LIBRARY
G

LABORATORY EXERCISES

IN

ANATOMY AND PHYSIOLOGY

JAMES EDWARD PEABODY, A.M.

Instructor in Biology in
The Morris High School, New York City

SECOND EDITION, REVISED

NEW YORK

HENRY HOLT AND COMPANY
1906

Copyright, 1898, 1902,

BY

HENEY HOLT & CO.

ROBERT DRT7MMOND. PRINTER, NBTW YORK

PEEFACE.

EVERY pupil in the study of human physiology should
be led to see that most of the materials required for ob-
servation and experiment in this subject are furnished by
the organs and tissues of his own body. The following
laboratory directions aim primarily to familiarize the pupil
with the working of his own organs of motion, circulation,
respiration, and digestion. Much of the necessary sup-
plementary material (soup-bones, meat, foods, etc.) can be
easily obtained by the student. The pieces of apparatus
needed for the class demonstrations and experiments (test-
tubes, bell-jars, thistle-tubes) are usually found in the
chemical or physical laboratory of the school.

At the beginning of each topic of study I have given
directions which in my experience have been found neces-
sary to guide the pupil in his observations and experi-
mjejits. The questions which follow these directions have
been framed with the object of leading the student to seek
the facts from the material itself. The student should be
trained especially to distinguish in the experiments observed
results from the inferences that may be drawn from those
results.

I have found that a considerable amount of laboratory
work can be profitably done by the pupil at home and
reported in class at the next recitation period. Hence it
is possible to carry on experimental work in the large
classes of the first year of the high school more satisfactorily
in biology than in any other subject. The exercises that

iii

304680

IV PREFACE.

can be prepared at home to good advantage are Nos. 4, 6,
7 (last half), 9, 10, 13, 14, 15 (first half), 16, 17, 24, 29,
31, 32, 33, 36, 41, 42, 43, 45, 46, and the larger part of
48 and 49. Whenever the abbreviation (Dem.) is found
in any part of an experiment, a demonstration will be
given by the instructor.

The most satisfactory method of recording laboratory
work I find to be this. The observations and conclusions
are stated briefly by the pupil in his note-book as the work
is done. Some little time is taken for discussion at the
close of the period, when the facts are clearest in mind,
special care being taken to see that correct inferences have
been drawn. That the work of the day may be more
firmly fixed in the pupil's mind, he is required to write on
paper of a certain kind and size, and to present at the next
lesson a carefully prepared statement of (1) the steps in the
experiment, (2) the results observed, (3) the conclusions
which were drawn from the experiment. These papers,
together with the drawings and other work prepared in
class, are arranged in a cover belonging to each pupil, and
constitute his laboratory book.

The descriptive terms dorsal and ventral, anterior and
posterior, median and lateral, employed in comparative
anatomy, are used in the following directions, since they
seem preferable to the more indefinite terms front and
back, upper and lower, middle and side, commonly used
in books on human physiology. I have adopted through-
out the food study the term nutrients (for food-materials,
foodstuffs), and nitrogenous substances (for proteids, albu-
minoids, gelatinoids, etc.); these terms are used in the
publications of the II. S. Department of Agriculture.

We have found the study of the material at the American
Museum of Natural History (especially the skeletons and

PREFACE. V

teeth of mammals) and of the animals in the Zoological
Park a valuable means of review and of awakening inter-
est in the subject. With a definite list of questions (see
pp. 73 and 107) in the hands of each pupil a division of
thirty to fifty can be directed in this work. Time should
be taken at the close of such study for a comparison of
notes and for general discussion.

Some knowledge of the cell is so essential to any intelli-
gent comprehension of the subject of human physiology
that it seems necessary to introduce frequent discussions of
protoplasm and its properties. Circulating protoplasm is
easily demonstrated in the cells of the plant Nitella or
Elodea. Epithelium (including gland and ciliated), muscle
and nerve cells should be shown if possible. The study of
yeast and bacteria is suggested to give the pupil some
acquaintance with the physiology of the cell, as well as a
series of facts relating to these organisms.

Since physiology precedes physics and chemistry in the
ordinary high school courses of study, it is necessary to
give the pupil a few ideas of the fundamental principles
of these subjects. It seems wise to discuss oxidation and
its products more or less thoroughly, and to dwell upon os-
mosis, atmospheric pressure, and the properties of acids and
alkalis. The structure and physiology of the organs of
special sense (eye, ear), as well as the thorough consider-
ation of levers, should be omitted, in my judgment, until
after a course in physics has been taken.

It is not expected that all of the following experiments
will be performed in the limited time usually assigned in
the curriculum to this subject. The exercises are, how-
ever, sufficiently varied to allow a wide range of choice.
The laboratory work on a given topic should, if possible,
be given before the study of that topic in the text-book,

vi PREFACE.

The teacher will find the following reference-books to
be valuable in experimental physiology: Stirling's " Out-
lines of Practical Physiology" (P. Blakiston, Son & Co.,
Philadelphia); Foster and Langley's " Practical Physi-
ology" (The Macmillan Co., New York); Klein's "Micro-
Organisms and Disease" (The Macmillan Co., New York).
Additional exercises are suggested in "Outlines of Ke-
quirements in Anatomy, Physiology, and Hygiene " (Har-
vard University).

Suggestions for many of the following exercises were
found in the publications of J. Y. Bergen, B. P. Colton,
H. Newell Martin, H. P. Bowditch, M.D., and in the
books mentioned above. Much of 'the outline for the
study of bacteria was suggested by Dr. T. M. Pruden,
College of Physicians and Surgeons, N. Y. Many valuable
suggestions have been given by Dr. C. B. Davenport of
Harvard University. I am especially indebted to Dr.
Margaret B. Wilson of the N. Y. Normal College for
careful criticism of my manuscript, and to my colleagues
in the biological department of the school for their sug-
gestions.

The cut of the microscope on p. 109 was kindly loaned
by Bausch & Lomb Optical Company. Most of the other
illustrations were prepared from drawings made by one of
my first-year pupils, Miss Marietta P. Gates.

J. E. P.

THE MOKRIS HIGH SCHOOL,
YORK CITY, Oct. 1, 190£.

TABLE OF CONTENTS.

PAGK

I. LESSONS IN PHYSICS AND CHEMISTRY.

1. Study of a Match 1

2. Study of Oxygen 5

3. Study of Air 9

4. Study of Atmospheric Pressure 12

5. Study of Hydrogen 13

6. Study of Evaporation — 16

7. Acid, Alkaline, and Neutral Substances 17

II. FOODS.

8. To Determine the Amount of Water in Foods 19

9. To Test Foods for Starch 20

10. To Test Foods for Grape-sugar 22

11. To Test Foods for Nitrogenous Substances (Pro-

teids) 23

12. To Test Foods for Fats and Oils 26

13. To Test Foods for Mineral Matters 27

14. Analysis of Flour 27

15. Study of Milk 29

16. Study of Food Charts 31

III. DIGESTION AND ABSORPTION.

17. Study of the Mouth 33

18. To Prepare Artificial Digestive Juices 35

19. Digestion of Starch 37

20. Digestion of Mineral Substances 38

21. Digestion of Nitrogenous Substances 39

22. Digestion of Fats 42

23. Principles of Osmosis 45

24. Outline for Recording the Digestion of the Nutri-

ents 49

vii

TABLE OF CONTENTS.

IV. THE BLOOD AND CIRCULATION.

25. Study of Beef Blood. . ; 50

26. Microscopic Study of Blood Corpuscles 58

27. Study of a Beef Heart. 54

28. Circulation of Blood in the Tail of a Tad-

pole 56

29. Pulse in the Pupil's own Body 57

V. THE SKELETON AND THE MUSCLES.

30. Structure of Bones 58

31. Composition of Bones 60

32. Classification of Bones 62

33. Study of the Muscles 62

34. Study of Beefsteak 67

35. Structure of a Joint 68

36. Study of the Joints in the Body , 70

37. Comparative Study of Mammalian Skeletons. . . 73
VI. RESPIRATION.

38. Action of the Diaphragm and Lungs 75

39. Circulation of Air in the School- room 77

40. Inspired and Expired Air. 78

41. Temperature of the Body 80

VII. THE SKIN AND THE KIDNEYS.

42. Study of the Skin . . -. 80

43. Study of Excretion 83

44. Study of a Sheep's Kidney 84

VIII. NERVOUS SYSTEM.

45. Sensations of Touch 86

46. Sensations of Taste and Smell 88

47. Study of a Sheep's Brain 90

IX. SUPPLEMENTARY WORK.

48. Study of Yeast 94

49. Study of Bacteria 100

50. Study of Living Vertebrates 107

X. THE COMPOUND MICROSCOPE.

51. Parts of the Compound Microscope 108

52. Rules for the Use of the Compound Microscope. 112
XI. LIST OF APPARATUS AND CHEMICALS FOR CLASS OF

TWENTY-FOUR,. . 115

LABORATORY EXERCISES

ANATOMY AND PHYSIOLOGY

4

(The abbreviation (Dem.) means that a demonstration will be
given by the instructor. )

i. STUDY OF A MATCH.

Materials : Sulphur-matches, phosphorus, sulphur, lime-water,
bottle and stopper, tumbler, pieces of board.

A. Phosphorus.

1. Rub the end of a sulphur-match on your

finger in the dark. What is the ap
pearance of the streak?

2. Light a match by rubbing the tip on a

rough surface. What is the color of the
flame at first? Describe the color and
smell of the fumes that first go off into
the air. (These fumes are called oxid
of phosphorus.)

3. (Dem.) Observe the instructor while he

cuts off a piece of phosphorus. (Caution!

Phosphorus must never be handled with

the fingers.)

a. What are some of the physical prop-
erties (color, odor, hardness) of
phosphorus ?

2 .LABORATORY EXERCISES.

b. Compare the smell of the phosphorus
with the smell of the match tip in
i (above). What, therefore, is
one of the substances found in the
head of a match?

4. (Dem.) After the water has been removed

from the phosphorus by means of
blotting-paper, what do you observe?
In what other part of this experiment
have you observed a similar substance?
Why is phosphorus kept under water?

5. (Dem.) What is the result of rubbing a

piece of phosphorus between two sticks
of wood? What causes this result to
take place? (To aid in answering this
question rub together briskly your two
hands and note the feeling.) (When
phosphorus burns it combines with the
oxygen gas found in the air and forms
oxid of phosphorus.) How was the
phosphorus made to combine with oxy-
gen?
B. Sulphur.

1. Examine some common sulphur. What

are its physical properties? What evi-
dence of sulphur can you see near the
match tip?

2. Light another match, and after the white

fumes have disappeared, smell cautiously
of the burning match head. (This gas
is called oxid of sulphur.) What kind
of odor has the gas?

STUDY OF A MAZCK. ' $

3. (Dem.) Light some sulphur with a heated

wire. What is the color of the flame?
Notice the smell of the burning sulphur.
In what other part of this experiment
have you noticed a similar odor? (When
sulphur burns it combines with the oxy-
gen gas of the air, forming oxid of sul-
phur.)

4. (Dem.) Rub a bit of sulphur between two

pieces of wood, as was done with the
phosphorus. What do you observe?
Why, then, is phosphorus put on the end
of a match?

C. Water.

1. After the wood of a match is burning well,

hold it a little distance beneath the
mouth of an inverted dry tumbler. What
do you see on the sides of the glass?

2. What is one of the substances, therefore,

that is formed when wood burns? Why
is the tumbler used in this experiment?

D. Carbon.

1. When the wood of the match has been

charred, extinguish the flame. (The
substance left is called charcoal or car-
bon.) What are some of the physical
properties of carbon?

2. Heat the carbon red hot. Does it burn?

How do you know?

3. (Dem.) Thrust a piece of wood through a

hole in the stopper that fits tightly in
the mouth of a bottle. Light the wood,

4 LABORATORY EXERCISES.

and insert the burning piece of carbon
into the bottle, closing the mouth with
the stopper. What do you observe?
Suggest an explanation of this fact.
4. (Dem.) Remove the stick, pour into the
bottle a little clear lime-water, and
shake. What change do you observe
in the lime-water? (When carbon burns
it combines with the oxygen gas of the
air, forming oxid of carbon, more com-
monly known as carbonic-acid gas or
carbon dioxid.) How, then, can the
presence of carbon dioxid be demon-
strated?

E. Mineral matters.

1. Burn a match as long as you can. What

are some of the physical properties of
the ashes? (The ashes represent the
mineral matter of the wood, carried up
from the earth in the sap. When the
water of the sap evaporated, the solid
substances were left behind as a part of
the wood.)

2. Heat these mineral matters as hot as you

can. Will they burn?

3. How could you determine, therefore,

whether or not a substance contained
mineral matter?

F. Summary.

i. Name in order the parts of a match that
will burn, beginning with the most in-
flammable.

STUDY OF OXYGEN. 5

2. 'Name the substance produced by the burn-

ing of each of the above ingredients, and
state how each can be recognized.

3. What are the ingredients of a match that

will not burn?

2. STUDY OF OXYGEN. (Dem.)

Materials : Apparatus-stand, test-tube with perforated stopper,
delivery-tube, tray of water, five bottles, a piece of glass to cover
each bottle; potassium chlorate, black oxid of manganese, phos-
phorus, sulphur, splinters of wood, piece of picture-wire, piece of
crayon.

A. Preparation of oxygen.

1. Mix a spoonful of pulverized potassium

chlorate with one-fourth this amount of
black oxid of manganese. Put the mix-
ture in a test-tube, and attach it to an
apparatus-stand in a slanting position.
Close the mouth of the tube with a stop-
per through which passes a delivery-tube.
The other end of the delivery-tube
should run beneath the surface of the
water in the tray. (See Fig. i.)

a. Heat the test-tube gently. What do

you observe?

b. Potassium chlorate and oxid of man-

ganese contain a large amount of
oxygen. How are these com-
pounds made to give up oxygen?

2. Fill the four bottles with water and cover

each with a piece of glass. Invert one
in the pan of water over the end of the

6 LABORATORY EXERCISES.

delivery-tube and remove the glass
cover.

a. Why does the bottle remain filled

with water? (See experiment 4.)

b. Continue to heat slowly the mixture

in the test-tube. What do you
observe? Does oxygen dissolve
readily in water? How do you
know?

3. When the escaping oxygen has filled the
bottle, cover it with the glass plate, re-
move it from the tray, and turn it right
side up. Fill the other bottles in the
same way. Why is the glass cover
placed over each bottle?

FIG.

To obtain pure oxygen the gas should be
run through two bottles as shown in Fig.
i. Place in the first water, and in the
second a solution of caustic soda. These
liquids absorb most impurities. When
the oxygen has been washed in this way,

STUDY OF OXYGEN. 7

collect it in a fifth bottle as described in
2 and 3 above.
B. Properties of oxygen.

1. What is the color of the oxygen obtained

in 4 above? Remove the glass cover
from the bottle and smell of it. What
do you find? Inhale some of the gas
through the mouth. Has it any taste?
Enumerate, therefore, some of the phys-
ical properties (color, taste, odor) of
oxygen. What are the physical proper-
ties of the oxygen in the air?

2. Prepare a burning spoon by tying a wire

about a small piece of crayon. Place
upon the top of the crayon some phos-
•phorus and light it. Remove the glass
cover from the top of one of the bottles
of oxygen and lower into it the burning
phosphorus.

a. What do you observe? Does phos-

phorus burn better in air or in
oxygen? What is the color of the
flame?

b. What do you see in the jar in which

the phosphorus has been burning?
Name this compound. (Compare
experiments J, A, 2, 4, 5.)

3. Into a second bottle of oxygen lower some

burning sulphur.

a. What do you observe? Does sul-
phur burn better in air or in oxy-
gen?

LABORATORY EXERCISES.

b. When the flame is extinguished cover
the bottle with the glass. Cau-
tiously smell of it. What is the
gas? (Compare with experiments
f, B, i, 3.) What are the phys-
ical properties of this gas?

4. Thrust a burning stick into a third bottle

of oxygen.

a. What do you observe?

b. Remove the stick quickly and blow

out the flame, leaving a glowing
end. Again thrust the stick into
the jar of oxygen. What is the
result ?

c. Repeat the preceding experiment sev-

eral times. What do you finally
observe? Explain this fact.

d. Into the bottle put some clear lime-

water and shake. What is the re-
sult and what do you infer ? (Com-
pare experiment J, D, 4.)

5. Heat the end of a picture-wire and dip it

into sulphur. When the little ball of
sulphur is burning well, lower the heated
picture-wire into the fourth jar of oxy-
gen. Describe the result. Will iron
burn in the air?

6. Did the oxygen burn in any of the preced-

ing experiments? Does the oxygen of
the air ever catch fire? How do you
know? What, then, does the oxygen do
in each experiment?

STUDY OF AIR. 9

7. (By burning or oxidation is meant the chem-
ical union between oxygen and some
other substance.) How can you tell
when oxidation is going on? Name the
compounds that have been formed by
oxidation in the preceding experiments.

3. STUDY OF AIR. (Dem.)

Materials : Tray of water, flat piece of cork about two inches in
diameter, small porcelain dish (or bit of crockery), phosphorus, glass
jar with wide mouth, piece of glass to cover the jar, cylindrical grad-
uate.

A. Preparation of nitrogen.

i. Place the porcelain dish (or piece of crock-
ery) on the piece of cork and float the
latter on the water in the tray. Into
the dish put a piece of phosphorus twice
the size of a pea. Light the phosphorus
and then quickly cover it with the in-
verted glass jar, keeping the rim of the
latter about an inch below the surface of
the water. (See Fig. 2.)

a. With what was the jar filled when it

was placed over the burning phos-
phorus?

b. As the phosphorus burns what do you

see within the jar? What is the
composition of this substance?
How was it formed? (See Exp.
1, A, 5.)

c. What ingredient, therefore, of the air

is being removed? Why does the

10 LABORATORY EXERCISES.

phosphorus after a time cease to
burn?

What change do you see in the level
of the water within the glass jar?
How do you explain this? (See
Exp. 4.)

FIG. 2.

e. What change do you see in the com-
pound that was formed within the
glass jar? Explain.

2. Slide a piece of glass beneath the mouth of
the bottle, turn the latter right side up,
taking care not to lose any of the water
that has risen in the jar. The ingredient
of the air left in the bottle is nitrogen.
Keep the bottle covered and shake the
water about to wash the nitrogen as
much as possible.

a. Drop a piece of blue litmus paper
(see experiment 7) into the water.
What change do you see? (This
proves that oxid of phosphorus
makes water acid.) •
B. Properties of nitrogen.

i. What are the physical properties of the
nitrogen in the bottle? What are the

STUDY Of AIR. 11

physical properties of nitrogen in the
air? Is, therefore, the nitrogen in the
bottle pure?

2. Place a piece of phosphorus on the burning

spoon and light it. Carefully remove
the glass cover sufficiently to lower the
burning phosphorus into the jar of nitro-
gen. Cover again as quickly as possible.

a. What do you observe?

b. What, then, is the most striking dif-

ference between the effect of oxy-
gen and nitrogen on heated phos-
phorus ?

3. If you are sure that air has been kept out

of the jar, see if sulphur, carbon, or iron
will burn in nitrogen.

a. What do you conclude?

b. Did the nitrogen itself burn in any of

the preceding experiments?

c. Does nitrogen make things burn?

d. What is the advantage of having air

composed of both oxygen and nitro-
gen?
C. Percentage composition of air.

1. Pour the water at the bottom of the jar

into a cylindrical graduate. How much
water is there? (This water took the
place of the oxygen as fast as the latter
was removed from the air by the burn-
ing phosphorus.) What, therefore, was
the volume of oxygen in the air?

2. Fill the jar with water and then pour it into

12 LABORATORY EXERCI8S8.

the cylindrical graduate. What is the
volume of the water, or in other words
how much air was in the jar at first?
3. The water measured in i above represents
the volume of the oxygen and the water
in 2 the whole volume of air in the jar.
About what fractional part of air is oxy-
gen? What per cent, of oxygen is there-
fore found in air? What per cent, is
nitrogen?

4. STUDY OF ATMOSPHERIC PRESSURE.

Materials: Tumbler of water, piece of paper, apparatus for
preparing oxygen, apparatus for preparing nitrogen. (See Figs. 1
and 2.)

A. Fill a tumbler nearly full of water and cover it

with a piece of paper, pressing it down firmly
upon the glass. Carefully invert the tumbler
and then remove the hand from beneath the
paper.

a. What do you observe?

b. Slowly turn the glass until the paper

stands vertically. Describe result.

c. Turn the glass upright. Describe the

appearance of the paper.

d. (The air exerts in all directions at the

level of the sea a pressure equal to
about fifteen pounds to the square
inch.) Keeping in mind this fact
explain the preceding experiments.

B. In the preparation of oxygen explain why the

STVDY OF BTDROGfitf. H

inverted bottles remained filled with water.
Measure the length and breadth of the tray of
water. How many square inches are there on
the surface of the water? If the pressure on
each square inch is fifteen pounds, what is the
pressure of the atmosphere on the whole sur-
face?

C. When the oxygen was removed from the jar in
the nitrogen experiment, why did the water
rise? Invert a jar of air and press it down
into the water. What is the level of the water
within the jar now? Explain.

5. STUDY OF HYDROGEN. (Dem.)

Materials : Two small bottles, each fitted with a rubber stopper
fn which are two holes, thistle-tube, delivery-tube, tray of water,
test-tube, wide-mouth bottle, pieces of zinc, diluted hydrochloric
acid, potassium permanganate solution.

A. Preparation of hydrogen.

i . Put some small pieces of zinc into the bottle
and insert the stopper. Through one
hole in the stopper pass the thistle-tube
until the lower end nearly touches the
bottom of the bottle. Pass one end of
the delivery-tube through the second
hole and let the other end of the tube
dip beneath the water in the tray. Pour
into the thistle-tube dilute hydrochloric
acid until the lower end of the thistle-
tube is covered.
a. What do you see within the bottle?

LABORATORY EXERCISES.

(This is an evidence that chemical
action is taking place.)

b. Feel of the bottle. What is a second

proof of chemical action?

c. What do you see at the free end of the

delivery -tube? This gas is hydro-
gen.

Fill a test-tube with water and invert it
over the mouth of the delivery-tube.

a. What other gas is collected in a sim-

ilar way?

b. Wrap the tube in a towel, still hold-

ing it upside down, and hold the
mouth near a burning match.
What do you hear?

Potassium
fermanganat

FIG. 3.

c. If an explosion occurs, fill the tube
with hydrogen a second time.
When the gas burns quietly, col-
lect a bottle as you collected the
oxygen, but keep it upside down

STUDY OF HYDROGEN. 15

after removing it from the tray of
water. (If the hydrogen does not
come off in sufficient quantity,
add some more hydrochloric acid
to the zinc in the bottle.)
3. To obtain pure hydrogen, first pass it
through a solution of potassium per-
manganate in a glass bottle and then col-
lect it in a tray of water. This solution
removes the impurities from the hydro-
gen. (See Fig. 3.)
B. Properties of hydrogen.

1. What are some of the physical properties

of hydrogen? Hydrogen is the lightest
known substance. Why, therefore, are
the bottles kept upside down?

2. Carefully lift one of the bottles of hydrogen

and thrust up into the mouth a burning
splinter of wood.

a. Does the carbon continue to burn?

b. What do you notice? What is the

color of the flame?

c. How, then, does hydrogen differ from

oxygen? from nitrogen?

3. Remembering that a mixture of oxygen

and hydrogen may cause a dangerous
explosion, collect a test-tube of hydro-
gen to make sure that all the oxygen has
been driven out of the bottle and deliv-
ery-tube. Remove the end of the de-
livery-tube from the water and attach
a piece of glass tubing that has been

16 LABORATORY EXERCISES.

drawn out until the opening is small.
Stand away from the tube and apply a
lighted match. (See Fig. 3.)

a. What do you observe? How does

the color of the flame differ from
that of B, 2, b above? (This dif-
ference is due to the heated glass
tube.)

b. Hold a dry glass tumbler over the

mouth of the delivery -tube. What
do you see on the sides of the
glass? What, therefore, is formed
when hydrogen burns?

c. What was formed when wood first be-

gan to burn? What was probably
one of the ingredients of wood?
(See experiment J, C, 2.)

6. STUDY OF EVAPORATION.

A. Pour a wine-glass of water into a saucer and

place it near a heated stove or radiator. Ex-
amine at the end of several (6-12) hours.
What do you observe?

B. Pour the same amount of water into a second

saucer, put it in a cool place, and compare
with (A) above at the end of several hours.

C. Into a third saucer put another wine-glass of

water, cover with a glass dish, and place be-
side (A). What do you find on examining the
dishes at the end of several hours? Explain.

D. Fill the wine-glass with water and place it beside

ACID, ALKALINE, AND NEUTRAL SUBSTANCES. 17

the first and third saucers. Compare the
amount of evaporation in the three dishes.
What do you learn?
E. From the preceding experiments:

1. Define evaporation.

2. State three conditions that are favorable

for evaporation.

3. Name three ways in which evaporation can

be lessened.

7. ACID, ALKALINE, AND NEUTRAL
SUBSTANCES.

Materials: Diluted hydrochloric acid, dilute caustic-soda solution,
water; red and blue litmus paper; evaporating-dish, alcohol or gas
lamp, glass stirring-rod.

A. Tests for acid, alkaline, and neutral substances.

1. Place a drop of diluted hydrochloric acid

on blue litmus paper. Result?

2. Place a drop of the diluted acid on the

tongue. What is the taste?

3. Put a drop of dilute caustic soda solution

(which is alkaline) on red litmus paper.
Result?

4. What is the taste of the caustic soda solu-

tion? How does it feel when rubbed
between the thumb and forefinger?

5. Put a drop of water on red and then on blue

litmus paper. Water is a neutral sub-
stance. How does a neutral substance
affect litmus paper?

18 LABORATORY EXERCISES.

B. Neutralization.

1. Pour a small amount of the hydrochloric

acid into an evaporating-dish ; add caus-
tic soda, drop by drop, stirring continu-
ally with glass rod, until pieces of red
and blue litmus paper remain unchanged
when dropped into the liquid. (This
process is called neutralization.)

2. Evaporate the liquid in the dish to dryness

over an alcohol or gas flame.

a. What is the appearance of the solid

that is left?

b. What is its taste? What substance,

therefore, is made by combining
hydrochloric acid and caustic soda?

C. Summary. From the above experiments —

1. Give some characteristics of an acid.

2. Give some characteristics of an alkali.
• 3. How can you tell a neutral substance?

4. Define neutralization.

D. Applications.

1. Drop small pieces of red and blue litmus

paper into a solution of each of the fol-
lowing substances : soap of several kinds,
lemon juice, ammonia, cream of tartar,
saliva, baking soda, apple juice, sugar,
milk, white of egg, and other common
substances.

2. Record your results by arranging all the

substances you have tested in a table
like the following;

TO DETERMINE THE AMOUNT OF WATER IN FOODS. 19

Acid.

Alkaline.

Neutral.

8. TO DETERMINE THE AMOUNT OF WATER
IN FOODS. (Dem.)

Materials: Piece of lean beefsteak; two potatoes; weighing bal-
ances.

A. Percentage of water in beefsteak.

1. Weigh the piece of meat and put it aside in

a warm dry place; weigh the next day.
Continue the weighings each day until
the figure remains constant. (The loss
is mostly water.)

2. Record your results in tabular form as fol-

lows:

Wt. of steak.

Loss of original wt.

Per cent, of loss.

Third day

etc.

B. Percentage of water in potatoes.

i. Remove a thin layer of peel from one of the
potatoes; weigh each of them and lay

20 LABORATORY EXERCISES.

aside in a warm dry place. Weigh each
day, and record results for each potato
in tabular form as above.
2. What is one use of the peel of potato?

9. TO TEST FOODS FOR STARCH.

Materials : Corn-starch, grape-sugar, white of egg, mutton tallow,
various food materials, water; iodine solution;* small butter-plate,
test-tubes, glass jar, alcohol-lamp.

A. Method of applying iodine test.

Put a small amount of corn-starch in a test-
tube, add water and shake the mixture.

1. Does the starch dissolve? How do you

know? (Let the mixture stand.)

2. Boil the mixture.

a. What change do you notice?

b. Has the starch dissolved? (Place

some sugar and water in another
test-tube, boil, and compare with
the boiled starch.)

3. Pour a little of the starch paste into a test-

tube, add a drop of iodine,* shake, and
record result.

4. Add a few drops of the starch mixture to a

large glassful of water ; stir in a few drops
of iodine. What is the result?

* A quart (1000 cc.) of iodine solution is made by dissolving in 5
teaspoonfuls (40 cc.) of water, one-half teaspoonful (4 grams) of
potassium iodide, and one-fourth this amount of iodine (1 gram).
This solution, when thoroughly mixed, should be diluted to make
one quart (1000 cc.). In a clean bottle this mixture will keep lit-
definitely.

TO TEST FOODS FOR STARCH. 21

5. Pour a small amount of iodine into a test-

tube of water. What do you observe?

6. Put a small amount of grape-sugar into a

test-tube; into a second test-tube some
white of egg mixed with water ; and into
a third tube put some mutton tallow
(fat). "Add a little iodine to each.

a. Do you notice any change in the color

of any of the substances?

b. Do any of the colors resemble at all

the change of color resulting from
the addition of iodine to starch?

7. From the preceding experiments state how

you can determine whether a substance
contains much starch, little starch, or no
starch.
B. Application of iodine test to various foods.

1. Test as many foods as you can by adding

hot water to a small amount of each on
a white butter-dish or saucer, and then
applying iodine (e.g., oatmeal, flour, raw
meat, egg, milk, parsnip, potato, onions,
apples (both green and ripe), beans, rice,
pepper).

2. Tabulate your results in columns under the

following heads :

Much starch.

Little starch.

No starch.

22 LABORATORY EXERCISES.

10. TO TEST FOODS FOR GRAPE-SUGAR.

Materials : Grape-sugar, corn-starch, white of egg, mutton tallow
raisins, onions, grapes, granulated sugar, and other foods; Fehling's
solution ; * test-tubes, alcohol-lamp.

A. Method of applying Fehling's test.

1. Dissolve a small amount of grape -sugar

(glucose) in water in a test-tube.

a. What is the difference in the effect of

water on grape-sugar and on starch ?

b. Add some Fehling's solution * and boil.

What changes do you notice?

2. Into the first of three test-tubes put some

white of egg mixed with water; into a
second tube some corn-starch ; and int->
a third tube some mutton tallow (fat).
Add Fehling's solution to each and boil,

a. Does any change take place in the

color of the Fehling's solution?

b. Do any of the colors resemble at all

* To make a quart (1000 cc.) of Fehling's solution dissolve 3 tea-
spoonfuls (34.64 grams) of pure pulverized copper sulfate (blue vit-
riol) in a little less than a half -pint of water (200 cc.). Make a
second solution by dissolving in a pint (500 cc.) of water twelve
heaping teaspoonfuls (150 grams) of Rochelle salt and 3 (5-inch)
sticks of caustic soda (50 grams). Mix the two solutions thor-
oughly, and dilute with enough water to make a quart (1000 cc.).
Fehling's solution does not keep for any great length of time, and
hence must be made up fresh a short time before it is needed. It
is more convenient to prepare it in small quantities from the tab-
lets that may be obtained of druggists. Before making any tests
boil a small quantity of the Fehling's solution in a clean test-tube.
If it retains its transparent blue color it is ready for use; otherwise
a fresh supply must be prepared.

TO TEST FOODS FOR NITROGENOUS SUBSTANCES. 23

the color of the Fehling's solution
when it was boiled with grape-
sugar?

3. How can you determine, therefore, whether
or not grape-sugar is present in a given
food?
B. Application of Fehling's test to various foods.

1 . Test as many different kinds of foods as you

can, first treating them with water, boil-
ing in a test-tube and then boiling with
Fehling's solution (e.g., onions, grapes,
both ripe and unripe, pears, granulated
sugar, honey, molasses, meat, egg).

2. Tabulate your results in columns under the

following heads:

Grape-sugar present.

Grape-sugar absent.

ii. TO TEST FOODS FOR NITROGENOUS
SUBSTANCES.

(Nitrogenous substances are also known as proteids and albumins. )

Materials: White of egg, corn-starch, grape-sugar, mutton tallow ;
piece of meat, milk, peas; concentrated nitric acid and ammonia;
test-tubes, beaker-glass, thermometer, alcohol-lamp.

A. Effect of heat.

i . Pour a small amount of the white of an egg
into a test-tube. (White of egg is com-

24: LABORATORY EXERCISES.

posed of nitrogenous substances.) Place
a chemical thermometer in the test-tube
and hold the tube in a beaker-glass of
cool water. Gradually heat the water,
stirring continually with the test-tube.

a. What change takes place in the egg

albumen?

b. At what temperature does this change

occur?

2. Boil some milk in a pan. What do you

notice? Heat several times and see if
same result follows.

3. Cook a small piece of meat. How does the

heat affect its outer surface? What is
your conclusion in regard to the compo-
sition of meat?

B. Smell when burning.

1. Place a small piece of lean meat on the top

of a coal fire and allow it to burn. Have
you ever noticed this smell before? If
so, what caused it?

2. In the same way test milk, peas, or beans.

Result?

C. Effect of nitric acid and ammonia.

i. Pour a little concentrated nitric acid on a
piece of hard-boiled egg in a test-tube.

a. What do you observe?

b. Wash off the egg with water, add a

little concentrated ammonia, and
note result.

2 Put into a test-tube some starch paste made
as in 9 above; into a second tube some

TO TEST FOODS FOR NITROGENOUS SUBSTANCES. 25

grape-sugar; and into a third test-tube
some mutton tallow (fat). Add a little
concentrated nitric acid to each of the
three.

a. Do you observe any change in the

color of either of these nutrients?

b. Pour off the acid and add a little con-

centrated ammonia. Is any effect
noticeable ?

3. Test with a drop of nitric acid the skin on

the tip of one of your fingers.

a. What is the result?

b. Of what material is the human body

partly composed ?

4. Apply the nitric acid and ammonia test to

as many foods as you can (e.g., gelatin,
peas, white meats, onions, fruits).

5. Tabulate your results in columns under the

following heads :

Nitrogenous substances present.

Nitrogenous substances absent.

D. From the above experiments state briefly three
.ways of testing foods for nitrogenous sub-
stances.

26 LABORATORY EXERCISES.

12. TO TEST FOODS FOR FATS AND OILS.

Materials : Ground flaxseed, corn-meal, milk, egg, butter, mutton
tallow; ether or benzine; beaker-glass, funnel, filter-paper.

Caution ! Never handle benzine or ether near a flame or a hot
stove, since the vapor of these substances is very inflammable.

A. Method of extracting oils.

To two or three teaspoonfuls of the ground
flaxseed add an equal volume of ether or ben-
zine ; stir the mixture and let it stand for ten
or fifteen minutes. Filter and place the liquid
aside in a good draught of air until the odor of
ether or benzine has disappeared.

1. What kind of substance have you obtained?

2. What 'is its smell?

3 . Why is benzine used to remove grease-spots

from clothing?

4. In the same way extract the fats from milk;

from egg ; from corn-meal.

B. Hold a piece of butter or mutton tallow in a

spoon over the stove.

1. What is the effect of heat on fats?

2. How, then, can you distinguish between a

piece of fat and a piece of proteid ?

C. Rub a little of the flaxseed on paper. Hold the

paper to the light.

1. What effect does fat have on the paper?

2. Does starch, sugar, proteid, or water have a

similar effect?

3. What, therefore, is a simple way of proving

the presence of fat ?

ANALYSIS OF FLOUR. 2?

13. TO TEST FOODS FOR MINERAL
SUBSTANCES.

Materials: Piece of meat, oatmeal, egg, milk; spoon or piece of
metal (platinum foil is best).

A. Method of testing for mineral matter.

Place a bit of dried meat on a spoon or on
platinum foil, and let it burn on a hot coal fire
or over a gas-flame until no further change
can be brought about by heat.

1. What is the appearance of the substance

which is left behind? (The ash is the
mineral substance.)

2. Does heat affect this residue?

B. In the same way test oatmeal, egg, and milk.

What do you learn in regard to the presence
of mineral substances in these foods?

14. ANALYSIS OF FLOUR.

Materials: Flour, water; concentrated nitric acid and ammonia,
iodine, Fehling's solution; cotton cloth, test-tubes, glass dish, piece
of metal (platinum foil is best).

Moisten some flour with water until it forms a
tough, tenacious dough; tie it in a piece of cotton
cloth, and knead it in a vessel containing water. Set
aside the dish with the water.
A. Gluten.

i. What are some of the characteristics of the
substance (principally gluten) within the
cloth? Draw it out into threads.

28 LABORATORY EXERCISES.

2 1 Test it with nitric acid and ammonia. What
kind of nutrient is gluten?

B. Carbohydrates.

1. Test with iodine a small amount of the

sediment in the water which you used at
the beginning of the experiment. What
part of the flour was washed through
the cloth?

2. Test with nitric acid and ammonia another

portion. Are nitrogenous substances
present?

3. Test a small portion of the sticky mass in

the cloth with iodine. What is the re-
sult, and what is your conclusion ?

4. Place a little flour in a test-tube, add water

and boil ; add Fehling's solution and boil
again. Is grape-sugar present in flour?

C. Mineral matter.

Place a small amount of dry flour on a piece
of tin or platinum foil and cause it to burn
over a very hot flame.

1. What changes take place?

2. What is left after the burning?

D. Summary.

1. What nutrients are present in flour?

2. State how each of these nutrients can be

separated from the rest.

STUDY OF MILK. 29

15. STUDY OF MILK.

Materials : Pint of fresh, rich milk ; nitric acid and ammonia,
Fehling's solution, iodine, caustic soda, osmic acid, vinegar; test-
tubes, lactometer, cloth, alcohol-lamp.

A. Fats.

Put the milk into a clean glass dish, and al-
low it to stand over night.

1. What layers can be distinguished?

2. Remove by means of a spoon the top layer

into a bottle or cup (No. i).

3. Place a drop of it on unglazed paper. Let

the paper dry for some time. What
kind of nutrient is shown to be present
in milk?
Nitrogenous substances.

1 . Boil the rest of the milk ; what change is no-

ticed? What kind of nutrient is affected
in this way by heat?

2. Remove the scum from the milk and place

it in a second cup (No. 2). Test a little
of it with nitric acid and ammonia. Re-
sult?

3. Add vinegar to the rest of the milk and

strain through a cloth. What kind of
substance is left in the cloth? Test it
with nitric acid and ammonia. Result?
Place this substance in cup No. 2.
Carbohydrates.

i . Test a small amount of fresh milk with Feh-

30 LABORATORY EXERCISES.

ling's solution. Result? (Milk-sugar or
lactose sometimes gives the test with
Fehling's solution like grape-sugar.)
2. Test milk with iodine. Is starch present?

D. Specific gravity of milk.

1. Pour some good rich milk into a tall glass

jar. Test it with a lactometer and re-
cord specific gravity.

2. Set the milk aside to allow the cream to

rise. Remove the cream and test the
skim -milk with the lactometer.

a. What change in specific gravity do

you note?

b. Explain this change.

3. Determine the specific gravity of a second

portion of milk. Dilute the milk with
water and again find specific gravity.
(Fresh unskimmed milk usually has a
specific gravity of 1028 to 1034.) How
can adulteration of milk be detected?

E. Microscopic examination of milk. (In class.)

1. Place a drop of milk on a clean glass slide,

and cover with a cover-glass. Examine
under the compound microscope.

a. What is the appearance of the oil-

globules ?

b. Are they all of the same size? (The

fat in milk is said to be in a state of
emulsion, each tiny sphere being
surrounded by a thin covering of
albumin.)

2. Place a drop of dilute caustic soda at the

STUDY OF FOOD CHARTS.

31

edge of the cover-glass. What is the ef-
fect of the soda on the oil -globules ?
Prepare a second drop of milk for examina-
tion as directed above (i). Place a drop
of osmic acid solution at the edge of the
cover-glass. What is the effect of the
osmic acid on the oil-globules ?
Reaction of milk when tested with litmus.

1 . Test some fresh milk with red and blue lit-

mus paper. Is it acid, alkaline, or neu-
tral?

2. Set the milk aside in a warm place and al-

low it to sour. Again test it with the
red and blue litmus paper. What is the
result? (The souring of milk is caused
by the action of certain micro-organisms
called bacteria. See study of bacteria,
49.)

16. STUDY OF FOOD CHARTS.

(In "Foods: Nutritive Value and Cost,"* or in " Principles of Nu-
trition and Nutritive Value of Food."*)

A. Composition of food materials.

(Make estimates from Chart i, p. n, and
compare with per cents, given in Table A, p.
27, in " Foods: Nutritive Value and Cost.")
i. Which kind of food (animal or vegetable)

* The.se pamphlets will be furnished free by the U. S. Department
of Agriculture, Washington, D. C«

32 LABORATORY EXERCISES.

has on the average the larger per cent, of
proteid ?

2. Which kind has the larger per cent, of fat?

3. Which kind has the larger per cent, of car-

bohydrates ?

4. Note the principal nutrients present in ani-

mal foods, and state what use the body
can make of this class of foods.

5. In the same way state the principal uses of

vegetable foods.

6. Name five animal foods that contain a large

per cent, of material for muscle-build-
ing.

7. Name five vegetable foods that contain a

large per cent, of material for muscle-
building.

8. Name five foods that could supply a large

amount of heat for the body.

9. Suggest reasons why any of the foods

named in answer to questions 6, 7, and
8 above would not be the most healthful
foods for the body.
B. Pecuniary economy of food.

(Make estimates from Chart 2, p. 22, and
compare with per cents, given in Table B, p.
27, in " Foods; Nutritive Value and Cost.")

1. Can larger amounts of animal food or of

vegetable food be purchased for ioc.?

2. Suggest some reasons for the fact you have

just stated.

3. Which kind of food material named on the

chart is cheapest? (That is, of which

THE STUDY OF THE MOUTH. 33

kind could you secure the largest amount
for ioc.?)

4. Which kind of food material is most ex-

pensive ?

5. Which of the three kinds of steak named on

the chart is the most economical?

6. About what fractional part of a pound of

each kind of nutrient is needed each day
by an American at moderate work ? (Last
line on p. 22 and p. 28.)
Which food on the chart comes nearest to
supplying the nutrients in the right pro-
portions?

8. Why is it better, therefore, to eat a variety

of foods rather than a single kind?

9. On p. 10 learn the definition of (a) the most

healthful food, (b) the cheapest food, (c)
the best food.

17. THE STUDY OF THE MOUTH.

Take a position with your back toward a strong
light and study your mouth-cavity by means of a
hand-mirror.
A. Walls of the mouth-cavity.

1. Press the forefinger against the upper,

lower, and side walls of the mouth; in
which of these regions are the walls rigid
(bone) ? in which regions are they yield-
ing (muscle)?

2. What differences do you note between the

LABORATORY EXERCISES.

outer and inner coverings of the cheek?
What are the characteristics of mucous
membrane (inner covering) ?

3. Pull aside with the forefinger one corner of

the mouth. Notice the small elevation
on the inside of the cheek. Opposite
what tooth does it lie? (The duct from
one of the salivary glands opens on this
elevation.)

4. Press the tongue down with the forefinger.

Make a drawing of the opening into the
throat

5. If possible, locate and describe the tonsils.
B. The teeth.

1. Close the jaws and open the lips; do the

front teeth of the upper jaw cover the
ends of the lower teeth or vice versa?

2. Are the front teeth of the upper jaw larger

or smaller than those of the lower jaw?

3. Count your teeth and record result in a

table like the following :

Right half of
upper jaw.

Left half of
upper jaw.

Right half of
lower jaw

Left half of
lower jaw.

Incisors
Canines
Bicuspids ....
Molars

Place a piece of string between the teeth
and describe motion of jaws in biting it
off . Describe the movements of the j aws
in chewing,

TO PREPARE DIGESTIVE JUICES. 35

C. The tongue.

1. What is the shape of the tongue?

2. Where is the tongue attached?

3. What parts of the walls of the mouth-cavity

can be touched by the tip of the tongue ?

4. What differences do you note between the

upper and lower surfaces of the tongue?

D. The use of the lips and tongue in speaking.

1. Pronounce .the vowels of the alphabet.

a. Are the lips closed or open?

b. Does the tip of the tongue touch the

teeth?

c. Does the tip of the tongue touch the

palate ?

d. What is the shape of the mouth-cavity

when you are pronouncing each of
these vowels?

2. What consonants necessitate the closing of

the lips? (These consonants are called
labials.)

3. What consonants require the tongue to

touch the teeth? (These are called the
lingual consonants.)

18. TO PREPARE DIGESTIVE JUICES. (Dem.)

Materials . Cardiac end of pig's stomach; pancreas of pig; gall of
ox ; strong gl \rcerm, 1% solution of hydrochloric acid, 1 5% solution
of sodium carbonate: solid pepsin, pancreatin, and ox -gall.

A. Preparation of pepsin solution.

Procure the stomach of a pig, wash it out
with a gentle stream of water. Tear off the

36 LABORATORY EXERCISES.

. mucous membrane from the cardiac (cesoph-
ageal) end of the stomach. Dry the mem-
brane between folds of blotting-paper, and
mince it finely. Place in a bottle and add 5
times its bulk of strong glycerin. Set aside
for several days, stirring occasionally. Filter
through muslin. (The glycerin dissolves the
pepsin.) The glycerin extract may be kept
almost indefinitely.

When required for use* in digesting nitro-
genous substances, add 10 times its volume of
.2% hydrochloric acid, and filter.

Instead of preparing the glycerin extract an
artificial gastric juice may be made by dissolv-
ing solid pepsin in water and adding the hydro-
chloric acid.

B. Preparation of pancreatin solution.

Leave the pancreas of a pig moistened with
water for a day ; then mince it well and add i o
times its volume of strong glycerin. Set the
mixture aside for several days, stirring occa-
sionally. Filter through muslin. (The gly-
cerin dissolves out the pancreatin.)

The glycerin extract acts on starch and nitro-
genous substances. When required to digest
fats add 10 volumes of 1.5$ solution of sodium
carbonate, shake and filter.

An artificial pancreatic juice can be made
by dissolving solid pancreatin in water and
adding the sodium carbonate solution.

C. Preparation of bile.

Procure the fresh gall-bladder of an ox : wash

THE DIGESTION OF STARCH.

37

ft, make a small opening with a knife, and col-
lect the bile in a bottle. (The bile of herbiv-
orous animals is green in color; human bile
when fresh is a golden-brown liquid.)

A solution of solid ox-gall in water may be
used instead of the contents of the gall-blad-
der, if the latter cannot be easily obtained.

19. THE DIGESTION OF STARCH.

Materials: Corn-starch, saliva, pancreatin solution; test-tubes;
alcohol-lamp.

A. By saliva.

Put a small amount of corn-starch in a test-
tube, add water and boil ; dilute the paste until
a smooth, thin mixture is formed.

1. Pour into a test-tube a small amount of this

starch mixture, and test with Fehling's
solution. What is the result and what
is your conclusion?

2. Allow some saliva to flow from the mouth

into a clean test-tube ; * test it with Feh-
ling's solution. What is your inference?

3. Pour some saliva into the starch paste made

at the beginning of the experiment, shake
the mixture and warm gently for a mo-
ment or two. Test with Fehling's solu-
tion. Result?
... What is the effect of saliva on boiled starch?

* Saliva sufficient for the class may be obtained by the teacher be-
fore the exercise.

38 LABORATORY EXERCISES,

5. Name several foods already studied which

could be partially digested by saliva.

6. Hold a small amount of the boiled dilute

starch paste in the mouth. What is the
taste at first ? Do you notice any change;
if so, what change?

B. By pancreatic juice.

1. Dissolve a little pancreatin in water. Test

a small portion of it with Fehling's solu-
tion. What is your conclusion?

2. Add some pancreatin solution to some of the

starch paste; warm and test with Feh-
ling's solution. Result?

C. What digestive juices of the human body act

upon starch? What change do they cause?

20. DIGESTION OF MINERAL SUBSTANCES.

Materials : Table-salt, phosphate of lime, diluted hydrochloric
acid; evaporating-dish, alcohol-lamp.

A. Soluble salts.

Put some table-salt into a test-tube, add
water, and shake well.

1 . Does the salt dissolve ? How do you know?

2. In what part of the alimentary canal may

salt become liquefied, and how?

3. What is meant by a soluble salt or soluble

mineral substance?

B. Insoluble salts.

Put some phosphate of lime (one of the con-

DIGESTION OF NITROGENOUS SUBSTANCES. 39

stituents of milk) into a test-tube, add water,
and shake well.

1. Does the substance dissolve? How do you

know?

2. Add a little diluted hydrochloric acid and

shake. What change do you observe?

3. Evaporate to dryness in an evaporating-

dish some of the liquid obtained in 2.

a. What is the appearance of the sub-

stance which is left?

b. Will it dissolve in water?

c. Into what kind of a salt has hydro-

chloric acid changed the insoluble
salt?

4. (Hydrochloric acid is one of the ingredients

of gastric juice.) In what part of the
alimentary canal are insoluble salts di-
gested, and how are they digested?

21. DIGESTION OF NITROGENOUS
SUBSTANCES. (Dem.)

Materials : Hard-boiled egg, pepsin, pancreatin, hydrochloric acid,
baking-soda; test-tubes, labels.

A. Action of gastric juice.
T. Experiments.

a. Thoroughly mince a piece of hard-
boiled egg and place a portion of
it in a test-tube; half nil the tube
with water. Label Test No. i,
minced egg + water.

4:0 LABORATORY EXERCISES.

b. Place in another test-tube the same

quantity of minced egg and water
as in tube No. i ; add a little di-
lute hydrochloric acid. Label Test
No. 2, minced egg + water + hydro-
chloric acid.

c. Into a third tube put some minced egg

and water, and add a small amount
of pepsin. Label Test No. 3,
minced egg -f water + pepsin.

d. Place some of the minced egg into a

fourth tube and add all three in-
gredients of gastric juice, namely,
water, a little hydrochloric acid,
and pepsin. Label Test No. 4,
minced egg + water + hydrochloric
acid-f- pepsin.

e. Put a lump of the hard-boiled egg in a

fifth test-tube; add water, hydro-
chloric acid, and pepsin, as in Test
No. 4. Label Test No. 5, lump of
egg + water + hydrochloric acid-H
pepsin.

/. Put all five tubes in a warm place (98°
F.) and shake them at frequent in-
tervals. Examine them at the end
of a few hours and at the end of a
day or two.
2. Results and conclusions.

a. Compare tests i, 2, 3, and 4.

(i) In which tube has the egg been
liquefied or digested?

DIGESTION OF NITROGENOUS SUBSTANCES. 41

(2) Are all three ingredients of

gastric juice necessary for
proteid digestion or not?

(3) To what, therefore, may some

cases of indigestion be due?
b. Compare tests 4 and 5.

(1) In which tube is digestion more

complete ?

(2) What do you learn in regard

to the effect of thorough
mastication of food?

(3) What provisions within the

stomach, however, might
accomplish the digestion
of even poorly masticated
food?

B. Action of pancreatic juice.
i. Experiments.

a. Into a test-tube put some of the

minced egg; half fill the tube with
water and add pancreatin; add to
the mixture a little baking-soda or
other alkali. Label Test No. 6,
minced egg + water + pancreatin +
alkali.

b. In a seventh tube mix the same quan-

tity of minced egg, water, and pan-
creatin as was used in Test No. 6 ;
pour in a few drops of hydrochloric
acid. Label Test No. 7, minced
egg + water + pancreatin + acid.
€. Put both tubes in a warm place (98° F.)

4:2 LABORATORY EXERCISES.

and shake them at frequent inter-
vals. Examine them at the end
of a few hours and at the end of
a day or two.
2. Results and conclusions.

a. In which tube has digestion taken

place?

b. Does pancreatin, therefore, perform

its digestive action by the aid of an
alkali or of an acid?

22. DIGESTION OF FATS.

Materials: Butter, olive-oil, lard, white of egg; sodium carbonate,
caustic soda, hydrochloric acid; bile, pancreatin; test-tubes, alcohol-
lamp, apparatus-stand; compound microscope, slide, cover-glass.

A. Effect of heat on fats.

1. Put a small piece of butter in a spoon and

hold the spoon over a hot stove. What
change takes place ?

2. How, then, can you distinguish between a

fat and a proteid?

3. Hold a piece of butter in your mouth. Does

it become liquid at the temperature of
the body?

B. Emulsion of fats.

i . In a test-tube shake up a few drops of olive-
oil with some caustic soda solution.

a. What change takes place in the ap-

pearance of the mixture after shak-
ing? (This mixture is called an
emulsion.)

b. Put a drop of the mixture on a glass

DIGESTION OF FAT8. 43

slide, cover with a cover-glass, and
examine with a compound micro-
scope.

(1) What is the appearance of the

oil droplets?

(2) Compare this appearance with

that seen in milk. (See ex-
periment J5 E.)

2. In a test-tube shake some olive -oil with a

mixture of white of egg (albumin) and
water.

a. What is the appearance of the mix-

ture?

b. Examine a drop under the compound

microscope as directed above.

3. Shake up a few drops of the olive-oil with

water in a third test-tube, and let tube
stand for a time.

a. Compare the mixtt-^e of oil and water

with the '.fixtures formed in i and
2 above.

b. What differences do you notice in the

tubes ?

4. Summary.

a. Define an emulsion.

b. State two ways in which an emulsion

can be made.
C. Saponification of fats.

i. Put a little lard or olive-oil in a test-tube,
add caustic soda, and boil,
a. What is the appearance of the mix-
ture?

44 LABORATORY EXERCISES.

b. Examine a drop under the compound

microscope as directed above. Do
you see any difference between this
mixture and that formed in B i
above?

c. Taste of the mixture. What kind of

substance has been formed?
2. What is meant by saponification?

D. Effect of acids and alkalis on fats.

1. Pour a little melted butter into each of two

test-tubes. Add to test-tube No. i
some diluted hydrochloric acid; to test-
tube No. 2 some sodium carbonate solu-
tion. Shake both tubes well, and allow
them to stand for a few moments.

2. Does the butter remain mixed better with

an acid or with an alkali? Why, then,
dre fats not digested in the stomach?

E. The digestive action of bile.

1. Test with litmus paper the bile solution. Is

it acid, alkaline, or neutral?

2. Pour a little melted butter into a test-tube ;

add some of the bile solution. Does the
mixture resemble that formed in B i or
B 3 above?

3. Examine a drop of the mixture under the

compound microscope. Does this ob-
servation agree with that made in 2 just
above?

4. Pour a little thin starch paste into a test-

tube ; add some bile, and after a time test
the mixture with Fehling's solution.
Does the bile act upon starch?

PRINCIPLES OF OSMOSIS. 45

5. Place in another test-tube a little minced

white of egg ; add bile and set aside for a
day or two. Does the egg dissolve?

6. State what kinds of food-stuffs are acted

upon by bile, and what kinds of food-
stuffs are not acted upon.
F. The digestive -action of pancreatic juice.

I-. Prepare some artificial pancreatic juice as
directed in J8 B, adding the sodium car-
bonate solution to make it alkaline.

2. Shake up a little melted butter with some of

this pancreatic juice. What kind of a
mixture is formed? Examine under the
compound microscope.

3. What kinds of food-stuffs are digested by

the action of pancreatic juice (compare
previous experiments), and what kind of
food-stuffs are not acted upon?

23. PRINCIPLES OF OSMOSIS. (Dem.)

Materials : Thistle-tube, beaker-glass, grape-sugar, starch, white
of egg, Fehling's solution, iodine, nitric acid, and ammonia. Procure
the intestines of a sheep;* clean and inflate them; tie at intervals,
and allow this animal membrane to dry.

A. Hold a thistle -tube upright, closing the smaller
end with the thumb. Into the larger end pour
a thick solution of grape-sugar (honey will
answer) until the liquid has half filled the tube
and nearly filled the bulb. Slit open one of

* See foot-note p. 46.

46 LABORATORY EXERCISES.

the tubes of sheep's intestine,* moisten it, and
tie it tightly over the larger end of the thistle-
tube/ taking care that none of the grape-sugar
solution escapes. Stand the thistle-tube (mem-
brane down) in a glass bottle filled with water
up to the level of the grape-sugar solution.
Mark on the bottle the level of the two liquids.
Connect a long piece of glass tubing to the
smaller end of the thistle-tube and support it
in a vertical position. (The experiment can
be demonstrated better in a large class-room
if a little red ink is dropped on the top of the
grape-sugar solution.) (See Fig. 4.)

1. At the end of several hours notice the level

reached by the liquid within the thistle-
tube. Measure the difference between
the level of the liquid within the thistle-
tube and the level of the liquid in the
bottle.

2. Remove with a glass-tube some of the water

on the outside of the thistle -tube (in the
bottle). Test it with Fehling's solution.
What is the result? How do you ac-
count for this result?

3. Which of the two liquids (the water in the

bottle or the grape-sugar solution in the

* Parchment paper may be used instead of the dried sheep's in-
testine to cover the end of the thistle-tube. Or a membrane may
be obtained which will answer the purpose by dissolving the mineral
portion of an egg-shell, leaving the lining membranes intact; the
membrane may then be tied to the end of the tube

PRINCIPLES OF OSMOSIS.

4:7

thistle -tube) was the more dense at the
beginning of the experiment?

Has more liquid passed into the thistle-tube
or out from it ? How do you know ?

When two liquids, therefore, of different
density are separated by an animal mem-
brane what change tends to take place?
Is the greater flow of liquid from the less
dense to the more dense or from the
more dense to the less dense?

FIG. 4.

6. Mark the level of the liquid in the thistle-
tube at the end of each successive twen-
ty-four hours. What inferences do you
draw?
B. Into a second this tie -tube carefully pour some

starch-paste, cover with animal membrane,

48 LABORATORY EXERCISES.

and invert in a bottle of water, adding red ink
as in A above. The experiment will be more
striking if the level of the liquids in the two
experiments is the same.

1. What is the level of the liquid within the

second thistle-tube at the end of twenty-
four hours? Take measurements as in
the preceding experiments.

2. Test the water in the bottle with iodine.

What is the result and what do you con-
clude ?

3. In what respects are the two experiments

(A and B) alike? How do they differ?

4. Why, therefore, is it necessary that starch

be changed to sugar before it can be used

in the body?

C. Prepare a third thistle- tube in the same manner
as in A and B, except that raw white of egg
should be used instead of sugar or starch.

1. At the end of twenty -four hours determine

by measurement the height of the liquid
in the thistle-tube.

2. Test the water in the bottle by boiling it

and then testing it with nitric acid and
ammonia. What is the result?

3. In what respects are the three experiments

alike? How do they differ?

4. (Protoplasm always contains water and al-

bumin.) Explain why the protoplasm
of cells can absorb liquid nourishment.
Can protoplasm soak out of cells ? Give
reason.

DIGESTION OF NUTRIENTS.

49

D. Summary.

1. From the above experiments give a con-

cise definition of osmosis.

2. State a law of osmosis that will hold good

for all the experiments.

3. Classify all the substances you have tested

in a table like the following:

CRYSTALLOIDS.

(Substances which will readily
pass through an animal mem-
brane.)

COLLOIDS.

(Substances which will not readi-
ly pass through an animal
membrane.)

24. DIGESTION OF NUTRIENTS.

Kind of nutrient.

In what re
gion of ali-
mentary ca-
nal is it di-
gested or dis-
solved?

By what juice
is it digested
or dissolved?

To what sub-
stance is it
changed?

In what re-
gion or re-
gions of ali-
mentary ca-
nal is it ab-
sorbed?

Nitrogenous food . .
Nitrogenous food . .
Fat . ....

Fat ...

Starch

Starch

Sugar

Soluble salt

Insoluble salt
Water .

50 LABORATORY EXERCISES.

25. STUDY OF BEEF BLOOD. (Dem.)

Materials : Concentrated nitric acid and ammonia, iodine solution,
Fehling's solution; test-tubes, alcohol-lamp, platinum-foil, bottle
and rubber stopper; three bottles of blood prepared as follows:

Bottle No. 1. — Take a bottle to the slaughter-house and get the
butcher to fill it with fresh blood. Carefully set it aside (in cold
storage room if possible), taking care not to jar in the least the con-
tents. At the end of several days the solid clot should be sur-
rounded by a transparent serum of a pale straw color. Label the
bottle Clotted Blood.

Bottle No. 2. — Get the butcher to collect some blood in a pail and
whip it rapidly for some time with a brush-broom or with his hands.
Fill bottle No. 2 with the red liquid remaining in the pail, labelling
it Defibrinated Blood.

Bottle No. 3. — Collect the stringy substance clinging to the broom,
wash it with water until it is white, and place it in bottle No. 3, in
a 4$ solution of formalin * or in 80$ alcohol ; label it Blood Fibrin.

A. Study of clotted blood.

1. Describe the preparation of clotted blood

(see Bottle No. i under Materials above).

2. Pour off all the liquid serum into another

bottle of the same size.

a. What proportion of blood appears to

be serum?

b. What is the color of the serum ?

3. The solid mass left behind in Bottle No. i

is the blood-clot.

a. Hold the bottle in a horizontal posi-

tion and compare the shape of the
clot with that of the bottle.

b. What is the size of the clot compared

with the size of the bottle? (See
2, a above.)

* 4% formalin is prepared by diluting 1 volume of formalin with
10 volumes of water,

STUDY OF PEEP BLOOD. 51

c. Gently shake the bottle. Describe

the consistency of the clot.

d. What is its color? Is the whole mass

of the same color?

4. Determine the composition of the blood-
serum by the following experiments :

a. Pour a small portion of the serum

into a test-tube and heat gradually
over an alcohol lamp ; what change
takes place? What kind of nutri-
• ent do you, therefore, conclude to
be present?

b. Dip a piece of unglazed paper into the

blood-serum and allow the paper
to dry. How is the paper affected ?
What is the second food-stuff
found in serum?

c. Test a little of the serum with iodine.

What is the result? Why ought
this result to have been expected?

d. Pour into another portion of the se-

rum some Fehling's solution and
boil. What is the result? Did
you expect this result? Can you
suggest any possible explanation
of this result?

e. Put a few drops of the serum on a

piece of platinum foil and heat as
hot as you can in a gas flame. De-
scribe the various changes that take
place and explain each. What
kind of material is left after the

52 LABORATORY EXERCISES.

blood is completely burned, and
what does this prove as to the
composition of serum?

/. Warm some blood-serum in a test-
tube. What do you find on the
inner surface of the upper part of
the tube? What ingredient is
therefore present in blood in large
quantity?

g. From the preceding experiments name
all the food materials you have
found present in blood-serum and
state those that are absent.

B. Study of defibrinated blood.

1. Describe the preparation of defibrinated

blood (see Bottle No. 2 under Materials
above).

2. What ingredient of blood has been re-

moved? (See Bottle No. 3.)

3. Where is this substance found in the clotted

blood?

4. What, therefore, is the effect of whipping

blood, and why?

5. Remove a piece of blood fibrin from bottle

No. 3.

a. What is its color?

b. Pull it apart. Describe some of its

characteristics. Is it elastic?

c. Test a piece of blood fibrin with nitric

acid and ammonia. What do you
conclude as to its composition?

C. Change in blood after mixing with oxygen.

MICROSCOPIC STUDY OF CORPUSCLES. 53-

. Pour a small quantity of defibrinated blood
into a glass bottle. Describe its color.

. Stopper the bottle tightly and shake it vio-
lently for a minute or two.

a. What change has taken place in the

appearance of the blood?

b. With what was the blood mixed dur-

ing the process of shaking?

c. In the human body where does this

change take place?

26. MICROSCOPIC STUDY OF CORPUSCLES.

(Dem.)

Materials- Prepared slides of frog's blood and of human blood;
compound microscope (500 diameters)

A. Corpuscles of frog's blood.

1. How many distinct types of solid bodies

(corpuscles) can you see in the frog's
blood?

2. Is there any variation in the form or size of

different corpuscles of the same type?

3. Draw two corpuscles (differing as much as

possible) of each type, much enlarged,
labelling nucleus and cell-body.

B. Corpuscles of human blood.

1. What is the form of the corpuscles in hu-

man blood? (Examine several corpus-
cles before deciding.)

2. In what respects do these corpuscles differ

from those found in frog's blood?

i

54: LABORATORY EXERCISES.

27. STUDY OF THE BEEF HEART. (Dem.)

Materials: The best material for demonstrating the structure of
the heart to large classes is an ox heart. In procuring the heart
from the butcher make sure that the pericardium is uninjured and
that the blood-vessels are left as long as possible

Cut around the pericardium just below its attachment to the
upper part of the heart, and lay the sac aside, so that it may again
be put around the heart. Attention should be called to the con-
nective tissue, of which the pericardium is largely composed, and to
its smooth, serous lining.

Dissect away the fat from the auricles in order that their shape
may be demonstrated. Make careful incisions into each of the four
chambers in such a way that when the walls are pulled aside, the
following structures may be demonstrated- the openings from the
auricles to the ventricles, the mitral and tricuspid valves that guard
these openings, the semilunar valves at the mouths of the arteries,
and the openings from the veins into the auricles. Call attention
also to the relative thickness of the walls in each chamber, and to
the differences between arteries and veins.

Many points can be shown more clearly if a second beef heart is
cut horizontally into three parts. The first cut should be made
through the two auricles, just above the auriculo- ventricular orifices;
the second should pass across the two ventricles, half-way between
the apex and the openings from the auricles. It is worth while to
make a careful dissection of the two hearts, since they can be pre-
served in 4$ formalin,* and so used year after year. If possible,
fresh sheep hearts, dissected as directed in the preceding paragraph,
should be supplied the students, so they can verify the facts demon-
strated by the teacher.

The following outline is suggested for recording the principal
facts relating to the structure of the heart.

A. Using the descriptive terms anterior and pos-
terior, dorsal and ventral, right and left (with
reference to the animal), locate the following

* 4% formalin is prepared by diluting 1 volume of formalin with
10 volumes of water.

STUDY OF THE BEEF HEART. 55

structures in the heart, giving, when possible,
the number of each:

1. Auricles. 5. Mitral valve.

2. Ventricles. 6. Papillary muscles.

3. Semilunar valves. 7. Chordae tendineae.

4. Tricuspid valve.

B. Name the chamber of the heart with which each

of the following blood-vessels is connected:

1. Aorta. 3. Pulmonary veins.

2. Pulmonary artery. 4. Venae cavae.

C. State all the differences which you note between —

1. Dorsal and ventral surfaces of the heart.

2. Anterior and posterior ends of the heart.

3. Auricles and ventricles.

4. Largest veins and largest arteries.

5. Mitral and tricuspid valves.

6. Mitral and tricuspid valves and semilunar

valves.

D. Enumerate the differences between the right and

left sides of the heart.

56 LABORATORY EXERCISES.

28. CIRCULATION OF THE BLOOD IN THE
TAIL OF THE TADPOLE. (Dem.)

Cut a hole a half-inch square near the end of a piece of thin board
three inches long and one inch wide ; glue a thin cover-glass over the
hole. Cover the rest of the piece of wood with absorbent cotton
soaked in water. Lay a live tadpole on the cotton, placing the tip
of the tail on the cover-glass. Lay a cover-glass on top of the tail,
and fasten cheese-cloth over the animal to keep it in place. Keep a
plentiful supply of moisture about the animal, by allowing the end
of the strip of cloth to dip into a dish of water. Examine the tip of
the tail with a compound microscope magnifying about 75 diameters

. i. At the highest focus note the epithelial cells
forming the outside layer of the body
covering. What is their shape?

2. What is the shape of the dark pigment-cells

seen just beneath the epithelial cells?

3. Focus still lower and study the flow of the

blood in the small capillaries.

a. Is the current steady in all the blood-

vessels which you see?

b. Do the red corpuscles alter in shape

as they move along?

c. Can you distinguish any colorless cor-

puscles?

d. Draw a small area of the tail, repre-

senting the course of the capilla-
ries. Indicate by arrows the
course of the blood in each capil-
lary.

NOTE. — If tadpoles cannot be obtained, the web of a frog's foot
may be examined after confining the frog on a larger piece of board
than that described above.

PULSE IN THE PUPIL'S OWN BODY. 57

29. PULSE IN THE PUPIL'S OWN BODY.

To feel the pulse place the forefinger of the left
hand on the radial artery of the right hand at the
lower end of the radius bone on the palm side.
Count the number of beats during a minute.

A. Variations in the pulse-beat.

1. Make out in your note-book a statement of

your pulse -rate taken under the follow-
ing conditions :

a. Before rising in the morning.
6. Just before eating breakfast.

c. Just after breakfast.

d. Just after some violent exercise.

2. What is your conclusion from these obser-

vations ?

B. Find your pulse in the following places on your

body, locating each with reference to the bones
of the skeleton :

1. On the side of the head in front of the ear.

Trace this artery as far as possible.

2. On the back of the head near the top of the

neck.

3. On the side of the lower jaw.

4. In the hollow back of the knee-joint,

5. On the ankle.

58 LABORATORY EXERCISES.

30. STRUCTURE OF BONES.

Materials (for each two pupils): A complete rib of sheep, care-
fully separated from its attachment to a vertebra; a piece of a rib of
beef, an inch long, sawed lengthwise in halves; a leg-bone of sheep,
from which meat has been removed; one-half leg-bone like the pre-
ceding, sawed lengthwise ; a piece of the shaft of a leg-bone of sheep,
sawed cross-wise; dissecting-needle and scalpel. (After completing
the study of the structure, lay aside the bones for the next experi-
ment.)

A. Structure of a rib (flat or tabular bone) .

1. What is the general form of the bone?

2. Try to bend it. What do you conclude?

3. Cut off a thin slice of the covering of the

enlarged end of the rib. Give some
characteristics of this cartilage.

4. Stick the point of the dissecting-needle into

the surface of the bone where it is free
from muscle. Peel off some of the thin
membrane of connective tissue. This
membrane is per-i-osf -te-um.

a. What are some of the characteristics

of periosteum? Try to tear it.

b. Where is periosteum found on the

rib? Where is it wanting?

5. Study the section of the rib, pricking the

different parts with the dissecting-needle.

a. In what respects does the outside

layer of hard bone differ from the
spongy bone in the interior?

b. Describe the color of the marrow.

What does this color suggest as

STRUCTURE OF BONES. 59

to the presence of blood? Is the
marrow hard or soft? Dig out a
bit of it and rub it on a piece of
paper. Hold the paper to the
light. Of what nutrient is mar-
row largely composed?
B. Structure of a soup-bone (long bone).

1. What is the general form of the bone ? How

does it differ from a rib? How do the
two heads at the end of the bone differ
from the shaft ? Can you suggest the
use of the heads?

2. What kind of tissue covers the end of each

head? Suggest a reason for this.

3. Where is periosteum found and where is it

absent?

4. In the longitudinal section of the long bone

distinguish periosteum, cartilage, hard
bone, spongy bone, and marrow. State
the region or regions of the bone in
which each is found.

5. Compare the cross-section of the shaft of a

long bone with the cross-section of a rib.
In what respects do the two resemble
each other? How do they differ?
C. Summary.

1. Name all the kinds of tissue found in

bones.

2. Suggest, as far as you can, the use of each.

3. Can you give any reasons to explain why

bones are not solid throughout? (Com-
pare with the frame of a bicycle.)

60 LABORATORY EXERCISES.

D. Drawings.

1 . Represent in a drawing the longitudinal and

cross-section of the piece of rib, indicat-
ing diagrammatically the different kinds
of tissue.

2. In the same way make drawings of the lon-

gitudinal and cross-sections of the long
bone.

31. COMPOSITION OF BONES.

Materials : Two clean ribs ; the two halves of the soup-bone used
in 30; diluted hydrochloric acid (6 parts water to 1 part acid) ; weigh-
ing balances; a piece of wire.

A. Action of acid on bone.

Compare the two ribs as to form and size;
place one of them in a bottle of diluted hydro-
chloric acid. Allow the bone to remain in the*
acid for a few days and then compare the two
ribs again.

1 . Has the acid changed the form of the bone ?

2. Has it changed the size of the bone?

3. Try to bend the two rib bones. What

change do you observe to have taken
place in the one which has been in the
acid?

4. Pour some of the liquid in which the bone

has been soaking into an evaporating-
dish and heat over an alcohol- lamp or
over a gas-flame until the liquid has dis-
appeared. What kind of substance is

COMPOSITION OF BONES. 61

left in the dish? (This substance is a
kind of mineral matter formed from the
mineral matter of the bone by the action
of the acid.) See experiment 20, B.
5. What properties of bone are due to the
presence of mineral matter?

B. Effect of burning bone.

Weigh half of the long bone used in 30. Tie
a piece of wire about it and place it in a hot
coal fire. Allow it to remain for a half -hour
and then remove it carefully by means of the
wire.

1. Write in your note-book a brief account of

all the changes which you observed while
the bone was in the fire.

2. Has the bone been changed in form or size?

3. What change can you see in the bone?

4. What part of the bone has been most af-

fected by the fire?

5. Try to break the bone; what is the use in

bone of the substance which has been
lost?

6. Weigh the bone and determine what per

cent, of the original bone remains as ash
(mineral matter) and what per cent, has
disappeared (animal matter).

C. Effect of boiling bones in water.

Place the other half of the soup-bone in a
pint of water and allow it to simmer on the
back of the stove for 4 to 6 hours. Strain the
liquid through a cloth and allow it to cool.
I. Describe the substance which is obtained.

LABORATORY EXERCISES.

2. Test a small portion of this " soup-stock
for nutrients. (Experiments 8-J3.)

32. CLASSIFICATION OF BONES.

From the articulated skeleton make lists of—

1. Long bones (distinguished by shaft and ar-

ticular extremities or heads).

2. Short bones (more or less cubical in shape).

3. Tabular or flat bones (flat like rib and with

no marrow cavity).

4. Irregular bones (all others).

33. STUDY OF THE MUSCLES.

Definitions.

1. The part of the muscle which contracts is

the belly; the bands or cords at the ends
are the tendons.

2. The end of the muscle, that is, the tendon,

which moves least is called the origin; the
tendon which moves most, the insertion.

3. Muscles which bend or flex the limb are

called flexors; muscles which straighten
or extend the limb, extensors.
A. The biceps muscle (a flexor muscle).

i. Clasp the front of the right upper arm with
the left hand; draw up or flex the right
forearm as far as possible. What
changes do you notice in the belly of the
muscle ?

STUDY OF THE MUSCLEB. 63

2. Place the tips of the fingers of the left hand

at the lower end of the belly of the right
biceps muscle and the thumb at its up-
per end. Flex and extend the right fore-
arm several times. What change takes
place in the length of the muscle ?

3. Enumerate, therefore, three changes you

have found to take place in the belly of
a muscle when it contracts.

4. Roll the sleeve above the biceps muscle.

Let the arm hang free, and with a tape-
measure get the circumference of the
upper arm around the middle of the belly
of the biceps muscle. Flex the forearm
as strongly as you can and then deter-
mine the circumference. What is the
amount of increase in size ?

5. With the thumb and forefinger of the left

hand grasp the tendon at the lower end
of the right biceps muscle; rotate the
right forearm. To which of the bones
of the forearm, therefore, is the biceps
attached? Point out on the skeleton
the rough prominence where the tendon
is attached to this bone.

6. (Dem.) Demonstrate on the shoulder-blade

the point of attachment of each of the
two upper tendons of the biceps.

7. Which tendon (upper or lower) of the bi-

ceps moves the more when you lift a
book? Which end is, therefore, origin,
and which insertion? Locate the belly

64: LABORATORY EXERCISES.

of the biceps with reference to the hu-
merus.

B. The triceps muscle (an extensor muscle).

1 . Clasp the back of the right upper arm with

the left hand; forcibly straighten or ex-
tend the right forearm as much as you
can. Locate the belly of the triceps with
reference to the belly of the biceps, and
with reference to the humerus.

2. By flexing and extending the forearm de-

termine the position of the lower tendon
of the triceps. To which bone of the
forearm is it attached?

3. (Dem.) Point out on the shoulder blade

and humerus the attachment of the three
upper tendons.

C. The flexor muscles of the fingers and of the thumb.

1. Clasp the right forearm near the elbow;

clench the hand quickly and forcibly.
Locate the belly of these flexor muscles
with reference to the bones of the fore-
arm.

2. Press the forefinger and thumb strongly to-

gether. What change is noticed in the
thick mass of muscle at the base of the
thumb? Along what bone does this
flexor muscle of the thumb lie?

3. What would be the form of the hand if the

flexor muscles of the fingers were located
in a position corresponding to the flexor
muscle of the thumb? What is gained
by placing these muscles in the forearm ?

STUDY OF THE MUSCLES. 65

4. Measure the circumference of the forearm

when the hand is open, and again when
it is tightly closed. Record your results.
Compare amount of increase with fig-
ures for biceps.

5 . Pull up your sleeve. Flex the fingers several

times i and note the movements of the
tendons in the wrist. Along what bones
do these tendons pass?

D. The extensor muscles of the fingers.

1. Straighten back the fingers as far as pos-

sible, and by feeling of the back of the
forearm locate the belly of the extensor
muscles of the fingers.

2. Move the middle finger alone. Describe

the movements of the tendons on the
back of the hand. What do you con-
clude?

3. Flex the middle finger of each hand until it

touches the palm of the hand; place the
two hands together (palms facing) so
that the tips of the forefingers, fourth
fingers, and little fingers touch, pressing
the backs of the middle fingers closely
together. Try to separate each of the
pairs of fingers, still keeping the middle
fingers pressed together. Explain re-
sult. (See 2 above.)

E. The muscles which move the ankle.

i. Stand on tiptoe and locate in the calf of the
leg the belly of the extensor muscles of
the foot which cause this movement. To

66

LABORATORY EXERCISES.

which bone is the lower tendon of this
muscle (tendon of Achilles) attached?

2. Determine the position of the flexor muscle
of the foot by flexing the ankle as far as
possible. Which is the larger, the flexor
or the extensor? Why?
F. The jaw-muscles.

Alternately close the jaws tightly together and
open them. Find the muscles which
cause these movements. Watch in the
glass and describe the movements of
these muscles.

Fill out in your note-book a table like the fol-
lowing :

Name of muscle.

Belly opposite
what bone
or bones.*

Origin at-
tached to what
bone or bones.

Insertion at-
tached to what
bone or bones.

Biceps

Triceps. .

Flexor muscles of fingers. . . .
Extensor muscles of fingers .
Flexor muscles of foot

Extensor muscles of foot

* Before deciding as to position of origin and insertion be sure to
put the forefinger on the middle of the belly of each muscle.

STUDY OF BEEFSTEAK. 67

34. STUDY OF BEEFSTEAK:

Materials : Slices of meat from the shank of beef about an inch
thick. Cut the slices into blocks about a half -inch square. The
structure is seen more clearly if the meat is allowed to dry in the air
for a few hours. Dissecting-needles, slide and cover-glass, com-
pound microscope \" -objective

A. Gross structure of muscle.

1. Pull apart more or less the small bundles of

which the meat is composed. What is
their shape ? Are they all the same size ?

2. What is the color of the meat? What do

you infer as to the presence or absence
of blood?

3. What are the characteristics of the tissue

(perimysmm) which surrounds and con-
nects the muscle bundles?

4. Can you distinguish any fat in the piece of

meat you are studying? Make sure of
your answer by rubbing it on a piece of
paper. If fat is present, where is it sit-
uated and what are its characteristics?

5. Is tendon (gristle) present? If so, give

some of its characteristics.

6. Make a drawing of the piece of muscle show-

ing cross and longitudinal sections ( X 5).
Label bundles, perimysium, and fat and
tendons if present.

B. Microscopic structure of muscle.

Separate with dissecting-needles a small por-
tion of the muscle ; cover it with water and tear

68 LABORATORY EXERCISES.

it apart with the needles until you have the
smallest portion of the bundle which you can
get. Place this bit of muscle on a glass slide,
add a drop of water, and tease it out with
needles; cover with glass and examine under
the high power of the compound microscope.

1 . Of what is the piece of muscle found to con-

sist?

2. Why is this kind of muscle called striped

muscle?

3. Draw a muscle-bundle as seen under the

microscope. Label fibres, cross-stripes.

35. STRUCTURE OF A JOINT.

Materials: Fresh leg-joint of lamb or veal; scalpel.

A. Movement at the joint.

1. Hold one of the bones in a fixed position;

in how many directions can the other
bone be moved?

2. What prevents the joint from moving in

other directions?

B. Muscles and tendons.

1. Dissect away the muscle with the scalpel;

by what are the muscles attached to the
bones?

2. Try to stretch or break these cords (ten-

dons) ; what properties of tendons does
this demonstrate?

3. What is the advantage of the absence of

muscle-tissue over joints?

STRUCTURE OF A JOINT. . 69

C. Ligaments.

1. What kind of tissue holds the bones to-

gether after the muscle is removed?

2. How is this tissue attached to bone so as to

allow movement at the joint?

D. Joint-cavity.

1. Cut through the ligaments with a scalpel so

as to open the joint-cavity; what is the
appearance of the liquid within (synovial
fluid) ?

2. Suggest the use of the synovial fluid.

E. Cartilage.

1 . Cut thin slices of cartilage from the ends of

the bones; what are the characteristics
of cartilage ?

2 . Why is cartilage placed at the ends of bones

where motion occurs?

F. Bones.

1. Describe the way the bones fit together at

the joint.

2. Is twisting motion possible at this joint?

G. Periosteum.

Stick the point of the scalpel into the sur-
face of the bone where all the muscle has been
removed. Peel off some of the thin .mem-
brane (periosteum).

1. What are the characteristics of periosteum?

2. Where do you find periosteum on long

bones?

H. Make a list of all the structures found in the
joint, giving the use of each.

70 LABORATORY EXERCISES.

36. STUDY OF THE JOINTS IN THE BODY.

A. Ball-and-socket joints.

1. Note on the articulated skeleton what bones

form the joint at the shoulder.

2. Point out the bones forming the hip-joint.

3. State the points of resemblance between

these two joints.

4. What differences can you see in the sockets

of the two joints? How does the head of
the femur differ from that of the humerus ?

5. Move your right arm and right leg at the

same time from a vertical position in an
arc sideways toward the right; state in
number of degrees the greatest range of
motion possible at the shoulder- joint and
at the hip- joint.

6. In the same way move the arm and leg in an

arc forward as far as possible ; backward
as far as possible. Compare the range of
motion at each joint.

7. Describe a cone with the extended arm and

leg; twist the arm and the leg at their
proximal ends. What kinds of move-
ments are, therefore, possible at these
joints other than those suggested in 5
and 6 above?

8. Press the thumb on the hip-bone during

these movements, then on the edge of
the shoulder-blade. Is either of the two
girdles movable? What advantages are

STUDT OF TEE JOINTS IN THE BODY. 71

gained by the difference in the structure
of these two girdles?

B. Hinge-joints.

1 . Determine from the articulated skeleton the

bones which form the hinge- joint at the
elbow.

2. What bones form the joint at the knee?

3. What projection at the elbow occupies a

position corresponding to the knee-cap
or patella?

4. Move the right forearm and the right leg at

the same time; state in which direction
(i.e., anteriorly or posteriorly) each is
bent.

5. Hold the humerus and the femur in a fixed

position. Is lateral motion possible at
the knee or elbow- joint ? Show from the
articulated skeleton the reason for this.

6. In how many directions can a hinge- joint

be moved? How, therefore, can you
distinguish between a ball-and-socket
and a hinge -joint?

7. Are the joints between metacarpals and

phalanges ball-and-socket or hinge?
Why?

8. Make a list of all the hinge- joints in the

body, naming the bones which form the
joint in each case.

C. Pivot- joints.

i. Place the right forearm on the table with
the palm of the hand upward. Without
lifting the elbow from the table turn the

72 LABORATORY EXERCISES.

hand until the palm of the hand rests on
the table.

a. Which of the bones of the forearm has

crossed the other?

b. Note on the articulated skeleton what

two bones form this pivot- joint at
the elbow.

2. Study the two top vertebrae of the spinal
column; move the vertebrae on each
other. Describe the provisions that en-
able a person to turn his head from side
to side.
D. Gliding joints.

1. Count on the articulated skeleton the bones

forming the wrist.

2. How many form the ankle?

3. Which bones are the larger, those of wrist

or ankle? What advantage is gained in
each case?

4. Move your right wrist and right ankle in as

many directions as you can. At which
joint is the greater range of movement
possible ?

5. Move your lower jaw in as many directions

as you can.

a. Between what bones does this move-

ment take place?

b. To which classes does this joint, there-

fore, belong?

6. Study the joints between the vertebras;

show how the vertebras, move on each

COMPARATIVE STUDY OF MAMALIAN SKELETON, 73

other, enabling one to bend the back or
twist the spinal column.

37. COMPARATIVE STUDY OF THE MAMA-
LIAN SKELETON.

(At the American Museum of Natural History, 8th Ave. and 77th St.)

NOTE. — The skeletons of the lion, horse, seal, musk-ox, sea lion,
and elephant are among those best adapted for observation.

A. Spinal column.

1 . How many vertebrae are found in the neck

(cervical) region?

2. How many vertebrae bear ribs (dorsal ver-

tebrae) ?

3. How many vertebrae in the lumbar region?

4. Can you determine how many vertebrae

have united to form the sacrum?

5. How many vertebrae in the tail (caudal ver-

tebrae) ?

6. In what regions of the spinal column are

curves noticeable? How do they differ
from the curves in the human skeleton?

7. Are spinous processes specially developed

in any region? (The head is supported
by muscles attached to these processes.)

B. Ribs and sternum.

8. How many pairs of ribs has the animal?

9. How many are attached to the sternum?
10. Is the sternum a single piece of bone? If

not, of how many parts does it seem to
consist ?

74 LABORATORY EXERCISES.

C. Anterior appendage.

11. Can you distinguish a shoulder-blade

(scapula) ?

12. Has the animal a collar-bone (clavicle)?

13. What fractional part of the length of the

anterior appendage is formed by the hu-
merus?

14. What is the relative size of radius and ulna?

15. Are radius and ulna anywhere united or is

it probable that rotation of the radius
about the ulna is possible?

1 6. Is the projection ("funny-bone '') on radius

or ulna?

17. How many wrist-bones (carpals) in the an-

terior appendage?

1 8. Does the animal walk on the palm of the

hand or on the tips of the fingers?

19. How many fingers (or toes) of anterior ap-

pendage does it use?

20. How many bones are there in each finger?

21. Is a thumb distinguishable?

22. What use does the animal make of the an-

terior appendages? (Walk, swim, fly,
catch prey, burrow, etc.)
D. Posterior appendage,

23. Is a knee-cap (patella) distinguishable?

24. What is the relative size of tibia and fibula?

25. How many ankle-bones (tarsals) are found

in the posterior appendage?

26. How many toes of the posterior appendage

does the animal use ?

27. Are the bones of the appendages long and

ACTION OP THE DIAPHRAGM AND THE LUNGS. 75

slender or short and clumsy? Does the
animal, therefore, seem to be adapted for
swift or for slow locomotion? Give rea-
sons for your answer.
E. Teeth.

28. What is the dental formula (number of in-

cisors, canines, grinders in each half-
jaw) ?

29. Did the animal probably eat animal or vege-

table food? Reason for answer?

38. ACTION OF THE DIAPHRAGM AND THE
LUNGS. (Dem.)

Procure a bell-jar with an opening at the top for a stopper. Place
a marble in the centre of a sheet of rubber, tie the rubber about it,
and stretch the sheet of rubber over the larger end of the bell- jar,
tying tightly. Secure a rubber stopper (provided with two holes)
which will fit the opening in the top of the bell-jar. Pass a thistle-
tube through one of the holes in the rubber stopper and tie a toy
balloon to its lower end. Through the other hole pass a glass tube,
attaching to the upper end a piece of rubber tubing closed with
a clamp. Insert the rubber stopper in the opening at the top of the
bell-jar with the toy balloon within the jar. Make sure that all con-
nections are tight, by applying paraffin to the top surface of the cork.

The balloon represents a lung; the thistle-tube to which it is tied,
the larynx and windpipe; while the bell-jar itself represents the
chest-cavity, and the sheet rubber the diaphragm.

A. Exhaust some of the air from the bell-jar by ap-
plying the mouth to the rubber tubing, and
then replace the clamp.

i. Is the pressure of air greater now within the
bell- jar or without?

LABORATORY EXERCISES.

2. What is the effect on the sheet lubber of re-

moving air from within the jar? Explain.

3. How is the toy balloon affected? Why?

FIG. 5.

B. Seize the marble tied into the sheet of rubber and
make the latter move up and down.

1. Does the air within the bell- jar have more

or less room when the rubber is pulled
down?

2. Is the pressure within the glass jar now

CIRCULATION OF AIR IN SCHOOLROOM. 77

greater or less than when the rubber dia-
phragm was pushed up into the glass
bell jar?

3. What is the effect on the rubber balloon of
thus increasing the size of the cavity in
which the balloon is hung? Why?
C. Application to the action of human diaphragm

and lungs.

1. In what respects does this model illustrate

the process of inhaling and exhaling air
in our own bodies?

2. In what respects does the model fail to il-

lustrate the process of respiration?

39. CIRCULATION OF AIR IN SCHOOLROOM.
(Dem.)

Materials: Concentrated hydrochloric acid, concentrated ammo-
nia; evaporating-dishes.

Pour into an evapora ting-dish some concentrated
hydrochloric acid ; into another dish pour some con-
centrated ammonia.
A. Bring the two dishes near together.

1. What is the effect?

2. Place the two dishes near the hot-water or

steam -pipes. Describe the course of the
fumes.

3. Place the dishes near the opening to a ven-

tilator. What course do the fumes take ?

4. Draw a diagram of the room and indicate

by arrows the course of the moving air
as demonstrated by the fumes.

78 LABORATORY EXERCISES.

B. Open a window, and place the two dishes near a
steam-pipe near the window.

1. Does the moving air take the same course

as before?

2. Does the open window help or retard the

ventilation of the room?

NOTE. — Gunpowder or flash-paper may be used instead of the
acid and ammonia.

40. INSPIRED AND EXPIRED AIR. (Dem.)

Materials : Thermometer, bottle fitted as described in C below J
lime-water.

A. Difference in temperature.

1. Note on a thermometer the temperature of

the air in the room.

2. Breathe for a few seconds on the bulb of the

thermometer. Note temperature.

3. What is the difference in temperature be-

tween inspired and expired air?

B. Difference in amount of moisture.

1 . Breathe again upon the polished bulb of the

thermometer. Describe result.

2. What substance is thus shown to be one of

the wastes excreted by the lungs?

C. Differences in chemical composition.

Secure a bottle fitted with a rubber stopper
with two holes. Through one hole in the stop-
per pass a glass tube (No. i) until it reaches
nearly to the bottom of the bottle. Pass the
end of another tube through the other hole, al-

INSPIRED AND EXPIRED AIR.

79

lowing the tube to project but a short distance
into the bottle ; attach a piece of rubber tubing
to the upper end of this tube (No. 2). Half -fill
the bottle with clear lime-water and insert the
stopper. (See Fig. 6.)

1. Apply the mouth to tube No. 2, exhausting

the .air from the bottle.
Describe result.

2. Draw into the lungs

through the lime-water
a considerable quantity
of air in this way. Does
any change take place
in the lime-water?

3. Does inspired air therefore

contain a large amount
of carbon dioxid?

4. Apply the mouth to tube

No. i (which passes
below the level of the
lime-water). Expel the
air from the lungs
through the lime-water.
Describe any changes
in the lime-water.

5. What is your inference

from 4?

D. Name three differences between inspired and ex-
pired air.

80 LABORATORY EXERCISES.

41. TEMPERATURE OF THE BODY.

A. Place the bulb of a chemical thermometer be-

neath the tongue, closing the lips over it.

1. To what point does the mercury rise?

2. Is the temperature which you have deter-

mined the same as that found by the
other pupils ?

3. Take your body temperature on a cold day,

then on a warm day; do you notice any
difference ?

4. Determine whether the body temperature

is the same after violent exercise as it is
before.

B. Production of heat.

1 . How was heat produced in experiment \ ?

2. How is heat produced in your body?

3. Is light produced in the human body (as in

42. STUDY OF THE SKIN.

Materials: Clean needle; printer's or mimeograph ink.

A. Epidermis.

i . Wash the hands thoroughly in warm water,
then dry them; rub together the palms
and fingers of both hands briskly for a
moment. What do you see on your
hands as the result? (This material was
a part of your non-living epidermis.)

STUDY OF THE SKIN. 81

2. Run the point of a clean needle beneath the

thin outer layer of the skin on the palm
of the hand.

a. Does the needle cause blood to flow?

Is the outer layer of skin (epider-
mis) supplied with blood-vessels?

b. Does the insertion of the needle cause

any pain? Can you feel the point
of the needle touch the skin?
Would you infer that nerves en-
tered the epidermis or not?

3. In what regions of the surface of the hand

is the epidermis thickest? How do you
know? In what region is it thinnest?

4. Press the tip of the forefinger on a piece of

cloth covered with some thick ink (prin-
ter's ink or mimeograph ink is best), then
press the finger-tip on a page in your note
book. Study the impression made.

a. Are the black lines (made by the

ridges on the finger) all of the same
width? Are they all parallel to
one another?

b. In the same way take the impression

of the tips of your other fingers and
of your thumb. In what respects
do these various impressions
differ?

c. Where else on your hand can you see

similar ridges?

d. What other lines are visible on the

palm of the hand?

82 LABORATORY EXERCISES.

B. Hair.

1 . On what portions of the hand is hair found ?

Where is it wanting?

2. Compare the hair on the surface of your

hand with that on the hand of an
older person. What difference do you
note?

3. Do blood-vessels run into the hair? How

do you know?

4. Which part of the hair is supplied with

nerves? How do you know?

C. Nails.

1. What different areas do you notice in your

thumb-nail? How do they differ in ap-
pearance?

2. Make a drawing of your thumb-nail, show-

ing these different regions.

3. Scrape off a little of the outer surface of the

nail; does this cause blood to flow? Are
nails supplied with blood-vessels?

D. Deeper layers of the skin.

1. With the thumb and forefinger of the right

hand grasp a portion of the skin on the
back of the left hand. Can you lift the
skin from the muscles and tendons lying
below ?

2. In the same way determine whether the

skin on the palm of the hand and on the
ringers is closely or loosely attached to
the underlying tissue. What do you
find to be true?

3. Determine the effect of pushing a clean

STUDY OF EXCRETION. 83

needle point a little distance into the
tissue lying beneath the epidermis.

a. Is the tinder skin (dermis) supplied

with blood-vessels? How do you
know?

b. Is the dermis supplied with nerves?

How do you know?
E. Blood system in the skin.

1. Press the finger of the right hand on the

back of the left hand; quickly remove
the finger. What difference do you note
in the color of the spot pressed and in the
skin about this spot? Give an explana-
tion of this difference.

2. From the preceding experiment can you ex-

plain the cause of sudden paleness in the
face?

3. State the difference in the relative quantity

of blood flowing through the cheek when
it is flushed and when it is pale.

43. STUDY OF EXCRETION.

A. Excretion from sensible perspiration.

1. Find the exact weight of your body imme-

diately after breakfast. Record the fig-
ure.

2. Exercise vigorously for several hours with-

out eating or drinking.

3. Find again the weight of the body. Do you

note any difference in weight?

84 LABORATORY EXERCISES.

B. Excretion from insensible perspiration.

1 . Lay the palm of your hand (when your body

feels cool) on a cold mirror. What evi-
dence do you find of the activity of the
skin?

2. Lay the back of your hand on the mirror.

a. Do you find any difference between

the amount of perspiration from
the palm and from the back of the
hand?

b. Study your hand on a hot day and an-

swer the same question.

44. STUDY OF THE KIDNEY OF THE SHEEP.

Materials: Fresh kidneys of sheep or pig in capsule, prepared for
the pupil as follows : Slit the capsule on convex side enough to allow
the kidney to be removed; cut the kidney from the convex border
toward the hilum sufficiently to open up the cavity within; replace
the kidney within the capsule; probe.

A. Exterior of the kidney.

1. Describe the capsule by which the kidney

is surrounded.

2. Carefully remove the kidney from the cap-

sule, taking care not to tear the latter.
Where is the capsule attached to the kid-
ney?

3. What is the shape of the kidney?

4. What is the color of the kidney? Why?

5. How many tubes can you find connected

with this organ? Can you suggest the
use of any of these tubes? (The depres-

STUDY of THE KIDNEY OF TEE SHEEP. 85

sion in the kidney to which the tubes pass
is called the hilum.)
B. Gross structure of the kidney.

1. Pull apart the halves of the kidney suffi-

ciently to look within.

2. What is the shape of the cavity near the

hilum '(sinus of the kidney)?

3. By means of a probe locate the tube (ureter)

which passes out from this cavity.

4. The layer on the outside of the kidney sec-

tion is called the cortical layer.

a. Does this layer anywhere reach down

to the sinus?

b. What characteristics distinguish the

cortical layer from the rest of the
solid portion of the kidney?
5- The bodies which form the medullary por-
tion of the kidney within the cortical
layer are called the pyramids of Malpighi.

a. Why is the name pyramid given to

them?

b. Do these pyramids project into the

sinus of the kidney?

c. Press one of the pyramids of Malpighi.

Can you see any substance ooze
out?

86

LABORATORY EXERCISES.

45. SENSATION OF TOUCH.

Materials: Pen and ink, pin, ruler, pair of scissors.

A. Blindfold a person, touch lightly some portion of
his body with a pen dipped in ink, and ask
him to point out with a pin the point touched,
as soon as you have removed the pen.

1. Measure the distance with a rular between

the ink-dot and the point touched with
the pin. Record result as directed be-
low in 4.

2. Try the experiment several times on the

same region of the body. Do the results
agree ?

3. Try the experiment on different parts of the

body.

4. Record results in tabular form as follows:

Part of body experimented upon.

Distance between points.

1st trial.

2d trial.

3d trial.

B. Apply lightly the points of a pair of scissors (sep-
arated about a quarter of an inch) to the palm
of your hand.

1. Can the points be felt as two, or do they feel

as one ?

2. Separate the points of the scissors a little

more than a quarter of an inch, and ap-

SENSATION OF TOUCH. 87

ply again. At what distance apart can
the points be felt as two?

In the same way determine at what dis-
tance apart the points can be felt as two
on the tip of the middle finger, on the tip
of the tongue, on the back of the neck,
on the back of the hand.

Record your results in tabular form as fol-
lows, placing the smallest distance first,
and arranging the distances in order from
smallest to greatest.

Part of body experimented upon.

Distance between points.

5. Apply the points of the scissors at the up-
per part of the arm, near the elbow, at
the wrist, and on the palm, noting at
what distance apart the points are felt
as two.

a. Is the distance greater as you ap-

proach the shoulder or as you near
the hand?

b. Does it make any difference whether

the points are applied in transverse
or in longitudinal axis of the arm?
C. Cross the middle finger of the hand over the fore-
finger, and rub the tips of these two fingers
against the point of your nose at the same

88 LABORATORY EXERCISES.

time. What impression do you receive in re-
gard to your nose?

46. SENSATIONS OF TASTE AND SMELL.

Materials: Potato, onion, apple, spices, flavoring extracts, sugar,
salt, mustard, quinine solution, vinegar.

A. Flavors of substances.

1. Secure a bit of potato, a bit of onion, and a

bit of apple; close your eyes and hold
your nose tightly ; place each of the three
in your mouth successively. Can you
distinguish by taste alone one piece from
the others?

2. Keeping the eyes closed, repeat the experi-

ment without holding the nose.

a. Can the foods be distinguished now?

b. What do these experiments teach you

in regard to the real nature of what
is commonly thought to be the
taste of certain foods?

c. Why are many foods tasteless to a per-

son with a cold in the head?

d. What method of taking disagreeable

medicines is suggested by these ex-
periments ?

3. Close your eyes and hold your nose; experi-

ment with spices, sugar, salt, mustard,
quinine solution, vinegar, peppermint,
vanilla, etc. Record your results as fol-
lows:

SENSATIONS OF TASTE AND SMELL. 89

Substances distinguished by
taste alone.

Substances distinguished by
taste and smell.

•

B. Wipe the tongue dry and place upon it a bit of

sugar.

1. Can the sugar be tasted?

2. To what condition must foods be brought

in order to be tasted?

3. What use of the saliva in the mouth does

this suggest?

4. Give a reason which may explain why sand

is tasteless?

C. Localization of taste sensations on the tongue.

1 . Place a bit of sugar on the tip of the tongue ;

another bit on the back of the tongue.

a. In which case is the sweet taste more

distinct ?

b. Determine whether sweet substances

are tasted more distinctly along the
middle of the tongue or at the edge.

2. By using a bit of salt determine in the same

way what region of the tongue is most
affected by saline substances.

3. Prepare a strong solution of quinine by dis-

solving 10 grains sulphate of quinine in
i oz. water by the aid of 5 drops sul-
phuric acid. Determine what portion
of the tongue is most sensitive to bitter
substances; the portion which is least
sensitive.

90 LABORATORY EXERCISES.

4. Test the various portions of the tongue with

vinegar.

5. Record your results as follows:

Kind of substance.

Part most affected.

Part least affected.

Sweet

Sour .

Bitter

Salt .

47. STUDY OF BRAIN OF SHEEP.

Materials : Sheep heads can be obtained from any butcher, and
the brain may be carefully removed in the following way: With a
small saw make two cuts along the top of the skull, each about
three-quarters of an inch from the mid-line of the head, care being
taken not to cut into the brain. The saw-cuts should extend from
front of the eye-sockets back to the openings into the ears. Con-
nect these longitudinal cuts by sawing across the skull in the regions
just indicated. In this way a rectangular piece of bone is loosened
which can be pried off by the use of a chisel. The cerebral hemi-
spheres of the brain, enveloped in tough dura mater, are thus ex-
posed. The bony top of the skull should be preserved in 4% solu-
tion of formalin (one volume formalin to ten volumes of water).

Continue the side cuts backward through the hard bony pro-
cesses by which the skull was attached to the spinal column, and
with a chisel pry off the rest of the top and back wall of the cranium.
Beneath it lie the cerebellum, the medulla, and the beginning of the
spinal cord.

To remove the brain from the skull the head should be supported
with the tip of the skull downward. By means of forceps take hold
of the dura mater on the ventral surface of the spinal cord and care-
fully pull it away from the base of the cranium. With dissecting
scissors or with the point of a scalpel cut off the various nerves,
leaving as much as possible of each nerve attached to the brain. If
the opening in the roof of the skull is not large enough to allow the
brain to be taken out easily, the sides can be cut away with bone
forceps.

STUDY OF BRAIN OF SHEEP. 91

If the work has been carefully done, when all the nerves are cut,
the uninjured brain comes out of the skull completely enclosed in
its membrane of dura mater. This connective tissue-sac should
then be cut along the mid-line of the dorsal surface, removed from
the brain, and placed in 4.% formalin solution. The brains, as fast
as they are removed, should be put in a shallow dish, the bottom
of which is covered with a soft layer of cotton, and over them should
be poured a 4£ solution of formalin. When the brains are ' once
hardened in this way they can be kept in alcohol and used year after
year.

To show the internal structure of the brain a horizontal cut should
be made about half an inch from the lower surface of the brain
through one of the cerebral hemispheres and through half of the
cerebeflum. By making a vertical cut also, along the ventral sur-
face, at one side of the median line the lower third of one-half of the
brain is removed, and the disposition of the gray and white matter
within the brain is shown.

Each two pupils should be supplied with a hardened brain pre-
pared as described, a piece of, or, if possible, a whole dura mater, a
rectangular piece of bone from the top of the skull with skin and
wool attached, a dissecting needle.

A. Protection of brain.

1 . What kind of outer covering has the sheep ?

How does it protect the brain?

2. Examine the piece of bone which was re-

moved from the top of the skull. What
layers can you distinguish? Why is this
arrangement of bone-tissue of great ad-
vantage as a means of protection?

3. What are the characteristics of the dura

mater (the sac covering the brain) ? Try
to tear it.

4. By means of a dissecting needle lift from

the surface of a portion of the brain a
thin covering called the pia mater. De-
scribe it. Does it cover all parts of the

92 LABORATORY EXERCISES.

brain? Does the pia mater have any
blood-vessels?

B. Fore-brain.

1. Describe the form of the two large masses

(the cerebral hemispheres) that consti-
tute the principal portion of the fore-
brain.

2. Where are the cerebral hemispheres at-

tached to each other? (The groove be-
tween them is called the longitudinal fis-
sure.)

3. What is the appearance of the dorsal sur-

face of the fore-brain? (The elevations
are called convolutions, the grooves be-
tween them, fissures.)

4. Near the anterior end of the ventral sur-

face of the brain notice two small masses.
(These are the olfactory lobes, which
connect with the nose region.) Describe
their form.

5. Moisten the section made in the lower por-

tion of one of the cerebral hemispheres
and examine it. Distinguish gray and
white matter. Where is gray matter
found and where is the white matter?

6. Note the cavity in the hemispheres. What

is its shape and size?

C. Hind-brain.

i. What is the form of the enlargement (the
cerebellum) on the dorsal surface of the
brain posterior to the cerebral hemi-
spheres?

STUDY OF BRAIN OF SHEEP. 93

2. Is it divided into two parts like the fore-

brain ?

3. What is the appearance of its outer surface?

(Compare with the surface of the cerebral
hemispheres.)

4. In the section of the cerebellum describe

the distribution of gray and white mat-
ter.

5. On the ventral surface of the hind-brain,

just beneath the cerebellum, note a band
of white matter (the pons = bridge) con-
necting the lateral portions of the cere-
bellum. Does the pons, therefore, run
crosswise or lengthwise of the brain?

6. The rest of the hind-brain is called the me-

dulla (or medulla oblongata) . Name and
locate, now, each of the three regions of
the hind-brain.

7. The portion of the nervous system which

forms a posterior continuation of the
medulla is the spinal cord. What is the
general shape of the cord? Describe its
cross section. Can you distinguish gray
and white matter? If so, locate each.
D. Mid-brain.

i. Carefully bend the brain near the middle
in such a way as to enable you to look
down between the cerebral hemispheres
and the cerebellum. This connecting
isthmus is the mid -brain. Describe its
position with reference to fore- and hind-
brain.

94 LABORATORY EXERCISES.

2. How many elevations can you distinguish
on the dorsal surface of the mid-brain?
'(These are the optic lobes which connect
with the eyes.)
E. Cranial nerves (Dem.).

From what region of the brain do each of the
following pairs of nerves originate and what is
their distribution?

1. First pair or olfactory.

2. Second pair or optic. (Note crossing of

these nerves on ventral surface of brain.)

3. Third, fourth, and sixth pairs.

4. Fifth and seventh pairs.
4. Eighth pair or auditory.

6. Ninth, tenth, eleventh, and twelfth pairs.

48. STUDY OF YEAST.

Materials for home work: Compressed yeast, molasses; two pint
bottles, small bottle, tin cup; refrigerator; stove; thermometer.

Materials for class demonstrations: (A, 9, 10, D); Flask, rubber
cork (two holes); U-tube, test-tube; chemical thermometer; glass
and rubber tubing; water-bath; condenser; compound microscope
(500 diameters), slide; cover-glass; lime-water, eosin or methyl
violet.

A. Study of the growth of yeast.

Mix about an eighth of a cake of compressed
yeast in a tablespoonful of water and stir until
a smooth thin mixture is formed. Add this to
about a half -pint of water in which a table-
spoonful of molasses has been dissolved. Place
this mixture in a wide -mouthed bottle which
holds about a pint; stopper very loosely.

STUDY OF YEAST. 95

1. State in your note-book the color of the

mixture. Does it appear clear or cloudy ?

2. What is the smell and taste of the mixture?

3. Place the liquid where the temperature is

70° to 90° F. Determine the exact tem-
perature by the use of a thermometer,
and record it.

4. At the end of several hours examine the liq-

uid. What evidence is there that the
yeast is ' ' working ' ' ?

5. At the end of 12 hours smell the mixture of

molasses and yeast remaining in your
large bottle. How does it differ from
that observed in 2?

6. Taste of the liquid at the same time. Com-

pare with result obtained in 2.

7. What differences do you note in the color

or in the general appearance of the mix-
ture since the experiment was begun?
(Compare with observations in i.)

8. Determine the effect of temperature on the

working of yeast in the following man-
ner:

a. Shake up the mixture when it is work-
ing well, and pour some off into a
small bottle; immerse the latter
up to its neck in ice-water for an
hour, or place it in a refrigerator.

(1) What is the effect on the ac-

tivity previously noticed in
the liquid?

(2) Warm the liquid again to the

96 LABORATORY EXERCISES.

temperature of the room and
record result.

(3) (Yeast is a plant.) Has it been
killed by the cold? Give
reason for your answer.

b. Pour some more of the working yeast

mixture into a tin cup, place it on
the stove and boil it. Allow the
mixture to cool to the tempera-
ture of the room, and turn it into
a small bottle.

(1) What effect does boiling have

on the activity of the yeast ?

(2) Keep the mixture for a day or

two. Was the yeast killed
by the heat?

c. Summary.

(1) What temperature do you find

to be most favorable for the
growth of yeast?

(2) What is the effect of extreme
. cold?

(3) What is the effect of a high de-

gree of heat ?

9. (Dem.) Nearly fill a bottle with a yeast
mixture which is working well. Insert
a rubber cork in the mouth of the bottle
through which passes one arm of a U-
tube. Half-fill a test-tube with lime-
water. Allow the free end of the U-tube
to dip below the surface of the lime-
water. Be sure all the connections are

STUDY OF JEAST.

97

in a

tight. Set the apparatus aside
warm place for a few hours.

a. What change has taken place in the

lime-water ?

b. What kind of gas is produced by the

growth of yeast?

io. (Dem.) Pour into another flask some of the
yeast mixture which has been working

FIG. 7.

for some time. Procure a rubber stop-
per with two holes. Through one hole
pass the bulb of a chemical thermometer
so that it reaches half-way down to the
bottom of the flask. Through the other

98 LABORATORY EXERCISES.

hole pass a glass tube, allowing it to pro-
ject just inside the flask. Connect this
glass tube with rubber tubing to a con-
denser (used in distillation). Place the
flask over a water-bath, and keep the
temperature at the point where the ther-
mometer registers 78° C. Collect the liq-
uid which comes from the condenser.

a. What is the smell and taste of the liq-

uid?

b. Apply a lighted match to a little of it.

Will it burn?*

c. What kind of substance is formed

when yeast "works," or when fer-
mentation takes place?

B. Into a half-pint of water put a spoonful of the

thin yeast mixture (of yeast and water) ; set
aside in a warm place beside the other mix-
ture. Examine at the end of 12 hours.

1. Do you see any evidence of activity in the

mixture?

2. What kind of substance was present in the

preceding experiments which is absent in
this experiment?

3. What do you infer from this experiment?

C. Summary.

1 . What conditions are necessary for the rapid

growth of yeast ?

2. What changes are caused by the yeast in a

mixture in which it is growing?

*The experiment will be more successful if the liquid is distilled
a second time.

STUDY OF TEA8T. 99

3. What substances are produced by the

growth of yeast?
D. Microscopic study of yeast. (In class.)

By means of a pipette put a drop from the
bottom of a yeast mixture on a glass slide;
cover with a thin cover-glass, and examine
under the high power of the microscope.

1. What is the color of the solid bodies (yeast-

cells) which you see ?

2. Yeast-cells form new cells by budding, the

bud (daughter-cell) usually remaining
attached to the cell (mother-cell) which
produced it.

a. Draw a group of cells showing a
mother-cell and two daughter-cells.

3. Can you distinguish a nucleus in any of the

yeast-cells? (The colorless vacuole is
not the nucleus.)

4. Place a drop of stain (eosin or methyl vio-

let) on the slide at the edge of the cover-
glass, allowing it to run beneath the glass
to stain the cells. Can you make out
any further facts regarding the structure
of yeast?

5. Add a drop of iodine to a little yeast mix-

ture and examine with the compound
microscope. What kind of bodies are
mixed in with the yeast-cells? What
does their color indicate as to their com-
position?

100 LABORATORY EXERCISES.

49. STUDY OF BACTERIA.

Materials for home work (A, B) : Three bottles (two provided
with stoppers), ice-box, thermometer; pint of milk; handful of dried
hay.

Materials for class-room work (C, D, E) : Arnold steam sterilizer,
flask, Petri-dishes, cotton-wool, inoculator, compound microscope
(500 diameters), slide, cover-glass, eosin, carbol-fuchsin or Lbemers
blue, corrosive sublimate solution (1:1000), made by dissolving
one antiseptic tablet in a pint of water.

Nutrient agar-agar is probably the best medium in which to grow
all kinds of bacteria. It can be readily prepared in the laboratory
or home kitchen from the following materials: 1000 cc water, 10
grams salt, 10 grams peptone, 10 grams Liebig's beef extract, small
amount of cooking soda, and 10 grams agar-agar (called, also, Japan
isinglass). If agar-agar cannot be obtained, 100 grams of the best
French gelatin may be used instead.

Dissolve the beef extract in the 1000 cc. water. The agar, cut
into small pieces, is then added, together with the peptone and salt.
The mixture should be heated to cause the agar to dissolve, care
being taken that it is not allowed to burn. Just enough cooking
soda is added to cause red litmus paper dipped in the mixture to
turn blue, that is, the liquid should be faintly alkaline. Filtering
the hot agar sometimes involves more or less difficulty. The pro-
cess can be easily carried on. however, within the steam sterilizer.
A glass funnel should be put in the mouth of a Florence flask (used
commonly in a chemical laboratory) , and one or two layers of ab-
sorbent cotton placed within the funnel If the agar, flask, and
funnel are kept hot within the sterilizer, the liquid will readily pass
through the cotton. After filtering, close the mouth of the flask
with a plug of absorbent cotton, and boil in the cooker for half an
hour. The flask may be set aside as stock agar until needed for
use. (If the agar mixture is not clear, it should be filtered through
the same cotton a second time.) In case any bacteria or mould
colonies appear within the flask, it should be heated within the ster-
ilizer for half an hour on two or three successive days.

A. Growth of bacteria in hay infusion (at home, .
i. Cut the hay into small pieces, place them in
a mason jar, and half fill it with water.

STUDY OF BA'Jl'ERTA. , . 101

Shake the mixture and put it in a warm
place, noting the temperature.

a. What becomes of the hay? Why?

b. What is the color and smell of the hay

infusion ?

2. Examine the mixture after each 24 hours
for a week.

a. What has now become of the hay?

Why?

b. What change takes place in the color

and smell of the liquid? (These
changes are caused by bacteria.)

c. What do you see on the surface of the

infusion? (This is composed of
countless numbers of bacteria.)
B. Growth of bacteria in milk (at home).

Secure three clean bottles of about the same
size, two of them provided with stoppers.

Into one of the bottles pour some good fresh
milk; cover and place in the ice-box, or in
some other cold place. Label the bottle " No.
i."

Pour into the second bottle about the same
amount of milk, and set it aside in a moder-
ately warm place, leaving it uncorked. Note
the temperature by means of a thermometer.
Label "No. 2."

Clean the third bottle and the cork in boiling
water. Boil some of the milk 5 minutes, and
pour it into the bottle while hot. Cork the
bottle and place it beside the second bottle.
Label "No. 3, Sterilized milk."

LABORATORY EXEHCISES.

Examine the three bottles of milk at the end
of. 12 hours.

1. Do you notice any difference in the smell or

taste of No. i, No. 2, and No. 3?

2. Boil the milk in bottle No. 3 again; clean

the bottle and cork in boiling water as
before, and replace the milk in the bottle ;
cork the bottle. Put bottle No. i back
in the ice-box ; return bottles No. 2 and
No. 3 to the place from which you took
them.

3. Examine all three bottles at the end of a

second 12 hours. Have any further
changes taken place?

4. Carry out the directions given in 2 above a

second time. Repeat your examina-
tions at the end of each successive 12
hours for two or three days, each time
boiling the milk in bottle No. 3. Record
in your note-book each time the changes
which you observe in each of the bottles.

5. The changes in the milk are caused by the

growth of bacteria from the air or on the
bottles or stoppers.

a. What effect does a cold temperature

have on the growth of bacteria?

b. What effect does boiling have on the

growth of these cells.

c. What is the most favorable tempe^a-

ture for the growth of bacteria?

d. What effect do some bacteria have on

the milk?

STUDY OF BACTERIA. 103

e. Compare the results obtained in this
experiment with those already ob-
tained in the experiment with
yeast.
C. Growth of bacteria on nutrient agar.

Pour a thin layer of the nutrient agar into
several Petri-dishes which have been heated
for a half -hour in the steam stenlizer, quickly
replacing the covers on the dishes, also the cot-
ton plug in the flask. Number the dishes 1,2,
etc., and write date of each part of the experi-
ment.

Keep some of the dishes carefully closed
throughout the experiments. Label each of
these dishes "Not exposed."

Open several of the other dishes, exposing
the gelatin to the air of the room for 10 min-
utes. Replace the covers, and label each dish
" Exposed to the air 10 minutes."

Open the other dishes sufficiently to spread
on the surface a little of the dust from the
floor or from the street. Label each dish " Ex-
posed to dirt."

Open a third set of dishes of the gelatin and
pour on the surface a thin layer of the city
water obtained from the school faucets. Label
each "Exposed to city water."

Set aside the dishes where the temperature
is about 70° F. Examine the dishes at the end
of a day or two.

i. Do you find any differences between the
dishes which have been exposed to the

104: LABORATORY EXERCISES.

air, the dirt, and the water, and those
which have not been exposed?

2. Draw a figure of the dish you are studying,

representing carefully the form and size
of the spots (colonies of bacteria or
mould) .

3. Study the same dish several days later.

Make a careful drawing as in 2 above.
Have the colonies changed in size or ap-
pearance since your last study?

4. Describe the color of the colonies.

5. Do any of the colonies appear to affect the

agar around them? (Smell of the agar.)
D. Microscopic study of bacteria.

Carefully lift the cover from one of the plates
of agar which has been exposed. Touch one
of the colonies of bacteria with the point of a
needle, and then rub the needle-point on a
clean glass slide; add a drop of water to the
spot touched by the needle, and cover with a
cover-glass. Examine with the highest powers
of the microscope.

1. What is the color of the tiny bodies (bac-

teria) which you see?

2. Do you find more than one kind of bacteria ?

If so, what is the shape of each ?

3. Do any of the bacteria seem to be in mo-

tion?

4. Place a drop of stain (eosin, carbol fuchsin,

or LoefHer's blue) at the side of the cover-
glass and allow it to run beneath the
glass, staining the cells. Can you make

STUDY OF BACTERIA. 105

out any further points of structure in the
bacteria ?

E. Sterilization.

Prepare three dishes of nutrient agar as di-
rected above.

Remove the cover from No. i, and allow it
to remain exposed to the air for several min-
utes. Label it "Agar No. i."

Remove the cover from a second dish, ex-
pose it as in No. i ; then pour over the surface
a thin film of corrosive sublimate (1:1000).
This solution is made by dissolving one anti-
septic tablet in a pint of water. Replace the
cover and label "Agar No. 2 + Poison."

Expose a third dish of agar to the air for the
same length of time as in No. i and No. 2.
Heat this dish for a half -hour every 12 hours
in a steam sterilizer or over a water-bath.
Label "Heated Agar." Keep all three dishes
covered, and set them aside where the tem-
perature is about 70° F.

Compare the three dishes at the end of three
days.

1. What differences do you notr between the

three dishes?

2. What is the effect of the poison (corrosive

sublimate) on the growth of bacteria ?

3. What effect does heating and cooling have

on the growth of bacteria?

4. In what two ways can a substance be ster-

ilized?

F. From all your experiments state —

106 LABORATORY EXERCISES.

1. What conditions seem to favor the growth

of bacteria?

2. What conditions seem to hinder the growth

of bacteria?
G. Practical questions in bacteriology.

1. Why are fruits cooked before canning?

2. Why should fruit-jars be filled completely

before screwing on the cover?

3. Why do fruit- jars sometimes burst long

after being filled?

4. Why is grass dried before it is put into the

barn?

5. Why are milk, meat, etc., put in the refrig-

erator in summer-time?

6. Why should the prohibition against spit-

ting in public places be rigidly enforced ?

7. Why should sweeping be done so far as pos-

sible without raising a dust ?

8. Why are hard-wood floors more healthful

than carpets?

9. Why should the teeth be brushed often?

10. Why should the refuse be removed from the

streets every morning early, especially in
summer-time ?

11. Why should sink-drains be carefully in-

spected ?

12. Why should wounds be carefully cleansed

and dressed at once?

13. Why are typhoid fever, diphtheria, and

other infectious diseases often better
treated in hospitals?

STUDY OF LIVING VERTEBRATES. 107

14. In what ways do bacteria prove to be of

benefit 'to mankind ?

15. In what ways do they prove to be "man's

invisible foes"? (Read "The Story of
Bacteria," "Dust and its Dangers,"
" Drinking-water and Ice Supplies, and
their Relations to Health and Disease,"
by T. M. Prudden, M.D. Published by
G. P. Putnam's Sons.)

50. STUDY OF LIVING VERTEBRATES.

A. Habitat.

1. Does the animal live on land or in water?

2. In what part of the world is it common?

3. What is the climate of that region?

B. Locomotion and breathing.

4. What appendages has the animal?

5. Which of these appendages are used in lo-

comotion?

6. How many digits of each appendage are

used?

7. What method or methods of locomotion

does the animal have?

8. In proportion to its size is its locomotion

rapid or slow?

9. What other use does the animal make of its

appendages?

10. What movements indicate that the animal

is breathing?
C- Food-getting.

11. What kind of food (animal or vegetable)

does it eat?

108 LABORATORY EXERCISE*.

12. How does the animal seize hold of its food?

13. Does it chew its food before swallowing?

14. If possible, describe the teeth.

D. Means of protection.

15. Does it have as an outer covering hair,

feathers, scales, or a naked skin?

1 6. Of what use to the animal is this outer cov-

ering?

17. Is this covering shed by the animal? If so,

when and how ?

1 8. What different colors do you find on the

animal?

19. Do these colors resemble at all the colors in

the natural environment of the animal,
i.e., is the animal protectively colored?

20. How can the animal protect itself against

its enemies?

E. Sense-organs.

21. What is the position of the eyes ? How are

they protected?

22. Locate the nostrils. Do you see them

close?

23. What evidence is there that the animal

hears? Can you see any ears? If so,
describe them.

51. PARTS OF A COMPOUND MICROSCOPE.

A. Base. — This is the solid foundation on which
the instrument rests. It is usually shaped like a
horseshoe.

B. Pillar. — The vertical column which is fastened

PARTS OF A COMPOUND MICROSCOPE. 103

M

FIG. 8.

110 LABORATORY EXERCISES.

to the base and which carries upon its upper end the
joint provided for inclining the instrument.

C. Arm. — This supports all the upper parts of the
instrument.

D.- Body. — The tube portion to which are at-
tached the magnifying parts of the microscope.

E. Nose-piece. — This is an extra piece attached
to the lower part of the body, which provides a
means of quickly changing the objectives.

F. Objectives. — These are the most important
magnifying parts of the microscope. They are so
called because they are nearest the object that is
being examined. The shorter objective is called the
low power, because it magnifies least. The longer
objective is the high power.

G. Eyepiece. — It is so called because it is nearest
the eye. The eyepiece magnifies the image formed
by the objective.

H. Draw-tube— This is the portion of the body
which moves in the outer sheath and which receives
the eyepiece. If the tube is drawn upward the
magnifying power of the microscope is increased.

1. Collar. — A nng attached to the draw-tube. It
is usually provided with a milled edge.

J. Coarse Adjustment. — This is a provision for
moving the body of the microscope up and down by
means of a so-called rack and pinion.

K. Milled Heads. — The wheels on either side of
the coarse adjustment. When the wheels are turned
toward the observer the body carrying the magni-
fying parts is raised.

L. Fine Adjustment. — This horizontal wheel is at-

PARTS OF A COMPOUND MICROSCOPE. Ill

tached to a fine screw. When it is turned in the di-
rection of the hands of a clock the body is lowered
very slowly. By turning in the opposite direction
the magnifying parts are raised.

M. Stage. — This is the part on which the slide
with the object is placed for examination. It is at-
tached to the arm.

N. Clips. — Two springs which are attached to the
upper surface of the stage and which serve to hold
the slide in place.

O. Mirror. — The mirror is used for reflecting the
light upon the object. The flat surface is called the
plane mirror. The hollow surface is the concave
mirror. The latter not only reflects but also con-
centrates light upon the object.

P. Mirror Bar. — This bar carries the mirror. It
can be turned so as to throw light upon the object
from any direction.

Q. Substage. — An arrangement below the stage
to receive various extra devices for increasing or
regulating the amount of light.

S. Iris Diaphragm. — This device enables one to
shut off or increase the amount of light that falls
upon the object. When the small lever beneath the
stage is moved toward the right the hole through the
stage is diminished in size.

112 LABORATORY EXERCISES.

52. RULES FOR THE USE OF THE COM-
POUND MICROSCOPE.

I. To lift the microscope, always grasp it firmly by

the pillar beneath the stage.

II. To use the low power-objective.

1 . Place the stand so the two arms of the base

face the window. Keep the microscope
out of the direct sunlight.

2. See that the nose-piece is in the position

which will bring the low-power objective
over the opening in the stage.

3. Move the tube up or down by the coarse ad-

justment until the lower end of the low-
power objective is a little more than a
quarter of an inch above the level of the
stage.

4. See that the plane side of the mirror is fac-

ing the source of light. Looking down
through the tube, move the mirror about
until the field of the microscope has the
best possible illumination. (The field of
the microscope is the lighted circular
area which appears when looking down
through the tube.)

5. Place the slide on the stage (cover-glass on

top) in a position so the object to be ex-
amined is over the centre of the hole in
the stage. Fix the slide in place with
the clips.

6. Look through the microscope and slowly

RULES FOR USE OF COMPOUND MICROSCOPE. 113

move the tube up by turning the coarse
adjustment until the object is seen as
clearly as possible. Be careful never to
push the tube down so the objective
touches the slide.
7. In examining a slide, focus the tube by

means of the fine adjustment.
III. To use the high-power objective.

1. Place the slide upon the stage and focus

upon it with the low -power objective as
directed in II above.

2. Turn the mirror so the concave surface

faces the source of light. Looking
through the tube, move the mirror about
until the field of the microscope has the
best illumination.

3. Place the eye at the level of the stage and

carefully turn the nose-piece so the high-
power objective is brought into position
above the hole in the stage. If the
lower end of the objective touches the
cover-glass, turn the fine adjustment
screw in a direction opposite to that of
the hands of a clock.

4. When the objective is in position look at

the object through the microscope and
focus slowly with the fine adjustment-
screw until the image is clearest. Take
great care, as directed in 3 above, to see
that the objective does not touch the
cover-glass.

5. After using the high-power objective, turn

LABORATORY EXERCISES.

the nose-piece so as to leave the low-
power objective in position over the
diaphragm.

IV. The pupil should learn to look through the

microscope using the right and left eye
alternately. Both eyes should remain
open.

V. Table of approximate magnifications of the

Bausch & Lomb microscopes:

1

Objective
. 2-inch

Eyepiece.
2-inch Ab
1-inch
2-inch
1-inch
2-inch
1-inch
2-inch
1-inch

Magnification,
out 15 diameters.
30
50
100 "
250 "
450 "
600 "
1100 "

2 . .

. . . 2-inch

3

§-inch

4 . .

. §-inch

5

^-inch

6 ..

. . . J-inch

7

rs-inch

8 ,

. .TV-inch

LIST OF APPARATUS AND CHEMICALS RE-
QUIRED TO SUPPLY A CLASS OF TWENTY-
FOUR.

An articulated skeleton can be obtained of the Kny-
Scheerer Co., 225 Fourth Avenue, New York City, for $25.
Large physiological wall-charts are most useful in oral reci-
tations. Those made by L. W. Joutel, 164 E. 117th St.,
New York City, cost $10 to $15 each, but they have been
found invaluable as a means of demonstration. The
micro-photographs prepared by W. H. "Walmsley, 4248
Pine St., Philadelphia, Pa., are also of great assistance in
teaching the minute anatomy of various organs and tis-
sues. In large quantities these prints (unmounted) cost
about 10 cents each.

The following supplies will be furnished to schools by
Bausch & Lomb Optical Co., 1123 Broadway, New York
City, at the special prices quoted. (The numbers and let-
ters refer to Bausch & Lomb's Catalogue.).

1 Compound microscope Bl, witli f" and |" objectives. $23 50

24 Magnifiers, 5-10" diameter, QR 6 30

1 Weighing balance, No. 8104 12 50

24 Evaporating dishes (porcelain), No. 10034, 45 cc 2 50

24 Alcohol-lamps, No. 8470, 100 cc 9 00

1 Gross slides, No. 1290 75

1 oz. round cover-glasses, f", No. 1274 75

24 Scalpels, No. 1450 6 30

24 Pairs forceps, straight, No. 1400 450

24 Pairs dissecting scissors, No. 1550 9 00

115

116 LIST OF APPARATUS AND CHEMICALS.

50 Dissecting needles, No. 1516 • $1 13

144 Test-tubes, No. 9460, 150 x 15 ram 216

1 Chemical thermometer, No. 9760 B 94

1 Lactometer, No. 9892 38

12 Iron apparatus stands, three rings, No. 10216 5 85

24 Pieces wire gauze, 3" x 3", No. 9840, per Ib 38

24 Glass stirring rods, No. 9326, per Ib 38

10 Ft. glass tubing, 5 mm., No. 9320, per Ib 30

6 Thistle tubes, 300 mm. , No. 9242 45

6 Beaker glasses, No. 8916, 200 cc 90

1 Glass bottle, No. 8958, 3 oz., with rubber cork, No.

10126, with two perforations 10

1 Bell jar, No. 8932, with opening at top, 200 x 150 mm. 7o

1 Piece of sheet rubber, 1 ft. x 1 ft., per Ib 1 50

2 Flasks, No. 9192, 250 cc 23

pair of bone forceps, No. 1374 1 88

Bone saw, No. 1536 3 00

Probes, No. 1590 180

Cylindrical graduate, No. 9660, 250 cc 57

Piece platinum foil, 1" x 1", No. 9960, per grm 75

Box slide labels, No. 1762 8

1 Arnold steam sterilizer, No. 6038A, heavy tin, copper

bottom . . 3 75

24 Petri dishes, 80 mm., No. 9150 3 60

1 Distilling apparatus, Muencke's, of glass with ground

joints, 500 cc 6 00

CHEMICALS.

4- Ib. hydrochloric acid, c. p. 500 cc., S. G. 1.190 22

% " nitric acid (cone.), c. p. 500 cc., S. G. 1.425 23

i " ammonia (cone.), c. p. 500 cc., S. G. 0.90 21

i " sulphuric acid, 500 cc., S. G. 1.840 19

1 oz. iodine, pure, resublimed 48

5 " potassium iodide 1 35

± Ib. ether sulphuris, 250 cc., S. G. 0.722 28

5 gr. caustic potash, white sticks 10

5 " " soda, purified sticks 10

100 cc. lime-water 10

LIST OF APPARATUS AND CHEMICALS. 117

100 pieces red litmus paper, 2" x i", No. 7600 ... $010

100 " blue litmus paper, 2" x ±", No. 7600 10

4 gr. quinine 20

500 cc. 95# alcohol, deodorized 58

100 cc. glycerin, refined, white 17

5 gr. pancreatin (Fairchild) ; 20

5 " ox-gall 10

5 " pepsin, powder 10

10 gr. common salt 05

1 " phosphate of lime, c. p 10

10 " glucose, crystallized, pure 10

500 cc. Fehling solution 83

10 gr. eosin, yellowish, dry 23

10 " methyl violet, dry 23

1 Ib. agar agar, best quality, in shreds 40

12 gr. peptone (U. S.), pure 25

2 Ibs. formaldehyde, 40£ 85

1 stick phosphorus 10

| Ib. sulphur flowers 10

i Ib. chlorate potash, pure crystals 15

£ Ib. oxid of manganese, pulverized 10

24 small pieces zinc, |" square 10

1 Ib. cotton wool 38

1 oz. potassium permanganate 10

BOOK IS DUE ON THE LAST DATE
STAMPED BELOW

AN INITIAL FINE OF 25 CENTS

WILL BE ASSESSED FOR FAILURE TO RETURN
THIS BOOK ON THE DATE DUE. THE PENALTY
WILL INCREASE TO SO CENTS ON THE FOURTH
DAY AND TO $1.OO ON THE SEVENTH DAY
OVERDUE.

.

AP» 25 1!

ON 7 1933

NOV 28 1938
6 1941

FEE 20 1941
MAR 5 1941

31964

LD 21-50m-l.'33

304680

UNIVERSITY OF CALIFORNIA LIBRARY