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LABORATORY DIRECTIONS IN
GENERAL BIOLOGY
BY EDWIN GRANT CONKLIN
PROFESSOR OF BIOLOGY
PRINCETON UNIVERSITY
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LABORATORY DIRECTIONS IN
GENERAL BIOLOGY
BY EDWIN GRANT CONKLIN
PROFESSOR OF BIOLOGY
PRINCETON UNIVERSITY
Third Edition
»
INTRODUCTION v^ „ lt.
A *
* v^
THE BIOLOGICAL SCIENCES
Read: Calkins, Biology, pp. 1-5; or
Sedgwick and Wilson; General Biology, pp. 6-8; or
Shull, Animal Biology, pp. 1-6; or
Woodruff, Foundations of Biology, pp. 1-5.
GENERAL BIOLOGY is the science which deals with the most
general and fundamental characteristics of living things,
whether plants or animals. The study of plants alone is known as
Botany, of animals alone as Zoology. A thorough study of any
plant or animal includes a knowledge of its (i) Physiology, which
deals with its physics and chemistry, its functions and activities;
(2) Morphology, which deals with its structure, whether gross
(Anatomy), microscopic (Histology), or developmental (Em-
bryology) and also with its classification (Taxonomy) ; (3) Ecol-
ogy, which treats of its relations to its environment ; (4) Biogeny,
which deals with the origin of the individual plant or animal
(Ontogeny, Heredity, Development, Genetics, etc.) or with the
origin of races, species and larger groups of individuals (Phy-
logeny, Evolution).
In studying any plant or animal it is desirable that it should be
considered from all of these aspects, but some organisms are
better suited than others for the study of one or another of these
subjects. Accordingly this course is divided unequally into three
parts, the first of which deals chiefly with the Physiology and
Morphology of the organisms studied, the second with their
Ecology and the third with Biogeny.
[3]
GENERAL BIOLOGY
THE AIMS AND METHODS OF LABORA-
TORY WORK IN BIOLOGY
The purpose of all laboratory work is to study nature at first
hand ; but in order to save time it is necesary to utilize knowledge
slowly acquired by many generations of previous students. There-
fore we do not follow Agassiz's motto: "Study Nature, not
Books/' but, rather, "Study Nature and Books." The educational
value of laboratory work lies chiefly in the cultivation of accuracy
and independence both of observation and of judgment, and in
the deeper and more lasting impression which is made of that
which we have actually seen and handled. Each student is ex-
pected to make for himself the observations and experiments
hereafter indicated. The assigned readings which are given at the
beginning of each topic should be carefully read before coming
to the laboratory. In the laboratory these Directions must be stud-
ied and followed. Only in this way can a great waste of time,
effort and material be prevented.
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 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.
Read: "How to Use and Care for the Microscope." Spencer
Lens Co. ; or
"Use and Care of the Microscope," Bausch and Lomb
Optical Co.
A. DESCRIPTION. The body or tube bears the lenses and is
supported upon a stand which also carries a mirror to cast light
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GENERAL BIOLOGY
upon the object examined through a hole in the flat stage upon
which the object is placed. This hole can be made of various di-
ameters by means of the iris diaphragm. A lens for concentrating
light, and known as a condenser, is 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 combination of lenses at the lower end of the tube is the
objective; 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 ob-
ject examined when its lower end is about */$ in. above the object,
the latter (high power objective) is in focus when it is about ^ 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 magnifica-
tion. 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 mic-
roscope case.
B. USE. i. Reflect light, from white clouds if possible, upon
the object. Where 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 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 smal cog wheel which fits into the rack and is turned
by the two milled wheels on each side of the tube. The fine adjust-
ment is by means of a milled screw head 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 direc-
tion it is raised. In using 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.
GENERAL BIOLOGY
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 an 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
lo-cker.
II. PREPARING OBJECTS.
The preparation of objects for examination under the micro-
scope is termed mounting. Objects are usually mounted on pieces
of glass 3x1 in., known as slides. Observe the following direc-
tions :
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 are 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 must be perfectly clean
and dry.
3. Having placed the object in a small drop of mounting fluid
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GENERAL BIOLOGY
take a cover glass in your left hand, rest one 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 with the name of the object and the method of preparation.
5. Never use reagents haphazard, 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 surounding
the object with some substance such as paraffin, preparatory to
cutting sections of it.
6. Miscroscopical slides which have been prepared in this way
are valuable, sometimes very valuable, and when such preparations
are given out for use they must be handled carefully. Do not crush
the cover glass or slide by focusing down on it. Do not pick up your
microscope with a slide on the stage, as it is very likely to fall on
the floor and be broken. Do not leave slides on the table when
you have finished with them but return them to the desk or to
the box from which you received them. A charge will be made for
every slide that is broken.
III. NOTES AND DRAWINGS.
i. Drawings should be 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. Make your drawings a record of
what you actually see and if you cannot see what the directions
call for consult an instructor. Do not attempt to make drawings
without the object before you and do not make rough sketches
and then finish them from memory. In general make outline draw-
ings without shading. Where certain structures occur in large num-
bers 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. Use hard pencils (4!!), with very sharp points,
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GENERAL BIOLOGY
and make the drawings large enough so that all details can be
represented without confusion.
2. To draw to scale : — Place paper at base of microscope and
endeavor 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.
IV. EXAMINATION OF COMMON OBJECTS.
1. Mount a few fibres of wool, cotton, linen and silk in water
on different slides, cover with cover glasses and examine first un-
der a low power, then under a high one. How do the fibres differ ?
Sketch and label one of each under the lower power and then under
the high power of the microscope, drawing to scale.
2. Examine a drop of 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 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 ?
[8]
.-:; •
PART I
GENERAL PHYSIOLOGY AND
MORPHOLOGY
A. CHEMICAL AND PHYSICAL CHARAC-
TERISTICS OF LIVING THINGS
Read: Sherman, Chemistry of Food and Nutrition, pp. 1-102;
or
Nutrition, pp. 1-102; or
Mathews, Physiological Chemistry, pp. 1-187; or
Hawk, Physiological Chemistry, pp. 1-147.
The bodies of all living things are composed of about 15 chem-
ical elements and a great number of chemical compounds : 97 per
cent of the human body consists of carbon, hydrogen, oxygen and
nitrogen, and 3 percent 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
contain carbon compounds, or "organic compounds." Compounds
of carbon, hydrogen and oxygen form Carbohydrates and Fats;
compounds of carbon, hydrogen, oxygen and nitrogen form Pro-
teins.
I. CARBOHYDRATES (Starches, Sugars, etc.).
Carbohydrates of physiological importance are : —
Monosaccharids (C6 H12 O6) — dextrose, levulose, glucose.
Disaccharids (C12 H22 O^) — cane sugar, malt sugar, milk sugar.
Polysaccharids (C6 H10 O5)n — starch, dextrin, glycogen, cellu-
lose.
I. MONOSACCHARIDS (glucose, fructose, etc.). Cannot be
split into simpler sugars.
a. Dextrose. Take a one per cent solution and test solution
as follows:
Boil 5cc. of Benedict's1 or Fehling's2 solutions in a test tube.
Result ?
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GENERAL BIOLOGY
Then add 8 drops of dextrose solution and boil again. Result?
This is the "dextrose test." Copper sulphate (Cu So4 in an alkaline
solution is "reduced" to yellow cuprous hydroxide (Cu OH) or
to red cuprous oxide (Cu2O) when boiled with a reducing sugar.
Test your urine for sugar in this way.
2. DISACCHARIDS (Sucrose, maltose, lactose) can be split into
monosaccharids by hydrolysis.
a. CANE SUGAR (Sucrose). Take a few drops of i% solu-
tion and test with Benedict's or Fehling's Fluid. Is it a reducing
sugar ?
b. HYDROLYSIS OF CANE SUGAR. Boil some of the i % solution
with a few drops of hydrochloric acid. Cool, neutralize, and apply
Benedict's test. Is a reducing sugar present?
3. POLYSACCHARIDS. Native starch, a. 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 nitrate with iodine. Explain result.
c. Test solubility in boiling water. Note character of resulting
solution. Dilute and add a drop or two of iodine solution. What
results, and why?
d. Cellulose (plant cell-walls). Cotton fiber is almost pure
cellulose. Note insolubility in water and alcohol. Is it insoluble in
acids ? Alkalies ? Does it react with iodine ? Treat with 40 per cent
sulphuric acid and then add iodine. What results? Treat with
Schultze's chlor-zinc-iodide.3 Explain results. This is known as
the "cellulose test."
1 Benedict Fluid: Copper sulphate, 17.3 grams; Sodium or potassium
citrate, 173.0 grams; Sodium carbonate, 200 grams; Distilled water to
make 1000 cc.
2 Fehling's Fluid: — (i) Copper sulphate, 34.65 grams; Distilled water to
make 500 cc. ; (2) Potassium hydroxide, 125.0 grams ; Rochelle salt, I73-O
grams; Distilled water to make 500 cc. (3) Mix equal parts of (i) and (2)
when needed for use.
3 Schultze's Chlor-zinc-iodide is made as follows: — (i) Dissolve no
grams of zinc in 300 cc. hydrochloric acid and evaporate to 150 cc. ; (2)
Dissolve 12 grams of potassium iodide in as little water as possible and
add 0.15 grams iodine; (3) Mix (i) and (2), and filter if necessary.
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GENERAL BIOLOGY
4. 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 into
two test tubes ; boil one of the tubes and leave the other unboiled.
Add to each tube an equal volume of dilute starch paste and place
tubes in incubator warmed to 40 C. for fifteen minutes. Then
divide the substance in each tube into two portions and test one
of each of these for starch (iodine) and the other for sugar
(Benedict's). What effect does ptyalin have on starch? What
effect does boiling have on ptyalin ?
II. LIPINS (Oils, Fats, Yolk. etc.).
1. OILS AND FATS, (i) Note 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 percent sodium carbonate in-
stead of water, examine with microscope, and note difference in
results. (This is an emulsion.) (3) Rub a thin film of butter on
a slide, and put on a drop of the dye known as Sudan III. Ob-
serve under microscope what occurs.
Stain thin sections of Castor bean and of Lima bean with Sudan
III. Is oil present in both?
2. CHEMICAL TESTS FOR FATS. The reaction with ether and
with fat stains are two well-known tests for fats.
III. PROTEINS (Albumins, Peptones, Albuminoids, etc.).
Use white of egg as type of protein.
1. Carefully pour white of egg into a dish. This is approxi-
mately a 12 per cent solution of a protein (albumin) in water.
Notice its consistency. Test its reaction with litmus paper; is it
acid, alkaline, or neutral? A 10 per cent solution of this white
of egg has been made by shaking it up with 9 times its volume of
distilled water and filtering.
2. COAGULATION, (i) Coagulation by heat. Have a water
bath with water at the boiling temperature. Put some of the un-
diluted albumin 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 coagula-
GENERAL BIOLOGY
tion by heat? (2) Coagulation by chemicals. To 5 cc. of the 10
per cent albumin 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) Test urine for albumin as follows: a. Boil 10 cc.
of urine in a test tube ; if turbidity appears add a drop or two of
strong acetic acid; if turbidity disappears it was due to phosphates,
if not to albumin, b. Put 2 or 3 cc. of strong nitric acid in a test
tube, then add urine, allowing it to run gently down the'iside of
the slanted test tube ; if albumin is present a ring of coagulum will
form between the acid and the urine.
3. CHEMICAL TESTS FOR PROTEINS: Xantkoproteic Reaction.
Dilute some of the 10 per cent albumin 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 the acid is
neutralized. Note color produced. (This is the essential feature
of this reaction.) Try in the same way a weak solution of gelatin
(albuminoid) ; does it coagulate? Does it give the xanthoproteic
color ?
4. ACTION OF ENYZMES ON PROTEINS. Thin pieces of boiled
white of egg were placed in artificial gastric juice, made by add-
ing pepsin to a 0.2 per cent solution of hydrochloric acid and
allowed to stand 24 hrs. Some of the digested albumin was placed
in one dialyzer and some fresh, undiluted albumin in another. Test
the water below each membrane for albumin.
IV. ENZYMES (Organic Ferments).
1. Chemical substances probably allied to proteins though they
have never been completely isolated. They are formed by animal
or plant protoplasm and act as catalyzers in many chemical re-
actions within living things.
2. They are classified, according to what they do, as :
Amylo-lytic or Starch Splitting (Diastase, Ptyalian, etc.).
Lipo-lytic or Fat Splitting (Lipase, Steapsin, etc.).
Proteo-lytic or Protein Splitting (Pepsin, Tripsin, etc.).
Sugar Splitting (Maltase, Invertase, Lactase).
Alcohol forming (Zymase).
Coagulating (Thrombin, Rennin).
Oxidizing (Oxidase, etc.)
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GENERAL BIOLOGY
3. You have already observed the action of ptyalin on starch,
and of pepsin on albumen. Write the chemical formula for the
former of these reactions.
V. HORMONES (Chemical Messengers).
Chemical substances, possibly enzymes, usually formed by duct-
less glands and poured into the blood. They stimulate or inhibit
many vital processes (Thyroidin, Adrenin, Secretin, etc.)
VI. VITAMINS.
Accessory food substances of unknown chemical nature, pro-
duced by animals and plants. May act as enzymes or hormones.
Essential to life, but minute quantities sufficient. (" Water-soluble
B," "Fat-soluble A," etc.).
VII. PROTOPLASM. (Living substance, material basis of
life).
Composed of all the preceding classes of substances together
with water and various salts. Protoplasm is not a single chemical
compound but is an organized mixture of many compounds, espe-
cially proteins. There are innumerable kinds of protoplasm.
B. MORPHOLOGICAL AND PHYSIOLOGICAL
CHARACTERISTICS OF LIVING THINGS
Protoplasm exists only in the form of cells, which are in-
dividual masses of protoplasm, each containing a denser body,
the nucleus.
I. CELL STRUCTURES.
Read: Calkins, Biology, pp. 6-29; or
Sedgwick and Wilson, General Biology, pp. 20-40 ; or
Parker, Elementary Biology, pp. 56-79; or
Shull, Animal Biology, pp. 70-83; or
Woodruff, Foundations of Biology, pp. 6-29.
A. PLANT CELLS.
i. Carefully tear in two a leaf and from the torn edge pick
off a small piece of the transparent covering (epidermis). Mount
in water and examine under the microscope. Draw about 10 ad-
jacent epidermal cells, making each cell about half an inch in
diameter.
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GENERAL BIOLOGY
2. In prepared sections through the root-tip of an onion ob-
serve the shape and size of the cells. Draw about 10 adjacent cells.
Having found one or more complete cells with round nucleus ob-
serve and make a drawing about 2 inches in diameter of a single
cell showing the following parts: i. Cell Membrane. 2. Nucleus.
3. Cytoplasm (protoplasm surrounding nucleus). In the nucleus
observe: 4. Nuclear Membrane. 5. Nucleolus. 6. Chromatin (stained
granular part of nucleus). 7. Achromatin (unstained part of nu-
cleus).
B. ANIMAL CELLS.
1. With the handle of a scalpel gently scrape the inside of
your lip or cheek and mount the scrapings in a drop of water.
Draw several cells. Run a drop of aceto-carmine under the cover
glass by placing the drop on one side of the cover and applying
a bit of filter paper to the other side. The nucleus stains deeply
owing to the fact that it contains chromatin. Draw one cell show-
ing nucleus, cytoplasm, and cell-membrane; making the drawing
about 2 inches in diameter.
2. In similar manner observe the cells and cell structures in
prepared slides of the skin of a frog.
2. Mount a drop of frog's blood and examine under the low
power and then under the high. Draw several of the red, also of
the white, corpuscles.
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 pro-
cess (Mitosis) or by the direct process (Amitosis).
(i). Indirect Nuclear Division (Mitosis).
In prepared slides of the growing root- tip of the onion observe
nuclei in the following stages of division :
(a) Early Phophase, in which the nucleolus has disappeared
and the chromatin granules have united to form threads; (b) Late
GENERAL BIOLOGY
Phophase, showing disappearance of nuclear membrane and
formation of chromosomes (chromatic rods) from the threads;
(c) Metaphase or Equatorial Plate, showing the chromosomes in
the equator of the cell, each dividing by a longitudinal split; (d)
Early Anaphase, showing the daughter chromosomes separating
toward the poles of the cells ; (e) Late Anaphase, showing union
of daughter chromosomes to form daughter nuclei; (f) Teleo-
phase, in which the cell-body divides and the nuclei ; return to the
"resting condition."
Draw a cell in each of these stages of division.
(2). Direct Nuclear Division (Amitosis). In prepared slides
of the follicile cells surrounding the egg of the cricket observe
various stages in the direct division of the nucleus. Draw cells
in which (a) the nucleolus is dividing, but the nucleus is still
spherical, (b) the nucleus is dumb-bell shaped, (c) the nucleus
is divided into two.
2. PROTOPLASMIC MOVEMENT. With 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 protoplasm, strands of which may be seen moving or
circulating. (3) Within this protoplasm is a clear spherical or
ovoid body, the nucleus. (4) Most of the center of the cell is occu-
pied by a purple, homogeneous fluid, the cell sap.
If the flowers of Tradescantia are not available use one of the
leaflets of the water weed Elodea canadensis. Observe the green
bodies (chloroplasts) within the cells. Do they circulate?
Make a drawing showing these structures, and indicate by ar-
rows the direction of the protoplasmic movement.
C. CLASSIFICATION OF PLANTS AND
ANIMALS
Read: Calkins, Biology, pp. 162-166; or
Parker, Elementary Biology, pp. 137-147; or
Parker and Parker, Practical Zoology, pp. 215-228; or
Shull, Animal Biology, pp. 260-274 ; or
Woodruff, Foundations of Biology, pp. 348-351.
All living things are classified as plants or animals depending
upon certain peculiarities of structure and function. In general
[15]
GENERAL BIOLOGY
plants have rigid cell walls of cellulose (C12 H20 O10), which is
lacking in animals ; the food of plants consists of relatively simple
chemical compounds, whereas that of animals is much more com-
plex; also plants are usually less active than animals.
The minor subdivisions of both animal and plant kingdoms
are very numerous and are known as Orders, 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 (1707-1778) 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 subdivisions
and classes named above. Enter in your laboratory notes in the
following manner the scientific name (copied from the labels of
specimens on exhibition) of some one member of each phylum
and class of the animal kingdom, so far as represented in the ex-
hibits :
PHYLUM CLASS GENUS SPECIES
Cnidaria Hydrozoa Hydra fusca
The animals and plants which will be studied in this course are
common forms which are found in the vicinity of the laboratory.
The particular forms to be studied are chosen because they illus-
trate especially well certain general principles or characteristics.
Locate in the tables of classification the position and relation
to other animals or plants of each organism studied in the labo-
ratory, museum or field.
D. METAPHYTA
Metaphyta are many-celled plants, with more or less differentia-
tion of the cells and tissues for particular functions. The lower
Metaphyta belong to the Cryptogamia or flowerless plants, the
higher ones to the Phanerogamia or flowering plants. Owing to
limitations of time, it is not possible in this course to study more
than one representative of the Metaphyta, and for this study one of
the higher flowering plants is chosen, viz., the common bean.
PHASEOLUS VULGARIS, String Bean
(Subkingdom Phanerogamia, Division Spermatophyta, Sub-
division Angiospermae, Class Dicotyledonae.)
[16]
GENERAL BIOLOGY
Read: Bigelow, Applied Biology, pp. 66-121; or
Coulter, Barnes and Cowles, Text Book of Botany,
Vol. i, pp. 295-484; or
Curtis, Nature and Development of Plants, pp. 1-129; or
Duggar, Plant Physiology, pp. ; or
Ganong, Text Book of Botany, pp. 1-178; or
Physiology of Plants, pp. or
Huxley and Martin, Practical Biology, pp. 460-481 ; or
MacDougall, Plant Physiology, or
Vines, Text Book of Botany, pp. 666-783, or
Woodruff, Foundations of Biology, pp. 61-114.
A. MORPHOLOGY.
I. SEED.
In beans which have been soaked for 24 hours in water ob-
serve : —
1. Shape, Size, Color.
2. The Seed Coat, a tough outer membrane.
3. The Hilum, or scar, where it was attached to the parent
plant.
4. Dry the surface of the seed and squeeze it gently; water
will exude from a small hole near the hilum, the Micropyle.
Draw a bean to show all of these features, in profile and also in
face view.
II. EMBRYO.
Remove the seed coat and observe the Embryo, which fills
the whole space within the seed coat ; note the following parts of
the Embroyo : —
a. Two Cotyledons or seed leaves, which constitute most of the
bean seed ; they are attached to one another by their bases. Mount
in water scrapings from one of the cotyledons and examine under
microscope; also test scrapings with iodine and others with
Benedict's Solution. What is the chief constituent of a Coty-
ledon ?
Separate the two Cotyledons and observe : —
b. The Hypocotyl (stem and root) on the margin of the
Cotyledons with its apex toward the micropyle.
c. The Plummule (bud) between the Cotyledons, composed of
two small primary leaves and a minute bud between them.
Draw an embryo to show the inner face of a cotyledon with
hypocotyl and plumule attached.
[17]
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sae with Stinging Cells, Gas-
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Colonies formed by budding.
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spheres, entirely marine ;
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, Cephalopoda (Squid)
Holothuroidea (Cucumber
Echionoidea (Sea Urchin)
Asteroidea (Starfish)
Ophiuroidea (Brittle Star
Crinoidea (Stone Lilies.
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Cyclostomata (Lamprey)
Pisces
a. Elasmobranchii (Sharks
a. Ganoidei (Armored fist
c. Teleostei (Bony fish)
d. Dipnoi (Lung fish)
Amphibia (Frogs, Toads)
Reptilia (Reptiles)
Aves (Birds)
Mammalia (Mammals)
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CHIEF SUBDIVISIONS OF THE PLANT KINGDOM
SUBKINGDOM
DIVISION
SUBDIVISION
CLASS
Thallophyta
(Plants with-
out true stems,
roots or
leaves)
Algae
(Sea weeds and
simpler fresh-
water weeds.)
Fungi
(Plants without
chlorophyll and
with saprophy-
tic nutrition)
A. Cryp togamia
(Flowerless
plants)
| II. Bryophyta —
j (Mosses and
'Liverworts)
III. Pteridophyta—
(Vascular
cryptograms)
B. Phanerogamia
(Flowering
plants)
5 IV. Spermatophyta
I (Seed Plants)
Gymnospermae —
(Plants with naked
seeds)
Angiospermae —
Plants with cov-
ered seeds)
1. Cyanophyceae, Blue-gr
Algae
2. Chlorophyceae, Gre
•{ Algae
| 3. Phaeophyceae, B r o "
Algae
[4. Rhodophyceae, Red Al
5. Myxomycetes, S 1 i
Moulds
6. Schizomycetes, Bacteri;
7. Phycomycetes, Moulds
8. Ascomycetes, Sac fung
9. Basidiomycetes, Sm
Rusts, Muskrooms
10. Fungi imperfe-ti (life
tories imperfectly knoi
5 u. Hepaticae, Liverwort:
| 12. Musci, Mosses
13. Eusporangiatae, Op'
glossum, Marattia,
etes
14. Leptosporangiatae, Fc
Marsilia
15. Spenophyllineae, Sp!
ophyllum
16. Equisetineae, Horse
17. Calamarineae, Calan
18. Lycopodineae, C 1
mosses
19. Lepidodendrineae, L
dodendren
20. Cycadolfilicineae, Cyc
filices
21. Cycadineae, Cycads
22. Bennettitineae, Benn
-{ tales
I 23. Cordaitineae, Corda
I Ginko, Gnetum
I 24. Pinoideae, Conifers,
[ Yews
[25. Monocotyledoneae, A
ocots
( 26. Dicotyledoneae. Di
GENERAL BIOLOGY
III. GERMINATION.
In young seedlings grown in moist blotting paper observe : —
1. The expanding Cotyledons. Color?
2. The branching Root which has grown out from the apex of
the hypocotyl.
a Mount a small branch of a root in water and examine under
the low power. Observe the delicate root hairs standing at right
angles with the rootlet. On what portion of the rootlet are they
most abundant?
3. The smooth round stem (hypocotyl) lying between the Coty-
ledons and the root.
4. Between the Cotyledons is the expanding plumule, showing
the primary leaves and the bud between them.
Draw a germinating plant to show all of these parts.
IV. SEEDLINGS. (1-2 weeks old.)
Carefully dig up a seedling 1-2 weeks old and observe: —
1. The cotyledons lifted above the soil by the growth of the
hypocotyl. Test portions of a cotyledon for starch and dextrose.
What is the significance of their withering during the growth of
the plant?
2. The branching roots which anchor the plant in the soil. Ob-
serve particles of soil attached to the root hairs. Do roots ever
grow from any portions of the stem except the extreme lower end?
3. The heart-shaped primary leaves with long stalk (petiole)
attached to opposite sides of the stem. At its distal end the petiole
expands into the blade with three main veins, each of which
branches repeatedly, thus giving rise to a net-veined leaf charac-
teristic of Dicotyledons (Exogens). On each side of the petiole,
near the base of the blade, is a rudimentary leaflet, the stipel, and
on each side of the base of the petiole is a small leaf, the stipulei.
4. At the apex of the stem is the bud from which the central
axis of the plant will develop, and a similar bud occurs in the axil
(upper angle between leaf and stem) of every leaf.
Draw a seedling showing all of these parts.
V. MATURE PLANT (8-10 weeks old).
(A). Vegetative Organs. Gross Anatomy.
In a mature plant observe : —
I. The further development of the root system. Root tubercles
[21]
GENERAL BIOLOGY
about y$ inch or less in diameter, and containing nitrogen-fixing
bacteria, may occur on some of the rootlets.
2. The disappearance of the cotyledons and the scars on the
stem where they were attached.
3. The primary leaves as in the younger plant.
4. The stem growing up between the primary leaves, and con-
sisting of nodes, from which leaves and branches arise, and inter-
nodes.
5. The secondary leaves are compound, each consisting of three
or more ovate leaflets, with rudimentary leaflets (stipels) at the
base of each. Are stipules present at the base of the petioles? Do
the secondary leaves occur in opposite pairs, as in the primary
ones?
6. In the axils of the leaves are buds which may give rise to
branches and flowers.
(B) Histology.
(I.) The Stem
i. Study a thin transverse section through an internode, first
under the low power and then under the high power. Note: —
a. The central pith often with a cavity and with pith-cells
around cavity.
b. The fibro-vascular bundles arranged in a ring outside the
pith. Commencing at the side nearest the pith in each bundle: (i)
Small openings which are cross sections of the spiral vessels; (2)
Larger openings, the pitted vessels; (3) Small thick-walled wood
cells between the vessels. These three constitute the wood or
xylem of the bundle ; (4) The cambium zone, composed of thin-
walled cells in radial rows 1(5) The bast or phloem, composed in-
ternally of bast-cells and sieve tubes and externally of rounded
bast-fibers with thickened walls.
c. The cortex, consisting of several layers of large, rounded
cells containing chlorophyll.
d. The medullary rays, radiating rows of cells passing between
the bundles.
e. The epidermis, composed of a single layer of squarish-
looking cells containing no chlorophyll and some bearing hairs.
Between some of the epidermal cells are openings, the stomata,
each bounded by two small guard cells.
Draw and label the section.
[22]
GENERAL BIOLOGY
2. Study a longitudinal section through part of an internode
and mount in water and study under microscope. Working from
the central cavity note the following: —
a. Pith cells.
b. Fibro -vascular bundles, each containing (i) Spiral vessels,
(2) Wood cells, (3) Pitted vessels, (4) Cambium zone, (5) Bast-
cells, (6) Bast-vessels, large elongated cells with oblique per-
forated septa (sieve tubes), (7) Bast fibers.
c. Cortex cells. .
d. Epidermis with occasional stomata.
Drazv section.
3. Study longitudinal section through a node and compare
it with that through the internode. Observe the bundles passing out
from the stem into the leaf. Draw.
(II.) The Leaves.
1. In prepared sections of a leaf observe the following parts:
a. Colorless epidermis, with occasional stomata on upper and
lower surfaces.
b. Mesophyll consisting of (i) Palisade cells, perpendicular to
surface and containing chlorophyll; (2) Spongy parenchyma,
composed of irregular branched cells containing chlorophyll, and
forming the lower half of the leaf substance.
c. Intercellular spaces through the whole mesophyll com-
municating with the exterior through the stomata.
d. Here and there sections of veins. Make out in them the same
parts as in the fibre-vascular bundles.
Draw the section.
2. Peel off a strip of epidermis from a leaf, mount in water and
examine under microscope. Observe : —
a. The large epidermal cells with wavy margins and no chloro-
phyll and occasional hairs.
b. Here and there the stomata with two curved guard cells.
containing chlorophyll, bounding each opening.
Draw.
3. Gently pull a mid rib (vein) in two across its long axis;
note the fine threads uniting the two broken ends ; cut them off
with sharp scissors, mount in water, and observe under microscope
that they are composed of partially unrolled spiral vessels.
Draw one of these.
[23]
GENERAL BIOLOGY
,
(C.) Reproductive Organs or Flowers.
1. Position. Where do flowers occur? Judging from their po-
sitions, to what vegetative parts are they homologous ?
2. Observe shape and color.
3. Parts of flower; observe : —
a. The green Calyx, composed of five sepals which are fused
to form a cup. What vegetative parts do they resemble ?
b. The showy Corolla, composed of five petals, one on the
upper (dorsal) side, the standard, two on the two sides, the wings,
attached by narrow stalks, two on the lower (ventral) side, united
by their median borders to form the keel, which is much folded and
twisted over the inner parts of the flower. What vegetative parts
do the petals represent?
c. The Stamens (male parts of flower) ten in number, with
broad bases, narrow filaments, and enlarged yellow ends, the
anthers; the nine ventral ones united by their bases to form the
stamen tube, and one dorsal one free (not fused). Tease out the
contents of anther in water and examine under high power; it
contains numerous pollen grains which produce the sperms, or
male elements.
d. The Pistil (female part of flower), a long greenish, taper-
ing body within the stamen tube, consisting of an enlarged basal
portion, the ovary or pod, a narrow filamentous portion, the style,
and an enlarged terminal portion bearing a tuft of delicate white
papillae, the stigma. Slit open the ovary and observe the ovules
attached along its ventral side; each contains the embryo sac in-
closing an egg; the latter develops into the embryo found within
the seed.
Draw a flower split open along the dorsal mid-line so as to show
all of these parts; also make separate figures of anthers and pollen,
of ovary and ovules.
B. PHYSIOLOGY.
I. METABOLISM.
i. PHOTOSYNTHESIS OF CARBOHYDRATES.
a. Chlorophyll.
Place about 100 sq. cm. of young leaves in 60 cc. of 95 per cent
alcohol, cover dish and place in a darkened water bath at 5o°-55°
[24]
GENERAL BIOLOGY
C for 5-10 minutes. Pour solution into clean test tubes and (i)
examine color in transmitted and reflected light. (2) Focus light
into interior of tube with a lens and observe fluorescence. (3)
Wrap one tube in black paper, leave another unwrapped, and ex-
pose both to bright light to observe effect of light. (4) Note the
color of the leaves which were in alcohol. (5) Observe also color
of etiolated and variegated leaves of Coleus. (6) Class demon-
stration of spectroscopic lines of chlorophyll (Ganong's Physi-
ology, pp. 82-84).
, Record in your note book results of these experiments.
b. Demonstration of effects of light on living leaves.
1. Keep a potted bean plant in a dark room for a day or two,
and then expose to sunlight for 2 hours, having previously screened
a portion of one leaf with (a) a strip of lead foil.
2. Remove screened leaves from plant, immerse in hot water,
and place in a flat dish of alcohol until white ; pour off alcohol and
cover leaves with a solution of iodine.
Sketch leaves and explain results.
(The leaves may be preserved afterwards in alcohol and devel-
oped again in iodine solution.)
c. Demonstration of Source of C02 in Photosynthesis.
Remove two leaves with petioles, place cut ends of latter in small
bottles of water and put one leaf in sealed jar containing soda
lime to absorb CO2, the other in sealed jar without soda lime;
expose both jars to sunlight for 2 hours and then treat both leaves
as in b (2).
Record and explain results in your notes.
d. Demonstration of Formation of 02 in Photosynthesis.
1. Observe bubbles of gas escaping from a submerged water
plant (Cabomba, Elodea).
2. Place supported funnel over plant and conduct bubbles into
test tube filled with water and held in inverted position in jar of
water.
3. Test collected gas with phosphorus match or with glowing
match stick.
Describe and explain results.
2. SYNTHESIS OF PROTEINS.
a. Demonstration of Source of Nitrogen.
i. Compare the relative growth of seedling beans in (a)
[25]
GENERAL BIOLOGY
Distilled water, (b) Pasteur's6 solution without sugar, (c) Det-
mer's7 solution.
2. Compare growth of peas in (a) Soil sterilized by steam,
(b) Soil rich in bacteria, (c) Soil inoculated with Nitrogen-
fixing bacteria.
Describe and explain results.
3. DEMONSTRATION OF RESPIRATION.
a. Place germinating seedlings of bean on moist filter paper
supported in a closed jar over baryta water. Observe the latter
after a day or two. What does the precipitation in the latter
indicate ?
b. Place other germinating seeds in a sealed jar from which
oxygen has been removed by any of the following methods: (i)
By exhausting air with an air pump, (2) by absorbing oxygen
over pyrogallate of potash, (3) by replacing air by hydrogen.
Compare growth of such seeds with others growing in jars con-
taining atmospheric oxygen.
What conclusions do you draw from these experiments?
c. Fill two thermos bottles with (i) Germinating seeds; (2)
Similar seeds killed by 5 per cent formalin. Place the bulb of a
delicate thermometer in the midst of the seeds and compare the
temperature in the two for the two or three days.
Explain results.
4. WATER ABSORPTION, MOVEMENT, TRANSPIRATION.
a. Demonstration of Osmosis.
Fill a parchment bag with molasses ; in the open end tie a glass
tube, and immerse the bag in a jar of warm water. Observe the
rise of molasses in the tube.
Explain.
b. Plasmolysis.
Mount filaments of Spirogyra on three slides from the follow-
ing solutions: (i) 5 per cent, (2) 10 per cent, (3) 20 per cent
cane-sugar solutions. Observe under microscope effects on cell
contents. As soon as contents of (2) or (3) begin to shrink re-
place solution by tap water and observe results.
Explain.
6 See p. 32.
7 Detmer's solution : — Calcium Nitrate, i gram ; Potassium Chloride, .25
gram; Potassium Phosphate, .25 gram; Magnesium Sulphate, .25 gram; Dis-
tilled water, 1000 cc.
[26]
GENERAL BIOLOGY
c. Plant Turgor.
Cut off three leaves and place the cut end of one in a satu-
rated solution of sodium chlorate, of another in tap water, and
leave the third in the air. At the end of one hour compare and ex-
plain results.
d. Demonstration of Root Pressure.
Cut off the stem of a vigorous plant 1-2 inches above the ground ;
attach to the stump by a tight-fitting rubber tube an S-shaped
glass tube with one limb drawn out into a long capillary tube, and
with oil in the loop of the S to prevent evaporation ; water the
plant and observe the rise of sap (or oil) in the capillary tube.
e. Demonstration of Water Movement.
Rate and Path of Ascent. Cut under water a colorless shoot and
transfer the cut end to a strong aqueous solution of Eosin; ob-
serve and time the rise of color in the nbro-vascular bundles to
the leaf. Cut sections of the shoot and observe where the color
occurs.
Describe results.
f. Demonstration of Transpiration.
1. Take a vigorous potted plant and cover the pot and soil with
waterproof coverings, so that all loss of water must be through the
stem and leaves. Weigh the plant on a good balance at intervals
and tabulate the loss through two or three days.
2. Apply to the upper and under surfaces of a leaf discs of
filter paper which has been treated with cobalt chloride (Ganong,
p. 190). In the presence of moisture the blue discs turn red.
Where is transpiration most active? Where are stomata most num-
erous.
II. IRRITABILITY.
i. Demonstration of Geotropism.
a. Place well-soaked seeds of bean and corn in different posi-
tions on a sheet of cork covered with cotton flannel and fasten
them in place by pins stuck around them. Set the sheet of cork on
edge in a glass jar containing 1-2 inches of water; cover jar tightly
and set in a warm place. Observe from day to day the direction of
growth of roots and stems. After this direction is well estab-
[27]
GENERAL BIOLOGY
lished turn cork sheet through 90° or 180° and observe subsequent
directions of growth of roots and stems.
Sketch experiment and explain results.
2. Demonstration of Phototropism.
a. Stem and leaves. Place growing seedlings of beans, corn or
oats in a dark box open on one side toward the light and observe
the leaf and stem positions after a few days.
b. Roots. Place seedlings of radish grown in a jar of water in
a dark box illuminated from one side and observe direction of
growth of roots.
What is the influence of light on the direction of growth in
shoots and roots?
3. Hydrotropism.
Plant various seeds in an inclined trough of wire netting filled
with wet sawdust. Observe and explain the direction of growth
of the roots.
SPIROGYRA.
Read: Huxley and Martin, Practical Biology, pp. 397-407; or
Parker, Elementary Biology, pp. 192-198; or
Woodruff, Foundations of Biology, p. 61.
(Subkingdom Cryptogamia, Division Thiallophyta, Subdivision
Algae, Class Chlorophyceae.)
1. Place a few filaments of the living plant in water on a
slide, cover and examine with low power. Draw a small portion of
one of the filaments showing its division into cells.
2. Examine with high power. Note the cell walls and the
connection between adjacent cells. Note also in each cell the long,
band-like, green chloroplastids. Count them and make out their
arrangement. Make a drawing about two inches in length of a
single cell, showing the chloroplastids and the connection with
adjacent cells.
3. Treat the preparation with iodine solution. Note the changes
of color in the rounded bodies imbedded in the chloroplastids.
These are reserve food bodies (pyrenoids), and their blue color
after treatment with iodine indicates the presence of starch.
4. Examine the cell wall carefully and note the thin layer
of cytoplasm which lines it internally, and the large vacuole filled
with cell sap, which occupies the greater part of the cell. Focus
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GENERAL BIOLOGY
carefully near the center of the cell and find the nucleus, sur-
rounded by a thin layer of the cytoplasm.
5. Add all of these parts to your drawing.
6. Asexual reproduction : — Examine a number of filaments
carefully to see whether there is evidence of recent multiplication
by transverse division of some of the cells. Draw.
7. Sexual reproduction : — Examine, with low power, a stain-
ed and mounted preparation which shows two filaments in process
of conjugation. Study with high power and draw as many stages
in the process of conjugation as can be found, including the fully
formed zygotes.
PROTOPHYTA
One-celled 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.
SPHAERELLA (HAEMATOCOCCUS)
(Protophyta, Flagellatae, Division Thallophyta, Subdivision Algae,
Class-Chlorophyceae. )
Read: Parker, Elementary Biology, pp. 23-35; or
Parker, Practical Zoology, pp. 240-250; or
Woodruff, Foundations of Biology, pp. 30-38.
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 ; spheriodal.
(c). Structure; a sac surrounding the contents, which
latter consist 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?
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GENERAL BIOLOGY
(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.
Draw various stages in this reproduction by fission.
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 proto-
plasmic body by a clear space, which is bridged by
protoplasmic strands ("bridles").
(b). Much smaller motile forms, each surrounded by
no separate cell wall, but with two flagella at the
pointed end of "beak." These are the micro-
zoo spores.
(3). In the macro-zoospores, note: Color, structure, contents,
sac (cell wall), flagella, 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 concessive positions assumed by the flagella and their
mode of bending to and fro. Treat with iodine: The protoplasm
is killed and the flagella are rendered conspicuous.
Draw individuals in motile stages to show all of the above men-
tioned points.
EUGLENA VIRIDIS.
(Flagellata, Plant or Animal?)
Read: Parker, Elementary Biology, pp. 44-4§; or
Parker and Parker, Practical Zoology, pp. 251-258.
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. Near the anterior end is a red pigment
spot, the stigma. (3) Shape, fusiform; the anterior end is blunter
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GENERAL BIOLOGY
than the posterior and bears a long flagellum which may be lost in
some specimens. The flagellum arises from the bottom of a pit, the
"gullet," or "mouth opening." Observe the contractile vacuole and
"reservoir" near the anterior end and the nucleus and the paramy-
lum bodies near the center of the body. What color do the paramy-
lum bodies take when stained with iodine? 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 anima crawls
about. The latter movements are characteristic of Euglena and
are called "euglenoid" movements. Draw at intervals to show
changes in shape.
Record the points in which Euglena resembles a plant ; also those
in which it resembles an animal. Which do you conclude that it is ?
Make drawings and notes to show all that you have observed.
SACCHAROMYCES CEREVISIAE, Yeast.
(Division-Thallophyta, Subdivision Fungi, Class- Ascomycetes.)
Read: Calkins, Biology, pp. 29-34; or
Parker, Elementary Biology, pp. 71-81 ; or
Sedgwick and Wilson, General Biology, pp. 184-191 ;
also
Woodruff, Foundations of Biology, pp. 213, 310.
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? Meas-
ure 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?
Where is it found? Do you ever find more than one? Is it con-
tractile ? 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
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GENERAL BIOLOGY
color of the cell due to the cell wall or contents? Is there any
opening in the sac through wh ich 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?
3. 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?
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 drawings of the yeast cells showing 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 num-
ber of buds to which the cell has given rise.
i. 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 sugar; (d) Pasteur's solution with sugar;4 (e) Mayer's
pepsin solution.5
Carefully label each tube and put a drop of yeast into each;
shake the tubes thoroughly and tightly plug the mouth of each
with a wad of clean absorbent cotton and allow them to remain
*Pasteur's Solution : — 5Mayer's Solution : —
Potassium phosphate 2.0 grams Cane sugar 15% sol. ...20 cc.
Calcium .2 Dihydropotassic phos-
Magnesium sulphate .2 phate I grams
Ammonium tartrate 10.0 Calcic phosphate I
(Cane sugar 150.0 " ) Magnesium sulphate ...I
Distilled water 837.6 Pepsin 23
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GENERAL BIOLOGY
for two or three days. Examine the tubes from day to day and
judge, from microscopic examination and the turbidity, in which
fluid the yeast grows best. In which are the most bubbles of gas
formed? Does the formation of gas bear any relation to the
growth? This is saprophytic nutrition.
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 sometimes occurs in yeast, but
is difficult to observe and may be omitted from your notes.
3. The effect of growth of yeast upon food supply, (a) Taste
of the Pasteur's solution with sugar in which yeast has been acting
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 containing 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)
Nature of the gas given off. Take two test tubes, fill the first y$
full of clear baryta water, fill the second about ^> 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 alkaline 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 you have observed in the experiments in this
section.
BACTERIA.
(Division-Thallophyta, Subdivision Fungi, Class Schizomycetes.)
Read: Calkins, Biology, pp. 34-43 or
Parker, Elementary Biology, pp. 82-94; or
Sedgwick and Wilson, General Biology pp. 192-204; or
Woodruff, Foundations of Biology, pp. 44-53.
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GENERAL BIOLOGY
A. PREPARATION OF CULTURES FOR
FUTURE STUDY
1. BACTERIA OF HAY INFUSION.
Fill three test-tubes l/2 full of a fresh infusion of hay: (i) care-
fully close one tube with cotton wool 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.
2. 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 buds ("eyes"). Ster-
ilize the potato in boiling water for thirty minutes, then cut 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.
3. BACTERIA OF HYDRANT WATER.
Take a sterilized gelatin culture plate in a Petrie dish, 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.
4. 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.
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GENERAL BIOLOGY
B. STUDY OF DIFFERENT STAGES, TYPES
AND CULTURES OF BACTERIA
I. ACTIVE STAGES.
Study bacteria from various media, viz. : Pasteur's Solution,
Beef Tea, Infusions of Hay and Peas, Potato and Gelatin Cultures,
Sewage, etc., and observe and draw the following forms:
1. Cocci; rounded forms occurring singly or in bead-like rows ;
without flagella.
2. Bacilli; rod-like or thread-like forms.
3. Spirilla; spiral forms which may consist of many turns
(Spirillum Spirochaeta) or of only a fraction of one turn (Vibrio
"Comma bacillus").
In these various forms observe the following points :
First ; size, measure.
Second ; structure. Can you notice any change of shape 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 (Brown-
ian movements). The former progressive, the latter vibratory
and irregular. 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 movements of
living ones.
II. RESTING STAGES.
Examine the scum ("Zooghca") 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,
the "bacterial jelly."
III. STAINING AND MOUNTING.
Spread a small drop of liquid containing active 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 the slide. If a permanent mount is
[35]
GENERAL BIOLOGY
desired thoroughly dry the glass after rinsing and mount4n 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.
IV. 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?
V. STUDY OF CULTURES IN HAY INFUSION.
Study the tubes of hay infusion which were prepared and set
aside on a previous day (see (A. i). 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? Determine
by microscopic examination what the cause of the turbidity is.
How do you account for the differences between the tubes ? Where
did these organisms come from and how did they get into 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 formation 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 ob-
servation, 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 fronvday 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 you have
observed and give your explanation of them.
VI. STUDY OF CULTURES ON POTATO. (See A. 2.)
Observe on the potato variously colored spots or "colonies."
Are all of these colonies bacteria? Are all the organisms in a
colony alike? What is the significance of this fact? What kinds
of organisms are most abundant in the air of the room? Can they
undergo drying without being killed? Can they grow and multi-
ply without food and moisture?
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GENERAL BIOLOGY
VII. GELATINE PLATE CULTURE FROM HYDRANT WATER.
Are colonies present on the plate? If so, how many? Are they all
alike in shape and color? What kinds of organisms are found in
the different colonies? Are they more or less numerous than in
air or milk?
VIII. AGAR PLATE CULTURE FROM MILK.
w*~-
By means of a "counting plate" determine the approximate
number of colonies present in the agar, and calculate the number
of bacteria present in I cc. of undiluted milk (the I cc. of milk
used in the culture was diluted 100 to i). Colonies which have
the form of minute footballs belong to the group of "colon bacilli"
and come from the intestinal tract of some mammal, in this case
probably from a cow. If colon bacilli are numerous it indicates
that the milk has not been taken under sanitary conditions. What
does the changed color of the litmus agar indicate ?
C. DEMONSTRATIONS.
I. Living Bacteria Seen With Dark-Field Illumination.,
II. Prepared Slides of Pathogenic Bacteria.
F. -PROTOZOA
One-celled animals 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. PARAMECIUM CAUDATUM, Slipper Animalcule
(Phylum Protozoa, Class Infusoria, Order Ciliata.)
Read : Calkins, Biology, pp. 60-75 '•> or
Parker, Elementary Biology, pp. 106-120; or
Parker and Parker, Practical Zoology, pp. 261-286; or
Sedgwick and Wilson, General Biology, pp. 168-172; or
Woodruff, Foundations of Biology, pp. 39-43, 244-248,
340-342.
A. MORPHOLOGY.
Put a small drop of water containing Paramecia on a slide; sur-
round it with cotton wool to limit the movement of the animals
and cover with a glass ; examine with the low power of the micro-
scope and then with the high power. Note:
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GENERAL BIOLOGY
1. 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. Note also movements of flexion (bending).
4. STRUCTURE. The two protoplasmic layers: (ectoplasm and
endoplasm).
a. Ectoplasm (Cortex) : the firm elastic outer layer; its deeper
part marked by oblique myophan striations.
( i ) . The cuticle, a delicate superficial layer differentiated from
the underlying protoplasm.
(2). Cilia, delicate vibratile filaments arising from the ecto-
plasm and protuding through openings in the cuticle. These open-
ings 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-
plasm arranged perpendicular to the surface; when the animal is
irritated, e. g. by iodine, a stiff thread can be shot out and pro-
jected beyond the cilia. They are probably defensive organs.
(4). Two contractile vacuoles in the ectoplasm of the dorsal
side about l/3 of the animal's length from each end. While dilating
they are nearly spherical, but at the moment of contraction sep-
arate canals can be seen radiating from them.
(5). The oral 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 ectoplasm at the posterior
end of the groove through which food passes into a narrow tube,
the gullet. Watch the ink collect at the inner end of the gullet into
a ball which is suddenly passed into the endoplasm. Watch the
course of the food ball within the endoplasm until it is finally
ejected through the anus.
(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 Endoplasm (Medulla) is the more fluid protoplasm
filling the central portion of the body. In it observe : —
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GENERAL BIOLOGY
(i). The food vacuoles, which are spherical spaces in the
endoplasm filled with water containing food particles.
(2). The circulation of the endoplasm 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 after the death of the
animal, or in stained specimens.
(4). The micronucleus is a much smaller body applied to one
side of the nucleus and resembling it in staining reactions.
Make a full-page drawing of an animal to show the above-
mentioned 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 Endoplasm. 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 com-
pletes the circuit.
3. Egestion. Observe, if possible, the egestion of ink from the
body. Show by a drawing where and how this takes place.
4. Digestion. Observe and draw the changes in color, etc., of
food as the vacuoles circulate through the body, also the changes
in the size of vacuoles and their fluid contents. What do these
changes indicate?
5. 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.
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
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GENERAL BIOLOGY
and observe the extrusion of a clear drop of fluid at the moment
of contraction of the contractile vacuole.
7. Respiration. Place a number of the animals in a drop of
phenolpthalein (which loses its rose-color in the presence of
carbon dioxide) and note the result; 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 a Paramecium in the process of division.
In a stained preparation note what changes take place in the nuc-
leus and micronucleus during this process. Can you detect any
difference between the two daughter individuals? How do the
contractile vacuoles, the buccal grooves and the gullets arise in
the two ? Draw three stages in fission to show all of these points.
2. Conjugation. Study and draw living individuals in the act
of conjugation. What portions of the body are in contact? Is there
any distinction of size or sex in the two individuals? In stained
preparations study the nuclear changes which takes place during
conjugation. Draw three specimens to show different stages in
the nuclear changes.
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
lens 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
manner test them with 1/50 per cent and i/io per cent acetic
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GENERAL BIOLOGY
acid, and also with a bubble of carbon dioxide. Place animals in a
tube heated at one end and cooled at the other. What results ? In
a similar manner test them with the electric current. Also test their
sensitivity to light and gravity. Record all of your results.
IV. AMOEBA PROTEUS.
(Phylum Protozoa, Class Sarcodina, Order Rhizopoda.)
Read: Calkins, Biology, pp. 44-59; or
Parker, Elementary Biology, pp. 1-22; or
Parker and Parker, Practical Zoology, pp. 229-238 ; or
Sedgwick and Wilson, General Biology, pp. 158-167.
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 eye?
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 (ectoplasm),
and an inner granular more opaque substance, the endosarc (endo-
plasm). Is the boundary between the two layers a sharp one?
Where 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 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.
4. Stained Specimens : In a prepared specimen, stained and
mounted, observe nucleus, ectosarc, indosarc, etc. Draw.
[41]
GENERAL BIOLOGY
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 by arrows. Where are the
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 nitrogeneous 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 stimuli ?
Does Amoeba show any reflex movement? Is its behavior more
or less varied than that of Parmecium?
Enter answers to all these questions in your notes or drawings.
G. METAZOA
Metazoa are many-celled animals in which there is differentia-
tion into at least two body layers, the Ectoderm and the Endo-
derm; the former is the organ of relation, the latter the organ of
nutrition ; in addition all have ova and spermatozoa. In all meta-
zoa 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
Endoderm; between these two a third layer, the Mesoderm, is
usually formed.
Ectoderm and Endoderm consist of cells closely packed to-
gether into a layer, such a grouping of cells being called Epithe-
lium. Mesoderm, at its first appearance, usually consists of scat-
tered cells with large spaces between them, such loosely connected
[42]
GENERAL BIOLOGY
cells being called Mesenchyme; later closely packed layers of
mesoderm cells may be formed that are known as Mesothelium.
The cells of the different layers of the gastrula differ from one
another, and in the course of further development differentiations
appear among the cells of the same layer. In this way Tissues, i. e.,
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 here-
with.
i. EPITHELIUM gives rise to
a. Epithelial tissue
b. Muscular tissue
c. Nervous tissue
d. Germinal tissue
2. MESENCHYME gives rise to :
a. Connective tissue
b. Skeletal tissue
c. Vascular tissue
d. Storage (reserve) tissue
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 :
FUNCTIONS
I. METABOLISM
II. REPRODUCTION
III. IRRITABILITY
Ingestion
Digestion
Egestion
Respiration
•{ Excretion
Circulation
Assimilation
Growth
Dissimilation
f Asexual
( Sexual
f Reception of
Stimuli
| Transmission
of Stimuli
Coordination
Movement
ORGANS
Mouth, Teeth
Stomach, Intestine
Anus
Trachea, Lungs, etc.
Kidneys, Bladder, etc.
Heart, Arteries, Veins, etc.
Have no special organs or sys-
tems
No special organs or systems
Ovaries, Testes, Uterus
Sense Organs
Nerves
Ganglia, Brain
Muscles
SYSTEMS
Alimentary
Respiratory
Excretory
Circulatory
Genital
Nervous
Muscular
[43]
GENERAL BIOLOGY
These various organs and systems will be considered in detail
in connection with each of the animals studied.
DEVELOPMENT OF OVUM
In prepared slides of Echinoderm eggs observe the following
stages: — i. Cleavage; i-cell, 2-cells, 4-cells, 8-cells, i6-cells, 32- or
64-cells. Observe the appearance of a cleavage cavity after the
8-cell stage.
2. Blastula: — Observe the hollow sphere composed of a single
layer of cells (Epithelium). Are there any indications that scat-
tered cells (Mesenchyme) migrate into the cavity of the blastula
(Blastocoel) ?
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 the 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.
HYDRA VIRIDIS OR FUSCA, Freshwater Hydra.
(Phylum Cnidaria, Class Hydrozoa.)
Read: Calkins, Biology, pp. 76-102; or
Parker, Elementary Biology, pp. 221-236; or
Parker and Parker, Practical Zoology, pp. 2&g-3i4', or
Woodruff, Foundations of Biology pp. 118-121.
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 undisturbed
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 examine wtih the low power of the compound microscope.
I. FORM.
The body: What 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 digestive cavity, the enteron. The tentacles
[44]
GENERAL BIOLOGY
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 expanded ; when fully contracted. For what purpose are the
tentacles used? Buds: — Young hydras of various sizes and stages
of development may be attached to the sides of the parent. Are
colonies formed by budding? Why?
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 down so as to
obtain views (optical sections) at various levels. Is the tentacle
hollow or solid? The elements of the two layers can 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 when the tentacle is extended or contracted?
(b) The interstitial cells are small rounded cells placed be-
tween 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
containing an oval, highly refractive capsule, the nematocyst. The
capsule is filled with fluid and contains a spirally wound filament
formed by the doubling in of the wall of the capsule at one pole.
The nematocysts form knob-like swellings on the tentacles. They
are of two 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
[45]
GENERAL BIOLOGY
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 ob-
serve the ejection of the threads of the nematocysts. Note that
the threads are turned inside out in the process of discharge, the
basal portion being discharged first. What 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 of a tentacle to show the characteristic layers,
and cellular elements.
III. REPRODUCTION.
1. 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,
constricting at the base, separates from the parent animal. Look
for such buds in various stages of development.
2. Sexual reproduction: hydra is monoecious (hermaphro-
ditic), 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
movement of the spermatozoa within the capsule. By gentle
pressure upon the cover glass break open the capsule and observe
the swimming 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 sexual or gams.
[46]
GENERAL BIOLOGY
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 (Klein-
enberg'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 endo-
derm?
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 vacuoles, 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 pro-
cesses like those of the ectoderm cells, but transverse in direction.
(b) The smaller secretory cells, pear-shaped and lying between
the bases of the larger ones. These last mentioned cells are num-
erous 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 Haller's Fluid. Cover and tap gently
upon the cover glass to separate the cells.
Select and draw good examples of the varieties of cells men-
tioned.
.
v « * *
.".•
^
r , ML is
[47]
GENERAL BIOLOGY
LUMBRICUS TERRESTRIS, The Earthworm
(Phylum Annelida, Class Chaetopoda, Order Oligochaeta. )
Read : Darwin, The Formation of Vegetable Mould through the
Action of Worms ; also
Sedgwick and Wilson, General Biology, pp. 41-104, or
Calkins, Biology pp. 131-161 or
Parker and Parker, Practical Zoology, pp. 318-341 ; or
Woodruff, Foundations of Biology, pp. 121-129.
A. EXTERNAL CHARACTERS.
Place a preserved worm in a dissecting dish, cover with water,
and observe : —
1. General form, color, iridescence.
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 2Qth and 35th somites, a swollen light-colored
region, the clitelluni. 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 secre-
tions of the epidermis.
7. 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
seen, and must be looked for with a hand-lens, or a dissecting
microscope. They can often be seen by drying the surface of the
[48]
GENERAL BIOLOGY
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
swollen areas on the ventral surface of the i5th somite. From
these openings, grooves are often found passing back to the clitel-
lum. (2) Openings of oviducts ; two small pores on ventral surface
of the I4th somite. (3) Openings of the seminal receptacles or
spermatheca, two openings 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.
Draw the anterior and posterior portions of the body to illus-
trate all that you hcwe 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
from behind forward 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 coelum, with the digestive tract 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. What is the
relation of the septa to the external grooves?
3. Seminal vesicles, large lobed bodies between the io!h and
1 5th somites, partly covering the digestive tract.
4. Dorsal or supra-intestinal blood vessel, generally full of
[49]
GENERAL BIOLOGY
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 vessels, or "hearts," which pass around to the ventral
side of the digestive 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 I4th
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 I7th and
i8th 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.
Make 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 in 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.
[50]
GENERAL BIOLOGY
IV. REPRODUCTIVE SYSTEM.
1. Seminal vesicles (for storage of own sperm) ; 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 (for receiving sperm from another
worm) ; 2 light colored sacs on the ventral surface of the body-
wall, on each side of the median line and attached to septa be-
tween the 9th 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 ap-
pear 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) Vasa 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 right and two on the left of the median line.
Make a sketch of the reproductive system and explain the func-
tion of each part.
V. NERVOUS 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
(connective) near the anterior end of the somite.
2. Circum-oesophageal nerve ring. Raise the oesophagus and
[51]
GENERAL BIOLOGY
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 pharynx.
3. Brain ; connected as above shown with the ventral nerve
cord, but lying dorsal to the pharynx. Note the nerves given off
from the brain and also from the connectives on the side of the
pharynx.
Make a drawing of the nervous system.
VI. BODY WALL.
Pin out part of the body wall quite flat and note that the mus-
cular 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 conspicuously 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
anterior.
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 ana cut it
open as in the specimen previously dissected, but only in the an-
terior 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.
[52]
GENERAL BIOLOGY
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 : —
1. White amoeboid corpuscles.
2. Yellow granules, from the chlorogogue cells (See D II. i).
3. Bacteria or other foreign bodies, especially Gregarina, which
are often present.
D. HISTOLOGY.
I. BODY WALL.
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 ves-
sels and connective tissue nuclei among them.
4. A thick layer of longitudinal muscle fibres or plates, ar-
ranged in elongated groups of elliptical form.
5. Peritoneum or coelomic epithelium, a thin layer of granular
protoplasm containing nuclei, lining the body cavity.
II. DIGESTIVE TRACT.
In its wall four layers are to be seen.
1. Chlorogogue cells, large and more or less elongated and
irregular.
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.
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.
[ 53 1
GENERAL BIOLOGY
3. A mesh work of fine fibres.
4. Very 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.
IV. BODY CAVITY.
Some of the sections will show the following structures :
1. The corpuscles of the coelomic fluid.
2. Blood vessels cut across and filled with coagulated blood.
2. 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 a full-page outline of a cross section to show all of these
organs and in the ventral sector fill in histological details of (a)
Body Wall, (b) Body Cavity and Nervous System, (c) Digestive
Tract.
CAMBARUS, The Crayfish.
(Phylum Arthropoda, Class Crustacea.)
Read: Huxley, The Crayfish, pp. 1-226; also
Parker and Parker, Practical Zoology, pp. 346-37-; or
Calkins Biology, pp. 166-186.
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 cephalo-
thorax. The entire body is covered by a hard calcarious shell the
exoskeleton 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 sz'ze and form.
Make a drawing of the crayfish as seen from the dorsal side.
[54]
GENERAL BIOLOGY
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 ventral side of 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 by a
transverse hinge and bears the anus. Carefully examine the third
abdominal somite. The following surfaces are found upon it: (a)
Tergum, 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 calcified
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 preceding 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. Protopo-dite : 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. Exopodite: 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.
(55}
GENERAL BIOLOGY
b. A groove, the cervical suture 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, podobranchiae ; eleven of them are attached to
the soft cuticle joining the appendages to the body arthrobranchiae.
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.
Starting at the posterior end carefully remove all of the ap-
pendages from one side with all the basal parts of each, see which
are alike and then draw one of each kind or set (15 figures for the
female, 15 for the male) keeping all of the small ones in water in
watch glasses.
I. ABDOMINAL APPENDAGES OR SWIMMERETS.
Composed of a two jointed protopodite, and an exopodite and
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 mastica-
tory 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)
Ischiopodite, cylindrical and with a groove around it. (4) Mero-
podite, very much longer than the last. (5) Carpopodite, about
half as long as the last. (6) Propodite, slender and long. (7)
Dactylopodite, the short, pointed terminal piece. Of these (i) and
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GENERAL BIOLOGY
(2) probably correspond to the protopodite of the abdominal ap-
pendages, 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 branchia
and epipodite upon the coxopodite 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 ischio-
podite are united into one piece.
e. The third or posterior maxilliped should be carefully studied.
Note: (i) The large basal part, protopodite, bears a long five
jointed endopodite and a slender many jointed external expedite,
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.
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, scaphognathite, 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 bear-
ing 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.
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GENERAL BIOLOGY
Compare your drawings of the different kinds of appendages,
labelling homologous parts with the same name; the 19 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. CIRCULATORY SYSTEM.
1. Heart.
Posterior to the cervical suture, a median chamber is laid bare,
the pericardial sinus, within which lies the polygonal, flat 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.
2. Arteries.
Running anteriorly from the heart are : (a) the opthalmic artery
in the mid-line and lateral to this, (b) a pair of antennary arteries,
(c) a pair of hepatic arteries; posterior to the heart are: (d) the
median abdominal artery from which (e) the sternal artery runs
to the ventral side just posterior to the heart.
Draw the heart and arteries.
II. REPRODUCTIVE ORGANS.
Carefully remove the heart to expose the reproductive organs.
(a) 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 thorac 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 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 open-
ings on the third, or middle, ambulatory appendages.
Make a drawing of your dissection, showing all these organs in
place.
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GENERAL BIOLOGY
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 stom-
ach is the "mid gut" having a short dorsal diverticulum on it.
The remainder of the intestine is the "hind gut." (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 stomach and
cut it open 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, the so-called "gastric mill." In the pyloric region
ridges, set with hairs, reduce the lumen of the stomach to a nar-
row slit.
IV. EXCRETORY ORGANS.
1. Green Glands.
In front of the stomach is a pair of sac-like structures, the
green glands, or nephridia; each consists of a ventral glandular
part and a dorsal saccular portion, the latter opens to the exterior
by a duct.
2. External Openings.
On the basal joint of each antenna observe a papilla with the
external opening of the green gland at its summit.
Draw a side mew of the digestive tract and excretory organs.
IV. NERVOUS 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
oesphagus 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.
[59]
GENERAL BIOLOGY
RANA, The Frog.
(Chordata, Vertebrata, Amphibia.)
Read'. Parker and Parker, Practical Zoology, pp. 1-228; or
Holmes, The Biology of the Frog, pp. 1-358.
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 absence
of a tail and of a neck.
a. The head. Observe:
1. The eyes are prominent and have lids ; the ears are marked
out 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 endo-
skeleton felt on the dorsal side of the head. Observe the move-
ments of the throat in respiration.
2. After the frog has been killed with chloroform (see below
II, i, a.) pass a bristle far into the anterior nares and one into
the ear through a hole cut in the membrana tympani; on opening
the mouth the bristles will indicate its communications with the
nostrils 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
buccal sac which can be distended, by means of a small blow-
pipe. Turn the fleshy tongue forward and notice its mode of attach-
ment. 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 openings
from the mouth cavity and six paired openings in the male frog;
four in the female. Note the small teeth.
b. The Trunk.
This tapers towards the posterior end where the cloacal aperture
is seen near the dorsal surface. Beneath the skin the hard endo-
skeleton can be felt on the dorsal side and on the anterior part of
the ventral side.
c. The limbs.
i. The anterior pair divided each into three regions, brachium
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GENERAL BIOLOGY
(upper arm), antebrachium (fore arm), manus (hand) ; 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 (thigh), crus (shank), pes (foot), the latter with
five long digits connected by a web. There is a large firm promi-
nence on the inner side of the ankle; callosites are found under
the joints of both pes and manus.
Draw entire frog and label parts named above.
II. INTERNAL CHARACTERS.
i. GENERAL.
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, the eponeurosis, through which in the median region is
seen the rachis abdominis passing from the pelvis to the sternum
and somewhat divided by transverse lines into segments or
myotomes. Through this muscle is seen the dark blood of the an-
terior abdominal vein in 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
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 sur-
face.
e. With 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.
f. The liver is conspicuous, forming a large brown mass with
the pericardial sac just anterior to it.
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GENERAL BIOLOGY
g. 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 protuberant larynx and
on each side of this a small soft body, the thyroid gland.
2. CIRCULATORY SYSTEM.
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.
a. Heart.
(i) Note the firm conical posterior portion of the heart, the
ventricle. (2) The cylindrical truncus arteriosus arises from the
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 venosus 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
and one large posterior or inferior vena cava. ) Two pulmonary
veins open into the left auricle by a single opening.
b. 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 followed by the blood in passing through
the heart.
c. Arteries (the efferent vessels).
The blood is carried through the common truncus arteriosus
which gives rise to a right and left subdivision. Each of these
divides into three branches derived from three embryonic arches :
1 i ) The most anterior branch or arch, the carotid, bears near
its point of origin a pinkish glandular enlargement, the carotid
gland. The common carotid divides into (a) the external carotid
— situated near the median line but distributed to the superficial
tissues of the head, and (b) the internal carotid which passes into
the cranial cavity to supply the brain and sense organs (eye, in-
ternal ear).
(2) The middle or systematic arch unites with its fellow on the
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GENERAL BIOLOGY
opposite side to form the dorsal aorta. Trace the systemic arches
dorsally around the oesophagus to their point of union. The dorsal
aorta extends to the posterior end of the body cavity where it di-
vides into two branches, the right and left iliac arteries to the hind
legs. From each systemic arch a subclavian artery passes to the
front leg. Named in order, beginning with the most anterior, the
following branches arise from the dorsal aorta: (a) coeliaco-
mesenteric (to liver, stomach and intestine), (b) ovarian (or
spermatic) to gonads, (c) renal (to kidneys).
(3) The posterior or pulmonary arch runs to the lungs giving
off on its way a large cutaneous branch which carries blood to the
skin for aeration when the animal is submerged.
d. Veins (the afferent vessels).
The blood is returned to the heart through five main trunks,
right and left anterior venae cavae, a median posterior vena cava,
and right and left pulmonary veins. The venae cavae are joined
together at the heart to form the sinus venosus, which opens into
the right auricle.
(1) Each anterior vena cava is formed by the confluence of
three veins: (a) external jugular, from face and throat; (b) in-
ternal jugular, from cranial cavity; (c) axillary formed by union
of the subclavian from the arm, and the musculo-cutaneous from
the skin and abdominal muscles.
(2) The posterior vena cava arises by the union of several large
branches coming from each kidney (renal vein) ; anteriorly it re-
ceives a large vein from each lobe of the liver (hepatic veins).
The anterior-abdominal vein (unpaired) arises from the right
and left iliac veins from the legs and runs to the liver and heart.
(3) Portal veins (veins arising from and ending in capillaries) :
Blood from the hind limbs is carried to the kidneys by the renal-
portal veins which enter the kidneys along their external borders.
The hepatic-portal vein carries blood from the stomach and in-
testine to the liver.
(4) The right and left pulmonary veins open into the left
auricle through a common opening.
Make a diagram of the heart and vascular trunks.
Before leaving the laboratory open the skull and spinal canal
as follows : Cut the skin along the median dorsal line and reflect it.
With forceps pick off the muscles from the vertebrae. Open the
neural canal by cutting into the membrane just posterior to the
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GENERAL BIOLOGY
skull, and bit by bit pick off the roof of the brain cavity with strong
forceps. Tag your specimen with your name and put it into a jar
of preserving fluid until the next exercise.
3. DIGESTIVE SYSTEM. (Preserved Specimen.)
Posterior to the heart note: (i) The liver with its larger left
lobe divded into two parts ; on raising the posterior border, the
gall 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 under the pos-
terior edge of the liver. (3) A convoluted tube, the intestine pass-
ing 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.
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 now exposed ; a probe may be run through it into
the rectum. (2) Uncoil the intestine and fasten to one side to ex-
pose the spleen (a small red body near dorsal part of mesentery).
(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.
4. URINO-GENITAL SYSTEM. (Preserved Specimen.)
Remove the stomach, liver, mesentery and connected organs.
(i) Posterior to the fat masses lie the reproductive glands, in
the male yellow oval 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-efferentia, 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
[64]
GENERAL BIOLOGY
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
duct on each side passing from the outer side of the kidney into
the cloaca. (In the male this serves also as a vas deferens.) (5)
The urinary bladder, a large bi-lobed sac ventral to the rectum (it
can be inflated through the cloaca by means of a blow-pipe).
Make a diagram of the urino-genital system of your specimen.
5. THE NERVOUS SYSTEM. (Preserved Specimen.)
a. DISSECTION.
Finish the exposure of the brain and spinal cord. With strong
forceps pick off bit by bit the roof of the skull, and 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 substance
(coagulation products after death) that can be washed away with
a stream of water from a pipette.
b. THE BRAIN.
If this is not injured in exposing it, note :
1. Rhinencephalon or anterior part made up of two olfa\ctory
lobes extending anteriorly from a common median part as two
cylindrical so-called olfactory nerves to branch inside the nasal
chambers.
2. Prosencephalon or cerebrum composed of two large masses,
the cerebral hemispheres, separated by a median groove,
pheres. Upon it is a very small pineal gland and below this a cen-
3. Diencephalon, a mass between and posterior to the hemis-
tral cavity, the third ventricle, bounded on the sides by masses
called optic thalami.
4. Mesencephalon, showing on the dorsal side a pair of large,
rounded, hollow bodies, the optic lobes.
5. Mentencephalon or cerebellum, a small mass extending
across the anterior edge of a large triangular cavity, the fourth
ventricle.
6. Myelencephalon or medulla oblongata, forms the remainder
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GENERAL BIOLOGY
of the brain posteriorly and contains the fourth ventricle which
is covered by a vascular part of the pia mater.
c. CRANIAL NERVES.
Ten pairs of nerves arise from the brain :
1. Olfactory, a direct anterior continuation of the olfactory
lobe.
2. Optic, also part of the original neural tube, arises from the
optic chiasma on the ventral side of the diencephalon.
3. Oculomotor, arises from the ventral surface of the mesen-
cephalon just posterior to the optic chiasma; distributed to some
of the eye muscles.
4. Patheticus, arises from the dorsal part of the brain just pos-
terior to the optic lobes ; distributed to one of the eye muscles.
5. Trigeminal, arises from the side of the anterior part of the
medulla; distributed to the scalp, face and jaw.
6. Abducens, arises near ventral fissure from anterior portion
of medulla; distributed to one eye muscle.
7. Facial, arises from the side of the medulla near the origin
of the 5th with which it leaves the cranial cavity by a single orifice;
distributed to the facial area.
8. Auditory, arises from the side of the medulla with the 7th;
sensory nerve to the ear.
9. Glossopharyngeal, arises with the loth, just posterior to the
7th and 8th ; distributed to the tongue and pharynx.
10. Vagus (pneumogastric), arises in conjunction with the
9th ; distributed to larynx, heart, stomach and lungs.
d. SPINAL CORD OR MYELON.
1. Forming the continuation of the medulla oblongata poste-
riorly, it rapidly tapers at about the fifth or sixth vertebra to form
a slender filament. On its dorsal surface is a median line, the
dorsal fissure.
2. On each side ten spinal nerves arise from the cord. By care-
fully raising the cord a little, towards the posterior end, and search-
ing with a pocket lens, the nerves are seen to arise each by two
roots, one dorsal, one ventral.
Make a sketch of the central nervous sytem and cranial nerves
as thus exposed.
[66]
GENERAL BIOLOGY
e. REMOVAL OF CENTRAL NERVOUS SYSTEM.
1. Cut the olfactory nerves away from the skull, gently turn
the brain back cutting all the nerves close to the skull and thus
remove as entire as possible the brain and spinal cord. Place in
a dish of water and study the ventral side with a pocket lens.
2. Optic cJiiasm 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
removing the brain).
3. Tuber cinereum, a rounded somewhat two-lobed elevation
posterior to the chiasm, continued ventrally into the conical in-
fundibulum, which bears at its lower end a small conical mass,
the pituitary body or hypophysis cerebri.
4. Crura cerebri, the large nerve bundles, extending anteriorly
on each side from the medulla toward the cerebral hemispheres.
5. 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.
f. PERIPHERAL NERVES.
a. Spinal Trunks. In the dorsal wall of the body cavity ob-
serve :
(i) Sciatic plexus: A number of large nerves, on each side of
the dorsal aorta, connected by branches and ending posteriorly in
the sciatic (leg) 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 ob-
liquely outward and posteriorly along the wall of the body cavity.
(3) Brachial plexus, formed from the union of the 2nd and 3rd
spinal nerves ; it goes to the arm.
b. Sympathetic System.
Raise the dorsal "aorta and notice the two slender longitudinal
sympathetic trunks 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 function,
surrounding the spinal nerves where they issue from the spaces
between the transverse processes of the vertebrae.
Draw these peripheral nerves.
[67]
GENERAL BIOLOGY
III. MUSEUM SPECIMENS.
Observe in the Museum, south wing, numerous preparations of
organ systems of different vertebrates, and compare them with
corresponding organ systems of the frog.
B. THE SKELETON.
In connection with a dried prepared skeleton, study a 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 humerus, 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, tibio- fibula, tarsus and digits) connected with the spinal
column by the pelvic girdle.
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
fragments 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. Note the appearance on the free 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
with cilia at one end.
Draw both kinds of epithelium.
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GENERAL BIOLOGY
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 fibrilae. (2) Numerous blood capillaries are
found among 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 envelopes each fibre and can be easily seen at places
where the fibres are broken or twisted.
e. 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. Draw.
III. NERVE.
a. Nerve fibres : Tease out a bit of fresh nerve in salt solution
and examine with a high power. Note: (i) Well 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 re-
fractive border (medullary sheath) and a central homogeneous
axis cylinder, well seen in torn specimens where also the very
delicate, innermost 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.
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
between the cell and the matrix. Draw.
V. BONE.
Examine with low power a section of bone (mammalian bone).
Observe : ( i ) Haversian canals, rounded spaces often filled with
air or dirt and then appearing black. (2) Lamellae, concentric lay-
ers about each haversian canal. (3) Lacunae, oval black spaces be-
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GENERAL BIOLOGY
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 swell and become
invisible, but a few (yellow elastic fibres) and some elongated
granular connective tissue cells remain visible.
b. Yellow elastic fibres : Tease out in acetic acid some of the
tissue immediately under the f rob'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.
D. EMBRYOLOGY.
I. Early Cleavage Stages. Examine entire frog's 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 fi*rst
plane of cleavage. Note in the four-cell stage the relative dis-
tribution 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 planes of the fourth cleavage in the upper and lower
cells. Examine a section of one of the early cleavage stages ; note
the nuclei surrounded by pigment. Draw.
II. 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 the thickness of the floor. Draw.
III. Gastrula Stages. Study surface views of three gastrula
stages showing: (i)The beginning of the dorsal lip of the blasto-
pore, (2) the backward-growth of the dorsal lip, and the appear-
ance of the lateral lips, and (3) the formation of the ventral lip.
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GENERAL BIOLOGY
In the latter the blastopore is circular in outline and the yolk plug
fills up its opening. Study a longitudinal section of a gastrula stage.
Compare with the section of the blastula and note all differences.
Observe especially:
a. The lifting up of the floor of the segmentation cavity.
b. The slit-like archenteron, opening behind the dorsal lip of
the blastopore.
c. The condition of the cells in the dorsal lip itself.
Draw to large scale showing ectodern, mesoderm and endoderm.
IV. Neural Plate. Study sections of three stages in the forma-
tion of the neural plate: (i) Stage with the neural plate widely
open, (2) Sides of the neural plate rolling in, (3) Neural plate
completely closed to form the neutral tube (brain and spinal cord).
Draw.
V. Tadpole. In cross sections of a young tadpole study and
draw :
1. Origin of eye-vesicle from the fore brain, and development
of the eye.
2. Cross section through the ear vesicles and hind brain, show-
ing the gill region, with the heart beneath.
3. Cross section through the middle of the embryo to show
neural tube and crest, notochord, aorta, pronephros, somites and
gut.
Draw and label.
VI. Museum Specimens. Observe in the Museum, south wing,
numerous preparations illustrating the development of vertebrates.
[71]
PART II
ECOLOGY
Read: Semper, K., Animal Life; or all of the following'.
Gadow, The Wanderings of Animals;
Needham, General Biology, pp. 3-55, 368-433 ;
Phillips, Habits of the Honey Bee.
The following directions for laboratory work are general in
character since they are intended to apply to various specimens
collected in the field or brought from the Museum and Vivarium.
Several specimens, illustrating different kinds of adaptations, etc.,
will be assigned, one after another, to each member of the class.
Keep laboratory records for each specimen, and then the results
of observations on the topics proposed.
A. RELATIONS TO INORGANIC ENVIRONMENT.
I. HABITAT.
Is the specimen a marine (Halobios), fresh-water (Limnobios)
or terrestrial (Geobios) form? What 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 species 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 organism show any particular adap-
tations to heat or cold ? In what conditions 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. What adaptation, if any, does it show to winds?
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GENERAL BIOLOGY
4. Light. Is it a form which seeks or avoids strong light, and
what adaptations does it show in this connection?
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 versa?
2. Does this species undergo migrations? If so describe them.
In the specimen assigned you by what means is the dispersal
of the species assured, and what are the barriers to such dispersal?
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 the mouth-
parts of the specimen 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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GENERAL BIOLOGY
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 heads :
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.
1. Does the form which you are studying belong in any of
these groups ? What 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?
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GENERAL BIOLOGY
2. Primary and Secondary Sexual Characters. The ovaries
and testes are primary sexual characters ; all other sexual charac-
ters, 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, if
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?
[75]
PART III
BIOGONY
A. ONTOGENY. Development of the Individual.
I. ASEXUAL REPRODUCTION.
Occurs by Fission, Budding, Segmentation, and has been studied
in the Protozoa and Protophyta, Hydra, etc. If time permits study
in detail prepared slides showing the process of fission in Sten-
ostoma.
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 tematode worm, Diplodiscus.
b. Amphigony; sexual reproduction with two parents.
i. Oogenesis and Spermatogenesis. Study prepared sections of ;
(i) Ovotests (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 rilled 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) Sperma-
togonia, cells with clear nuclei, at periphery, (b) Spermatocytes I,
large cells with chromatin in clumps, (c) Spermatocytes II,
smaller cells with densely staining nuclei, (e) Spermatozoa, with
progressively elongating nucleus and cell body.
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GENERAL BIOLOGY
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 ma-
ture egg and sperm to half the usual number. When the egg is fer-
tilized 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 and sperm 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.
Enumerate the evidences that the chromosomes contain the in-
heritance factors.
III. COMBINATIONS OF SEXUAL AND ASEXUAL REPRODUCTION.
1. Metagenesis. Alternation of asexual reproduction with sex-
ual, 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 and draw Mu-
seum 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, and show how they may be explained
in accordance with Mendelian principles.
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.
[77]
GENERAL BIOLOGY
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 the series.
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. Draw 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 phylogenetic
relationships.
2. Compare the branchial clefts in an embroyo chick and shark,
and indicate the phylogenetic significance of this resemblance.
c. Paleontology.
Study in the Museum the paleontological history of some family
of animals, and trace its Evolution.
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) Mutation.
[78]
GENERAL BIOLOGY
Read on Ontogeny : Conklin, Heredity and Environment ; or
Punnet, Mendelism ; or
Walter, Genetics.
Read on Phytogeny : Darwin, Origin of Species ; or
Morgan, A Critique of the Theory of
Evolution ; or
Scott, The Theory of Evolution.
[79]
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