver".

3. Following the stomach is a much folded intestine, with walls
so thin that it is not practicable to trace it in detail. The hinder
portion of the intestine runs through the heart and opens by the
anus into the cloacal chamber, ventral to the posterior adductor
muscle. The general arrangement of the digestive system is well
shown by a median sagittal section of a preserved specimen.

Draw the alimentary canal.

XIII. ASTERIAS VULGARIS. (The Starfish).
A. EXTERNAL CHARACTERS.

Examine a specimen and note that :

1. It consists of radiating arms and a central disk.

2. That the surface by which the animal clings, the oral surface,
is different from the other, aboral surface, and that both surfaces
are covered with short spines.

53

3. On the abo'ral surface of the disc, near the junction of two
of the arms is a small, conspicuously colored, circular body,
the madrcporic plate. The two arms adjacent to this plate are some-
times referred to as the "bivium" and the remaining three as the
"trivium". The radial symmetry of the animal is disturbed ex-
ternally only by the madreporic plate. Examine this plate with a
lens and determine its structure.

4. On the oral surface is the mouth. Xote its size and see if it
is provided with jaws of any sort.

5. Radiating from the mouth are the ambulacra! grooves, one on
each arm. In these grooves are the ambulacra!, or tube feet. Do
they have a definite arrangement ? Along the sides of the grooves
are slender spines which differ from those covering the general
body in being movable.

6. Scrape the tube feet from a portion of an ambulacral groove
of a dried specimen and notice the pores through which the feet
pass to organs within the arm. Notice also the exposed ambulacral
plates, and determine their relation to the pores.

Draw figures of the oral and aboral surfaces of a starfish and a
diagram to show the relation of the ambulacral plates and pores.

7. On the aboral surface of the body find the dermal branchiae,
folds of the soft part of the body-covering, extending out between
the calacarious plates, which give the body its rigidity. Look with
a hand lens for small two- jawed structures around the bases of the
spines. Remove some of these pedieellaria and examine under the
microscope.

Draw a pedicellarium.

B. INTERNAL STRUCTURE.

Make the dissection under water and in cutting through the
integument be careful not to injure the underlying soft parts.

With scissors cut through the aboral wall near the tips of the
rays of the trivium. Carry the cuts along the sides of the
rays to the disk. Lift up the integument at the tip of each arm
and carefully cut away the mesenteries which attach the organs to
it. Cut the membranes which extend into the disk opposite the
junction of the arms, and remove the three rayed flap of integument
thus freed, cutting as close as possible to the madreporite, but
leaving this in place.

I. DIGESTIVE SYSTEM.

In studying this system you should constantly bear in mind the

54

peculiar method by which the animal feeds, as the digestive system
is highly modified to suit this method.

1. The short cone-shaped intestine and the intestinal caeca were
probably removed with the integument. The intestine probably
does not function and may be regarded as a vestige. It opens near
the center of the disc, on the aboral side, by a very minute anus
which is hard to see.

2. The stomach, which occupies the greater part of the space
within the disc, is composed of a small aboral portion, the pyloric
division, that receives the ducts from the hepatic caeca, and a larger
lobed, cardiac division, into which the mouth opens. The cardiac
portion may be everted through the mouth thus being turned wrong
side out. Five pairs of muscles, which draw this portion of the
stomach back into place, may be seen attached to the ridges formed
by the ambulacral plates in each arm.

3. In each arm is a pair of long, glandular organs, the hepatic
caeca. The ducts from each pair unite and join the pyloric division
of the stomach by a common duct. These are digestive glands.
What reason is there for ten enormous digestive glands? Does
this have anything to do with the method of feeding?

Make a drawing of the digestive system of the disc and of one arm.

II. REPRODUCTIVE SYSTEM.

Turn the hepatic caeca to one side and note the ovaries or testes.
The sexes are separate, but the gonads have the same general
appearance in both sexes. They vary in size according to the season
of the year, sometimes being so small that they are not easily
found, and again being nearly or quite as large as the hepatic caeca.
With a pair of forceps lift up one of these organs and see where it
is attached. It is at this point that the reproductive cells reach the
exterior. How many gonads are there ?

Draw the gonads in one arm of your figure.

IV. WATER- VASCULAR SYSTEM.

i. Carefully remove the side of the stomach next to the bivium.
being very careful not to disturb the stone canal, which runs from
the madreporic plate to the margin of the membrane about the
mouth. By the side of the stone canal is a thin band of tissue
formerly supposed to be a heart. It is now generally believed to
be connected with the reproductive system, and is commonly referred
to as the axial organ. It has nothing to do with the system now
under consideration.

55

2. The circular canal, which is joined by the stone canal at the
outer margin of the peristomal membrane, follows the margin of
the membrane and thus encircles the mouth. Originating from
it at points very near the ampullae of the first tube feet are nine
small vesicles, Tiedemann bodies. They are smaller than the am-
pullae and project toward the mouth. The position where the tenth
Tiedemann body might be expected is taken by the stone canal.

3. Leaving the circular canal are five radial water tubes, one
for each arm. These tubes lie along the oral surfaces of the
ambulacral plates, and are accordingly not visible on the inside of
the animal. The position of the tube can be best understood by
making a transverse section of the arm. It will then be seen either
in injected or uninjected specimens, lying immediately below the
ambulacral plates. In injected specimens it may be followed by
dissecting on the oral side, from the circular canal to the ex-
tremity of the arm where it ends in a small tentacle.

4. Along the sides of the ambulacral ridges, within the body
cavity, are rows of little bag-like ampullae. Determine their relation
to the ambulacral pores. In a dissection it is hard to find the
connecting tubes which join the radial tubes to the tube feet, but
they can sometimes be seen in sections of the arms of injected
specimens. They can readily be seen in microscopical preparations.

The wa'er vascular system is very distinctive for the echinoderms,
and you should understand perfectly: (i) How the tube feet are
extended. (2) AYhat causes them to adhere. (3) The connection
between tube feet, ampullae, connecting canals, radial water tubes,
circular canal, stone canal and madreporite. (4) How it is possible
to extend one foot without extending others.

Make a drawing showing the arrangement of the water vascular
system.

IV. NERVOUS SYSTEM.

This is not easily studied by dissection. It consists of a nerve
ring which encircles the mouth, and lies just ventral to the circular
water canal, and five radial nerves that extend down the arms just
beneath the radial water tubes, to end at the tips of the arms in
pigment spots. The whole central nervous system is superficial
and forms a portion of the outer covering of the body. The radial
nerves can be seen by separating the rows of ambulacral feet, but
it is much more satisfactory to study them in prepared sections.

56

C. PREPARED SECTIONS.

Study prepared sections of the arm of a starfish and observe :

1. The hepatic caeca. How are they supported? What is their
structure ?

2. The radial canal, connecting tubes, tube feet and ampullae.

3. The thickened, deeply staining nerve, between the tube feet
and below the radial water tube.

4. The perihaemal canal, divided by a thin partition, and lying
between the radial water tube and the radial nerve.

Make a drawing of a section of an arm which will show these
points.

D. PHYSIOLOGY.

a. Observe a living specimen in the Vivarium and Note : ( i )
Method of Movement. (2) Method of Feeding. How does it open
an oyster? How does it swallow the oyster?

b. Place a starfish in a dish of sea water and observe its reactions
to the following stimuli :

( i ) Mechanical; touch the end of an arm with your pencil and
note the response.

(2) Gravity; place the animal on its aboral surface and observe
how it rights itself.

(3 ) Place the animal so that bright sunlight falls on the tip of an
arm and note the response.

RANA SP. (The Frog).
A. GENERAL STRUCTURE.
I. EXTERNAL CHARACTERS.

Note the smooth moist skin over the entire animal ; the absence
of exoskeleton ; the head, trunk, two pairs of limbs ; the ab-
sence of a tail and of a neck.
a The head. Observe :

1. The eyes are prominent and have lids; the ears are covered
over by a modified part of the skin, membrana tympani, posterior to
the eyes; the two anterior nares, or nostrils; the position of the
mouth opening; the soft flexible throat and hard parts of the
endoskeleton felt on the dorsal side of the head.

2. Pass a bristle far into the anterior nares and one into the
ear through a hole cut in the membrana tynipani; on opening the
mouth the bristles will indicate its communications with the nostrils

57

and tympanic cavity. The second bristle appears in the Eustachian
recess at the side of the posterior part of the mouth. In the male
a small opening anterior to this recess leads into the bnccal sac
which can be distended, by means of a small blow-pipe. Turn the
fleshy tongue forward and notice its mode of attachment. Note the
slit of the glottis and the posterior opening of the mouth into the
oesophagus; pass a bristle into the former and a large probe into
the latter. There are thus two median and six paired openings,
from the mouth cavity in the male frog. Note the small teeth.

b. The trunk.

This tapers towards the posterior end where the cloaca! aperture
is seen near the dorsal surface. Beneath the skin the hard endoskele-
ton can be felt on the dorsal side and on the anterior part of the
ventral side.

c. The limbs.

1. The anterior pair divided each into three regions, brae Ji him,
antebrachium, nianus; the latter with four digits, the innermost of
which bears a swollen cushion in the male.

2. The much longer posterior pair each divided into three re-
gions, femur, cms, pes, the latter with five long digits connected
by a web. There is a large firm prominence on the inner side of the
ankle; callosities are found under the joints of both pes and mauus.

II. INTERNAL CHARACTERS.

a. Place the frog under a bell-jar with a sponge saturated with
chloroform ; when dead pin out under water on its back.

b. Cut through the skin along the median ventral line from the
posterior end to the jaw (raising the skin from the body and not
cutting deep ) ; cut transversely at each end of first cut and turn
aside the two large flaps thus made.

c. On the flap of skin on each side is seen a large vein near
the shoulder, the musculo-cutaneous vein. The muscular walls of
the abdomen are covered by a thin, shining connective tissue sheath,
apoiieurosis, through which in the median region is seen the racJiis
abdominis passing from the pelvis to the sternum and somewhat
divided by transverse lines into segments or mvotomes. Through
this muscle is seen the dark blood of the anterior abdominal vein
on the median line.

d. With a pair of forceps raise the body wall and carefully cut
it through by a slit to the right of the median line ; continue this
cut from pelvis to sternum and make transverse cuts as in the

58

skin so as to throw back a flap of body wall on each side; the left
one should show the anterior abdominal vein on its exposed
surface.

e. \Yith forceps raise the sternum and carefully cut off the
fibrous bands seen passing to soft organs dorsal to it ; with strong
scissors cut through the sternum and other hard parts on the
median line carefully holding it up away from the soft parts dorsal
to it. Turn each half outward and pin firmly; pin the anterior
limbs out at full length.

d. The liver is conspicuous, forming a large brown mass with
the pericardia! sac just anterior to it.

f. Carefully cut away the membranous pericardium to expose
the heart ; then with great care clean off bit by bit the tissue covering
the vessels at the anterior end of the heart.

g. ( i ) Xote the firm conical posterior portion of the heart, the
ventricle. (2) The cylindrical truncns artcriosiis arises from the

m>

right side of the base or anterior end of the ventricle and passes
obliquely forward to divide into two large branches. (3) The
atrium forms a thin walled sac dorsal to the truncus and anterior
to the ventricle (it is divided internally into two auricles). (4)
The sinus venosns can be seen by carefully raising the ventricle to
one side ; it forms a thin sac dorsal to the ventricle and atrium and
receives three large veins (two anterior or superior venae cavae
and one large posterior or inferior vena cava. } Two pulmonary
veins open into the left auricle by a single opening. ( 5 ) Each
branch of the truncus divides into three arteries, the most anterior
is the carotid, the most posterior the plumino-cutaneous and the mid-
dle one the systemic aortic arch which unites with its fellow dorsal to
the heart to form the dorsal aorta.

Make a diagram of the heart and vascular trunks.

h. Pulsations of the heart. Observe : ( i ) A regular sequence
of contraction and dilation. ( 2 ) The atrium contracts, then the
ventricle, and immediately after the truncus. ( 3 ) On raising the
ventricle, the sinus venosus can be seen to contract before the
atrium. The contraction proceeds in the same order as that fol-
lowed by the blood in passing through the heart.

i. Anterior to the heart note the broad flat transverse mylo-
hyoid muscle through which can be seen the long first vertebral
nerve or hypoglossal. Note also the hard portuberant larynx and
on each side of this a small soft body, the thyroid gland.

]. Posterior to the heart, note the following viscera: (i) The

59

liver with its larger left lobe divided into two parts ; on raising the
posterior border, the yall bladder is seen as a greenish sac on the
right side; also the hepatic-portal vein, which enters the left lobe of
the liver. The stomach, an elongated white body on the left side un-
der the posterior edge of the liver. (3) A convoluted tube, the in-
testine passing from the stomach to the right and then posteriorly to
finally enter the pelvic cavity as an expanded rectum. It is slung by a
delicate membranous fold of peritoneum, the mesentery, which is
full of blood vessels. (4) The fat masses, long slender yellow
masses on each side in the dorsal part of the body cavity anterior
to the reproductive glands. ( 5 ) The urinary bladder, a large bilobed
sac ventral to the rectum (it can be inflated through the cloaca by
means of a blow-pipe).

k. Cut off all the dorsal part of the liver with strong scissors,
cut open the body wall in the pelvic region without injuring the
rectum, (i) The cloaca is now7 exposed; a bristle may be run from
it into the rectum. (2) Uncoil the intestine and fasten to one side
to expose the spleen ( a small red body near dorsal part of mesen-
tery). (3) The pancreas is also seen as a pale-colored compact
mass in the mesentery between the stomach, liver and small intestine.
The bile duct from the gall bladder passes through the pancreas
to open into the small intestine. ( 4 ) The oesophagus is a short
straight tube ; pass a probe from the mouth into the stomach.

Make a drawing of your dissection to show all of these parts.

1. Remove the stomach, liver, mesentery and organs connected
with it. ( i ) Posterior to the fat masses, lie th<: reproductive glands,
in the male yellow, rounded testes ; in the female, folded or lobed,
yellow ovaries ( when the eggs are nearly ready for laying, each is
a large sphere, light on one side and dark on the other, and the
lobes of the ovary are so distended by great masses of ova as to fill
most of the body cavity). (2) Sexual ducts: in the male, each testis
sends numerous small thread-like ducts, vasa-cfferentia, into the
kidney lying just posterior and dorsal to it. In the female the
oviduct is a long convoluted tube opening into the cloaca posteriorly
and passing forward on each side to open by a funnel into the body
cavity near the oesophagus. It has no connection with the ovary.
(3) The kidneys are elongated, red masses close to the vertebral
column ; on the ventral surface of each is an elongated yellowish
body the adrenal body. Entering the kidneys on their external side
are the renal-portal veins; leaving the kidneys on their mesial side
are the branches of the inferior vena cava. (4) Ureter, a whitish

60

<luct on each side passing from the outer side of the kidney into
the cloaca. ( In the male this serves also as a vas deferens. )

Make a diagram of the urino-genital system of your specimen.

m. Tag your specimen with your name and put it into a jar of
preserving fluid until the next exercise.

III. THE NERVOUS SYSTEM. (Preserved Specimen.)

a. Cut the skin along the median dorsal line and reflect it. Re-
move the muscles from the vertebrae. Open the neural canal by
cutting into the membrane just posterior to the skull, and bit by
bit, pick off the roof of the brain cavity with strong forceps or
scissors. Remove the dorsal part of the vertebral arches in the
same way. A delicate pigmented membrane ( pia mater} covers the
brain and the spinal cord but may be concealed in the latter
region by soft tissue ( coagulation products after death ) that can
be washed away with a stream of water from a pipette.

b. T/ie Brain; if this is not injured in exposing it, note:

1. RhineiicepJialou or anterior part made up of two olfactory
lobes extending anteriorly from a common median part as two
cylindrical so-called olfactory nerves to branch inside the nasal
chambers.

2. ProsencepJialon composed of two large masses, the cerebral
hemispheres, separated by a median groove.

3. Tlialameuccplialon, a mass between and posterior to the
hemispheres. Upon it is a very small pineal gland and below this
a central cavity, the third ventricle, bounded on the sides by
masses called optic tlialaini.

4. MesencepJiaion, a pair of large, rounded, hollow bodies, the
optic lobes.

5. Metencephalon or cerebellum, a small mass extending across
the anterior edge of a large triangular cavity, the fourth ventricle.

6. Myelencephalon or medulla oblonyata, forms the remainder of
the brain posteriorly and contains the fourth ventricle covered
over by a vascular part of the pia mater.

c. Spinal Cord or My el on.

1. Forming the continuation of the medulla oblongata outside
the skull it rapidly tapers at about the fifth or sixth vertebra to form
a slender filament. On its dorsal surface is a median line, thi>
dorsal fissure.

2. On each side ten spinal nerves arise from the cord. By
carefully raising the cord a little, towards the posterior end, and

61

searching with a pocket lens, the nerves are seen to arise each by
two roots, one dorsal, one ventral.

J\Iake a sketch of the central nervous system as thus exposed.

d. Cut the olfactory nerves away from the skull, gently turn
the brain back cutting all the nerves close to the skull and thus
remove the brain (as entire as possible), and part of the spinal
cord. Place in a dish of water and stuclv the ventral side with a

•/

pocket lens.

1. Optic chiasm or commissure, a transverse elevation at the
posterior end of the cerebral hemispheres continued up on the
sides of the brain towards the optic lobes as the optic tracts, and
giving rise in the other direction to the optic nerves, (cut off in re-
moving the brain ) .

2. Tuber cinereum : a rounded somewhat two-lobed elevation
posterior to the chiasm, continued ventrally into the conical iufundi-
bulum, or slender neck bearing a small conical mass, the pituitary
body or hypophysis cerebri.

3. Crura cerebri : the anterior continuation of the medulla as
the large nerve mass dorsal to the above parts, extending anter-
iorly on each side toward the hemispheres.

4. Ventral fissure ; a median longitudinal groove along the ven-
tral side of the medulla and spinal cord.

Draw the ventral surface of the brain and spinal cord.

e. Peripheral Nerves: a. Spinal Trunks, (i) Sciatic ple.vns:
A number of large nerves, on each side of the dorsal aorta connected
by branches and ending posteriorly in the large sciatic nerve, while
anteriorly it is formed from the 7th, 8th, and 9th spinal nerves.
(2) Anterior to the sciatic plexus, three pairs of small spinal nerves,
the 6th, 5th, and 4th pass obliquely outward and posteriorly along
the wall of the body cavity. (3) Branchial nerve; formed from the
union of the 2nd, and 3rd spinal nerves; it goes to the arm.

b. Raise the dorsal aorta and notice the two slender longitudinal
sympathetic trunks passing dorsal to it, one on each side. ( i) Each
trunk has numerous enlargements or ganglia giving off fine nerves.
(2) Large lateral trunks connect these ganglia with the spinal
nerves. (3 ) Periganglionic glands; white masses of unknown func-
tion, surrounding the spinal nerves where they issue from the spaces
between the transverse processes of the vertebrae.

IV. MUSEUM SPECIMENS.

Observe in the Museum, south wing, numerous preparations of

62

organ systems of different vertebrates, and compare them with
corresponding organ systems of the frog.

B. THE SKELETON.

In connection with the dried prepared skeleton, study the fresh
skeleton, boiled for a few minutes after removing the skin and
viscera.

I. GENERAL ARRANGEMENT OF PARTS OF THE SKELETON.

a. The main axis consists of the vertebral column continued
anteriorly as the central part (brain case) of the skull.

b. Connected with the main axis are the supporting parts of
the appendages, and the lateral parts of the skull.

1. The anterior appendages consist of a free limb (containing
a hiimcrus, radio-ulna, carpus and digits, supported by a shoulder
girdle or pectoral arch.

2. The posterior appendages consist of a free limb (containing
a femur, tlbio- fibula, tarsus and digits) connected with the spinal
column by the pelvic girdle.

II. VERTEBRAL COLUMN.

f

Made up of nine separate vertebrae and of a posterior Urostyle.

a. Remove the third vertebra, and note :

1. Solid flattened ventral part (centrum), with anterior concave,
and posterior convex surfaces.

2. Neural arch ; arising dorsally from the centrum and enclosing
a space which forms with that of the other vertebrae, the neural
canal.

3. Processes of the vertebrae; on each side, one transverse
process, four articular processes, — one on each side of arch anteri-
orly (pre-zygapophysis) , one on each side of arch posteriorly (post-
sygapophysis) , — a median spiuous process arising from dorsal sur-
face of the arch.

b. The first vertebra (atlas), articulates anteriorly by two
surfaces with the skull.

The eighth vertebra (sacrum} has a large transverse process join-
ing the pelvic arch and a centrum convex anteriorly and with two
tubercles posteriorly to articulate with the-

c. Urostyle, a single rod-like bone continued posteriorly as a
cartilage and with a dorsal ridge anteriorly, inside which is a small
neural canal opening laterally by two small foramina, one on each
side.

Draw the third vertebra to show the points mentioned

63

III. THE ANTERIOR APPENDAGES.

a. The shoulder girdle or pectoral arch on each side is closely
united to the sternum to form an incomplete ring of bones to which
the free limbs are attached.

b. The paired lateral parts of the shoulder girdle are : ( i )
Scapula; large ossified plate extending dorsally from the articulation
of the free limb. (2) Supra-scapula ; a very large cartilage con-
tinued dorsally from the scapula. (3) Coracoid ; a flat elongated bone
extending ventrally and inward from the articulation of the limb
towards its fellow from which it is separated by an epicoracoid car-
tilage. (4) Precoracoid; a cartilaginous band anterior to the cora-
coid and parallel to it, and more or less concealed by an ossified
clavicle along its anterior edge.

c. The median unpaired parts are: (i) Sternum; a short flat
bone directly posterior to the epicoracoid cartilage. (2) Xiphister-
nuni ; a broad bilobed cartilage extending posteriorly from the ster-
num. (3) O mo sternum; a small cartilage anterior to the epicoracoid
cartilages, and separated from them by the sternum.

d. Skeleton of the free-limb: (i) Humerus; the single bone of
the brachium. (2) Radio-ulna; a bone representing two fusecr
bones ( radius and ulna ) . When the arm is extended at right angles
to the body with palm ventral, the radial side is anterior, the ulnar
side posterior. (3) Carpus; making a complex joint between fore-
arm and digits of hand and composed of six small nodules of bone
or cartilage: First, proximally two (radiale, ulnare], side by side,
articulating respectively with radius and ulna ; second, distally three
(carpalia), of which the external is much the largest and artic-
ulates with digits 4, 3, 2, while the two small inner ones articulate
with digit i, and rudimentary digit i1; third, a bone (centrale)
on the inner side of the wrist between the proximal and
distal rows. (4) Digits: each of the four digits contains a long
mctacarpal and three long phalanges, except the innermost finger
which has but two phalanges. A single metacarpal bone on the inner
( radial ) and palmar side represents an additional radial digit, or
support for the cushion of the thumb.

Draw and label the pectoral girdle and one anterior appendage.

IV. POSTERIOR APPENDAGES.

a. The hip-girdle or pelvic arch on each side is firmly united with
its fellow and joined to the sacrum, (i ) At the acetabiilum or artic-
ular facet for the femur, three radiating fissures mark out the divi-
sion into three parts: ilium anteriorly articulating with the sacrum;

6.

ischinm posteriorly united with its fellow into one mass; pubis or
part wedged in between the ilium and ischium and united with its
fellow on the ventral line.

b. Bones of the free-limb. ( i ) In the thigh one long bone, the
femur. (2) In the crus or leg, the tibio- fibula representing a fused
tibia and fibula. When the leg is extended as the arm was, the
anterior side is the tibia! side. (3) Tarsus: this is made up chiefly
of two long proximal bones fused at the ends and representing a
tibialc (or astragalus} and a fibulare (or calcancum). Between these
and the digits are three small distal tarsalia, the inner or anterior
one articulates with digit i, the flat larger outer one with 2 and 3 and
(as a cartilaginous continuation) with 4 and 5.

c. Digits. There are five, each with a metatarsal and three pha-
langes, except the first or tibial digit which has two phalanges, (i)
The hard cushion on the inner side of the sole is supported by what
seems an additional inner or tibial digit, represented by three short
bones articulating with the same inner tarsalium that digit i does.

Draw and label the bones of the pelvic girdle and leg.

V. THE SKULL.

a. In the dry skull note the following parts and draw the whole
on a large scale, as seen from above, (i) The cranium or brain-
case. (2) The sense-capsules, auditory and olfactory. (3) The
facial bones separated more or less widely from the cranium. (4)
The foramen magnum, or passage from the neural canal into the
cranium. (5) The convex condyle on each side of the foramen
magnum corresponding to the two parts of the atlas. These are
upon the e.voccipitals. (6) Pro-otics or bones anterior to the exoc-
cipitals, forming on each side the roof and anterior wall of the
auditory capsule. (7) The squamosal, a hammer-shaped bone, run-
ning from the pro-otic downward and posteriorly towards the articu-
lation of the lower jaws. (8) The fronto-parietals: two long parallel
bones in the roof of the cranium with a median suture between them.
(9) Nasals: immediately anterior to the latter and triangular in out-
line. (10) Pre-ma.rillae : between the nasals and the gape anteriorly,
(n) Ma.riUae: extending from the latter bone on each side along
nearly all the upper edge of the gape. (12) Quadrato-jugal: a deli-
cate bone forming the boundary of the gape between the maxilla
and squamosal on each side.

b. On the ventral surface note and draw the following: — (i)
Parasphenoid: a dagger-shaped bone, running along the floor of the
cranium or roof of the mouth. (2) Sphcnethmoid or girdle bone :

65

a large bone enclosing the anterior third of the brain case. (3)
Palatines slender bones ventral to the nasals, (on the roof of the
mouth), passing outward from near the anterior end of the parasphe-
noid to the ma: illae. (4) Vomers two irregular bones anterior
to the last and bearing teeth fas do the premaxillae and maxillae. (5 )
Pter\goids: a tri-radial bone on each side attached to anterior wall of
auditory capsule, to the squamosal and to the inner side of the
maxillae. (6) The Mandible or lower jaw made up of a right and
left half or ramus, each of which has a main piece (angulo-splenoid)
extending from the auditory region and covered anteriorly by a
scale-like external bone (dentary) and also a short nodular piece
(mento-Meckelian ) at its anterior tip where it joins its fellow
ramus in the median line.

c. (i) In a slightly boiled or fresh skull remove carefully the
membrane or investing bones with forceps or scalpel and draw the
chondro-cranium that is thus laid bare, together with the following
bones that remain as ossified parts of the cartilaginous skull: First,
exoccipital ; second, pro-otics ; third, sphenethmoid ; fourth, quadrate ;
fifth, mento-meckelian. (2) This cartilaginous skull forms a case
for the brain, olfactory and auditory organs; on each side a long
sub-ocular arch or palato-qnadrate cartilage standing out a\vay from
the cranium is produced as a snspensorimn at its posterior end
for the articulation of the mandible; the latter is Mcckd's cartilage,
ossified at its anterior tip as the mento-Meckelian bone. (3) Xote
the fontanelles or imperfect parts of the roof of the cranium; the
foramina for passage of nerves from the brain through the chondro-
cranium ; the partly ossified coluniella aitris extending from the tym-
panum to an opening, fenestra oi'alis, in the auditory capsule.

d. The hyoid : this consists of a broad flat body of cartilage in the
floor of the mouth, and of four pairs of processes, (i ) The anterior
cornua arising from the anterior edge of the body on each
side as long slender cartilaginous rods attached near the fenestra
ovalis. (2) Posterior coma or thyro-hyals; a short thick bony piece
joined on each side to the posterior edge of the body near the middle
line. (3) On each lateral edge anteriorly and posteriorly (or at the
angles of the body), a short rounded cartilaginous process.

Draw tJie hyoid.

VI. MUSEUM SPECIMENS.

Observe in the Museum, central section, numerous skeletons of
vertebrates, and compare the bones of the appendages with those you
have studied in the frog.

66

C. HISTOLOGY.

I. EPITHELIUM.

a. Columnar epithelium : Gently scrape the inner surface of a
frog's intestine that has been preserved in Miiller's fluid. The frag-
ments removed, under a high power, are seen to be composed of
elongated cells each with a nucleus and having one end more pointed
than the other.

b. Ciliated epithelium: Cut off a bit of the mucous membrane
from the tongue or roof of the mouth of a freshly killed frog, mount
in physiological salt solution and examine under a high power. Xote
the appearance on the edge due to the cilia, as the cilia become less
active individual ones can be distinguished. Scrape off some of the
epithelium and examine under a high power in physiological salt
solution ; note the shape of the individual cells and the group of
cilia at one end. Draw both kinds of epithelium.

II. MUSCLE.

a. Tease out a bit of injected frog's muscle preserved in alcohol,
(i) It is composed of elongated fibres, some of which may be split
up somewhat into fibrillae. (2) Numerous blood capillaries are
found amongst the fibres.

b. Examine with a high power: (i) Each fibre shows alternate
darker and lighter bands. (2) A delicate sarcolemma or structure-
less membrane envelops each fibre and can be easily seen at places
that are broken or twisted.

c. Tease out fresh muscle in salt solution and examine with high
power to note the above points ; treat with acetic acid and observe
the oval nuclei in the fibre. Drazv.

III. NERVE.

a. Nerve fibres: Tease out a bit of fresh nerve in salt solution
and examine with a high power. Note: (i) \Yell defined fibres,
each with a double contour, together with white fibrous tissue make
up the mass of the nerve. (2) Each fibre has a highly refractive
border (medullary sheath) and a central homogeneous a.vis cylin-
der, well seen in torn specimens where also the very delicate, outer-
most membrane (primitive sheath), may be some times made out.

b. Ganglion cells : Examine prepared specimens of ganglion cells
that have been stained to make out the structure of the cells. Draw
a nerve fibre and a ganglion cell.

67

IV. CARTILAGE.

Dissect out the tip of the delicate xiphisternal cartilage of a fresh
frog, or slice a bit of the cartilage from the head of the femur with
a razor; mount in salt solution and study under the high power.
Note : ( i ) Large rounded cartilage cells scattered through a nearly
invisible and structureless matrix which forms a refractive halo
about each cell. (2) A distinct nucleus (or two) in each cell. (3)
After some time the cells contract and thus a space is formed be-
tween the cell and the matrix. Draiv.

*

V. BONE.

Examine with low power a section of bone (mammalian bone).
Observe: ( i ) Havcrsian canals, rounded spaces often rilled with air
or dirt and then appearing black. (2) Lamellae, concentric layers
about each haversian canal. (3) Lacunae, oval black spaces be-
tween the lamellae. (4) Canaliculi, minute dark lines radiating
from the lacunae. (5) Other lamellae are to be found not arranged
about canals, but filling in spaces not occupied by such systems.
Draw.

VI. CONNECTIVE TISSUE.

a. White fibrous tissue : ( i ) Tease out a bit of fresh tendon in
water ; with a high power it is seen to be made up of fine wavy
fibres in bundles ; each fibre has faint outlines and does not branch.
(2) Treat with acetic acid; most of the fibres become invisible, but
a few (yellow elastic fibres) and some elongated granular con-
nective tissue cells remain visible.

b. Yellow elastic fibres : Tease out in acetic acid some of the
tissue immediately under the frog's skin. Under a high power note :
Branched fibres with well defined outlines ; these may not be found
until several specimens have been examined. Draw both white and
yellow fibres.

68

PART II.

ECOLOGY.

The following directions for laboratory work are general in
character since they are intended to apply to various specimens from
the Museum and Vivarium. Several specimens, illustrating differ-
ent kinds of adaptations, etc., will be assigned, one after another, to
each member of the class. Keep laboratory records for each speci-
men separate and distinct ; first record the scientific name of each
specimen, and then the results of observations on the topics pro-
posed.

A. RELATIONS TO INORGANIC ENVIRONMENT.

I. HABITAT.

Is the specimen a marine (Halobios), fresh-water (Limnobios) or
terrestrial ( Geobios ) form ? \Yhat are the evidences upon which
your conclusion is based ?

1. If aquatic, is it a bottom form (Benthos) or a top form
(Plankton) ? Give evidence for your conclusion.

2. If terrestrial, is it fitted for life in arid or swampy regions,
or for subterranean, arboreal, or aerial life ? Give reasons for your
answer.

3. Are there any evidences that this animal or its ancestors have
ever changed habitat? If so, what are they?

4. Draw the specimen, devoting particular attention to those
adaptations which have relation to the habitat.

II. CLIMATE.

1. Temperature. Does the animal show any particular adapta-
tions to heat or cold? In what condition does it pass the winter?
The summer?

2. Moisture. Does it show adaptations for the prevention of
the loss of moisture, or to protect it against too great moisture?

3. Winds. \Yhat adaptation, if any, does it show to winds?

4. Light. Is it a form which seeks or avoids strong light, and
what adaptations does it show in this connection?

69

III. MOVEMENT.

1. Is the animal free-moving or sedentary? (a) If free moving
is it passively carried by winds or currents, or does it move active-
ly? Do the organs of locomotion indicate that it is fitted for swim-
ming, walking, running, creeping, leaping, burrowing, or flying?
Draw one or more of the locomotor organs, (b) If sedentary is it
free or attached ? Show by drawings the means of attachment. Are
there any rudiments of locomotor organs? Are sedentary animals
descended from free-moving ones, or vice verso,?

2. Does this species undergo periodical migrations? If so des-
cribe them.

3. In the specimen assigned you by what means is the dispersal

of the species secured, and what are the barriers to such dispersal ?

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IV. GEOGRAPHICAL DISTRIBUTION.

i. To what Zoogeographical Region of the earth is the animal
native ?

B. RELATIONS TO ORGANIC ENVIRONMENT.

I. FOOD.

Animals are monophagous or polyphagous, depending upon
whether they live upon a single kind of food or on several kinds ;
they are carnivorous, herbivorous, or omnivorous depending upon
whether they eat flesh, plants, or both.

1. Correlation of Food and Structures. Determine by means of
the organs of prehension, the teeth, or the character of trie mouth
parts of the speciment assigned you what is the nature of its food.
Draw these characteristic structures.

2. Correlation of Food and Habits. Point out, if possible, the
correlation between the food and the habits of the animal you are
studying.

3. Storage of Food. Is this animal able to store up food in
any form? If so describe the process.

II. MEANS OF DEFENSE AND OFFENSE.

1. Active. Is the animal you are studying able to defend itself
actively or not? If so, draw and describe some of the organs used
for this purpose.

2. Passive. If it defends itself passively describe the methods
and structures by which this is done.

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III. INTERRELATIONS BETWEEN DIFFERENT SPECIES.

If the species which you are studying is always associated with
some other species, in which of the following groups does it belong?

1. Commensalism. The commensal alone benefits, but the host
is not injured. In the case in hand which is the commensal and
which the host? Is the commensal permanently fixed to the host,
or free to separate on occasions ?

2. Symbiosis. The symbionts derive mutual benefit from asso-
ciation. These also may be free or fixed.

3. Parasitism. The parasite benefits at the expense of the host.
Is the parasite an endoparasite or an ectoparasite? Is it temporary
or constant?

IV. COOPERATION BETWEEN INDIVIDUALS OF THE SAME SPECIES.

Associations of individuals of the same species fall under one
or another of the following" h^ads :—

a. Colonial forms without division of labor.

b. Colonial forms with division of labor.

c. Association of separate individuals without division of labor.

d. Association of separate individuals with division of labor,
(i). Does the form which you are studying belong in any of

these groups ? \\hat advantage, if any, is derived from association
without division of labor? If physiological division of labor is
present is it associated with structural diversity? If so, draw each
of the types present, and determine their relations to one another.

(2). Study a colony of bees, or of ants, and draw figures of the
males, females and workers. Observe the varied activities of the
members of the colony. If other members (castes, slaves) are
present in the ant colony make a study of them also. Note the
way in which the food is stored and the young are cared for. Study
a section through honey comb, and if possible, observe the method
in which it is formed. Observe and draw to scale worker cells,
drone cells and queen cells, and if possible observe the kinds and
relative quantities of food which are fed to the larval workers and
queens.

V. SEXUAL REPRODUCTION.

i. Sex. In many plants and lower animals the sexes are united
in the same individual (Hermaphroditism) ; in higher animals the
sexes are generally separate (Gonochorism ). To which class does
your specimen belong ?

2. Primary and Secondary Sexual Characters. The ovaries and
testes are primary sexual characters ; all other sexual characters^
which are dependent for their development upon the primary ones,
are secondary sexual characters. Draw and compare the secondary
characters which distinguish male and female, and, it possible,
determine the significance of each.

3. Semination. Is semination internal or external? Draw the
structures of the male and female which serve to bring the sperma-
tozoa to the ova.

4. Types of Development. Where does the development of the
embryo occur ? Is the animal oviparous or viviparous ? Do the
embryos obtain their food by their own activities (larval develop-
ments), or from the mother (foetal development) ?

5. Care of Eggs and Young. In the species you are studying
are the eggs and young cared for? If so, how?

PART III.
GENETICS.

A. ONTOGENY. Development of the Individual.

I. ASEXUAL REPRODUCTION occurs by Fission, Budding, Segmen-
tation, and has been studied in the Protozoa, Hydra, Taenia, etc.
If time permits study in detail prepared slides showing the process
of fission in Stenostoma.

II. SEXUAL REPRODUCTION.

a. Monogony ; sexual reproduction with only one parent.

1. Parthenogenesis (virgin reproduction). Observe and draw
water fleas (Daphnia) containing broods of young produced from
unfertilized eggs. The same phenomenon may be seen in plant
lice (Aphides.)

2. Paedogenesis (infant reproduction). Observe and draw
stages in the development of unfertilized eggs in the larvae (sporo-
cysts, rediae ) of the trematode worm, Diplodiscus.

b. Amphigony ; sexual reproduction with two parents.

i. Oogenesis and Spermatogensis. Study prepared sections of;
(i) Ovitestis (hermaphrodite gland) of the snail, Planorbis, and
draw a portion of the section to show the ova, the spermatozoa,
and the method of development of each. (2) Ovary of the frog,
showing eggs of very different sizes. Note the enormous size of
the nucleus (germinal vesicle). It is filled with nuclear sap, in
which are scattered nucleoli and fine threads of chromatin. Note
the distribution of the yolk and pigment in the egg. Draw. (3)
Testis of frog, showing mature spermatozoa, their heads attached
in bundles to nurse cells and their tails extending into the lumen
of the seminiferous tubule. Around the walls of the tubule are
seen the following stages in the formation of spermatozoa: (a)
Spermatogonia. cells with clear nuclei, at periphery, (b) Sper-
matocytes I, large cells with chromatin in clumps, (c) Sper-
matocytes II, smaller cells with densely staining nuclei, (e)
Spermatozoa, with progressively elongating nucleus and cell body.

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2. Maturation and Fertilization. The last two cell divisions in
the oogenesis and spermatogenesis are known as the "maturation
divisions" and lead to the reduction of the chromosomes in the
mature egg and sperm to half the usual number. When the egg
is fertilized the normal number is again restored.

Carefully study the maturation and fertilization of the egg of
Ascaris megalocephala, with especial reference to the chromo-
somes. Observe that in the maturation of the egg (also of the
sperm) the number of chromosomes is reduced to two, and in the
union of the egg and sperm the number is increased to four, the
normal number. Draw eggs showing all of these points.

3. Cleavage. Observe that in the cleavage of the egg of
Ascaris each chromosome is split longitudinally, so that each
daughter nucleus receives two chromosomes from the egg and two
from the sperm. Draw.

4. Development of Frog. Study entire frogs' eggs in various
stages of cleavage.

Early Cleavage Stages. Examine eggs divided into two, four,
eight and sixteen cells. Note in the two-cell stage that a grayish or
slate colored area, crescentric in form, is present on one side of the
egg, and that it is, as a rule, bisected by the first plane of cleavage.
Note in the four-cell stage the relative distribution of the pigment
on the anterior and posterior sides of the egg. Note in the eight-
cell stage the relative sizes of the upper and lower cells, also the
distribution of the pigment in the cells, and the location of the
grey crescent. Note in the sixteen-cell stage the position of the
fourth planes of cleavage in the upper and lower cells. Examine
a section of one of the early cleavage stages; note the nuclei sur-
rounded by pigment.

Later Cleavage Stages. Examine two of the later cleavage
stages (Blastula stages). Note the comparative sizes of the cells
in the upper and in the lower hemispheres of the embryo. Examine
a section of a late cleavage stage. Note the large cleavage cavity ;
the thinness of the roof, and especially the character of the superfi-
cial cells at the level of the floor of the segmentation cavity. Out of
these cells all of the main parts of the body develop.

Gastrula Stages. Study surface views of three gastrula stages
showing : ( i ) The beginning of the dorsal lip of the blastopore,
(2) the back-growth of the dorsal lip, and the appearance of the
lateral lips, and (3) the formation of the ventral lip. At this time
the blastopore is circular in outline and the yolk plug fills up its

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opening. Study a longitudinal section of a gastrula stage. Com-
pare with the section of the blastula and note all differences.
Observe especially :

(i). The lifting up of the floor of the segmentation cavity.

(2). The slit-like archenteron, opening behind the dorsal lip of
the blastopore.

(3). The condition of the cells in the dorsal lip itself. Draw
to large scale showing ectoderm, mesoderm and endoderm.

Neural Plate. Study sections of three stages in the formation
of the neural plate: (i) Stage with the neural plate widely open,
(2) Sides of the neural plate rolling in, (3) Neural plate com-
pletely closed to form the neutral tube (brain and spinal cord).

Tadpole. In cross sections of a young tadpole study and draw :

(i ). Origin of eye-vesicle from the fore brain, and development
of the eye.

(2). Cross section througn the gill region, with the heart
beneath.

(3). Cross section through the ear vesicles and hind brain.

(4). Cross section through the middle of the embryo to show
neural tube and crest, notochord, aorta, pronephros, somites and
gut.

5. Museum Specimens. Observe in the Museum, south wing,
numerous preparations illustrating the development of vertebrates.

III. COMBINATIONS OF SEXUAL AXD ASEXUAL REPRODUCTION.

1. Metagenesis'. Alternation of asexual reproduction with
sexual, as in hydromedusae.

2. Heterogeny. Alternation of monogonic reproduction with
amphigonic, as in fluke worms.

IV. HEREDITY. Germinal likeness or variation as contrasted with
environmental.

1. Mendelian (alternative) inheritance. Study ajnd draw
Museum exhibits illustrating this kind of inheritance.

2. Give Mendelian formulas and ratios to the third filial genera-
tion (F3) for the offspring of (a) two homozygous parents, (b)
two heterozygous parents, and (c) one homozygous and one hete-
rozygous parent. Explain sex as a mendelian character and show
by formulas and ratios in which of these three groups it belongs.

3. Describe any cases of inheritance, known to you, which seem
to be non-Mendelian.

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4. All members of the class are invited, but not required, to
fill out a Family Record blank, giving details of their own heredity
for the use of the Committee on Eugenics.

B. PHYLOGENY. Development of Races, Species and larger
subdivisions.
I. VARIETIES AND SPECIES.

1. Varieties. In a large series of individuals of the same species
pick out and draw individuals which represent the mean and the
extremes of variation.

2. Species. In a genus containing a large number of species,
pick out and draw species which represent the mean and the ex-
tremes of variation.

II. HOMOLOGIES.

a. Comparative Anatomy.

1. Draw and label corresponding parts of the limb skeletons
of three vertebrates, having different modes of locomotion.

2. Draw and label corresponding teeth of three vertebrates,
which eat different kinds of food.

3. Draw and label corresponding parts in the appendages of a
lobster, or crayfish, and a crab.

4. Drawr and label corresponding parts of the skeleton of a
starfish and a sea-urchin.

How are such likenesses (homologies) to be explained?

b. Comparative Embryology.

1. Study and draw the adult and larva of an ascidian, and of
a barnacle, and show how embryology throws light on relationships,

2. Compare the branchial clefts in an embryo chick and shark,
and indicate the phylogenetic significance of this resemblance.

c. Paleontology.

2. Study in the Museum the paleontological history of some
family of animals, and point out its phylogenetic significance.

III. EXPERIMENT.

With the aid of books which will be assigned you, describe the
principal races of some one domestic animal or cultivated plant and
compare them with the original wild stock.

IV. FACTORS OF EVOLUTION.

Explain the origin of the peculiar structures of the specimen
assigned you according to the following theories: (i) Lamarckism.
(2) Darwinism. (3) Orthogenesis. (4) Mutation.

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