A Manual 
of 
Laboratory Studies 
in Biology 
Linville & Olmstead A MANUAL 
OF 
LABORATORY STUDIES 
IN BIOLOGY 
TO ACCOMPANY LINVILLE'S 
The Biology of Man and Other Organisms 
HENRY R. LINVILLE, Ph.D. 
BY 
Formerly Head of Department of Biology in the De Witt Clinton High 
School and in the Jamaica High School, New York City; Co- 
author, Linville and Kelly's Textbook in General Zoology; 
Author, The Biology of Man and Other Organisms 
AND 
ROSSITER D. OLMSTEAD, B.S. 
Head of the Science Department, Children's University School, 
New York City 
NEW YORK 
HARCOURT, BRACE AND COMPANY HARCOURT, BRACE AND COMPANY, INC. 
COPYRIGHT, 1924, BY 
PRINTED IN THE U. S. A. PREFACE 
This series of laboratory studies is published to accompany 
Linville's 77ie Biology of Mem and Other Organisms. The 
book will meet the usual demand for a laboratory guide, 
but it is hoped that it will serve an even greater purpose 
than that of assisting overworked teachers to lighten the 
burdens created by large classes. Like the accompanying 
textbook, the Manual is the outcome of much thinking 
about how to present the subject of biology in the most 
interesting and effective way. 
The authors have tried to introduce each laboratory 
study on the basis of the natural, or possibly the acquired, 
interest of the student. The development of the study is 
carried along with interspersed pieces of information, or 
suggestions and questions. In some of the studies the 
questions are numerous; in others few. The variety in the 
form of the presentation is in part due to the varying avail- 
ability of the subject matter, and in part to a frank effort 
to experiment in a field which has been much trampled 
over by the leaden feet of uniformity. If the authors 
have disregarded the form of question and the itemized 
list of points that give the elusive mind of an unwilling 
student no chance of escape from the obligation to answer, 
it is because the authors believe that a new attitude in 
making laboratory studies will help the teacher get better 
results under more cheerful circumstances than may have 
been possible formerly. 
This change of attitude carries with it an intention to 
impart here and there some idea to serve in every study 
as the basis for further suggestion on the part of the student. 
iii iv 
PREFACE 
The information given in these scattered paragraphs within 
the Studies is so placed as to provide for the continued 
development of new phases of the study. The authors 
trust, however, that the information thus given is always 
in itself to the point and worth while. 
While providing for a continued development of interest 
in the laboratory studies, the authors have also paved the 
way for the practical development of a new educational 
plan in laboratory procedure. As a rule, teachers and writers 
of laboratory manuals select a small project, and organize 
a definite and speedy way of working it out. That ac- 
complished, the next step is to take a related project, and 
organize the effort of the class to work that out also. The 
relation between the two projects may or may not be noticed 
by the student. However, the "experiments" are done, 
and progress is recorded. 
But the present authors incline to the belief that the 
relation existing between processes in nature is liable to be 
slighted in the understanding, or missed altogether, by those 
who pursue the method of study just noted. In order to 
comprehend the important relation to be found between one 
set of facts and another, studies must be so organized as 
to make it possible for the student to see the relations as 
they work out. To do this takes time. We may not know 
whether it takes more time, or less, to study the biological 
principles in their relations than to study scraps of interest- 
ing information with the hope that they may be applied 
later on. The best that teachers of biology can do in the 
time allotted to their work is to formulate a method, and 
to try to apply it tow ard the accomplishment of their aims. 
As an indication of the method the authors have followed, 
Laboratory Study 4, Oxygen and Oxidation, may be 
examined. In this study the student learns how to obtain 
oxygen. lie also finds out something about the properties 
of a gas. He studies oxidation as a process, and learns PREFACE 
v 
something' of the relation of oxygen to other elements in 
the manifestation of the process, lie goes on in the same 
study to comprehend the connection of the release of energy 
and the formation of new compounds with the process of 
oxidation. He builds up a conception of the process; he 
is able to formulate his own definition of it, and to under- 
stand its industrial application and importance. 
The authors would like also to call attention to the study 
on Osmosis. Here again topics that are sometimes spread 
over several only slightly connected projects are treated 
as functionally related facts. The authors believe students 
will really understand osmosis after following this study. 
The phases of osmosis as they are presented in unrelated 
fashion are not easily understandable by the adolescent 
mind. 
The advantage of the plan of the Studies is nowhere shown 
better than in the animal and plant forms considered. The 
study of the Earthworm is an examination of the whole 
earthworm, except the internal anatomy. The student 
realizes that he is dealing with something more than a 
specimen. The creature is living. It moves, it breathes, 
it responds to stimuli, it reproduces, and it bears an economic 
relation to man himself. 
The authors have endeavored to introduce throughout 
certain features that may be regarded as integrating in 
their effect, as well as being of fundamental importance 
in themselves. Among these are the following: 
1. How organisms maintain their own life as well as the life 
of the species. 
2. The relation of an organism to other organisms on which 
it subsists, and among which it lives. 
3. The special relation of each species to the welfare of man, 
and the extent to which it may be modified in character 
or abundance to suit the needs of man. 
4. The adaptation of structure to function. 
5. The occurrence of beauty of form and color in life. vi 
PREFACE 
6. The fundamental biologic functions of sensation, motion, 
respiration, food-taking, digestion, absorption, circula- 
tion, assimilation, excretion and reproduction. 
A fundamental biologic principle which the authors have 
illustrated and applied in Laboratory Study 40 and else- 
where in the series is important enough to have still greater 
emphasis. It is perhaps not too strong a statement to say 
that one's understanding of biology is meager indeed if the 
conception of the great cycle of change from organic to 
inorganic, and from inorganic to organic, existence has been 
left out of account. It is this great and inclusive con- 
ception that constitutes one of the most vital stimuli to the 
imagination that science affords. 
The Laboratory Studies are arranged in the order that has 
now become general. In their sequence and treatment some 
of the later studies clearly require the understanding of 
facts and principles that have been discussed in earlier 
studies. However, considerable flexibility in the sequence 
of studies as followed by a class is possible. 
There is sometimes a demand for an extended series of 
suggestions to teachers. The authors have decided to 
depend on the Studies themselves to provide all the sug- 
gestions necessary for every teacher, save possibly the least 
prepared ones. And for these even a book of suggestions 
would hardly suffice. 
August 1, 1924 
The Authors CONTENTS 
LABORATORY 
STUDY 
PAGE 
1. Physical Change 1 
2. Chemical Change 1 
3. Acids and Bases 2 
4. Oxygen and Oxidation 2 
5. Nitrogen 6 
6. Analyzing Water 7 
7. Osmosis 8 
8. The Tests for the Organic Nutrients 12 
9. Paramcecium 15 
10. Amceba 17 
11. The Malarial Parasite 18 
12. Hydra 19 
13. The Starfish 20 
14. The Earthworm 21 
15. The Hookworm 23 
16. The House-Fly 24 
17. The Mosquito 26 
18. The Honey-Bee 28 
19. A Colony of Ants 30 
20. Wasps 33 
21. The Beetle 34 
22. The Metamorphosis of a Moth or a Butterfly 35 
23. The Grasshopper 37 
24. The Crayfish 39 
25. The Spider 42 
26. The Slug 43 
27. The Fish 44 
28. The Frog 46 
29. The Toad 50 
30. The Newt 52 
31. The Garter Snake 53 
vii viii 
CONTENTS 
LABORATORY 
STUDY 
32. The Turtle 54 
33. Birds 55 
34. Chickens 58 
35. Hens' Eggs 60 
36. Mammals 62 
37. Horses 64 
38. Cattle and Cattle Industries 66 
39. Milk 69 
40. The Relations of Organisms in a Limited En- 
vironment 72 
41. Bacteria 74 
42. Yeast 77 
43. Pleurococcus 79 
44. Mold 79 
45. Mushrooms 81 
46. Spirogyra 82 
47. A Moss 83 
48. Ferns 84 
49. Soil in Relation to the Growth of Plants ... 86 
50. The Response of Roots to Earth and Water . 88 
51. The Response of Plants to Light 89 
52. Roots 91 
53. Stems 93 
54. Leaves 95 
55. The Parts of a Flowering Plant 98 
56. The Pollination of Flowers 100 
57. Fertilization 102 
58. Fruits and Seeds and Their Dispersal 103 
59. The Germination of Seeds 105 
60. Cotyledons and Endosperms in Germination . . 108 
61. Regions of Rapid Growth in Plants 109 
62. Corn 110 
63. The Bean 113 
64. Wheat 115 
65. The Human Mouth 117 
66. Foods in Healthful Living 120 
67. The Digestion of Starch 124 
PAGE LABORATORY 
STUDY 
CONTENTS 
ix 
68. The Digestion of Protein 125 
69. The Digestion of Oil or Fat 126 
70. The Balanced Meals of a Day 127 
71. The Circulatory System 128 
72. Respiration 131 
73. Ventilation 133 
74. Excretion 135 
75. The Human Eye 137 
76. The Human Ear 139 
77. The Care of the Bones 141 
78. Athletics 143 
PAGE MANUAL OF LABORATORY 
STUDIES IN BIOLOGY 
LABORATORY STUDY 1 
PHYSICAL CHANGE 
The substance of the things we see about us does not 
always remain the same. Sometimes the size changes; 
sometimes the appearance changes, as the color or texture; 
and sometimes the state changes, as from liquid to solid 
or solid to liquid. So long as the change does not involve 
an alteration of chemical composition, we call it a physical 
change. 
1. What physical changes may take place in a piece 
of wood? 
2. When have you seen iron change physically, always 
remaining iron? 
3. What are the physical changes that may appear in 
water? 
4. What are some physical changes that may take 
place in air? 
LABORATORY STUDY 2 
CHEMICAL CHANGE 
Considerable changes in matter are taking place con- 
stantly in nature and in the arts. When a change occurs in 
the properties or qualities of a substance, as well as in its 
appearance, we call it a chemical change. 
1. What happens in the burning of wood that leads 
you to think that a chemical change takes place? 
1 2 
OXYGEN AND OXIDATION 
2. What are the changed properties apparent in a 
piece of iron rust that indicates a chemical 
change? 
3. Pour some sodium carbonate (washing soda) into 
a test tube containing some dilute hydrochloric 
acid. What is the evidence that a chemical 
change takes place? 
LABORATORY STUDY 3 
ACIDS AND BASES 
There are two classes of substances that are distinguished 
by their effect on certain chemical indicators, such as litmus 
paper, the chief property of which is provided by a saturation 
of logwood dye. 
The color of a piece of litmus paper is red when dipped 
into acetic acid produced in vinegar, or blue when dipped 
into sodium carbonate solution (washing soda), or into a 
solution of sodium hydroxide (common lye). Substances 
that are neither acid nor alkaline are said to be neutral. 
Such substances have no effect on the litmus paper. 
Bring from home a list of ten or more articles of 
food solutions which you have tested with the litmus 
paper. Which are acid? which are alkaline? and 
which are neutral? 
LABORATORY STUDY 4 
OXYGEN AND OXIDATION 
Oxygen is an important element in the air. It is mixed 
with the gas nitrogen, small quantities of carbon dioxide, 
argon, and water vapor. In volume, oxygen is about one 
fifth of the air. It is present everywhere in chemical com- OXYGEN AND OXIDATION 
3 
bination in the world of material things. We shall see how 
life itself depends on oxygen. 
I. OBTAINING OXYGEN 
The materials useful for obtaining oxygen are easy to 
secure. The laboratory pneumatic trough or a fairly deep 
vessel may be partly filled with water. Fill a jar or wide- 
mouthed bottle with water. Close the jar and invert it, 
lowering it into the water of the deep vessel until the mouth 
of the jar rests on the shelf on the pneumatic trough, or on 
two flat metal or glass articles in the bottom of a vessel. 
What is the reason the water does not run out of 
the inverted jar? 
Next take a large test tube to which a rubber one-hole 
stopper has been fitted. Thrust through the hole of the 
stopper a glass tube from twelve to eighteen inches long, 
bent to turn down into the test tube a short distance, and 
near the end bent to turn up into the mouth of the jar. 
Mix one to two teaspoonfuls of potassium chlorate and 
manganese dioxide in a dish and pour one or two teaspoons- 
fuls of the mixture into the test tube. The tw7o chemicals 
each contain a large amount of oxygen which they give off 
in the presence of heat. Close the mouth of the test tube, 
and adjust the outer end of the bent tube under the mouth 
of the jar. Support the test tube in the clamp of an iron 
stand, or hold it near the top by a loop of paper while you 
move the flame of an alcohol lamp or a gas flame back and 
forth across the lower end of the test tube. Soon you will 
see the bubbles of gas and air passing up through the water. 
What are you learning about the properties of gas 
at this stage of the experiment? 
When all the water has left the jar, close the mouth 
under water, reinvert it, shake the jar to "wash" the oxygen 4 
OXYGEN AND OXIDATION 
free from the smoke of heated chemicals as much as possible. 
Why should you expect oxygen itself to be transparent? 
II. 
OXIDATION 
Next light a long pine splinter, extinguish the flame, and 
immediately remove the stopper from the jar of oxygen, 
thrust the glowing ember into the jar, and note the result. 
What happens to a glowering ember if left in the air? Thrust 
a lighted splinter into the oxygen, and compare the flame 
with a flame in the air. 
What have you learned thus far about the impor- 
tance of oxygen? 
Try lighting several splinters, lowering them into the 
oxygen jar and quickly closing the jar with the cover. What 
happens to the flame? Afterward uncover the jar and thrust 
a lighted splinter into the jar. What happens? You may 
be puzzled by what you see. 
But let us study the burning of a splinter in the air. What 
happens to the splinter as the flame progresses? You sec 
a black substance being disclosed. This is carbon. As the 
burning continues what happens to the carbon? When the 
burning is over what is left? Will this substance burn? 
If you can burn up a whole stick by holding it in an iron 
spoon, wreigh a stick and afterward weigh the ashes left. 
What per cent of the weight of the stick disappears into 
the air? 
Now if the oxygen you had in the jar disappears, 
and if the carbon in the burning stick disappears, you 
are on the track of a very important chemical process. 
What do you think has happened? 
This chemical process which is called oxidation is impor- 
tant because, in the combination of oxygen with some other 
element, energy is set free and work is done. The commonest OXYGEN AND OXIDATION 
5 
forms of energy in the cases of oxidation are heat and light, 
lint it is also important to note that, while the two elements, 
carbon and oxygen, disappear in this experiment they are 
not destroyed, for they exist as a gas in the air. How they 
act toward a flame, we see in the test of putting a lighted 
splinter into a jar where the gas-carbon dioxide-has been 
collected. 
1. If we multiply the burnable substance in a stick 
by many tons of carbon, as in the coal used by 
a furnace in a house or in a factory, what hap- 
pens chemically, and of what importance may 
the process of oxidation be in these cases? 
2. What happens to the carbon dioxide formed? 
III. COMPARISONS 
It is important to know whether oxygen will combine 
chemically with any other element. Let us take a piece of 
magnesium such as is used in taking flashlight pictures, or 
in making fireworks. Try burning a piece by touching a 
match to it. 
What forms of energy are set free? 
Weigh a piece of magnesium. Then burn it and weigh 
the white powder resulting. 
How do you explain the result you obtain? 
Collect a new jar of oxygen. Take a piece of picture wire 
a foot in length. Fray out one end; heat it and dip into 
a spoonful of sulphur or paraffin. Dip the wire, while 
burning, into the jar of oxygen. 
On comparing with the other two cases of oxida- 
tion, what do you think is probably formed in this 
case? 
It is interesting also to note that iron will combine 
with oxygen, or will oxidize, in a low temperature in the 6 
NITROGEN 
presence of moisture. The result of this oxidation is the 
substance, iron rust. 
Taking into account the facts you have learned, 
try to formulate your own definition of Oxidation. 
In Laboratory Study 72 you will learn something on 
oxidation in the animal body and in plants. Oxidation will 
then appear to be the most fundamental process in life. 
Textbook, pages 83, 251, 336, 347, 399. 
LABORATORY STUDY 5 
NITROGEN 
Since Nitrogen comprises so large a portion of air, it is 
well to learn something of it by separating a little from a 
volume of air. Fill the pneumatic trough with water well 
above the suspended shelf. A deep vessel with sunken sup- 
ports for an inverted bottle will also serve. Drop into a 
small crucible a piece of phosphorus. Float the crucible 
on the water. Touch a lighted match to the phosphorus. 
While it is burning invert over it and hold in place a jar 
containing air, lowering the bottle so that the mouth is 
beneath the surface of the water. Shortly after you have 
covered the phosphorus with the inverted jar, note the escape 
of large bubbles from the mouth of the jar. 
1. Explain what you have just seen. 
2. What is being formed during the burning of the 
phosphorus? 
3. Why does water come into the jar? 
4. What have you learned about the approximate 
amount of oxygen in air? 
When the burning has ceased, let the fumes settle. 
Remove the bottle, close the mouth and set aside. ANALYZING WATER 
7 
Have you reason to believe that all the oxygen in 
the jar has been consumed? 
Explain. 
Test the gas remaining in the jar with a glowing ember 
and also with a lighted splinter. 
What do you learn? 
You have obtained a quantity of nitrogen in nearly pure 
form. 
What is the practical effect on burning or combus- 
tion of the large amount of nitrogen present in the air? 
LABORATORY STUDY G 
ANALYZING WATER 
Although water occurs widely in chemically unchanging 
condition, it can be "unmade" and made again. "Unmak- 
ing" or decomposing water is a striking experiment, and 
incidentally teaches much that is fundamental in science. 
I. 
THE APPARATUS 
A prepared piece of apparatus, called a eudiometer, can 
be obtained. This consists of a U-tube into each arm of 
which an electrode or terminal of exposed electric wire is 
extended. The electric current may be furnished by a direct 
current of a general circuit, or by dry batteries. 
The arms of the U-tube should be filled with water in 
which is placed a small quantity of sulphuric acid to cause 
the electric current to be set up through the water. When 
the bubbles begin to pass to the collecting tubes take note 
of the disappearance of water as such. 
What is the relative amount of the two gases 
coming off? 8 
OSMOSIS 
II. STUDYING THE RESULTS 
When the collecting tubes arc supplied with gas, invert 
and test each gas in turn with a glowing ember on a splinter. 
1. But first note whether either gas has an odor. 
2. Does the gas in the larger amount or in the smaller 
amount encourage burning? 
3. Next test both gases in turn with a lighted splinter, 
and tell which one of the gases actually burns? 
The more abundant gas is hydrogen, the less abundant is 
oxygen. In their relative amounts they give the basis for 
the chemical formula for water, which is II2O, meaning two 
parts of hydrogen and one part of oxygen. We have taken 
the compound water, and have divided it into hydrogen 
and oxygen. Since we see that oxygen encourages burning, 
the burning of the hydrogen must have been "encouraged" 
to take place by oxygen. 
1. Where did the oxygen just referred to come from? 
2. When hydrogen burns, what is being formed? 
3. Where does this result bring us? 
LABORATORY STUDY 7 
OSMOSIS 
Most of the fundamental biologic processes that are 
carried on in the bodies of plants and animals are chemical 
in character. But here is one, Osmosis, that is purely 
physical. When you do this study, you will be able to tell 
why it is physical. 
We often wonder how it is possible for water to pass 
from the ground upward through the roots and the stems 
to the tops of very tall trees. Similarly, you might wonder 
how a portion of your breakfasts, or the oxygen you breathe OSMOSIS 
9 
in, may make its way into blood vessels, and leave them 
later on in reaching the smallest muscle fibers of your little 
finger. A study of the process carried on with artificial 
cell contents and cell walls will aid us in understanding the 
matter. 
I. PREPARATION OF APPARATUS 
Prepare four sacs by pouring liquid celloidin into test 
tubes, turning the tubes about until the inner surfaces have 
been covered. Then dry out the solvents ether and alcohol, 
by waving the tubes about. Gently loosen at the margin 
the films thus formed, and pour water inside and back of 
the films. Draw out the film sacs and lay them in water 
until you are ready to use them. Thrust a glass tube through 
a cork or rubber stopper. Tie the open end of the film sac 
about the stopper as shown in the illustration on page 248 
in the textbook. 
Or, you may take four "thistle" tubes of small bore. 
Take squares of fresh sausage skins or parchment paper 
large enough to tie over the flange of the "thistle." Smear 
vaseline under the flanges to stop crevices when the squares 
are tied in place. Now tie the skins or pieces of parchment 
paper in place with many turns of common linen or shoe- 
maker's thread. 
What part of a real cell does the film, the skin or 
the paper, represent? 
Prepare one small beaker of a solution of grape sugar 
(glucose) or molasses, and one of boiled starch (very thin), 
and one of uncooked white of egg. Carefully pour into each 
sac nearly to the top the solutions of glucose, starch and white 
of egg. Into the fourth pour clear water. Why fill this 
fourth with water? If the water soon ceases dripping from 
your apparatus while it is held in the air, it is watertight. 10 
OSMOSIS 
In the " set-up " what in the living cell are we 
representing with sugar, starch and white of egg? 
What represents the substances taken from the soil 
by a plant? 
II. SETTING UP THE EXPERIMENT 
Fill four battery jars with water. Lower the prepared 
cells into the battery jars until the water in the jars is level 
with the solution in the thistle tubes or sacs. Adjust them 
there with clamps extending over the edge of the battery 
jars. All solutions now have an even start. Note the hour. 
1. In twenty-four hours what has happened? 
2. Has any sugar or starch or white of egg passed 
through the membrane into the surrounding 
water? 
3. How did you find out? 
III. STUDYING THE RESULTS 
Place a spoonful of sugar on a piece of paper, and near it 
pour a few drops of water. Gently connect the sugar with 
the water. 
Describe what happens. 
Do the same thing with a mass of boiled starch, and also 
with uncooked white of egg. Note what happens. 
Next drop a spoonful of sugar into a tumbler of water 
and into another some boiled starch, and into a third some 
uncooked white of egg. In a few minutes test the water in 
each tumbler for the presence of the substance poured into it. 
What has happened in each case? 
You have noted an important fact about substances that 
in some cases are soluble in water, and in other eases slightly 
or not at all soluble. The process by which soluble sub- 
stances like any kind of sugar mix readily with water and OSMOSIS 
11 
scatter throughout the solvent is called diffusion. This proc- 
ess is apparently hastened in solutions in which the solid 
has a great attraction for water. You saw the attraction 
being manifested when the spoonful of sugar lay adjacent 
to the water. 
1. How does the physical attraction between water 
and a soluble substance manifest itself when a 
membrane is interposed between the two? 
2. What is the result when the membrane is inter- 
posed between water and an insoluble sub- 
stance? 
3. Supposing the glucose in the cell contents of the 
root-hairs attracts the soil water carrying the 
minerals in solution, what do you think may 
happen to the glucose in the succeeding cells, 
on the way upward to the leaves, that would 
make it possible for the stream of water and 
minerals to continue? 
4. What do you think may happen to the incoming 
minerals that prevents a clogging of the path- 
way to the leaves? 
5. What happens to the water that makes it possible 
for the stream to continue flowing? 
We come now to the matter of considering now it is 
possible that starch which cannot pass through the mem- 
brane nevertheless is found in plant cells. If starch is made 
in leaves, we must explain how it comes to be found in the 
roots also. If we eat the starch in bread and potatoes, is 
starch also found in the tissues of the body? We know that 
starch is not found in animal tissue. Some of these points 
we may be able to answer now, but others will be taken up 
in connection with the food-making process in plants. 
1. What must happen to the starch that we eat? 
2. What may happen to the starch that is made in 
the leaves? 
3. Similarly, what may happen to the protein that we 12 
TESTS FOR ORGANIC NUTRIENTS 
eat in the form of egg, meat or cereal, before 
osmosis can occur? 
4. Why is it correct to say that osmosis is a funda- 
mental biologic process? 
5. And why do we call it a physical process? 
Textbook, pages 248, 249. 
LABORATORY STUDY 8 
THE TESTS FOR THE ORGANIC NUTRIENTS 
Chemists have studied the composition of foods, and 
have discovered four distinct kinds of organic nutrients 
(from plant or animal sources, see textbook, page 331) 
occurring in varying proportions in the foods we consume. 
Sometimes all four nutrients occur in a single food, as in 
bread, but more frequently one of the nutrients predomi- 
nates in the composition, one or two other organic nutrients 
being present in smaller percentages. The four organic 
nutrients are starch, sugar, protein, and oil or fat. Frequently 
starch and sugar are called carbohydrates (see textbook, 
page 332). 
The chemists have not only discovered these nutrients, 
but also they have worked out certain tests by which the 
presence or absence of a nutrient may be ascertained. This 
study will show what these tests are, and how they may 
be applied. 
I. THE TEST FOR STARCH 
A lump of laundry starch contains nothing but starch. 
Drop a piece of it into a test tube containing water. Heat 
to boiling point and set aside to cool. Prepare a dilute 
solution of iodine, mixed with a small quantity of potassium 
iodide. Pour a little of this into the test tube containing 
starch. TESTS FOR ORGANIC NUTRIENTS 
13 
1. What is the result? 
2. Into a second test tube place a piece of bread; 
carry through the same process; tell the result 
and state your conclusion. 
3. Experiment with a piece of cooked meat in the same 
way, and state the result and the conclusion. 
II. THE TEST FOR GLUCOSE 
Pour into a clean test tube of water a small amount of 
corn syrup. Heat to the boiling point, and before cooling 
pour in a small quantity of Fehling's solution, which is a 
mixture of copper sulphate, potassium hydroxide and 
Rochelle salt. 
1. Describe what you see. 
The resulting color and precipitate (sediment) is the 
test for glucose, but fruit sugar and milk sugar, though 
not cane sugar, will show similar precipitates. 
2. In a second test tube drop a piece of bread, and 
boil. Pour in some Fehling's solution; describe 
the result and state your conclusion. (Heat is 
known to have effect in transforming starch into 
sugar.) 
3. Experiment with a piece of cooked meat in the 
same way, stating the result and your con- 
clusion. 
III. THE TEST FOR PROTEIN 
White of egg is practically pure protein. Drop a piece of 
cooked white of egg into a clean test tube with water. After 
observing the result add a little concentrated nitric acid and 
boil. Cool, and add a little strong ammonia (ammonium 
hydroxide). 
1. What is the color of the white of egg after the 
treatment with nitric acid, and also after the 
ammonia treatment? 
2. Apply the test to a piece of meat, state results and 
conclusions. 14 
TESTS FOR ORGANIC NUTRIENTS 
3. Try also on a piece of bread, stating results and 
conclusions. 
4. Probably you have some marks on the skin of 
your fingers from this experiment. What does 
this mean? 
IV. THE TESTS FOR OIL 
There are two simple tests for oil or fat. They are both 
physical in character. For the first test, prepare plain 
white sheets of paper four or five inches square or larger. 
Drop on one some olive oil or lard. Drop on another some 
water. Let both dry. 
What difference do you notice? 
Grind small lots of different seeds with mortar and pestle, 
or pound them in small pieces of cloth, transferring the 
pieces to the squares of paper. Or take common articles of 
food, and place them on the squares of paper in an oven 
for an hour or more, but not where it is hot enough to 
scorch the paper. 
What is your conclusion about the presence of oil 
or fat in seeds? 
For the other test, prepare a series of cylindrical stand 
tubes or other convenient vessel that can be closed tightly 
with a stopper. Place in the series samples of the same 
materials used in the other test. Pour into each enough 
ether to cover the contents. Close tightly and set aside 
for twenty-four hours. 
At the end of that time, pour small quantities on 
squares of white paper, comparing the results with the 
result of pouring on ether itself and water. What is 
your conclusion in each case? 
Textbook, pages 331, 334. PARAMCECIUM 
15 
LABORATORY STUDY 9 
PARAMCECIUM 
If you should take a bit of pond weed or even a wisp of 
hay and place it in a jar of water, a brown scum will appear 
on the top of the water in a few days. If a drop of this scum 
is examined under the microscope it will be found to be 
teeming with life, hundreds of minute animals swimming 
rapidly back and forth. The largest of these forms that 
whirls its way across your field of vision has a shape similar 
to the sole of a slipper. This is a paramoecium, one of the 
simplest of animals and a good representative of that large 
group of one-cell animals, the Protozoa. It is interesting 
because all its life activities are carried on in the simple 
cell. 
Place a drop of the scum from a hay infusion (hay standing 
in water for several days) on a clean slide, cover with a glass, 
and examine with the high power lens of the compound 
microscope. Observe the shape of the animal. Is the heel 
or toe of the "slipper" forward as the animal swims? Is 
this always true? By means of a few cotton fibers placed 
in the drop of water under the cover glass you will be able 
to study more closely those individuals that are imprisoned 
between the fibers. Notice the minute hair-like organs 
(cilia) that cover the body. Of what importance are they? 
I. LOCOMOTION 
How does paramcecium propel itself through the 
water? 
II. FOOD TAKING AND EXCRETION 
Find a depression, the gullet, that extends crosswise from 
the forward end to a little distance beyond the middle of 16 
PARAMCECIUM 
the animal. If you observe closely you will be able to see 
small particles of food being swept into this gullet. How is 
this taking-in of food carried on? 
What are the functions of the cilia? 
Notice the movement of the particles of food throughout 
the transparent interior of paramoecium. Now locate the 
clear areas, the contractile vacuoles, that are to be found half 
way between the center and each end. Watch one closely 
and see what happens. 
What is the function of the contractile vacuoles? 
III. RESPIRATION 
Air is mixed with the water in which paramoecia are 
living. 
How can paramoecium obtain its supply of air? 
Place a drop of iodine on the slide near the cover glass 
and draw it under the cover glass by means of a bit of 
blotting paper. This will make the nucleus visible. This 
is a very important part of the animal. 
IV. THE NUCLEUS 
Find out all you can about the nucleus from your 
textbook. 
Make a drawing of paramoecium at least two 
inches long showing these parts: cell wall, gullet, 
cilia, food particles, vacuoles, and nucleus. A drawing 
made up of your own observations is better than one 
copied from the book. 
When the paramoecia are increasing rapidly you are 
likely to see a few specimens looking as if they were about 
to be cut through the middle. 
V. REPRODUCTION 
What do you think this means? AM(EBA 
17 
When the hay infusion has been standing a long time, 
you are likely to find two paramoecia joined side by side. 
This is called conjugation. Internal changes are taking 
place, and each is receiving a minute bit of nuclear sub- 
stance from the other. Following this process the animals 
are able to increase more rapidly. 
Can you make out where the animals are joined, and 
whether the united ones are smaller or larger than the 
single ones? 
Textbook, pages 6-7. 
LABORATORY STUDY 10 
AMCEBA 
If you are fortunate and have considerable patience you 
will be able to find in the sediment on both sides or the 
bottom of the jar from which you obtained paramoecium 
something that appears at first under the high power of the 
microscope to be a colorless, irregular little speck. This 
is another protozoan called the amoeba. Often amoeba 
lives in slimy pools even in vacant lots. 
Obtain an amoeba. With the help of the teacher, watch 
it closely for several minutes and note its outline. Does 
the shape change while you watch it? The little projecting 
knobs that you see are called pseudopodia (false feet). Is 
there any evidence of a gullet as found in paramoecium? 
I. LOCOMOTION AND FOOD-TAKING 
What are the functions of the pseudopodia? 
II. CELL STRUCTURE 
Notice the differentiation of the protoplasm into a color- 
less outer layer (the ectoplasm) and a granular inner layer 18 
THE MALARIAL PARASITE 
(the endoplasm). Careful observation will show a contractile 
vacuole, and staining with iodine will bring out the nucleus 
Make a drawing of the amoeba, including in it and 
labeling only such parts of the cell as you have actu- 
ally seen. 
Textbook, pages 7-8-9. 
LABORATORY STUDY 11 
THE MALARIAL PARASITE 
There are several species of Protozoa that cause disease, 
the most important of which belong to the genus Plasmodium 
which is responsible for malaria in man. This organism 
spends the asexual part of its life cycle in the blood. It gets 
into the red blood corpuscles where spores are produced. 
The spores break out from the red blood corpuscles, and 
this causes a fever. The spores attach themselves to other 
cells and the process begins again. Now if an Anopheles 
mosquito bites the patient, some of the spores are taken 
with the blood into the body of the mosquito. Here the 
spores produce male and female cells which unite to form a 
fertilized egg (the sexual stage). From this ultimately come 
little filament-like spores which get unto the salivary glands 
of the mosquito. This process in the mosquito takes about 
eight or ten days, and then if the insect bites someone else 
the spores get into the blood and cause the disease. 
What is the biological principle involved in each of 
the following preventive measures that are employed 
against malaria? 
1. The screening of windows and doors of hospitals 
and houses in malarial zones. 
2. The drainage of marshy and swampy lands. 
3. The removal of rain barrels and any similar places HYDRA 
19 
where small amounts of water might collect from 
time to time. 
4. The spraying of kerosene in a thin film over cer- 
tain bodies of water that can not be drained 
easily. 
5. The introduction of fishes into bodies of water in 
malarial regions. 
6. The erection of roosts to harbor bats in malarial 
regions. 
Textbook, pages 10-12. 
LABORATORY STUDY 12 
HYDRA 
Hydra belongs to a group of marine and fresh water 
animals. You will be interested in the unusual way in which 
members of this group obtain and digest their food. The 
fresh water hydra, either green or brown, lives in ponds 
or streams attached to some water plant. 
I. FOOD-TAKING AND REACTION TO TOUCH 
Examine the sides of the aquarium and the stems of the 
water plants for hydras. Remove one of them carefully, 
by means of a camel's hair brush, to a watch glass or a slide 
with a hollow cell, and place it under the low power of the 
microscope. What shape is the animal? Does this change, 
as you gently touch the hydra? How many arms or ten- 
tacles do you see, and how are they arranged? The mouth 
is located at the center of one end surrounded by the arms. 
What seems to be the function of the tentacles? 
Do you see any small individuals budding from your 
hydra? Also you may see little lumps projecting from the 
II. REPRODUCTION 20 
THE STARFISH 
sides of the hydra. The one nearest the base is the ovary in 
which egg cells are produced, and that nearest the other end 
is the spermary in which sperm cells are produced. 
Describe the methods of reproduction in hydra. 
Make a drawing of an extended hydra showing the 
mouth, tentacles, body, buds, and the sex organs, if 
they are present. 
Make another drawing of the animal as it appears 
when contracted. 
Textbook, pages 18-19. 
LABORATORY STUDY 13 
THE STARFISH 
This curious five-pointed star-shaped animal lives in the 
sea, as does the whole group of "spiny skinned'' animals, 
the Echinoderma, of which it is a member. We may classify 
them as "pests" because they feed on oysters and clams. 
They are remarkable because if they are cut in two, each 
half will regenerate an entire new animal. 
Examine a dried or preserved specimen of a starfish. Do 
you find an anterior and a posterior end? Do you consider 
the word "starfish" a good name for the animal? Such an 
arrangement of parts is called radial symmetry. With the 
aid of a hand lens observe the rough dorsal (upper) surface 
of the arms or rays. The short blunt projections are called 
spines and are a part of the skeleton which is made up of limy 
plates bound together. Of what use are the spines? 
Observe the ventral surface and notice the grooves in each 
ray which come together in the center. In each groove you 
will find rows of short, cylindrical tube feet which are a part 
of a complicated apparatus for locomotion. In the center 
of the ventral side is the mouth. At the end of each ray is THE EARTHWORM 
21 
a tiny red spot called the eye-spot (noticeable only in living 
animal), so called because it is sensitive to light. 
Make a drawing of the ventral side of a starfish 
and label all the parts you have seen. 
The starfish has an interesting method of obtaining and 
eating its food. Find out about this from your textbook. 
Textbook, pages 23-27. 
LABORATORY STUDY 14 
THE EARTHWORM 
In case you do not know where earthworms may be found 
in abundance, ask one of your friends who is a fisherman. 
If you give him half a chance he will undoubtedly tell you 
how these insignificant animals have helped him to secure 
many a delectable meal. The great English naturalist, 
Charles Darwin, found out that earthworms perform a ser- 
vice to mankind of far greater importance than that of 
serving as an effective bait on a fishing trip. His researches 
proved them to be the original plowmen. For further infor- 
mation concerning the activities of these dwellers in the soil 
consult chapter VI in the textbook. 
I. LOCOMOTION 
Let a living earthworm crawl over your hand, or if you 
object to this, place one on some moist blotting paper in a 
shallow tray. Notice that the body is made up of a series 
of rings called somites or segments. How many do you 
find in your worm? What is the difference between the 
front (anterior) and the hinder (posterior) ends? Touch 
both ends with a pencil and see if they are equally sensitive. 22 
THE EARTHWORM 
What is the approximate length of the worm when it is 
stretched out? When it is contracted? Does the under 
(ventral) surface feel different from the upper (dorsal) sur- 
face? What is the reason for this? By means of a hand 
lens find out the number of bristles or setae on each seg- 
ment. Have you ever seen an earthworm stretched out 
while a robin is trying to capture it? What is happening? 
Describe carefully the way in which the earthworm 
moves. 
II. RESPIRATION 
The earthworm has neither lungs nor gills. Can you 
think how it is able to secure its air? Have you ever seen 
earthworms lying partly outside their holes on the lawn? 
What conditions seem to disturb them and make them with- 
draw from their holes? Why do we see so many earthworms 
on top of the soil after a heavy rain? 
How and under what conditions does the earth- 
worm receive its air? 
Cover one half of the pan with a piece of cardboard. Does 
the earthworm prefer the darkness to the light? 
III. SENSATION 
What senses would you say the earthworm possesses? 
IV. REPRODUCTION 
The swollen band that you see about the worm is called 
the clitellum, and it secretes a sac for the eggs when they 
are laid. 
Search for one of these sacs, about the size of a 
grain of wheat, in the soil of a box of earthworms, in 
the laboratory. THE HOOKWORM 
23 
V. EFFECT ON THE SOIL 
Examine your lawns or the terrarium carefully for little 
pellets of earth that have passed through the body of the 
animal. It is in this way that the worm does the plowing. 
What importance was attached to this phenomenon as a 
result of Darwin's work? 
Make a drawing of the earthworm showing the 
mouth, segments, clitellum and the setae. 
Textbook, pages 27-30. 
LABORATORY STUDY 15 
THE HOOKWORM 
The hookworm is a small round worm about one half 
inch long that lives as a parasite in the human intestine. 
It has interfered with the physical and mental development 
of a large number of children and adults in our Southern 
states for many years. Early treatment tends to alleviate 
the ill effects in infected children, but it is of vastly greater 
importance that each child shall be educated in certain 
principles that will tend to prevent infection. 
The female worm that lives in the intestine sucking the 
blood and sending a poison into the system lays about 
3,000 eggs a day which pass out of the body with the excre- 
ment. In places where there are no sewerage systems and 
where sanitary conditions are bad, the eggs get on the ground 
and are spread around by rains. The eggs hatch into tiny 
worms which get on the bare feet of children and adults, 
particularly in wet weather. They bore through the skin 
and cause what is known as "ground itch." Then they 
travel in the blood and finally get into the intestine. After 24 
THE HOUSE-FLY 
an attack of ground itch it takes about seven months for 
the worms to arrive in the intestine and begin sucking blood. 
The following recommendations were made to school 
children in infected districts of our Southern states (Ala- 
bama State Board of Health, Teachers Bulletin on "Hook- 
worm Campaign in Alabama," 1912): 
1. Never go with bare feet unless the ground is perfectly dry. 
2. Never go with bare feet through muddy places. 
3. Always wear shoes when it is raining. 
4. Always wear shoes when the ground is wet. 
5. Always wear shoes when the dew is on the ground. 
6. If you have ground itch get it treated at once. 
7. Always take treatment for hookworm disease within three 
months after an attack of ground itch. 
8. Build and use at schools and homes privies that will prevent 
soil pollution and keep Hies and other animals from gain- 
ing access to the contents. 
Explain the biological principle underlying each one 
of these recommendations. 
Textbook, pages 33-35. 
LABORATORY STUDY 16 
THE HOUSE-FLY 
As a destroyer, man has succeeded far better against 
lesser enemies, and even against certain beneficial species, 
notably the passenger pigeon and the American Bison, than 
he has against the house-fly. In spite of many indifferent 
" swat-the-fly " campaigns, this pest persists in inconceiv- 
able numbers. Wherever you find man there the house-fly 
abounds and always to man's detriment. How well the 
fly is fitted to survive, and why he is always a source of 
danger, will be evident from the following study. THE HOUSE-FLY 
25 
I. 
LIFE HISTORY 
Examine with a hand lens some of the maggots or larvae 
of flies that breed in decaying fish or meat.1 Do they have 
legs? In about a week these larvae become pupae. Ex- 
amine a pupa. What color is it? Is it able to move or to 
eat? After five or six days the skin of the pupa splits open 
and the adult fly emerges. 
1. Is it true that a little fly can grow into a big one? 
2. Are all house-flies the same size? 
3. Write a short account of the life history of the 
house- fly. 
II. THE ADULT 
Examine either living specimens of house-flies placed in 
small vials or preserved specimens. You should use a hand 
lens for this work, and in addition, if it is possible, you should 
observe a fly under the low power lens of the compound 
microscope. Notice the divisions of the body. How many 
divisions or segments are there in the middle region or 
thorax? How many in the abdomen? How does the size 
of the eyes aid the fly? Watch a fly as it eats and observe 
the shape of the "tongue." Can you see this when the 
fly is not eating? Does the fly possess biting, sucking, or 
piercing mouth parts? 
Where are the fly's wings attached? How many pairs 
are there? Back of each wing you will see a little white 
"balancer." How many legs are there, and to what por- 
tion of the body are they attached? Notice especially the 
coverings of the body and legs. 
1 You must keep in mind that house-flies breed preferably in horse 
manure. The larval and pupal stages that you are studying may be the 
progeny of the blue bottle fly or blow fly, both of which lay eggs in meat, 
but they are similar to the corresponding stages of the house-fly. Ask your 
teacher about the specimens you are working with, to make sure. 26 
THE MOSQUITO 
1. Explain how flies are able to distribute germs and 
hence why they are a source of danger. 
2. What means would be effective in combating this 
pest. 
3. Make a drawing of a house-fly (x 5) and label all 
parts that vou have seen. 
Textbook, pages 36-38. 
LABORATORY STUDY 17 
THE MOSQUITO 
If you have ever noticed the countless tiny objects jerkily 
wending their way through the water near the surface of 
some stagnant pool or rain barrel, then you have come in 
intimate contact with the early stages in the life of a mos- 
quito. These young mosquitoes are interesting creatures 
to study at close range, and in order to do this you should 
take some of them into the laboratory and place them in 
small jars. If you place a few by means of a pipette in 
small vial you may study them easily with a hand lens. 
I. EGGS 
The eggs are grouped in tiny raft-like masses that float 
on the surface of the water. Approximately how many 
larvae may hatch from one of the egg masses? 
Make a sketch of an egg mass. 
II. LARVAE 
You may see some larvae hanging just below the surface 
of the water. Which is nearer the surface of the water, the 
the head (the larger end), or the abdomen? What is the 
function of the tube at the end of the body? On the head THE MOSQUITO 
27 
arc tiny hair-like tufts that brush food particles into the 
mouth. 
Make a drawing (at least one and one half inches 
long) of a larva, labeling the parts that you have 
been able to distinguish. 
III. PUP.® 
The head and the thorax of the pupa are quite large in 
comparison to the rest of the body. Does the pupa hang 
in the same position from the surface of the water as does 
the larva? How is breathing carried on? Does it swim 
about as much as the larva? Are you able to distinguish 
the eyes? the wings? 
Make a drawing (at least one inch long) of the pupa, 
labeling the parts you have seen. 
IV. THE ADULT 
If you are fortunate you may see an adult emerge through 
a break in the top of the pupa skin and then rest there for 
a few minutes before it is able to fly. Observe a preserved 
specimen and determine its sex (the males have feathery 
antennae). How many parts to the body? How many 
legs? How many wings? 
Make a drawing (at least one and one half inches 
long) of the adult. 
V. RELATIONS TO MAN 
Do all mosquitoes bite? Is your specimen one of the 
common type (Culex), or is it a malarial mosquito? How 
can you distinguish the two? How can mosquitoes dis- 
tribute malaria and yellow fever? Explain how the mos- 
quito prevented the French from building the Panama 
Canal? What is the common means of extermination em- 
ployed against the mosquito? How may everyone help? 28 
THE HONEY-BEE 
What animals aid in exterminating mosquitoes? (It is said 
that a certain locality at Mitchell's Lake near San Antonio, 
Texas, was once notoriously malarial. Many roosts were 
built for the purpose of harboring bats, and now the locality 
is freed from malaria.) What is the significance of this? 
Write a short story on the relation of mosquitoes 
to man, using the above questions to guide you. 
Textbook, pages 10-12, 38-41. 
LABORATORY STUDY 18 
THE HONEY-BEE 
The honey-bee is an excellent example of a social animal 
that shows high development of communal life. In the hive 
we have many individuals living together and working for 
the good of the group, and though certain individuals per- 
form highly specialized tasks they all are benefited by this 
division of labor. Bees are interesting also because of their 
economic importance. Although several millions of dollars' 
worth of honey is produced annually in the United States, 
this fact is insignificant when compared with the activities 
carried on by bees in the pollination of flowers, which helps 
to make possible the continuance of many interesting or 
useful species of plants. 
I. WORKER 
Examine a preserved specimen of a worker and notice 
the size, the divisions of the body, and the body covering. 
Describe the antenme. How many do you find. How many 
eyes are there? Are they all alike? Study the mouth parts 
with a strong hand lens (if possible from a prepared slide 
under the low power of the compound microscope). How 
are they fitted for obtaining nectar. THE HONEY-BEE 
29 
Where are the wings attached? How many are 
there? How many legs does the insect have and 
where are they attached? Notice that the third seg- 
ment on each hind leg has rows of curved bristles 
bordering a concave area where the pollen is carried. 
This forms the pollen " basket." It should be ex- 
amined under the microscope. 
How many rings or segments are there in the 
abdomen? At the end of the abdomen the sting will 
be found. Of what use is the sting to the bee? 
Make a drawing (side view) of a worker and label 
all parts that you have seen. 
Compare specimens of queen bees and drones with the 
worker. 
In what respect does the queen bee differ from the 
worker? 
In what respect does the drone or male differ 
from the worker? 
Examine a colony of bees in an observation hive. 
How many different forms are there in the hive? 
How do they compare in size, shape, and number? 
What are the duties of each type of bee? Is the hive 
clean? What bees are responsible for this? Notice 
that any cracks are filled up with a brownish, waxy 
" bee glue." 
II. THE COLONY 
III. THE COMB 
Observe the comb. What is the shape of the cells? 
How are they arranged? Are all of the cells alike? 
Are they all used for the same purpose? How may 
one distinguish a queen cell? Where is the honey? 
Why are " supers " placed on a bee hive? 
IV. LIFE HISTORY 
Where are the eggs laid? The eggs hatch after about 
three days into larvae. What is the appearance of the 30 
A COLONY OF ANTS 
larvae? How and with what kind of food are the larvae 
fed? In a week or so the larva changes to a pupa. Do you 
see any pupae? These emerge in about two weeks as adult 
workers. When a queen is desired the workers connect 
three cells in one large one and then give the larva a special 
diet of "royal jelly," while the larvae that become workers 
are fed on digested honey and pollen. Workers develop 
from fertilized eggs and drones come from unfertilized eggs. 
Write a story on the " Communal Life of the 
Hive." 
Textbook, pages 41-44. 
LABORATORY STUDY 19 
A COLONY OF ANTS 
Ants, like bees, are interest ing on aecount of their complex 
social life. One may learn much about them by studying a 
colony in the laboratory. Perhaps the simplest way to do 
this is to transfer a colony that has been dug up to a Fielde 
Ant Nest. This nest was devised by Miss Adele Fielde, an 
American student of ants, and may be easily constructed by 
anyone. 
In order to construct the nest two pieces of glass, 
4x5 inches, are needed for the top and bottom. The walls 
are made of strips of glass one-half inch wide which are 
glued to the foundation plate (flat side down) along the 
edges. Two thicknesses are necessary for the walls so as 
to allow the ants to move around freely. At one corner an 
entrance one-half inch wide is left. The nest is divided 
into two chambers, a living room and a dining room, by a 
glass partition made of two strips, each one inch wide. An 
opening is left at one end of the partition to serve as a door A COLONY OF ANTS 
31 
connecting the two rooms. Ants are annoyed by the light, 
so in order to make the walls opaque they are covered with 
strips of calico or cambric one inch wide which are glued 
on with the edges overlapping the top and bottom. In order 
that the nest may be well ventilated when the top glass 
plates are laid on, strips of Turkish toweling one inch wide 
which have been folded over once, are cemented on the top 
of the glass walls and partition. After the glue has dried, 
and the nest is ready for use, a bit of moistened sponge is 
placed in the inner chamber. The top is then covered by 
two glass plates, each one-half the size of the foundation 
plate. A piece of cardboard the size of the foundation plate 
is laid over the top plates to keep out the light, and all the 
parts may be kept in place by rubber bands. 
The nest is now ready for its inhabitants. An ant's nest 
is dug up with a strong trowel, and all of the colony includ- 
ing eggs, larvae, pupae, and adults along with some of the 
soil is carefully transferred to a fruit jar. In order to transfer 
the ants to the nest the Fielde nest is placed on a board or 
pan which is floated in some water in a still larger pan. The 
contents of the fruit jar are placed on the board near the 
Fielde nest and are spread out carefully in order to dry out 
as soon as possible. After a time the ants discover the dark 
moist chamber and transport their belongings into the nest. 
When most of the ants have moved in, the hole is plugged 
up with absorbent cotton, and the nest is removed from the 
board. The ants will live this way for some time, and their 
activities may be studied by removing the pieces of card- 
board or lifting the nest up and observing it from below. 
Miss Fielde states that the food, which should consist of tiny 
bits of apple, banana, sponge cake moistened with honey, 
etc., may be introduced into the food chamber. No bits 
of food not eaten should be left in the nest, and the nest 
should be cleaned weekly to prevent the growth of mold, 
which is a great enemy of ants. The cleaning may be done 32 
A COLONY OF ANTS 
by removing the cover from the food room whereupon the 
ants retire to the other darkened room. The entrance is 
now plugged up with cotton and the chamber cleaned with 
a bit of cheese cloth moistened with alcohol. The glass 
cover is left off until the alcohol has evaporated. 
THE COLONY 
Observe the activities of the ants in a Fielde nest, 
and study an individual with a hand lens. Do the 
antennae appear to be important organs? Are the 
eyes as large relatively as those of other insects you 
have studied? What kind of mouth parts does the 
ant possess? How do you know? How does the ant 
carry an object? Where are the legs attached? Do 
they seem to be efficient organs of locomotion? Does 
your colony have a queen or queens (individuals larger 
than the rest)? 
The eggs are laid, and then stuck together in tiny bundles. 
The larvae are small white grubs, and when young feed 
upon regurgitated food that is supplied by the workers. 
Later they eat bits of food that is brought to them by the 
workers. You may see the ants dragging some of the larvae 
about. If so, find out the reason for this. The pupae (these 
are the "ants eggs" that are sold by the goldfish dealers 
for turtle food) in their light-colored cocoons resemble wheat 
grains and are carried about by the workers, with the result 
that the embryos get the proper degree of temperature and 
moisture for their development. You may see some young 
ants that have just emerged from the pupae cases. Are 
they the same color as the adults? Do they appear to be 
able to take care of themselves? 
Write a story of your observations of an ant's nest. 
Textbook, pages 44-47. WASPS 
33 
LABORATORY STUDY 20 
WASPS 
Wasps may be seen in the late spring, in summer and in 
the autumn. They are best studied alive. Held in a small, 
clear vial, stoppered loosely with cotton, it is possible to 
examine one with ease. You should know the kind of wasp 
you are studying, whether it is (1) a solitary wasp, the 
lustrous blue mud-dauber (Pelopoeus), or (2) the brown, 
stout-bodied social wasp, the hornet (Vespa), that con- 
structs the great globular nests of w7ood-pulp, or (3) the 
more slender "yellow jacket" (Polistes) that forms the 
pendant cluster of wood-pulp hexagonal "cells" under 
the eaves of the house, or under logs or stones. 
I. THE ADULT 
With a hand lens make an examination of the wasp in 
the vial. By this time you are familiar with the sections 
of the body and the organs that are typical of the body of 
an insect. 
Make a comparison of the body of the wasp with 
that of another insect you have studied. 
If possible, transfer the wasp to a larger bottle having 
clear glass. If your wasp is a "yellow jacket," put into the 
bottle with it a clover blossom or other flower and a small 
splinter. If the wasp is a mud-dauber, put in a pellet of 
mud. 
1. What does the wasp do with its mouth parts? 
2. What evidence of breathing can you observe? 
II. THE LIFE HISTORY 
Obtain a nest containing the living young of a wasp. 34 
THE BEETLE 
1. If you have the paper-making wasp, what do you 
find in the open " cells " of the nest? 
2. What do you find in the closed cells? 
If you can secure a mud-dauber's nest, cautiously break 
it open from the top down. The adult is not at home. 
What do you find? Tell about it. 
Textbook, pages 48, 49. 
LABORATORY STUDY 21 
THE BEETLE 
"June Bugs," or more properly May Beetles, are the big 
brown beetles that annoy us by flying in our open windows 
on summer evenings. They annoy the farmer, however, 
more than anyone else because their larvae (white grubs) 
feed upon the roots of strawberries, potatoes, grains, nursery 
stock, etc. 
Examine a living preserved specimen of a May beetle and 
notice the size, covering, and divisions of the body. Con- 
sidering the relative size of the eyes and antennae, which 
do you judge to be of greater value to the insect? Observe 
the mouth parts by means of a hand lens, and determine 
howT the beetle obtains its food. (If there are any living 
beetles in the laboratory watch them while they are feeding.) 
Are there divisions between the head, thorax, and 
abdomen plainly marked? Where are the legs at- 
tached? How many are there? Do you think they 
are well fitted for the work they have to do? Why? 
How many wings do you find and where are they 
attached? What is the function of the fore wings? 
How are they used in flight? Is the beetle as good 
a flyer as the house fly? Explain. THE METAMORPHOSIS OF A MOTH 
35 
Examine if possible some of the larvae of the May beetle. 
What color are they? Are the legs well developed? Notice 
the spiracles (breathing pores). 
Make a drawing, dorsal view, of the May beetle. 
About three years are required to complete the life history 
of a May beetle. The eggs are laid in the soil, and the 
grubs remain there for two summers. The pupa stage 
requires about two months, but the newly formed adult 
stays in the ground until the following spring. 
Textbook, pages 51-55. 
LABORATORY STUDY 22 
THE METAMORPHOSIS OF A MOTH OR A 
BUTTERFLY 
It is a common thing for people to fail to distinguish 
between a butterfly and a moth. In general we may say 
that a butterfly, when it alights, folds its wings vertically 
over its back, while the moth's wings are extended horizon- 
tally. The butterfly has knobbed antennae, while the moth's 
are feathery or pointed. Butterflies are active in the day- 
time and moths at twilight or at night. The butterfly's 
body is usually less heavy or bulky than that of the moth. 
The monarch butterfly which feeds on milkweed, or the 
cabbage butterfly, may be used for this study. The latter 
will probably be easier to secure. 
I. THE EGGS 
Examine some eggs of the butterfly with a hand lens. 
Where were they found? What is their shape? How many 
do you find? 
Make a drawing (X 10) of the eggs. 36 
THE METAMORPHOSIS OF A MOTH 
II. THE LARVA 
Observe some larvae in a cage from time to time. How 
do they eat? Are they all the same size? Explain. How 
many segments are there in the body? Do you find a head, 
a thorax, and an abdomen? How many legs does the larva 
have? Where are they attached? Are they all alike? Is 
the larva active? What finally becomes of it? 
Make a drawing of a larva (X 2). 
III. THE PUPA 
What does the larva do in passing into this state? Is the 
pupa active? Is there any protection for it. Where was 
the pupa found? After examining several pupae are you 
able to learn what is happening? 
Make a drawing of a pupa (X 2). 
IV. THE ADULT 
Examine some mounted specimens and also observe some 
of the living butterflies in a cage, if possible. How many 
parts are there in the body? How many wings are there 
and where are they attached? How many legs are there and 
where are they attached? What is the shape and what is the 
length of the antennae? How many eyes are there? Does 
the butterfly eat in a manner similar to the larva? Of what 
does its food consist? How are the mouth parts adapted 
to securing the food? Examine a bit of a butterfly's wing 
under the low power of the compound microscope. What 
does it look like? When you hold the insect by the wings 
a bit of powder may come off on your fingers. What is this 
powder? Is it of any use to the butterfly? 
Make a drawing of a butterfly showing all the parts 
you have seen. 
Write a short life history of the butterfly you have 
studied. 
Textbook, pages 55-60. THE GRASSHOPPER 
37 
LABORATORY STUDY 23 
THE GRASSHOPPER 
As one strolls through a grassy meadow in the heat of a 
late summer's day he is sure to be conscious of an insect 
life that is vibrant and active in spite of the oppressive 
warmth. Not the least noticeable of these creatures are 
the grasshoppers that spring up before him, their wings 
crackling as they cleave the hot currents of air that rise 
from the sun-baked soil. As the grasshopper alights from 
his short flight, his colors blend so well with those of his 
surroundings that it is only with difficulty that one is able 
to discern him. How well he is fitted to carry on the struggle 
for existence will be evident from the following studies. 
I. LOCOMOTION 
Observe closely the living grasshoppers in a cage or in 
the field. How do the insects move about? Are there any 
special adaptations for such methods of locomotion; what 
are they? 
Describe the grasshopper's manner of walking and 
jumping. 
When you are in the field pay careful attention to the 
insect's method of flight. Determine, if possible, the func- 
tions of the front and hind wings in flight and at rest. 
Describe the manner of flight of the grasshopper. 
II. FOOD-TAKING 
Observe the grasshoppers feeding in the cage or in the 
field and notice the food that they prefer. How is feeding 
carried on? 
Would you consider the grasshopper a pest or a 
friend? Why? 38 
THE GRASSHOPPER 
111. PROTECTION FROM ENEMIES 
Take a living grasshopper in your hand. Does it seem 
to have any means of protecting itself? Do you experience 
any difficulty in distinguishing the grasshopper in its natural 
surroundings in the field? 
How are grasshoppers protected against their 
enemies? 
IV. EXTERNAL ANATOMY 
Examine a preserved specimen. The body is divided into 
three regions: the head, the thorax, and the abdomen. 
Examine the head with a hand lens. What is peculiar about 
the eyes? There are three simple eyes that you should see, 
one in the center of the forehead and one above each of the 
antennae. Pull off the upper lip, the labrum, and notice 
beneath it the jaws or mandibles. Remove one and examine 
it closely. What do you think it is used for? How many 
antennae are there? What is their function? 
Make a drawing of the head (front view) and label 
those parts that you have seen. 
How many parts are there in the thorax? How many 
pairs of wings do you find and where are they attached? 
How many pairs of legs are there, and where does each 
pair join the body? How many rings, or somites or segments, 
do you find in the abdomen? Notice a tiny row of pores on 
each side of the abdomen, one on each side of a somite. 
These are the spiracles. What is their function? If you 
find a pair of spine-like organs on the end of the abdomen 
your specimen is a female. These organs are used for digging 
when the female lays her eggs. 
Make a drawing of the insect (side view) labeling 
such parts as you have seen. Be careful to make a 
good drawing of the large jumping leg and distinguish THE CRAYFISH 
39 
the three main parts - the thigh or femur, the tibia, 
the foot or tarsus. 
V. REPRODUCTION 
As has already been intimated, the female lays her eggs 
in the soil by means of the spine-like ovipositors on the end 
of the abdomen. Try to recall your experiences with grass- 
hoppers during the past summer. At what time did they 
first become abundant? Were they large or small? Did 
they have wungs? How do you account for the fact that in 
general the large grasshoppers are not seen until after the 
small ones? Do they have a " complete " or an " incomplete " 
metamorphosis ? 
Write a short account of the life history of a grass- 
hopper. 
Textbook, pages 62-64. 
LABORATORY STUDY 24 
THE CRAYFISH 
Crayfishes are found in fresh water in regions where there 
is lime in the soil. The hard outer skeleton of the animal 
is supplied with lime compounds from the food it consumes. 
The plants on which the crayfishes feed take lime in solu- 
tion from the soil. Where crayfishes are abundant, they 
sometimes frequent low or marshy places and dig "wells" 
to the water, carrying mud to the surface and forming crude 
"chimneys" about the openings. In brooks, rivers and lakes 
they crawl or swim about at the bottom, concealing them- 
selves under jutting rocks when necessary to escape the 
notice of large fishes, or when lying in wait for small fishes, 
tadpoles or insect larvae. 40 
THE CRAYFISH 
I. LOCOMOTION 
Live crayfishes don't mind performing in public. Watch 
them crawling along the gravelly bottom of a temporary 
aquarium. Can you make out whether they have a system 
of moving their numerous legs? Do you notice any differ- 
ences in the structure of the legs? Do they use the large 
legs (chelipeds, claw-feet) in walking? Do crayfishes make 
any use of their "feelers" (antenna? and antennules') as an 
aid in finding their way? 
If you lower a stick in front of a crayfish, does the animal 
notice it? What sense seem to warn it of danger? How 
does it escape quickly? Watch to see when the swimmerets 
of the abdomen are working and what they are doing. 
Write a story of what you have learned in this study 
thus far. 
II. BREATHING 
Living things have to breathe to live; it is the same with 
both plants and animals. This is why respiration or breath- 
ing is called a fundamental biological process. To discover 
the location of the breathing organs of the crayfish, place 
a live one in a tray of water. Fill a pipette full of carmine 
solution (it is harmless), and press out a quantity along the 
side of the crayfish until you have discovered where the 
carmine is drawm in and where it is sent out from the body. 
What is the meaning of the facts you have noted? 
Examine a specimen of a crayfish from which a portion of 
the shell has been removed. Find the "gill-bailers" which 
set up a circulation of air-laden water. Study the texture 
of the gills. 
In what way do the gills appear to be adapted to 
the function of breathing? THE CRAYFISH 
41 
III. FOOD-TAKING 
Place a small piece of meat on a long needle or on a 
pointed glass rod, and try leaving the meat cautiously on 
the bottom near the crayfish. Do not tease the crayfish. 
Watch carefully to see if any organs are moving. What 
happens? For comparison place a small live fish or tadpole 
or snail in the water near the crayfish. Follow the work of 
the claw-feet and the mouth-parts. In the mouth-parts are 
the very small maxillee, the maxillipeds, and the heavy 
jaws called the mandibles. 
What are the organs of the body that take part in 
the capture and the consumption of food, and what 
does each organ do? 
IV. THE EXTERNAL ANATOMY 
The cells of the skin of the crayfish are filled with an 
accumulation of a lime compound. The shell thus formed 
serves the function of protecting the animal from being 
attacked by large fishes. It also acts as a surface for the 
attachment of muscles in the body, and gives the animal 
its definite form. 
Can you see any advantage to the crayfish in its color? 
Are there mechanical advantages in the solid shell of the 
head and thorax (chest) regions, and in the movable seg- 
ments or somites of the abdomen? Is there an advantage 
to the crayfish in having its eyes on stalks? These points 
illustrate well one of the important biological principles 
called adaptation to use or function. 
1. Give a description of other illustrations of this 
principle in the external organs of the crayfish. 
2. Make a drawing of the side view of the crayfish 
(X 1), and label the parts. 
3. Make a drawing of a leg and gill attached (X 2), 
and label. 
4. Make a drawing of the ventral (under) surface of 
the abdomen (X 2), and label the parts. 42 
THE SPIDER 
V. IMPORTANCE TO MAN 
You may have heard more about the value of lobsters 
(a near relative of the crayfish) as food for human beings 
than you have heard of crayfishes. But in France there are 
farms on which crayfishes are raised for the market. Lob- 
sters are expensive food now, owing to the fashion for eating 
them. Crayfishes are cheap. 
In what parts of the United States do you think 
crayfish farms might be started, considering the 
points of suitability of soil and the character of the 
population to which crayfishes might be sold? 
Textbook, page 65. 
Linville and Kelly: Textbook in General Zoology (Crayfish), 
page 125. 
LABORATORY STUDY 25 
THE SPIDER 
A walk through a field on a dewy morning will reveal 
masterpieces of spider architecture in all their glory. The 
silvery beauty of the orb wrebs and the funnel webs strikes 
the eye at once. When we realize, however, that each web 
is an ambuscade for some unwary insect, then we may 
appreciate its full significance. The orb web is the seat 
of activities of the garden spider which we may add to our 
list of friends. 
If possible, large living specimens of the garden spider 
in wide mouth bottles should be used for this study; other- 
wise, preserved specimens will serve the purpose. 
Notice the two divisions of the spider's body. The first 
division is made up of the head and thorax together; the 
second is the abdomen. THE SLUG 
43 
How does this arrangement differ from that of 
insects? To what part of the body are the legs at- 
tached, and how many pairs do you find? Compare 
the spider's eyes with those of an insect as to number 
and size. 
There are no antennae; those appendages which appear 
to resemble antennae are really mouth-parts. 
With the aid of a good hand lens locate near the posterior 
end of the abdomen the three pairs of tubercle-like spin- 
nerets. These are the organs with which the spider spins 
the thread for its web. 
What are some of the uses that the spider makes of 
this silk? How does the spider care for its young? 
Make a drawing (dorsal view) of a spider and label 
all the parts that you have seen. 
A field trip will reveal some interesting types of spider's 
webs. 
Textbook, pages 67-68. 
LABORATORY STUDY 26 
THE SLUG 
If you have had any experience in gardening you have 
come in contact either directly or indirectly with slugs. 
They often do considerable damage to garden crops by feed- 
ing on the succulent young leaves. They have a habit of 
feeding at night. During the day they remain in some cool 
dark place. They are often troublesome pests in green- 
houses. The slugs may be trapped by placing boards or 
other flat objects wherever they are present; they will be 
found hiding beneath the boards during the day. 44 
THE FISH 
THE LIVING SLUG 
Observe a living slug in a vivarium or in a large beaker 
containing some cabbage or lettuce leaves. Describe the 
shell. Is the slug like other snails in this respect? Look at 
some snails in the laboratory aquarium. How does the 
animal move? What do you observe as to its rate of loco- 
motion? Does it leave any traces behind as it moves about? 
Of what use is the mucus to the slug? How many tentacles 
are there? Locate the eyes and see what happens to them 
when they are touched. Do you think the slug has an effi- 
cient sense of vision? What are the functions of the ten- 
tacles. Find the mouth and observe the animal eating. 
How is eating carried on? Examine the mouth with a hand 
lens and notice the rasp-like tongue or radula. Find the 
breathing pore on the right side of the body. 
Make a drawing of the slug, showing all the parts 
that you have seen. 
Compare the slug with the different snails that you find 
in the laboratory aquarium. 
Textbook, pages 77-79. 
LABORATORY STUDY 27 
THE FISH 
Since all fishes live in the water they must necessarily 
possess a bodily form together with organs of locomotion, 
breathing, and sensation which enable them to meet effi- 
ciently the requirements of such an environment. They are 
interesting because they possess bodily adaptations that are 
different from those of animals that live on land. 
The goldfish lends itself easily as an object for study. 
By selective breeding man has been able to develop the THE FISH 
45 
brilliant hues of the goldfish, although its ancestors were 
dull-colored individuals that lived in certain streams in 
China. What do you think would happen if you set a gold- 
fish free in one of our streams? 
I. LOCOMOTION 
Observe the fish as it swims about in the aquarium. How 
many fins has it? How many of them are in pairs? The 
front pair are the pectoral fins; the pelvic fins are the pair in 
the middle of the body on the ventral side. On the upper 
side of the body is the dorsal fin. The unpaired fin on the 
ventral side is the anal fin, and the tail fin is called the 
caudal fin. Which of the fins are used to propel the fish 
forward? What fins are used in moving upwards? in mov- 
ing downwards? in turning? in balancing? When the 
fish is motionless in the water observe its shape from a posi- 
tion directly above it. How does the shape adapt the fish 
to life in the water? Make an outline drawing of what 
you have just observed. A cross-section of an airplane 
strut shows a shape similar to the sketch you have just 
made. What is the advantage of such a shape? 
Describe the locomotion of the fish and state the 
use of each type of fin. 
Drop a little fish food in the aquarium and notice how 
the fish takes in its food. Does it chew the food? 
Do you see any nostrils? Does the fish use them for 
breathing? What is their function? 
Can the fish move its eyes? Do they have lids? What 
would you say concerning the vision of the fish? 
Notice the movements of the mouth. Why is it con- 
tinually opening and closing? Does there seem to be any 
relation between the movements of the mouth and those of 
the gill-covers (opercula)? 
II. FOOD-TAKING AND RESPIRATION 46 
THE FROG 
Describe the manner in which a fish (a) obtains its 
food, (b) breathes. Make a drawing (side view) of the 
fish, labeling all parts. 
III. GILL STRUCTURE 
Remove the operculum from a preserved specimen. How 
many gills do you find? How are they arranged? Remove 
a gill and observe that it is composed of a bony arch with 
spiny gill rakers and many feather-like filaments. What 
is the purpose of the operculum? Of the rakers? Of the 
filaments? 
Make a drawing of a gill, labeling the parts. 
IV. REPRODUCTION 
In New York State, for example, the open season for 
brook trout is from April 15th to September 1st, and the 
State Game Laws make it illegal to take trout that are less 
than five inches long. It is known that trout that are six 
inches long may lay eggs, and that the spawning season is 
from September to the latter part of November. The female 
trout seeks a spot on the gravel bottom of the brook near 
the opening into a larger stream and there lays her eggs. 
Write your comments upon the wisdom of this 
New York State Game Law. 
Textbook, Chapter IX. 
LABORATORY STUDY 28 
THE FROG 
The frog belongs to that class of Vertebrates, the 
Amphibia, all of whose members spend at least some part 
of their life history in the water. Because there are many 
points of similarity between the frog and man it is well to THE FROG 
47 
study it in some detail. As you study it be watchful for 
adaptations to special functions 
I. A LIVING FROG 
Take a frog from an aquarium or a moist cage. How does 
it feel? Account for the difference in color of the ventral 
and dorsal sides, and for any benefits that may or may not 
be derived from this coloration. 
Watch the movements of the nostrils, the throat, and the 
body wall and determine how breathing takes place. Would 
this account for the frog's ability to stay under water for 
so long a time? 
Just how does breathing occur in the water and 
out of it? 
When you touch the eyeball what happens? Is there 
anything peculiar about the movement of the eyelids? 
Where are the ears found? 
How does the frog move on land? Determine its stroke 
in swimming. Howr does the foreleg differ from the hind 
leg? 
1. What adaptations does the frog possess for loco- 
motion on land and in the water? 
2. Make a drawing of a frog (dorsal or back view), 
being careful to include all external organs that 
you have observed and to show the distinctions 
between the forelegs and the hind legs. 
Place the frog in a cage with a few flies and see how the 
frog obtains its food. 
II. THE DISSECTION 
Open the mouth of a freshly killed or preserved specimen 
of a frog, pull out the tongue and notice how it is attached. 
Do you find any teeth? Do they look as though they are 
used for chewing? Force a very small piece of fine wire or 48 
THE FROG 
a bristle through a nostril and notice the connection with 
the mouth. Just back of the tongue find a slit, the glottis, 
which opens into the windpipe. Behind it you will find an 
opening to the gullet or the oesophagus. 
Make a drawing of the mouth wide open and label 
all parts that you have observed. 
Place a frog on its back in a dissecting pan and pin down 
the legs. Cut forward through the skin and abdominal 
muscles with the scissors from the hind legs to the floor of 
the mouth along the midventral line. Be careful not to 
cut too deeply. (Avoid this by holding the skin up with 
the forceps while you are cutting.) Cut away all of the skin 
so as to expose the powerful ventral muscles and the muscles 
of the legs. Carefully remove the ventral muscular wall 
and identify the following organs: 
1. The Blood System. 
Notice the three-chambered heart with two thin mem- 
branous auricles and a conical, muscular ventricle point- 
ing downward. Trace the blood vessels leaving the heart 
as far as you are able. 
2. The Respiratory System. 
Find the two dark membranous lungs, one on each side 
of the heart. With what do they connect? Thrust a blow- 
pipe or a glass tube that has been drawn to a jet into the 
glottis and blow gently, meanwhile observing the shape the 
lungs take. 
3. The Digestive System. 
The large, reddish, three-lobed, conspicuous mass is the 
liver. In the folds of the liver you will notice a small greenish 
body, the gall bladder. The bile duct is a tiny tube leading 
from this to the beginning of the small intestine. Trace its 
course. THE FROG 
49 
Be sure to locate and recognize the following organs of 
the digestive system: the oesophagus opening into the thick- 
walled, light-colored stomach; a slender, coiled tube, the 
small intestine, leading from the stomach and terminating 
in the cloaca; the pancreas, a long yellowish mass near the 
stomach. (Notice its attachment.) 
Make a careful drawing showing all of these organs 
in their proper places. 
Remove the digestive system and find the following organs: 
4. The Excretory Organs. 
The kidneys are a pair of dark reddish, elongate organs 
lying against the back. 
5. The Reproductive Organs. 
If the specimen is a male frog there will be two light- 
colored oval testes to be found near the kidneys. If the 
specimen is a female the ovaries may contain (in early spring) 
a large number of eggs which nearly fill the entire body 
cavity, and which must necessarily be removed before you 
can study the other organs. The oviducts are light-colored 
ducts that lead to the cloaca. 
A small, round, red organ near the intestine 
6. The Spleen. 
Make a drawing of the reproductive organs. 
In April when from the ponds the frogs are heralding the 
approach of spring, the mother frogs are busy laying their 
eggs in masses of jelly, and usually fastening them to sticks 
in the bottom of the pond. If a mass of these eggs is placed 
in an aquarium jar in the laboratory the development of 
the eggs may be watched from day to day. Some pond 
III. THE LIFE HISTORY OF A FROG 50 
THE TOAD 
scum, such as spirogyra, should be added and a fresh supply 
put in from time to time as the young tadpoles develop. 
Be careful that the water does not get too warm. 
As soon as the eggs hatch, look for tiny fringes on either 
side of the head of the tadpoles. These are the gills. What 
is their function? Watch the young tadpoles from day to 
day and notice what happens to the gills. When does this 
change take place? 
Observe older specimens of tadpoles in other aquaria in 
the laboratory (or preserved specimens may be used), and 
locate the gill slits. By dropping a bit of finely powdered 
carmine in the aquarium the course of the water through 
the mouth and out the gill slits may be traced. 
Observe some specimens on which the legs have started 
to develop. Which pair comes first? As the legs increase 
in size what becomes of the tail? 
Write a complete life history of the frog. 
Textbook, pages 92-95, 100-101. 
LABORATORY STUDY 29 
THE TOAD 
It is true that the toad can scarcely be called an object of 
beauty, yet we must admit that its ugliness is only skin deep. 
Those who know it well make no excuses for its outward 
appearance. It is a humble fellow that inauspiciously goes 
about doing its bit unconsciously, incidentally making the 
world a better place for us to live in. This fact alone makes 
the toad deserving of respect at least. 
I. THE DEVELOPMENT OF THE TOAD 
Sometime about the first of May, in the Northern States, 
the female toad deposits her eggs among the water weeds THE TOAD 
51 
near the bottom of some pond or in the still water of a slug- 
gish stream. They are long, clear strings of jelly-like mate- 
rial, at first, but soon become discolored. If some of these 
eggs are brought into the laboratory and placed in an aqua- 
rium along with some water plants their development may 
be easily watched from day to day. 
Make a calendar-like chart in your notebook and record 
your observations from day to day. Be sure to make obser- 
vations (a) when the eggs hatch, (6) about three days after 
hatching, (c) about ten days after hatching, (d) thirty days 
after hatching, (e) forty days after hatching, (f) and, if 
possible, when the tadpoles become young toads. 
Your record should show when the gills appear, 
when they disappear, when the tadpole begins to eat, 
its food, when the hind legs appear, when the front 
legs appear, and the changes that occur in the tail. 
Compare the development of the toad with that of 
the frog. 
In early July the young toads are found leaving the ponds 
in great numbers. Their migrations are inconspicuous, 
except on rainy days, when so many appear that the unin- 
formed think they are being rained down. How can you 
explain the coincidence of large numbers of small toads with 
the rainy weather? 
II. THE ADULT TOAD 
The toad to be used for study may be kept fairly comfort- 
able in a screen cage placed over some wet moss in a box or 
large pan. Be sure that the moss is always kept moist. 
Study the living toad and determine how the color and 
the appearance serve to protect the toad against its enemies. 
What other means of protection does the toad possess? 
Notice the eyes. Does their prominent position serve the 
toad well? Compare the front and hind legs as to size, 52 
THE NEWT 
number of toes, and character of the feet. Account for any 
differences that you observe. If you place some house- 
flies, or some other living insect in the cage, you may see 
how the toad captures its food. What is the purpose of the 
movements of a toad's throat? What are some enemies of 
the toad? 
Write a short account of how toads may be helpful 
to man. 
Textbook, pages 95-98, 100-101. 
LABORATORY STUDY 30 
THE NEWT 
A great many people incorrectly call this little animal a 
lizard. The latter belongs to an entirely different group of 
animals, the reptiles, which includes also the turtles and the 
snakes. You will see why the newt or salamander should 
not be called a lizard when you come to the study of reptiles, 
and this study should show you why it is classed with the 
frog and the toad as an amphibian. It has an interesting 
life history, that is carefully described in your textbook. 
What color is the newt in your aquarium? Have you 
ever seen one that is another color? Where? Notice how 
it swims. What appendages are used? Does the tail help 
the newt when walking? What is the manner of walking? 
How many toes are there on the front feet? On the hind 
feet? Are any of them webbed? Notice the newt's eyes. 
Do you think it can see as well as the toad or frog? How 
do you account for its being found, like the earthworm 
and the young toad, usually only after a rainy spell? If 
you place some small earthworms in the aquarium you may THE GARTER SNAKE 
53 
see the newt eat. What kind of food would it eat on land 
and how would this be obtained? 
Describe the newt's methods of locomotion and 
how it obtains its food. 
Show how frogs, toads, and salamanders resemble 
one another. 
Familiarize yourself with the newt's life history. 
Textbook, pages 98-100. 
LABORATORY STUDY 31 
THE GARTER SNAKE 
These are the denizens of the stony hillside or the meadow 
that glide silently away as you approach. You may come 
across one sometime which is greatly swollen behind the head 
and that moves with difficulty. This simply means that the 
reptile has been enjoying a repast that undoubtedly con- 
sisted of some unlucky toad or frog. 
You may learn a great deal about snakes by bringing in 
a garter snake from the fields and keeping it in a screened 
box in the laboratory for a day or two. 
Notice the color and markings of your specimen. (Not all 
garter snakes are marked alike.) 
Is it full grown? What does the snake do when it 
is disturbed? What is the shape of the tongue? Is 
the tongue a weapon of offense? What do you think 
it is used for? Watch the ventral (under) plates care- 
fully as the snake moves about the box. How is 
locomotion accomplished? How many sense organs 
do you find on the snake? What are the enemies of 
the garter snake? 
Write a short account of the economic importance 
of snakes. 
Textbook, pages 102-106. 54 
THE TURTLE 
LABORATORY STUDY 32 
THE TURTLE 
The word "reptile," which means crawling or creeping, 
is well applied in the case of the turtle. In time of danger 
this creature is not at all handicapped by its inability to 
make rapid flight in the face of an enemy. It merely assumes 
a passive resistance by retiring into its well-nigh impregnable 
fortress and waits for the danger to pass. Some turtles are 
terrestrial, spending all of their time on land; others are 
aquatic, and still others spend part of the time in the water 
and part on land. Be sure you know under which one of 
the types your specimen belongs. 
THE LIVING TURTLE 
Observe a living turtle. How does it differ from its rela- 
tive, the garter snake? Describe the movements of the 
turtle in the water. Take the turtle out of the water and 
place it on the table. Describe the movements out of the 
water. Where does it seem to get along better, in or out of 
the water? Are there the same number of toes on the front 
and hind feet? Are any of these toes webbed? What sort 
of a covering is there on the legs and head? Touch any of 
the soft parts of the turtle with your pencil. Are they 
sensitive? What benefits, if any, does the animal derive 
from the shell? Compare the upper part, the carapace, with 
the lower part, the plastron. 
Make accurate drawings of the carapace and of the 
plastron, showing the number and arrangement of the 
plates. 
Observe the head. Can it extend out far from the shell? 
Is there any similarity between the turtle's head and that BIRDS 
55 
of the garter snake? Watch the eyes and determine how 
the animal winks. Find the nostrils. Watch the move- 
ments of the throat. Does the turtle appear to breathe 
like any other animal that you have studied? Most of the 
water turtles are carnivorous. Of what would their prey 
consist? Are there any teeth? How does the turtle bite 
off bits of its food? 
Compare the turtle with (a) the garter snake, (b) 
the salamander. 
Textbook, pages 106-107. 
LABORATORY STUDY 33 
BIRDS 
Bird neighbors are always interesting creatures. Their 
joyous songs and their beauty bring cheer to human beings. 
They become more interesting when we learn about their 
peculiarities, their migrations, and especially about what 
they do. It is only when we learn what they actually do that 
we become fully cognizant of their importance to man, and 
awake to the necessity of giving them our protection. 
I. A LIVING BIRD 
For this study, living canaries or pigeons in cages in the 
laboratory should be used. If this is not practicable, the 
work may be carried on independently by each student. 
English sparrows in the street, or robins on the lawn, serve 
as excellent subjects. 
Notice the shape of the bird's body. How is it adapted 
for flying? Are there any other animals that have feathers? 
How are the feathers arranged as an aid to the bird in flight? 56 
BIRDS 
Where are the largest and strongest feathers on the bird's 
body? The broad feathers that cover the body, giving 
it its outline, are called contour feathers; down is the name 
given to the small soft feathers of young birds, or to those 
that are next the skin on the mature birds. Examine a 
contour feather from some bird and notice the quill, the 
stiff part; the vane, which is the broad blade-like part of 
the feather. If a part of the vane is examined under the 
microscope it will be seen to be made up of delicate fibers, 
the barbs, which are further divided into barbules. It is 
because of the interlacing of the hooks on the barbules that 
the feather is resistant to the air, and also flexible during 
flight. Name as many uses of feathers as you can. 
What organs of the body play an important part in flight? 
Notice carefully the shape of the wing. The front edge is 
thicker than the hinder edge, and the wing itself is convex 
upward. (The wings of an airplane are convex, and also the 
leading edge is thicker than the trailing edge. Aeronautical 
engineers have found that this type of wing section is the 
most efficient.) What is the point of this fact? How is the 
body propelled through the air? What part does the tail 
play in flight? 
What is the method of locomotion employed when on the 
ground? Are the feet well adapted for this method of loco- 
motion? How many toes on each foot? How are the feet 
adapted to perching? How may they be used other than 
for perching and for locomotion? 
Notice the shape of the beak. How does the bird obtain 
its food? How is the food ground up, preparatory to diges- 
tion? How does the bird drink? 
Do birds have an acute sense of hearing? Give evidence 
to prove your answer. Are the ears visible? Where are they 
located? Give reasons for believing that a bird may have a 
well-developed sense of sight, and can see plainly both far 
and near. What senses are most useful to the bird in helping BIRDS 
57 
it to obtain its food? What birds have you seen capturing 
insects, or eating weed seeds? 
Make a drawing (side view) of a bird, labeling such 
parts as you have seen. 
Beginning in the winter and continuing through the spring 
and summer months until the close of school, make observa- 
tions of the birds in your neighborhood and keep records of 
what you have observed. Your record should show (1) the 
name of the bird, (2) date, (3) where it was seen, (4) com- 
parative size, (5) coloration, (6) what it was doing, (7) shape 
of beak, (8) distinctive features such as method of flight or 
conspicuous identification marks, etc., (9) food and how it 
is obtained. If possible you should make observations of 
its nesting habits. Finally, you should look up information 
concerning its migratory habits, and the relation of the bird 
to other animals and to man. 
Your list should include such common birds as the English 
sparrow, robin, chickadee, downy woodpecker, bluebird, 
Baltimore oriole, crow, catbird, phoebe, song sparrow, chip- 
ping sparrow, yellow warbler, and others. 
II. IDENTIFICATION AND THE HABITS OF BIRDS 
Write a story on the economic importance of birds. 
Some reference books that will help you in learning about 
the relations of birds to one another and to other animals 
and man are: 
Pearson and others - Birds of America, 3 vols. University 
Society of New York, Inc. 
New York State Museum publications - Memoir, 12. 
Chapman - Birds of North America. 
Reed - Bird Guide. 
Textbook, pages 112-122. 58 
CHICKENS 
LABORATORY STUDY 34 
CHICKENS 
What cattle are among mammals, so chickens are among 
birds - fundamentally and biologically essential to man in 
the food they each produce. And after each species has 
produced its maximum, the reserve flesh of the animals 
themselves is drawn upon for human food. The food wealth 
of the two species is marvellously great 
The ancestors of chickens are still in existence, the Jungle 
Fowl of India. Considering the large number of varieties 
of chickens now common everywhere, it is obvious that 
variation in the species has been extensive, and also that the 
variations have been rapidly improved upon through selec- 
tion by the chicken fanciers. 
I. AS BIRDS 
How many varieties do you know, and what are the 
characteristics of color and form of the birds, and the 
color of the eggs they yield? 
Comparisons of the structural features and the habits 
of chickens with those of typical birds will bring out some 
interesting facts connected with the adaptations in chickens 
to life in a restricted habitat. 
1. Have you seen chickens trying to fly? What 
success do they make of it? Explain. 
2. Are chickens good runners? What use do they 
make of their capacity to run? 
3. To what extent do chickens follow the habits of 
other birds in bringing up their young? 
II. CHICKEN FARMING 
There are chieken farms nearly everywhere in the vicinity 
of large cities, or in the regions where food is produced that CHICKENS 
59 
may be shipped to large cities. Every farm lias its own 
chickens for the egg and meat product yielded. 
1. What are some of the problems to be met in 
practical chicken farming? 
2. Why do some fail and some succeed in this 
business? 
3. Knowing the feeding habits of birds, do you think 
chickens may be of any indirect benefit to the 
farmer? If so, what? 
in. AS FOOD 
Poultry that is being prepared for the njarket is often fed 
intensively for two weeks with clean grain mixed with butter- 
milk. Incidentally, this creates a market for buttermilk. 
1. What is the difference in cost between " milk- 
fed " chickens and other kinds on the retail 
market? 
2. In what form and condition are chickens sent to 
the markets? 
The nutrient content of chicken is much the same as in 
other meats, except that the fat is not so abundant in the 
muscle itself. Connective tissue is largely absent from the 
"white meat," making that kind of meat easily digestible. 
1. Have you observed any other fact about chicken 
meat that may make it desirable? 
2. Pound for pound as the fowl is sold, is chicken 
meat more, or less, expensive than other meat? 
We have realized that the eggs of birds are the carriers 
of the germ or embryo of the young undeveloped bird. 
When eggs that have been fertilized by the spermatozoa of 
the male bird before laying are placed in a protected spot 
in a temperature equal to the body heat of the bird slightly 
over 100 degrees, they will develop to hatching within 
twenty-one days. A setting hen or an incubator will pro- 
IV. IN DEVELOPMENT 60 
HENS' EGGS 
vide the necessary conditions. If the laboratory has an 
incubator, some interesting studies in development may 
be made. 
Take from the incubator at certain stated periods of 
development one egg at a time. Provide a labeled dish for 
the egg when the shell has been removed. 
1. On the second day of incubation, and also on the 
fifth, the eighth, the twelfth, and the sixteenth 
days, remove from the incubator one egg, and 
pick off the shell and the shell membrane and 
drop carefully into the dishes for demonstration 
to the class. 
2. Follow as much as you can the development of the 
systems of organs, and observe the gradual 
transformation of food reserve into chick, and 
the preparation of the young for independent 
life. 
Textbook, pages 199-201. 
LABORATORY STUDY 35 
HENS' EGGS 
Animals, like plants, produce eggs as a means to con- 
tinuing the species. In the case of birds, and of some other 
animals, the egg is deposited by the mother, and the young 
contained in it develop more or less under her protection. 
Man has found that hens' eggs are valuable as food, and as 
a result of his discovery over twenty billion hens' eggs are 
produced in this country each year. 
I. PARTS OF AN EGG 
The shell of an egg protects the contents while permitting 
the yonng to obtain air during development. 
Lower an uncooked egg into a vessel of cold water 
and tell what you see, bearing on this point. HENS' EGGS 
61 
Cut a hole in a paper box large enough to permit an egg 
to fit in without dropping through. Set the box and egg 
over an electric light bulb and examine the egg contents. 
This is called "candling" in reference to the old-time custom 
of using a candle for the test. 
Describe what you see. 
Next remove the shell, beginning at the large end and 
noting what you saw while candling. Note the number of 
membranes you come in contact with. Cut the membrane 
carefully with scissors, letting the contents out through a 
large opening into a shallow dish without breaking the inner 
egg membrane. 
1. Note and describe the white of the egg and two 
ropey cords (chalazae) that help to suspend the 
yolk in the fluid white; also take note of the 
yolk itself and especially the little margined 
spot on top, the germ or embryo of the young 
chick. 
2. Take a hard-boiled egg, and apply the tests for 
nutrients, and report what you find. 
II. THE PRODUCTION AND THE CARE OF EGGS 
A map indicating the distribution of chickens in the 
United States shows that nearly all are to be found in the 
eastern half of the country. But they are most abundant 
in the North Central States. All through that country 
limestone is plentiful. Egg shells require lime. Where there 
is no limestone, chickens must be fed ground oyster shells, 
or other limey substance, to give hardness to egg shells. 
Food also must be abundant in order that eggs may be 
produced at all. 
What kinds of food are consumed by chickens? 
Eggs are laid in the largest quantity in the spring and 
early summer, in the months of March, April, May and June. 62 
MAMMALS 
Eggs are cheapest at that time. A large number are put 
into cold storage in those months, and large broods of 
chickens are raised. 
What steps must man have taken in dealing with 
the race of chickens to bring about so great an 
abundance? 
When eggs are plentiful and cheap they are shipped in 
large quantities to the vicinity of large cities and held there 
in cold storage. When fresh eggs become scarcer in late 
summer, and through the fall and winter, these cold storage 
eggs are sold. 
1. What is the difference in the price of cold storage 
eggs and the fresh eggs at the same time? 
2. What is the object of cold storage? 
3. Do you know of any actual differences between 
cold storage eggs and the fresh ones? 
4. What is your opinion of the system of placing eggs 
in cold storage? 
Take some eggs of various ages and sources, and "candle" 
them over an electric light bulb. 
Describe what you see, and give your opinion of the 
internal condition of the eggs. Break some of the 
" bad " eggs and tell what you find. 
Textbook, pages 315, 316. 
LABORATORY STUDY 36 
MAMMALS 
Mammals constitute the highest group in the animal 
kingdom, at the top of which stands man himself. Man 
has long been dependent on mammals for food, clothing. MAMMALS 
63 
and for help in doing his work. Hence from an economic 
standpoint they are the most important of all animals. 
A LIVING MAMMAL 
For this study, living rabbits, guinea pigs, dogs or cats, 
should be used. 
Describe the external appearance of the animal. How 
many divisions are there in the body? What kind of a 
covering does the body have? (This is applicable to all 
mammals at some period in their life history.) What are 
the uses of this type of covering? 
How is locomotion accomplished? Does the animal walk 
on its feet or on its toes? Are the fore and hind limbs 
similar to the arms and legs of man? Do you find any claws 
or nails? Of what use are they? What are some of the 
uses of the limbs other than for locomotion? 
What kinds of food are preferred by the animal? What 
adaptations does the animal have for securing food? How 
are the teeth fitted for this kind of activity? 
Notice the movements of the body as the animal breathes. 
Is the rate of breathing the same as your own? 
Locate the nostrils. What can you say as to the 
animal's keenness of scent compared to other animals 
that you have studied and compared with man? 
Where are the eyes placed? How many eyelids are 
there? What sort of an external ear is present? Do 
you think it is an important aid in hearing? Do you 
think the animal has a keen sense of hearing? Give 
evidence to support your answer. Are there any 
special organs of touch present? What parts of the 
body are more sensitive than others? 
What does the animal do when frightened? What means 
of defense has it? What are some of its enemies? 
How are the young nourished and eared for after birth? 64 
HORSES 
Of what economic importance is the animal? 
Make a drawing (side view) of the mammal and 
label all the parts you have seen. 
Make a list of the important characteristics that 
distinguish mammals from other animals. 
Textbook, pages 123-137, 181-199. 
LABORATORY STUDY 37 
HORSES 
Of the larger domesticated animals none is better known 
than the horse. So great is the adaptability of the horse 
to the wishes of man that it does not occur to us to recall 
his wild, ungoverned ancestors. 
I. THE STRUCTURE OF THE HORSE 
The horse belongs to the great Class Mammalia, the same 
Class of vertebrates to which human beings belong. 
What main divisions of the body and appendages 
are common to us and the horse? 
You will notice that because our way of standing differs 
from that of the horse, - we on our rear appendages and 
the horse on all fours, - when we estimate height of body 
we are measuring different dimensions. Furthermore, man's 
height is measured in feet and inches while a horse's height 
is measured in "hands." A "hand" means the width of 
an average man's hand, about four inches. The measure- 
ment is taken at the front leg by standing a pole against the 
horse and noting the height to the top of the shoulder. HORSES 
65 
Measure three or four horses and thus get an idea 
of the height of the average horse you see. 
Examine the picture of the horse's skeleton on page 183 
of the textbook, and compare with the parts as seen in a 
live horse. 
1. Describe the position in the front leg of the elbow, 
the wrist (wrongly called the knee), and the long 
hand bones with the nail of the third finger (the 
front hoof). 
2. Describe also the position in the hind leg of the 
knee, the ankle (hock) and the long foot bones 
with the nail of the third toe (the hind hoof). 
3. Study the " Evolution of the Horse " (page 151 in 
the textbook), and account for some of the facts 
you noted in answers 1 and 2 above. 
4. Find and describe the " ergot " and the " chest- 
nuts " on the leg as mentioned on page 185 of 
the textbook. 
5. Try estimating the age of a horse in accordance 
with the description given on page 185. 
II. THE HABITS OF THE HORSE 
Information can be obtained on the following points by 
observing almost any horse. 
1. What are a horse's feeding habits, the use of the 
lips and the teeth and the direction of movement 
in biting? 
2. What are differences between the gaits of horses, 
walking, trotting, galloping? 
3. How does the horse defend itself? 
4. Have you seen indications of definite response by 
a horse to the treatment given it, either ill 
treatment or good treatment? 
III. THE USES OF THE HORSE 
The number of horses in active service has decreased 
because of the enormous number of automobiles that are 66 
CATTLE AND CATTLE INDUSTRIES 
in use; but there are still a great many things that horses 
do. 
What kinds of work may continue to be done by 
horses? 
Textbook, pages 150, 151, 182-187. 
LABORATORY STUDY 38 
CATTLE AND CATTLE INDUSTRIES 
Cattle or oxen are without question the most indispensable 
of all our domesticated animals. Owing to our dependence 
on them for food in the form of milk or meat there must 
always be space and food for them. 
I. THE STRUCTURE OF THE BODY 
The parts of the body of the ox are easily comparable 
with those of the horse, although oxen have entirely dif- 
ferent foot structure. These parts have their technical 
names, which indicate their similarity to corresponding parts 
in other mammalian vertebrates, even in man. But owing 
to the custom followed in the meat industry, special common 
names have come to be applied. 
There are fifteen of these names which ought to be fam- 
iliar to everyone. An outline of a cow is easily made, and 
within such an outline the parts can be marked off by com- 
parison with a chart showing them. Suitable drawings 
may be obtained from Bulletin 28, U.S. Department of 
Agriculture (Atwater and Bryant). 
1. Make a similar chart and try to apply your sketch 
by examining a side of beef hung up in a butcher 
shop. Become familiar with the following: 
Neck, chuck, ribs, shoulder clod, fore shank, CATTLE AND CATTLE INDUSTRIES 
67 
brisket, cross ribs, plate, loin, flank, rump, 
round, second cut round, hind shank. 
2. Also take the opportunity at the butcher shop to 
note and report on the size and appearance of 
important internal organs, especially the heart, 
the liver and the kidneys. 
II. THE DAIRY INDUSTRY 
In the study of milk (Laboratory Study 39) many im- 
portant points about the dairy industry are brought out. 
Consider them here also. Alderney, Jersey, and Holstein 
cows produce the largest quantity and the best milk. 
1. Ascertain the origin of each of these breeds, and 
the time they were brought to this country. 
2. From the publications of the Bureau of Animal 
Industry of the Department of Agriculture and 
from milk distributing agencies, including dairy- 
men's leagues, ascertain the extent of the dairy 
industry. 
3. Do any suggestions occur to you for making dairy 
products less expensive while maintaining the 
system of protection against unhealthful con- 
ditions? 
The meat industry is the largest manufacturing industry 
in the United States. The center of this industry is within 
the region where most of the cattle, as well as the hogs, 
are fed in the final stage of preparation for the market. The 
North Central States include this region. Thus Chicago, 
Kansas City and Omaha are the chief cities where the meat 
food of this country is prepared, and from which it is sent 
out in refrigerator cars everywhere. But all the great plains 
states rear the cattle. 
III. THE MEAT INDUSTRY 
As you have seen beef unloaded from trucks or 
from cars, in what form does it reach the wholesalers 
and the retailers? 68 
CATTLE AND CATTLE INDUSTRIES 
Meat is sometimes kept in cold storage at the centers 
of the meat industry or near large cities for months or even 
for one or two years. 
What do you think is the object of this custom? 
(See Textbook, page 864.) What classes of society are 
benefited? 
Beef sometimes is dried, canned, corned, or preserved in 
salt, saltpeter, boric acid, benzoate of soda, wood smoke, 
etc. (See Textbook, page 365.) 
What is the cost of these preparations of meat as 
compared with fresh meats, and what is the advantage 
of preserving meat? 
As you observe the great pieces of beef unloaded at the 
retail butchers' shops you will notice marks on the surface 
made by rubber stamps. 
What do you read in these marks, and what do they 
signify? 
In 1906 Congress enacted a law creating a thorough system 
of federal meat inspection and a general pure food law. But 
federal meat inspection had been in existence for fifteen 
years before that time. 
1. What are some of the reasons for having inspec- 
tion of meat? (For one point read the Text- 
book, page 31-32.) 
2. What can be done with meat that is found to be 
impure? 
There are a great many by-products of the meat industry. 
Among them are gelatin, beef extracts, glue, tallow, tripe, 
rennet, leather, hair, horn, fertilizer. 
Tell what these various materials are, and some- 
thing of the processes of preparing them. 
Scientific study of the different cuts of beef show that the 
cheaper cuts are as valuable pound for pound, and in some MILK 
69 
cases more valuable from the standpoint of protein content 
and energy, than are the higher priced cuts. 
In purchasing beef for protein primarily, the neck, shanks 
and shoulder clod have been found to be the most economical 
cuts, and the rib, loin and round the most expensive. 
Since authorities in this matter have estimated that 
the average family expends one third of its weekly 
food bill on meat, how much could a family save in 
a week through purchasing the cheaper meat cuts? 
Some authorities urge that the family meat bill be re- 
duced to one sixth of the whole food bill in the interest of 
improved health conditions. 
What is the basis of this advice? (See Textbook, 
pages 354-360.) 
Textbook, pages 188-191, 312-313 
LABORATORY STUDY 39 
MILK 
Milk is a natural food; it requires no artificial manufac- 
turing process for its preparation. All female mammalian 
animals secrete milk in mammary glands for their young. 
Long experience has taught us that the milk of cows is 
highly nutritious for human beings. Choice breeds of cows 
produce more milk than their own young require. 
I. THE COMPOSITION OF MILK 
Examine a test tube of fresh milk that has stood a few 
hours in a cool place. 
1. What do you find at the top? 
2. Why does it lie at the top? 70 
MILK 
Pour the top substance into another test tube, place a 
small quantity on a piece of white paper, and compare the 
mark left with the spot left by a piece of lard or olive oil. 
What do you find out? 
Drop into the test tube of the skimmed milk a quantity 
of acetic acid or vinegar. For comparison take a test tube 
of skimmed milk that has become sour naturally. Test the 
two with litmus paper, and compare the reaction with that 
of fresh milk. Filter the milk artificially curdled. Wash 
the curd with water to clear out the acid. 
Apply the nitric-acid-ammonia test (see page 13) to 
the curd and note the result and its meaning. 
The watery remainder is called whey. Boil a quantity 
to evaporate most of the acid, and pour in some Fehling's 
Solution. 
What is shown by this test? 
Boil down the remainder of the whey in a crucible. When 
the water is evaporated and all the burnable contents are 
consumed, 
What is left? 
II. HOW MILK IS PRODUCED AND PROTECTED 
Every farmer has a few cows for the use of his family. 
In sections where it is profitable to maintain dairies large 
numbers of cows are kept. 
In what sections of the country are there likely to 
be large dairies? Why? 
The dairy industry has become so important that the 
best breeds of milch cows are kept. They produce the best 
milk and the largest quantity. MILK 
71 
What conditions do you think would favor the 
production of good quality and large quantity in milk? 
The traditional way of milking by hand is now being 
largely displaced by the mechanical milker operated by a 
gasoline engine. 
What advantages are to be gained by this change? 
Before milking, the utensils are scalded with boiling water 
and the udders and flanks of the cows are washed with a 
moist cloth. The hands of the milk handlers are cleaned. 
The milk is strained through sterile cotton or cloth into a 
mixing tank over a metal cooler, and kept cool at 50° to 
55° Fahr, until it is delivered to the consumer. 
Explain the purpose of all this care and the biologi- 
cal principles involved. 
The laws of most states require that dairy barns be kept 
clean, well lighted and ventilated, and free from dust, and 
that the health of the cows be looked after. Inspectors 
from the city boards of health visit the farms and the large 
receiving stations to inspect the conditions and the milk. 
Tests are made to determine the richness in fat and protein 
of the milk by the lactometer which gauges the specific grav- 
ity or weight of the milk as compared with water. Tests 
also are made of the purity of the milk by analysis to see if 
adulterants have been put in. Other tests are made to 
determine the number and kinds of bacteria present. The 
best of milk contains bacteria that cause souring. Milk is 
also pasteurized by being heated for twenty to thirty min- 
utes at a temperature of 140° to 145° Fahr, to destroy bac- 
teria of any communicable disease that may be present; 
typhoid fever, scarlet fever, diphtheria, or tuberculosis. 
How, in your judgment, has all this expense been 
justified? 72 
ORGANISMS IN A LIMITED ENVIRONMENT 
III. PRODUCTS OF MILK 
The important products obtained from such milk as is 
not sent as "whole" milk to the market are butter, cheese 
and sugar of milk. 
Learn something about the manufacture of each of 
these products. 
Textbook, pages 313-315. 
LABORATORY STUDY 40 
THE RELATIONS OF ORGANISMS IN A 
LIMITED ENVIRONMENT 
In Chapters XVII and XXV of the textbook that accom- 
panies this Manual certain important general conceptions 
in biology are presented and discussed. The study which 
the authors offer here is intended as a suggestion to students 
to think of life in terms of relations, for, as the chapters 
referred to clearly show, no organism lives isolated from 
others. 
I. A SMALL POND IN THE WOODS 
There is a bit of charming mystery about a pond in 
the woods. Its very attractiveness is a manifestation of the 
simple and quiet adjustment between life and the envi- 
ronment. 
1. From your own first-hand observation of such 
places, what influence do the conditions of light 
have on the amount of vegetation about the 
margin? 
2. If there are trees growing within the pond, is the 
pond temporary or permanent? Explain. Is 
there any other reason why you think the pond 
is temporary or permanent? ORGANISMS IN A LIMITED ENVIRONMENT 
73 
3. If there is green vegetation in or upon the pond, 
where is it, near the margin or in the middle? 
Explain. 
4. Is there vegetation that has root in the mud, cat- 
tails, pond lilies or pickerel weed, or vegetation 
that floats on the surface, such as hyacinth or 
duckweed or both? 
5. Is the pond connected with a brook, or has it an 
outlet in the form of a brook? If a brook connects 
with it, what difference do you notice between 
the bottom vegetation (Spirogyra, etc., see Text- 
book, page 215) in the pond and in the brook? 
II. LIFE RELATIONS 
1. Examine the bottom green vegetation where the 
sun shines for an hour or more, and note 
whether it ever floats to the top, apparently 
enclosing bubbles of air or gas. 
2. If gas collects, what kind may it be? 
3. When gas is formed by plants, is it of any use to 
other organisms? 
There may be insects flying over the pond. Doubtless 
there are numerous specimens of larval forms of certain 
insects crawling about on the bottom. Besides, there are 
probably adult insects on the surface, water striders and 
whirligig-beetles, and some burly diving beetles that sound 
the depths if they need to. 
1. What lace-winged insects are flying about above 
the surface whose young crawl beneath? 
2. What do they appear to be looking for? Do they 
capture anything? 
3. What about frogs and tadpoles? What are they 
living on? You must be patient to find out. 
4. And the pond snails: watch them as they crawl 
up and down on submerged blades of grass or 
on stones, and tell what you think they are 
living on. 
5. Are there other forms of animal life that ought to 
be mentioned? 74 
BACTERIA 
There are probably at or near the pond rotting logs and 
fungi of many kinds living on dead and decaying vegetation, 
slowly but steadily disintegrating and returning to inorganic 
nature the substances that at one time were part of a living 
thing 
1. Which of these inorganic substances would plants 
use again? 
2. What do you see that seems to fall under this 
description? 
Textbook, Chapters XVII and XXV. 
LABORATORY STUDY 41 
BACTERIA 
Bacteria, or "germs" as they are often erroneously called, 
are the simplest and most widely distributed forms of life 
known. They cannot be seen with the naked eye, and so 
for the most part people still fail to connect the results 
of their activities with the terms "germs" and bacteria. 
Because they are usually thought of in connection with 
disease, the whole group suffers an unjustified condemna- 
tion. In reality a large number of species by their activities 
serve mankind by aiding in the complete disposal of his 
debris and by enriching the soil from which he gains his 
sustenance. By doing the following experiments you will 
obtain a more intimate acquaintance with these forms of 
plant life and their activities. 
I. DISTRIBUTION 
(Note. For this experiment use petri dishes containing sterilized agar- 
agar that is slightly alkaline.) 
1. Expose a petri dish containing sterilized agar-agar to the 
laboratory air for five minutes. Cover the dish, label 
it, and set it aside at room temperature. BACTERIA 
75 
2. Expose another dish to the air out of doors for five 
minutes. Cover the dish, label it, and set it aside as 
before. 
3. Rub the tips of your fingers gently over the surfaee of 
the sterilized agar in another petri dish. Cover the 
dish, label it, and set it aside. 
4. Plaee a fly in a petri dish and let it walk across the sur- 
face of the sterilized agar-agar. Cover the dish, label 
it, and set it aside. 
5. Place a little milk in a petri dish containing sterilized 
agar-agar and pour off any excess fluid. Cover, label, 
and set aside. 
6. Flood the surface of the agar-agar in a petri dish with 
water from the tap and pour off the excess water. 
Cover, label, and set aside. 
7. Place a dish of sterilized agar-agar with the rest of the 
dishes to serve as check. 
Examine the petri dishes daily and note the appearance of 
little dots on the culture medium. Where do they appear 
first? Where do they appear in the greatest numbers? 
These dots are colonies of bacteria, and each one represents 
the progeny of one bacterium. 
What do these experiments show you concerning 
the distribution of bacteria? 
II. FOODS PREFERRED BY BACTERIA 
Place the following materials in test tubes and add a little 
water to each: (1) raw or cooked meat, (2) the white of 
an egg, (3) some crushed beans, (4) some sugar or molasses, 
(5) a bit of bread, (6) some melted butter. Place these 
tubes in a warm place and keep watch of them for two or 
three days. Notice any changes in the appearance and 
odor of the foods. Bacterial growth in foods causes putre- 76 
BACTERIA 
faction. Do you find putrefaction occurring in any of the 
tubes? In which does it seem to be greatest? 
What conclusions do you draw from this experiment 
concerning the kinds of food preferred by bacteria? 
III. EFFECT OF MOISTURE ON BACTERIA 
Place in two sets of test tubes bits of the following foods: 
(1) crushed beans, (2) dry bread, (3) dried egg albumen, 
(4) cracker, (5) flour. To one set of the test tubes add a 
little water to their contents. Leave the other set dry. 
Set all the tubes aside in a warm place and watch daily as 
directed in the preceding experiment. 
What effect does moisture have upon the growth of 
bacteria? 
IV. EFFECT OF TEMPERATURE ON BACTERIA 
Into each of four test tubes place a bit of meat and some 
water, or a solution of Liebig's Extract of Beef may be used. 
Close all tubes with plugs of absorbent cotton. Place one 
tube in the refrigerator, one in a warm place, as near a radia- 
tor, one in a place at ordinary room temperature; boil one for 
a few minutes and place it with the one at ordinary room 
temperature. Examine these tubes daily and note the 
rapidity of putrefaction in each tube. 
What effect has temperature upon the growth of 
bacteria as shown by the results of your experiment? 
V. EFFECT OF PRESERVATIVES ON BACTERIAL GROWTH 
Fill each of ten test tubes about one third full of a solution 
of Liebig's Beef Extract. To the tubes add the following 
materials: # 1, | gram of salt; # 2, one gram of salt; # 3, one 
gram of sugar; # 4, five grams of sugar; # 5, two drops of 
formalin; ft 6, five drops of formalin; ft 7, a few drops of a 
saturated solution of boric acid; ft 8, one spoonful of vinegar; YEAST 
77 
# 9, one spoonful of alcohol; # 10, no addition. Set all of the 
test tubes aside in a warm place and examine daily. 
A preservative is an agent that is supposed to retard or 
prevent bacterial growth. Notice the extent to which the 
various preservatives prevent decay. Tabulate your results. 
Which of the substances used do you judge to be 
the most effective preservatives? 
Textbook, pages 222-227, 458-460, 491-496. 
LABORATORY STUDY 42 
YEAST 
When anything containing a large amount of sugar spoils, 
the sugar is changed to carbon dioxide gas and alcohol, and 
we say that fermentation has taken place. This process 
is caused by countless numbers of tiny yeast plants growing 
in the solution. Incidentally the same process is used in 
the raising of bread and in the production of alcoholic 
beverages. 
I. FERMENTATION 
To 100 cc. of water add 10 cc. of molasses and one half of 
a fresh yeast cake. Pour some of this mixture into a fer- 
mentation tube until the arm is full then plug the tube with 
cotton and place the rest in a flask with a delivery tube 
leading from it into a test tube of lime water. Set both 
pieces of apparatus in a warm place and leave over night. 
Examine the fermentation tube and account for what has 
happened. What color is the lime water? What does this 
show as to the gas that was given off? Smell of the contents 
of the flask. What characteristic odor is present? 
What is fermentation? What causes it? What are 
the results of fermentation? 78 
YEAST 
II. CONDITIONS OF FERMENTATION 
Fill three fermentation tubes with a mixture of molasses, 
water, and yeast. Boil the contents of one of the fermenta- 
tion tubes, place it along with one of the other tubes in a 
warm place. Place the third tube in the refrigerator. Let 
these tubes stand for a couple of days and then examine 
them for the presence of carbon dioxide and alcohol. In 
which tube did the yeast grow most rapidly? How do you 
know? In which did it grow the least? 
Under what conditions is fermentation most likely 
to occur? What effect does boiling have on the growth 
of yeast? What effect does cooling have on the growth 
of yeast? 
III. SOURCE OF YEAST PLANTS 
Place a mixture of molasses and water in a large beaker 
or a shallow dish and leave it exposed to the air for a day or 
so. Now pour the solution into a fermentation tube, plug 
with cotton, and set in a warm place. Examine in a day or 
so for the presence of yeast. Has fermentation taken place? 
How do yeasts get into foods? 
IV. STRUCTURE OF YEAST PLANT 
Remove a few drops from the bottom of a solution of 
molasses, water, and yeast in which fermentation is taking 
place by means of a pipette or glass tube and place a drop 
on a microscopic slide. Add a drop of iodine (the starch 
is stained blue and the yeast cells unstained). Cover with 
a cover-glass and examine under the high power of the 
compound microscope. What is the shape of the yeast 
plants? Do you find a nucleus? Do you find any cells that 
are budding (one cell growing out of another in the shape of 
a small bud). This is the common method of reproduction 
of yeast plants. MOLD 
79 
Make a drawing of a few yeast cells (one half to one 
quarter inch in diameter) showing the process of 
budding. 
Textbook, pages 227-229. 
LABORATORY STUDY 43 
PLEUROCOCCUS 
Many of the most primitive green plants are found in a 
group called Algae. One common member of this group 
is the green coating on the north side of trees and wooden 
posts. It is known as pleurococcus, and all the plant ac- 
tivities are carried on in a single cell. 
Examine a specimen of pleurococcus under the microscope 
and locate the different parts of the cell. You will find 
several of these cells together in a small group. Why is 
this? 
Make a sketch of pleurococcus and label the cell 
wall, the nucleus, the cytoplasm, and the chlorophyll. 
Be sure that you know how the life activities of this plant 
are carried on. 
Textbook, pages 214-215. 
LABORATORY STUDY 44 
MOLD 
When any food such as bread, cheese, meat, jelly, etc., is 
left exposed to the air for a time it becomes covered with a 
fuzzy, powdery growth of mold. The mold grows best under 
certain conditions, and it is often advantageous to be 80 
MOLD 
familiar with these conditions in order to keep foods from 
spoiling. The following study should reveal the conditions 
necessary for the appearance and steady growth of mold. 
Take five pieces of dry bread and moisten four of them. 
Expose all five pieces to the air of the laboratory for about 
thirty minutes, then place each in a sterilized jar or wide 
mouth bottle and plug the mouths of the bottles with 
cotton. Place the jar containing the dry bread (#1) and 
one of the jars containing moist bread (# 2) in a dark 
place in the laboratory so as to be exposed to ordinary 
room temperature. Place another jar (# 3) in the refrig- 
erator and another (# 4) in a warm place such as above 
or near a radiator. The last jar (# 5), cotton plug in place, 
should be placed in a pan or beaker of water; the water 
boiled for ten minutes and then the jar placed near ft 1 and 
ft 2. Watch the jars daily for any changes that occur and 
for one week keep a daily record of each jar in your notebook. 
Where does mold come from? 
In what jars did the greatest growth of mold occur? 
In what jars did the least growth of mold occur? 
What conditions are necessary for a luxuriant 
growth of mold? 
STRUCTURE 
Remove some of the thread-like structure (mycelium) and 
place it in a drop of water on a slide and examine under the 
microscope. The little knobs on the ends of some of the 
hyphoe (each thread is called a hypha) are sporangia and 
contain spores. Do you see many sporangia. Look for 
some of those that have broken open and notice the great 
number of spores that are coming out. Each mold spore 
under favorable conditions will germinate into a new mold. 
Explain the significance of the great number of sporangia 
and spores. The hypha? that penetrate the bread and 
absorb food are called rhizoids. MUSHROOMS 
81 
Make a labeled sketch of the structure of a mold 
showing the method of branching of the mycelium, the 
sporangia and rhizoids. 
Textbook, pages 229-231. 
LABORATORY STUDY 45 
MUSHROOMS 
Mushrooms are fungi. Fungi are without green coloring 
matter or chlorophyll in their tissues. Hence they are unable 
to create food out of inorganic material, and must live on 
other organic matter, living or partly decayed. 
But mushrooms exist solely on decayed vegetation. In 
soil made rich by the disintegrated particles of leaves, sticks 
and other organic material, they spring into existence from 
their spores that have been dropped by currents of air in 
damp spots. Mushrooms live also under cultivation in 
cellars or in underground places that contain soil fertilized 
by various organic substances. 
I. WHERE MUSHROOMS LIVE 
When have you seen mushrooms spring up in 
places where you had not observed them before? 
Explain. 
Some mushrooms are known to contain poisonous sub- 
stances, fatal if consumed by human beings even in small 
quantities. These poisonous forms are called "toadstools," 
although their structure is the same as the eatable kind. 
On the basis of the cost of mushrooms and the best 
information obtainable as to their value, are mush- 
rooms cheap as food, or not? 82 
SPIROGYRA 
II. THEIR BIOLOGICAL SIGNIFICANCE 
We have studied the constructive process of photosyn- 
thesis, page 96, and realize the difference between green 
plants and fungi which do not construct or build up food. 
Since mushrooms consume organic substance they maintain 
a relation toward matter similar to that held by animals. 
1. In what way may mushrooms, even the poisonous 
ones, serve a biological function in nature? 
2. If there were a lack of organisms that help to 
destroy life, what would happen in nature? 
3. Logically, must we cease to destroy the fungi of 
human disease, or plant diseases? When, if 
ever? 
Textbook, pages 232-234. 
LABORATORY STUDY 46 
SPIROGYRA 
The Algae are the lowest of all green plants. They are 
nearly all aquatic forms, although a few are found in moist 
places. One of the common forms of fresh water Algae is 
Spirogyra, a green pond scum that is found floating in slimy 
mats in ponds and sluggish streams. 
Examine some living Spirogyra from the laboratory 
aquarium. What color is it? How does it feel when you 
take some of it out of the water? Place a few threads on a 
slide in a drop of water, cover with a cover-glass and examine 
under the high power of the microscope. Do the threads 
branch? Of what are they composed? Notice the chloro- 
phyll bands and the cell nucleus. The latter will be stained 
brown if a drop of iodine is placed on the slide and drawn 
under the cover-glass by means of a bit of blotting paper. 
The clear cell sap fills the interior of the cell. A MOSS 
83 
Make a drawing of a few cells of Spirogyra, label 
ing the parts that you have seen. 
If you search the slide carefully you may see little pro- 
jections growing toward each other on two filaments that 
are lying close together. This is the early stage of a sexual 
form of reproduction called conjugation. In other filaments 
you may see that these projections have joined together 
and that the cell contents have united to form a dark ellip- 
soidal zygospore which is found within one of the cells, the 
other cell remaining empty. 
Make a labeled drawing showing two filaments of 
spirogyra conjugating. 
Textbook, pages 215-218. 
LABORATORY STUDY 47 
A MOSS 
When coming upon some green mossy bank in the woods 
you may have wondered what the slender reddish stalks 
with their pointed caps wrere for, and why there was such a 
profusion of the tiny plants. In the following study you 
will see that the story of the life of a moss, or its life-cycle, 
is quite as complicated and no less interesting than the life- 
cycle of the frog or the moth. 
Examine with the aid of a hand lens, a fresh specimen of 
a moss plant on which the fruit has developed. The fruit 
is represented by the slender reddish stem with the spore- 
capsule on the end, the whole thing growing from the top 
of a leafy female moss plant. This is known as the sporo- 
phyte. How' are the leaves arranged on the stem? Is the 
stem branched? What kind of a root system is present? 
Remove the cap or hood from the capsule and notice the 84 
FERNS 
little lid that holds the spores in the capsule. This lid 
comes off when the spores are ripe. If you remove it you 
will see a row of little teeth-like structures around the edge 
of the capsule through which the spores shake out. 
Examine some spores under the high power of the micro- 
scope. From a prepared slide or a chart find out what the 
spores develop into. 
The little moss plants develop from buds on this tiny 
thread (protonema) some becoming male plants with anthe- 
ridia (pollen bearing organs) at the top of the plant, and 
others female plants with archegonia (where the ovules are 
produced) also at the top. Examine male and female moss 
plants and notice the differences between them. If possible 
examine prepared slides or charts showing these structures. 
Hence the leafy plant represents the sexual stage of the 
moss or the gametophyte. 
Make a drawing of your plant showing both the 
sporophyte and gametophyte stages and label all 
parts. 
Which generation of the moss is the most commonly 
seen, the asexual or sexual? 
Textbook, pages 235-238. 
LABORATORY STUDY 48 
FERN'S 
Ferns are among the highest of the non-flowering plants. 
Familiar as ferns are to us, the method of reproduction of 
ferns and other non-flowering plants was for a long time 
unknown even to the biologists. For that reason they 
applied to all non-flowering plants the name Cryptogams, 
which means secret or unknown reproduction. FERNS 
85 
1. WHERE FERNS LIVE 
As a rule, ferns live in shady places, and where the soil 
is damp and rich. Masses of the large brakes, however, 
often grow in the open light along the borders of forests. 
1. What is the most conspicuous part of the fern 
plant, and what are the details of its structure? 
2. From your own observation, what do you think is 
the reason a fern environment is considered 
beautiful? 
3. What part of a fern plant is new every year, and 
what part is perennial or continuous? 
Whenever you see on the under surface of the frond or 
£af of a fern a series of small regularly placed brown specks 
/ou may know that the plant has begun its annual cycle of 
changes, at the end of which two kinds of fern plants will 
have made their appearance. The little brown specks, 
called sori (sing, sorus) are coverings of many extremely 
small spore cases containing still smaller spores. 
II. THE LIFE HISTORY OF FERNS 
1. Break open one of the sori under the objective of 
a compound microscope, separate and open a 
spore case in a drop of water on a glass slide, 
and observe the form and appearance of fern 
spores. 
2. Since it is said that a single fern plant may pro- 
duce 50 million spores, what tends to prevent 
the actual existence of so many plants? 
The spores of ferns are thrown by the bursting of the spore 
cases (called Sporangia) over an area of a few square feet. 
If the spore falls in a favorable situation it produces a small 
thread, called the protonema, as in the mosses. From this 
comes the small heart-shaped prothallus. 
Search about the surface of fern flower-pots and moist 
frames in a greenhouse for some prothalli, and place one on 86 
SOIL AND GROWTH OF PLANTS 
a glass slide in water for examination with the low power of 
the compound microscope. 
Examine top and bottom until you find the arche- 
gonia and antheridia described in the textbook. Give 
a description of what you see. 
The prothallus is the sexual generation of the fern. The 
drawings on the textbook indicate the form and the details 
of structure of the reproductive organs. Search among 
your specimens of prothalli for one that shows a stage of 
development comparable to one of the figures on page 241 
of the textbook. 
What is there about the specimen that indicates 
that the cycle of alternation of generations has been 
completed? 
At the base of the little plant the prothallus is absorbed 
and a permanent rootstock is developed. This is the part 
you dig up for putting in the pot, and the one from which 
the fronds in nature spring up each year, looking like a 
bishop's crozier. 
Textbook, pages 238-242. 
LABORATORY STUDY 49 
SOIL IN RELATION TO THE GROWTH OF 
PLANTS 
Wherever we are, most of us get used to seeing plants 
with which we are familiar growing in the soil. We may not 
know whether they would grow better in a different soil. 
By improving the soil by natural or artificial fertilizer, 
farmers and gardeners add greatly to the productivity of 
the land. SOIL AND GROWTH OF PLANTS 
87 
I. GROWTH IN NATIVE SOIL 
In some soils certain plants do better than others. In 
part this is due to a difference in the mineral needs of plants, 
in part to a difference in the temperature, and in part to a 
difference in the water needs of plants. 
Prepare four to six Hower pots of soil native to the vicinity, 
and, so far as is known, unfertilized. Plant in separate pots 
seeds of peas, corn, oats, radishes and as many others as 
you have pots to provide for. Water, and place in as favor- 
able a situation as possible. This experiment should be 
going on while other work is being planned and carried out. 
Report results for a series of weeks. State your 
conclusions on the facts. 
II. COMPARISON OF GROWTH IN SOILS OF DIFFERENT 
ORIGIN 
Prepare flower pots of similar size, one with sand; a second 
with clay if obtainable; a third with black soil obtained 
from near the bases of trees where leaves have collected 
and rotted; a fourth a mixture of sand and black soil, and 
if obtainable, mixed with clay also. For this experiment 
select seeds which, like the radish, grow quickly and give 
a good basis for comparison in the size of the root formed. 
Make observations on the results, and state your 
conclusions after carrying the experiment two or three 
weeks. 
Textbook, pages 256, 287-289. 88 
RESPONSE OF ROOTS TO EARTH AND WATER 
LABORATORY STUDY 50 
THE RESPONSE OF ROOTS TO EARTH 
AND WATER 
It seems natural for roots to grow into the earth and for 
stems to grow away from it. But we may not know that, 
under certain circumstances, roots will overcome many 
obstacles to go directly into the soil, and under other cir- 
cumstances, actually grow away from it. 
Obtain two small glass plates about 4" x 5". Cut a piece 
of absorbent cotton to fit between them. Soak up the 
cotton in water, and lay a row of seeds across the middle 
that have been soaked twenty-four hours. Have the seeds 
pointing in all possible directions. Space out the top glass 
with pieces of stick to give the seedlings room to grow. 
Bind the whole together across the ends with two rubber 
bands. Stand the "set-up" on edge and mark with a label. 
Moisten the cotton when needed, and after the seeds have 
started to germinate turn the plates one-fourth around. 
Keep on turning every twenty-four hours. 
I. RESPONSE TO THE EARTH 
Describe what has happened to the roots, and make 
a sketch of the entire experiment, indicating the 
results. 
II. RESPONSE TO WATER 
Prepare another set of plates, cotton, and soaked seeds. 
Place diagonally across one plate a series of chips of cork, 
leaving spaces large enough for roots to pass between. 
Cut a triangular piece of cotton to fit between the plates 
above the pieces of cork. Lay a few soaked seeds on the 
cotton alongside the pieces of cork. Bind the plates together THE RESPONSE OF PLANTS TO LIGHT 
89 
with rubber bands, and stand the "set-up" on edge, vacant 
space down, in a shallow dish containing a little water. 
Keep the cotton moist and watch for results. 
1. At the end of four or five days after the germina- 
tion of the seeds has begun make a sketch of 
the apparatus, indicating the results. 
2. Will roots cross an air space to reach a larger 
supply of water than is available nearer at 
hand? If not, why not? 
3. So far as the tests show, which response, to earth 
or to water, is the stronger in roots? 
4. Is it possible that roots solve their whole problem 
in obtaining water? If so, how? 
Textbook, page 246. 
LABORATORY STUDY 51 
THE RESPONSE OF PLANTS TO LIGHT 
Everyone lias noticed that light has a considerable influ- 
ence on plants. And from our study of the work of leaves 
we have learned that light is essential to one of the chief 
functions of those organs, the manufacture of carbohydrates. 
But not until we observe plants closely do we realize how 
great is the apparent effort of plants to adjust themselves 
to the source of light itself. 
I. THE RESPONSE OF SEEDLINGS 
It might well be supposed that seedlings, being unformed 
as they emerge from the ground, would respond readily to 
the light. 
Start growing near a window, boxes or pots of bean or 
corn seedlings. After the seedlings have grown above the 
ground three days, note their positions from the perpen- 
dicular, and note the positions especially of the leaves. 90 
THE RESPONSE OF PLANTS TO LIGHT 
Mark the side of the container that is away from the win- 
dow with a label and turn it 180° and indicate the date. 
1. How long is it before the seedling has again grown 
over toward the light? 
2. Turn it 180° a second time, and make note of 
whether any part of the plant begins to grow 
vertically instead of bending toward the light. 
Potted plants, of course, are older than seedlings. Most 
potted plants have woody stems, and may have grown in 
an environment where the light was more ecpially distri- 
buted than it is in a laboratory window. Take a potted 
hydrangea, coleus or geranium that has not been changed 
from its position recently 
II. THE RESPONSE OF POTTED PLANTS TO THE LIGHT 
1. Turn the plant 180° and label with date. Describe 
the position of the leaves as compared with those 
that were on the room side. 
2. Describe what happens in a few days to the leaves 
that have just been turned to the room side. 
What part of the leaf seems to be most active 
in bringing about the changed position? 
3. At the end of a week turn the plant 180° again, and 
note what has happened. 
III. LIGHT RELATIONS IN A FOREST 
If a forest or "wood lot" is not accessible, study the 
conditions found in a park where there are trees fairly close 
together as well as some widely separated. 
What difference in general form do you note be- 
tween trees of the same species that grow close to- 
gether and one that grows by itself, no obstruction 
being near? Explain. 
Where a good many trees grow close together, whether 
of the same species or not, many of the lowermost branches 
are likely to be dead. 
Why is this? ROOTS 
91 
In going along a road through the woods you must have 
noticed the greater number of branches of trees extending 
over the road than into the forest. 
How could you distinguish a newly made wood road 
from one that had existed a long time? 
Textbook, pages 268, 273, 274. 
LABORATORY STUDY 52 
ROOTS 
Roots are definite organs of the plant. In general they 
are the part of the plant that exists in the soil, though there 
are roots that exist in the air, and there are parts of plants 
found in the soil that are not roots. But wherever roots 
exist, they perform much the same function of holding the 
plant in place or taking up water and its contents for the 
use of the plant. 
There are two classes of roots, normal roots which extend 
into the soil or water directly from the base of the stem. 
There are also adwn/tVioits roots which occupy unusual posi- 
tions. An example of a normal root are the fibrous roots 
of grass. An example of adventitious roots are the roots 
that branch out from the lowest joints of the stem of the 
corn plant. 
I. KINDS OF ROOTS 
Name two other plants that have normal roots and 
one that has adventitious roots. 
Among normal roots there are single, long, and slender 
tap roots, thick, soft, or fleshy roots, and thick, spongy roots 
of plants that grow in the water but do not reach the bot- 
tom. Among adventitious roots there are roots that come 92 
ROOTS 
from the drooping branches of certain small fruit shrubs, 
and roots that penetrate the stem tissues of other plants, 
drawing sustenance therefrom. 
Give the names of examples of as many of these 
kinds as you can. 
II. THE FUNCTIONS OF HOOTS 
Roots are capable of adjusting themselves to widely 
varying conditions. They respond readily to conditions in 
their environment (see Laboratory Study 50). And they are 
capable of overcoming serious handicaps in making their 
way through the soil. 
There are four important functions that may be carried 
on by roots; but not all roots do carry on all four functions. 
All roots absorb water and minerals in solution from the 
soil, and occasionally from the air. All roots aid in sup- 
porting or holding the plant to a definite spot, even those 
roots that extend into the water only. Thirdly, roots store 
up food which the leaves manufacture, some holding large 
quantities. A fourth function is the occasional one of propa- 
gating or starting a new plant. 
1. Which of these functions do the following plants 
manifest? Take them in turn and discuss, 
(a) The oak; (b) the bean; (c) the carrot; 
(d) the raspberry; (e) the water hyacinth. 
2. Describe briefly the work of root-hairs. 
(See Textbook, pages 246, 258, and the study of Osmosis, 
in Manual, page 8.) 
III. ADAPTATIONS IN HOOTS 
The particular adaptations seen in roots are adjustments 
of form to the functions which are being carried on. Here 
are a few facts about roots which the student is asked to 
explain on the basis of adaptation to function or use. STEMS 
93 
1. Roots have no leaves or flowers. 
2. Roots have a thimble-like cap on the growing tip 
of the young roots. 
3. Roots have microscopic single-cell, thin-walled 
root-hairs near the tips of roots, but none in older 
parts of the roots. 
4. Roots show a more definite response to the presence 
of water than to anything else. 
5. Roots spread over a great area of ground and 
penetrate many feet vertically. 
6. Roots are far more flexible than stems. 
7. Roots are plentifully supplied with bast fibers 
which are very tough. 
8. Many plants that live two years are capable of 
storing large amounts of food in their roots. 
Good explanations of these facts will insure a clear under- 
standing of the subject of roots. 
Textbook, pages 246, 258. 
LABORATORY STUDY 53 
STEMS 
The stem is a conspicuous organ of the higher type of 
plant. On its parts or branches it bears buds, leaves, flowers, 
and fruits. From its buds it develops additional branches, 
and by means of certain interior cells it adds to the amount 
of living plant material year after year. 
I. KINDS OF STEMS 
There are several more or less clearly distinguishable 
types of stems, the features of which are indicated in the 
form of the whole plant. There are the slender stem, the 
spreading stem, the creeping stem, the climbing stem and 
the underground stem. Examples of all of these will occur 94 
STEA IS 
to the student, except perhaps the underground stems. 
The white potato, the onion, and the horse radish are under- 
ground, condensed stems. They fit into the description of 
stems in that they have buds, leaves and branches. 
Give an example of each of the other kinds of 
stems. 
Some of the functions of stems are obvious, and others 
have to be ascertained by experimentation. 
II. FUNCTIONS OF STEMS 
What are the obvious functions of stems? 
To determine the less apparent functions of stems, cut 
two willow twigs a foot or more in length. Strip from each 
a band of bark about an inch long. Pour water into a jar 
so that the water will stand below the level of the band of 
bare wood. Keep the surface of the water at this point. 
Watch the willow twigs for a few weeks. Report 
what you see, and state your conclusions. 
III. TISSUES OF STEMS 
Cross-sections of stems or twigs of an oak, or other common 
tree, ami of many thousands of species of smaller plants, will 
show a certain definite arrangement of tissues or groups of 
cells. A cross-section of the stem of a corn plant shows 
entirely different arrangement of kinds of cells. Stems of 
the first kind are characteristic of dicotyledonous plants. 
Those of the second kind belong to monocotyledonous 
plants. Chapter XXII on the bean shows two stages in 
the development of a dicotyledonous stem. Chapter XXI 
shows the structure and arrangement of the tissues in a 
monocotyledonous stem. 
1. Identify the tissues beginning at the center, and 
give some notion of the function of each. LEAVES 
95 
2. Cut cross-sections of twigs of trees and determine 
the age of each by noting the number of annual 
rings. 
Textbook, pages 247-249, 258-260. 
LABORATORY STUDY 54 
LEAVES 
Nothing in nature brings us quite so much joy as does the 
coining of the green leaves in spring. During the summer 
months we continue to appreciate their verdure and shade, 
and an autumn landscape again brings exclamations of 
praise from our lips. While the beauty of leaves escapes 
none, the fact that we and all animal life are dependent upon 
them for our existence is not so generally recognized. The 
truth of this statement will be obvious when you have 
completed the following studies. 
I. LEAF FORMS AND THE PARTS OF A LEAF 
1. Make a sketch of the leaf of a maple or of an oak, 
and label the blade, the midrib, the veins, and the 
petiole, or leaf stalk. 
2. Sketch also the leaf of a lily or corn plant. 
In what respect does the leaf described in # 2, differ from 
the leaf of the maple or oak? In what respects is it similar? 
'rhe maple and oak leaves are called dicotyledons (plants 
having two small leaves in their seeds), and the corn and 
lily leaves are called monocotyledons (plants having one small 
leaf in their seeds). 
To which group do most of the plants with which 
you are familiar belong? 96 
LEAVES 
Examine and sketch a compound leaf such as a horse- 
chestnut or an ash. How does it resemble and differ from 
those you have already drawn? 
What are the functions of the veins? How does 
the broad thin shape of the leaf fit it for the work it 
has to do? 
II. STRUCTURE 
Examine under the microscope a prepared slide of a cross 
section of a leaf. Observe carefully the following parts: 
the upper layer of cells or epidermis beneath which is a row 
of elongate cells, the palisade layer, which contain chloro- 
phyll; the spongy parenchyma, which is made up of the 
irregular cells beneath the palisade layer and which also 
contain chlorophyll; air spaces; a cross-section of a vein; 
the lower epidermis where you will find the openings of 
stomata, or breathing pores. 
(Optional.) Make a drawing showing the cross-section of 
a leaf. 
How does the leaf get its water? Its carbon di- 
oxide? 
III. PHOTOSYNTHESIS 
Cover a portion of a leaf of a hydrangea or coleus top 
and bottom by pinning on pieces of sheet cork, spacing 
out with very narrow pieces of cork to permit the circu- 
lation of air under the cork. Leave the plant in the sun- 
light about forty-eight hours. Then remove the leaf and 
dip it in boiling water to kill the living protoplasm inside. 
Now place the leaf in wood alcohol until the green chloro- 
phyll has been removed. Soak out the alcohol and test the 
leaf with iodine for starch. Record your results. Repeat 
this experiment, using the leaves of similar plants which 
have been kept in the dark for a day or longer. 
Prepare another experiment by smearing vaseline in spots 
above and below the middle of a leaf. What factor are 
you experimenting with? LEAVES 
97 
What substance is manufactured by green leaves 
and what conditions are necessary for the process? 
What does the chlorophyll do? What are the air 
spaces in the leaf for? 
Starch is a basic organic food substance and cannot be 
formed in any way but the one described. Place a large 
glass funnel over some water plant (such as elodea) sub- 
merged in water in a tall battery jar. Fill a test tube with 
water and invert it over the end of the funnel so that any 
gas that is given off will displace the water. Set this material 
in the sun for a few days and keep careful watch to note 
the results. 
What gas collects in the test tube? Test with a 
glowing splinter in the test tube. 
Where did the gas come from? Of what process is 
it a by-product? What can you say of the importance 
of photosynthesis to man? 
Place a small branch with a good many leaves on it through 
a large hole rubber stopper that fits a wide mouth bottle. 
Pour some water in such a bottle and place it on a glass 
plate. Stopper the bottle and leave the end of the branch 
in the water. Seal the branch in the hole in the stopper with 
paraffin and place a bell jar over the plant and bottle. The 
bell jar should be sealed to the glass plate with vaseline and 
the whole apparatus set in the sunlight in as cool a place as 
possible. Observe the jar in a day or so and account for 
any change in its appearance. 
IV. 
TRANSPIRATION 
Where do plants get their water? Why do they need 
it? Explain fully. What would be the result if plants 
did not give off this excess of water? 
This process of giving off water by plants is called tran- 
spiration. 
Textbook, pages 243-264. 98 
THE PARTS OF A FLOWERING PLANT 
LABORATORY STUDY 55 
THE PARTS OF A FLOWERING PLANT 
As we have seen, man is ultimately dependent upon green 
plants for his food supply. Most green plants in order to 
carry on their species must produce seeds. Without 
flowers there can be no seeds, so we may say that in an 
important sense man owes his continued existence to the 
flowers. 
Examine a complete specimen of a buttercup, or other 
flowering plant, that you may obtain. Notice that the plant 
is divided into four important parts: the roots, the stem, 
the leaves, and the flower. These are the organs of 
a flowering plant. 
THE PLANT 
THE ROOTS 
How does the size of the root system compare with the 
rest of the plant that is above the ground? What is the 
character of the roots: are they fleshy, like those of the 
beet, carrot, and turnip; fibrous, thread-like as those of 
grasses? 
Of what service to the plant would the roots be in 
a wind storm? In what other ways would roots be of 
service? 
THE STEM 
Is the stem smooth or hairy? Is it strong? De- 
scribe its method of branching. What is the arrange- 
ment of the leaves on the branches? How does the 
stem aid the leaves in receiving a large amount of 
light? At what places on the stem are the flowers 
found? Tell as many uses of stem as you can. THE PARTS OF A FLOWERING PLANT 
99 
THE LEAVES 
Are there many leaves on your specimen? Are the leaves 
simple (the blades united into one piece) or compound (the 
blades deeply cut and the leaflets as the divisions of the leaf 
are called are attached to the petiole or leaf stalk or to the 
midrib)? Is the leaf hairy or smooth? parallel-veined or 
netted-veined (the veins branching so as to form a network)? 
How many flowers are there on your specimen? 
Where are they located? What are their colors? 
Working from the outside toward the center of the 
flower, find a circle of pale yellow sepals which to- 
gether make up the calyx. How many sepals are 
there? Proceeding toward the center you will notice 
a circle of brilliant yellow petals which together make 
up the corolla. How many petals do you find? What 
is the function of the calyx? What is the function of 
the corolla? Inside the corolla you will find a whorl 
of stamens. How many stamens do you find? The 
slender stalk of the stamen is called the filament and 
at the end you will find the anther, a little case where 
the pollen is produced. The pollen is the powdery- 
like substance that you see on the anthers. Examine 
some pollen grains under the microscope and make 
a sketch of them. In the center of the flower you will 
see the pale green pistil. The pistil is composed of 
three parts: the broad round base which contains the 
ovary inside of which are found the ovules, the slender 
stalk called the style, and the stigma at the top of the 
style. The stamens and pistils are the most important 
parts of the flower. Can you tell why? 
THE FLOWER AND ITS PARTS 
Examine the fruit of the buttercup or of the flower that 
you have studied. What parts of the flower make up the 
fruit? How many seeds do you find in the fruit? 
THE FRUIT 
Make a drawing of the plant showing all parts. 100 
THE POLLINATION OF FLOWERS 
Make a drawing of the flower, labeling the parts 
you have seen. 
Make a drawing of a single stamen, labeling all the 
parts. 
Make a drawing of the pistil, labeling all parts. 
Make a drawing of a fruit and a single seed. 
Textbook', pages 208-213. 
LABORATORY STUDY 56 
THE POLLINATION OF FLOWERS 
We have already learned that the pistil and stamens are 
the most important parts of the flower. If the pistil is 
removed, or if the stamens are removed and the pistil 
covered with a paper bag, no seeds will be produced. When 
this is proved it is sufficient evidence that the pollen and the 
pistil are necessary for the production of seeds. Pollen must 
in some way or other get to the stigma. We shall see that 
the adaptations of plants to this end are remarkable. 
INSECT POLLINATION 
Examine a buttercup (or other flower) and note the 
arrangement of the flower parts, particularly the stamens 
and pistils. Pull off a petal and with the aid of a hand lens 
examine the pointed base. What do you observe? Taste 
this part. 
What would happen when a bee or some other 
insect in search of nectar visits this flower? Would 
self-pollination be likely to occur in the buttercup? 
Examine a tulip and note the arrangement of the flower 
parts. What are the relative lengths of the pistil and 
stamens? Ts the pollen sticky? The nectar is found at the 
base of the pistil. THE POLLINATION OF FLOWERS 
101 
What would happen when a bee visits a tulip in 
search of nectar after having previously paid visits 
to other tulips? 
Examine a nasturtium, and notice the arrangement of the 
stamens and pistil. (If the anthers hold pollen, the pistil 
is below them, while if the stamens have given up all their 
pollen, the pistil projects up into the entrance of the 
flower with its three-pronged stigma outspread.) Bite off 
the end of the calyx tube and taste the nectar. 
Tell what would happen if a bee seeking nectar 
visits a nasturtium when the stamens contain pollen. 
What would happen if the stamens had shed their 
pollen? 
Examine a specimen of "butter-and-eggs" and notice 
the tubular two-lipped corolla. Look inside for the stamens 
and pistil, and find the nectaries. Bees in search of nectar 
alight upon the lower lip of the corolla and the weight of 
the insect forces the lip down and makes an entrance into 
the corolla tube. 
What would happen when a bee covered with pollen 
from another flower of butter-and-eggs makes its way 
into the corolla tube? 
Examine carefully the flower parts of salvia. Notice 
particularly the arrangement of the stamens. How are 
they adapted to dusting their pollen on the back of a bee 
in search of nectar at the base of the pistil? Would the 
stigma receive the pollen as the bee goes into the corolla 
tube or as it backs out? 
Describe just what would happen when a bee 
visits salvia in search of nectar. 
WIND POLLINATION 
Examine the catkins of an oak tree, with the aid of a 
hand lens, when the anthers are shedding their pollen. Are 102 
FERTILIZATION 
all of the organs of the flower present? Shake a catkin 
gently over a piece of paper. What is the substance that 
falls upon the paper? Does it appear to be abundant? Is 
it as sticky as the pollen of the buttercup? The catkins 
are the staminate flowers (flowers with stamens); the pis- 
tilate flowers (flowers with pistils) are less conspicuous and 
are found in the axils of the leaves. Examine some pistilate 
flowers with a lens and determine if the calyx and corolla 
are present. What is the shape of the pistils? Is it well 
adapted to the work that it has to do? Why would not 
the flowers of the oak be pollinated by means of insects? 
How are the flowers of the oak tree pollinated? 
The flowers of the elm, birch, hickory, walnut, corn, and 
many other plants are also pollinated by the wind. Some 
of these may be brought into the laboratory and examined 
after the manner of the oak blossoms. 
What is meant by pollination? 
What adaptation do flowers possess that depend 
upon insects for pollination? 
What adaptations do flowers possess that depend 
upon the wind for pollination? 
Textbook, pages 211-213, 261-264. 
LABORATORY STUDY 57 
FERTILIZATION 
Pollination we have learned is the transfer of pollen from 
the stamens of one flower to the stigma of another. Ferti- 
lization begins where pollination leaves off and is completed 
when the nucleus of the male cell (the pollen grain) unites 
with that of the egg cell in the ovule. 
You may perform an experiment to see how this process 
of fertilization is begun. Shake the pollen from a tulip on FRUITS AND SEEDS AND THEIR DISPERSAL 
103 
a 3 per cent solution of cane sugar in a concave slide, cover 
with a cover glass and examine with the low power of the 
microscope. Now place the slide under a small bell jar with 
wet blotting paper or a moist sponge to prevent the evapo- 
ration of the sugar solution. Try narcissus pollen on a 5 per 
cent solution and sweet pea pollen on a 15 per cent solution. 
If other kinds of pollen are available try them on solutions 
of different strengths. 
Examine after a day or so with the low power of the 
microscope. The small tubes growing out from the pollen 
grains are pollen tubes. 
Make a sketch of a few pollen grains showing the 
pollen tube. 
The pollen grains on the stigma put forth these pollen 
tubes which grow down the pistil into the ovule and which 
serve as a pathway for the male nucleus. You can best get 
an idea as to the path taken by the pollen tube by a care- 
ful study of Figure 131 in the textbook. 
From the study of fertilization, what organs of the 
flower appear to be most important? 
Write a short story about pollination and fertiliza- 
tion, being careful to distinguish between them. 
Textbook, pages 261-264. 
LABORATORY STUDY 58 
FRUITS AND SEEDS AND THEIR DISPERSAL 
Fruits come after the flowers. Often it is possible to 
identify accurately the part of the flower that develops 
directly into the fruit. The word fruit suggests something 
eatable, but a great many fruits are neither eatable nor, in 104 
FRUITS AND SEEDS AND THEIR DISPERSAL 
fact, conspicuous in any way. But all fruits have the same 
biological function to perforin. Can you suggest what this 
function is? 
What part of the flower of the bean plant or the 
pea becomes the fruit? Explain. 
I. THE RELATION OF FRUITS TO FLOWERS 
The familiar apple is one of the most complicated of 
fruits, relative to its development from the flower. Examine 
the dried objects at the end of the apple opposite the stem. 
The minute outside parts are the tips of the five sepals 
(see page 99). At the center are sometimes to be found 
the dried stamens and the stigma of the old pistil. A 
longitudinal section and a cross-section of apples show at 
the middle the seeds joining at the base of the ovary and 
protected by the tough ("core") inner wall of the ovary. 
Next comes the soft eatable outer ovary wall, and, separated 
by a ring of ducts, the outside fleshy basal portion of the 
calyx. 
Do you know of other fruits that are constructed 
in a similar way? 
Most fruits consist of the ovary wall hardened, or softened, 
and the seed or seeds contained within. 
Describe three examples of this type of structure. 
II. THE ADAPTATIONS OF FRUITS AND SEEDS TO 
DISPERSAL 
In all cases of fruit or seed dispersal it is well to remember 
that neither the plant nor the animal that may take part 
in any act of dispersal knows the meaning of its participa- 
tion in the phenomenon. Even human beings who wander 
through the woods, and, on finding their clothing covered 
with "pitch-forks" or "stick-tights" scrape them off and THE GERMINATION OF SEEDS 
105 
throw them on the ground, are acting as much without 
thought of the favor they are doing the species of weed 
as does the cow that beats her tail against the fencepost, 
loosening a few of the clinging fruits. 
What is the advantage to the various species of 
plants of having adaptations to dispersal? 
The following are means to dispersal of fruits and seeds: 
the wind, edibility, minute clinging hooks, explosion (pods 
popping open), and the fitness for floating on water. 
What are the adaptations to dispersal characteristic 
of the following fruits? Describe each adaptation in 
detail, and tell how the dispersal is carried out: The 
milkweed; the maple; the cockle bur; the hickory nut; 
the sedge; the wild geranium; the violet; the touch- 
me-not; the apple; the tomato. 
Textbook, pages 290, 291. 
LABORATORY STUDY 59 
THE GERMINATION OF SEEDS 
We have all noticed that stored seeds remain for a long 
period of time unchanged. Under certain conditions seeds 
will quickly show signs of life, and the miniature plant, 
hidden within, will unfold and manifest the characteristics 
of the species. Analysis and experimentation with essential 
factors in the environment of growing seeds will disclose 
the importance of each factor. 
Prepare a series of five or six bottles holding about eight 
fluid ounces, bottles that can be closed with a stopper and 
sealed with melted paraffin. Crumple up an equal number 
I. WATER AND GERMINATION 106 
THE GERMINATION OF SEEDS 
of pieces of blotter or filter paper, and place them in the 
bottoms of all the bottles. 
Take a small handful of sun-dried, not kiln-dried, pea 
seeds (grocery store seeds will not do), weigh out ten to 
twelve seeds, and pour them into each bottle. Use metric 
system scales if you weigh the seeds. 
Next measure out with a graduated cubic centimeter cyl- 
inder varying quantities of water. Since one gram is equal 
to one cubic centimeter of water, you can definitely relate 
a known quantity of seeds to varying quantities of water. 
If you have no metric scales, measure quantities of seeds 
and water in any small container. 
Arrange the series to have a small quantity of water at 
one end and a large quantity at the other end, where the 
seeds should be immersed in more water than they can 
absorb. Seal the bottle and set them aside under the same 
exterior conditions. Why seal the bottles? 
1. What are the conditions, exterior and interior, that 
are the same? 
2. What is the importance of being careful to keep 
all these conditions similar while varying the 
conditions of moisture? 
3. Carry the experiment through four to six days, 
observing and noting each day what has hap- 
pened. 
4. At the end of that time what is your conclusion 
relative to the influence of water in germina- 
tion, expressed in terms of percentage, if 
possible? 
II. AIR AND GERMINATION 
The special inquiry we can make relative to the influence 
of air on germination concerns the particular part of air 
that furthers the process. 
First, soak some sun-dried pea seeds for twenty-four hours. 
Prepare four eight-ounce bottles with stoppers. Collect 
in one pure oxygen (see page 3), in a second pure nitro- THE GERMINATION OF SEEDS 
107 
gen (see page 6), in a third carbon dioxide (see page 
131), and in a fourth air. The bottles should be equipped 
with some crumpled blotter or filter paper and what appears 
from the experiment under Section 1 of this study to be a 
favorable amount of water. The stoppers of the bottles 
should have a plugged opening in each, large enough to 
receive the ten to twelve seeds when you are ready to drop 
them in. 
1. Carry out further necessary steps in the experi- 
ment, and report what you have done. 
2. Observe the experiment four to six days, report 
results noted, and give your conclusions con- 
cerning the part of air which aids seeds to 
germinate. 
We come now to a third factor which may be supposed 
to operate in bringing about the germination of seeds. In 
a general way we know that seeds are not germinating out 
of doors in winter, at least in the latitude of our northern 
States. Do they germinate when the weather is the hottest? 
Prepare another set of eight-ounce bottles, with clean 
blotter or filter paper in the bottom, and with what you 
regard as a favorable amount of water in each. Drop into 
each ten to twelve sun-dried pea seeds. These may be 
closed in with plugs of absorbent cotton to prevent rapid 
evaporation and to permit some air to enter. Find at least 
four places wdiere the temperature is fairly constant but 
different from other situations included in the experiment. 
III. HEAT AND GERMINATION 
1. Find such situations, take note of the degree at 
which the temperature is constant, and report. 
2. Make observations and take note of results for 
four to six days. 
3. What are your conclusions as to the most favorable 
temperature for the germination of pea seeds? 
Textbook, pages 253, 258. 108 
COTYLEDONS, ENDOSPERMS IN GERMINATION 
LABORATORY STUDY 60 
COTYLEDONS AND ENDOSPERMS IN 
GERMINATION 
Seeds of various kinds form an important portion of the 
food of many kinds of animals, including man. The germ 
or embryo of seeds is often a small part of the whole seed. 
The material constituting the remainder of the seed, whether 
it is separate from the embryo or stored within a part of it, 
is nutritious. The probability is that this material is useful 
also to the plant which produces it. An experiment will 
help us to ascertain the facts. 
I. THE COTYLEDON IN GERMINATION 
Start several pea seeds growing in a box of sawdust. 
When the stems are one to two inches high, take up a few 
seedlings carefully and cut one cotyledon from two seedlings, 
and both cotyledons from two others, leaving two specimens 
uncut. 
Cover a tumbler of water with netting, binding it about 
the edge with a string. Poke holes through the netting large 
enough to admit the roots, and small enough to retain the 
cotyledons above the water. Adjust in place the six pea 
seedlings, and keep in place with the glass filled with water. 
Observe for four to six days or longer. 
Report on the facts, and state your conclusion on 
the importance of the cotyledons of the pea seed in 
germination and early development. 
TT. THE ENDOSPERM IN GERMINATION 
Grow corn seedlings in moistened sawdust. When the 
stems have begun to appear above the surface, remove six REGIONS OF RAPID GROWTH IN PLANTS 
109 
seedlings carefully. Prepare a tumbler of water as in 
Section 1 of this study. 
Cut vertically from two corn seedlings one half the endo- 
sperm, being careful not to disturb the remainder. Cut away 
the entire endosperm from two others, leaving the cotyledon 
whole. Keep two seedlings unchanged. Thrust the roots 
of all six through holes in the netting, and set aside as in 
Section 1. 
Report on the facts, and state your conclusion on 
the importance of the endosperm of the corn seed in 
the process of germination and early development. 
Textbook, pages 253, 254; for comparison, see also page 258. 
LABORATORY STUDY 61 
REGIONS OF RAPID GROWTH IN PLANTS 
Plants make phenomenal growth in a single season, and 
even in a single day. Do you know whether two nails 
driven into a tree a foot apart will in the course of time 
grow farther apart? To locate the region of growth in an 
old plant, and to find the point or region of the greatest 
growth in a plant of any age, is a process worth investigating. 
I. SEEDLINGS 
Take a few two to three-inch pea seedlings grown in moist 
sawdust, and make equidistant marks with a fine brush and 
India ink on the entire root and stem. Cover a tumbler 
with a netting and poke holes large enough to admit the 
roots. 
1. Observe the development for four to six days, and 
describe the results. 
2. Does any part of the stem or root attain an appar- 110 
CORN 
ently maximum length, or is the growth in length 
continuous? 
Select a favorable stem on a potted plant such as a coleus 
or a geranium. With a brush and India ink make marks 
exactly one inch apart from the base of the stem to the tip 
of a prominent branch. 
II. OLDER PLANTS 
Observe the plant for one to two weeks, and de- 
scribe the results. Is the stem of an older plant fixed 
in length at any point? 
LABORATORY STUDY 62 
CORN 
Corn is a native of this Continent, but is now grown 
widely over the world in improved varieties. One-third of 
our cultivated land is used for growing corn, and over three 
billion bushels are produced yearly. No food plant we have 
produces so enormously. Yet we ourselves eat little of it. 
Nevertheless, it is excellent food, and it is cheap. 
I. THE CORN PLANT 
The seeds of the corn plant are planted in hills of a few 
seeds each in the spring in temperate to hot portions of the 
country. The plant grows rapidly and blossoms in the 
months of May, June and July, depending on the latitude. 
Describe the process of pollination in the corn plant 
and the result of that process. (See textbook, page 253.) 
The corn plant matures or ripens in late summer or early 
fall, when the whole plant becomes yellow and the grains 
hard. 
1. Examine an ear of corn and describe what you see. CORN 
111 
2. Section a grain of soaked corn lengthwise while it 
lies flat, and examine the parts you discover. 
Identify endosperm and embryo and parts. 
3. Try the nutrient tests to discover the facts that 
may justify the statement that corn is an im- 
portant food plant. 
Corn is grown in rich soil where a plentiful supply of 
water is available. Deep plowing and harrowing improve 
the chances of the plants. Before the young plants have 
appeared above the ground, and during the entire time of 
their growth, various enemies attack them; first, the crows, 
then cutworms, army worms, grasshoppers, and a parasitic 
plant, called smut, that grows in a black lumpy mass on 
the ears. 
II. CULTIVATING AND HARVESTING CORN 
What is done to check the ravages of some of these 
enemies of the corn plant? 
Soon after the plants have grown a few inehes cultivation 
begins, and continues until the tassels of staminate flowers 
have appeared. 
What is the benefit to be derived from cultivating 
plants? 
Sweet corn is mature enough to eat in July. Field corn 
must harden to be fit for its uses. 
How is the harvesting of field corn carried on? 
III. DISPOSING OF THE PRODUCT 
From 85 to 90 per cent of the field corn never leaves the 
farms where it is produced. The remainder is shipped to 
the market, and is distributed about the world for various 
purposes. 
What happens to the corn that never leaves the 
farm? Why? 112 
CORN 
Corn bread is made from corn meal, ground after the 
bran and the embryo have been removed. The old process 
of grinding eliminated only the bran. 
What nutrient of the grain in general is left out of 
corn meal now? 
Beside corn meal, other corn products are corn starch, 
corn syrup or commercial glucose, and oil. From the oil 
a valuable cooking oil is obtained. Oil is transformed into 
soap, into a tanning material, into a substitute for rubber, 
and into water-proofing and insulating material. The oil 
cake remaining after the oil is extracted from the embryo 
is fed to livestock. 
1. What branch of human knowledge has made these 
discoveries possible? 
2. Make a longitudinal section through the embryo 
as the grain lies flat. Draw X 3. Label the parts. 
3. Make a transverse section through the middle. 
Draw X 3. Label the parts. 
Textbook, chapter XXI and pages 297-299 at end of study. 
Prepare a moist chamber of a wide flat-bottomed, covered 
jar, with two layers of moistened filter or blotting paper 
and a little excess water. Soak corn seeds twenty-four hours. 
Drop into the moist chamber a dozen or more soaked seeds. 
IV. DEVELOPMENT 
1. Identify the plumule and the radicle in develop- 
ment, telling what they are developing into. 
2. When the root-hairs appear make a drawing of 
the whole seedling. THE BEAN 
113 
LABORATORY STUDY 63 
THE BEAN 
Beans are common in temperate and tropical regions 
throughout the world. They are cultivated and cared for 
because they are nutritious. In most places they are 
cheap, and unlike most plants their growth in the soil 
improves the condition of the soil itself. 
I. THE PLANT AND ITS PARTS 
Because beans may be grown indoors, it is possible to 
provide at least small plants at various seasons. But in 
early spring better plants may be obtained. Seeds planted 
at different times will yield maturing plants during a long 
period. Dig up bean plants for the laboratory study, wash 
off the roots and lay them out for examination. 
1. Sketch in outline the entire plant, noting the 
arrangement of the leaves on the stem, the 
veining of the leaves, the form and branching 
of the stem, the root system and the tubercles 
of nitrogen-fixing bacteria on the roots. 
2. Take a blossoming plant for the study of the 
flower. Identify and observe the parts in the 
calyx, the corolla, the stamens and the pistil. 
3. Make a careful drawing of a flower. 
4. What adaptations do you observe in the flower to 
pollination by insects? 
5. What parts of the flower in the older blossoms are 
developing into the fruit? 
6. Open a young fruit and describe what you see. 
II. BEANS AS FOOD 
The widespread use of beans for food is evidenee of value. 
But food tests will give us definite information. 
1. Apply the nitric acid-ammonia test to some seeds 
that have been soaked several hours, and state 114 
THE BEAN 
whether the protein content seems to be high 
or low. 
2. Apply also the starch test, stating the conclusion 
you draw from it. 
3. Do you find glucose and oil in the bean seeds? 
4. What other food is frequently eaten with beans? 
Why? 
We may have bean seeds all the year round, and green 
beans in the summer time. But in large cities and in some 
tropical countries green beans may be obtained continuously. 
The green beans are shipped from the South to the cities. 
What additional needs of our bodies do green beans 
supply? 
III. THE DEVELOPMENT 
Plant some sun-dried bean seeds in moistened sawdust 
or soil. Soak another lot for twenty-four hours. Place some 
of this lot in a moist chamber on damp filter or blotter paper, 
and leave until they germinate. Take other soaked seeds 
and examine the structure of the seed and the embryo 
contained in it 
1. Open a seed along the convex edge with the point 
of a knife, lay out the halves and identify the 
seed coats, the cotyledons, the delicate plumule 
and the radicle. 
2. Make a sketch of the embryo in place. 
3. From your examination of the germination stages 
appearing in the moist chamber specimens, de- 
scribe the early changes in the plumule and the 
radicle. 
If you are watching the course of development in the 
planted seeds you may see a loop of the young seedling 
that is pushing its way up through the crust. This is a 
portion of the new stem that develops from a minute 
region called the hypocotyl that lies near the junction of WHEAT 
115 
plumule and radicle below the point where the cotyledons 
are attached. 
1. Do you see an adaptation to use in the doubling 
of the hypocotyl on its way to the light and air? 
2. What appearance develops in the cotyledons after 
their emergence that gives a notion of their 
function? 
3. What happens to the cotyledons later on that shows 
their function in development? 
4. What is the meaning of the large amount of rich 
food in the bean seed for the young plant itself? 
Textbook, chapter XXII and pages 348, 354. 
LABORATORY STUDY 64 
WHEAT 
Wheat is grown in considerable quantity in forty-three 
of the states of the Union. In the year 1923 we produced 
781,737,000 bushels. 100,000,000 bushels of this went into 
the production of macaroni. Wheat is the most important 
grain food we consume. The amount of labor and the 
wealth concerned in the care of wheat and in the creation 
of its chief product, flour, are tremendous. 
In the most northern states and in Canada varieties of 
"spring" wheat are grown, while the states south of this 
district grow more "winter" wheat. Spring wheat is sown 
in early spring, and winter wheat is sown in the autumn. 
Both reach maturity in June and July. 
I. THE WHEAT PLANT 
Why should the two kinds be sown? 
Wheat is a member of the grass family of plants. The 
flowers are inconspicuous, and the pollination is carried on 116 
WHEAT 
chiefly by the wind blowing pollen from one wheat plant to 
another. Examine a "head" of a wheat plant. 
1. How are the grains situated, and how are they 
protected in development and during harvesting? 
2. Crack open a grain and describe what you see. 
3. Examine a particle of the interior on a glass slide 
in water with the compound microscope, and de- 
scribe what you see. 
II. CULTIVATING AND HARVESTING WHEAT 
Wheat grows in fertile soil with a light mixture of clay 
and lime. The top soil must be fairly deep to maintain the 
supply of nitrogen and other elements used in large quanti- 
ties by the plants. Plowing and harrowing prepare the 
ground for the drill. With the drill, drawn by horses, the 
grains of wheat are sown in shallow trenches a few inches 
apart, the machine covering the seeds as it goes along. 
Why is no further cultivation possible or necessary 
during the growth of the plants? 
During the growth of the plants numerous enemies attaek 
it. Among them are the wheat rust (see page 231 of the 
textbook) and the insects, the chinch bug and the Hessian 
Ascertain the extent of the damage done by these 
enemies, and the means being taken to eliminate 
them. 
When the wheat begins to turn yellow, or to ripen, har- 
vesting is on. The farm implements used in this proeess 
are the old-fashioned "cradle," the old reaper, the newer 
reaper and binder, and the harvester that clips off the tops 
only. When the grains in the heads are thoroughly dried 
or "cured," threshing of the wheat follows. 
From current-events discussion, recall and mention 
the proposals that have been made, or have been put THE HUMAN MOUTH 
117 
into effect, to prevent waste and exploitation in han 
dling and disposing of wheat to the flour mills. 
III. THE MANUFACTURE OF BREAD 
Wheat bread is doubtless the most important single 
article of food among civilized peoples. 
Why is this so? 
The manufacture of flour is more centralized in certain 
cities of the country. 
What are the cities, and what are the factors that 
have brought this about? 
The baking of bread lias also become industrialized in 
large centers. 
Do you think the results have been beneficial on 
the whole? How? 
Textbook, pages 230, 292, 301-303. 
LABORATORY STUDY 65 
THE HUMAN MOUTH 
Have you thought of the number of functions with which 
the human mouth is concerned - eating, tasting, feeling, 
breathing, speaking? The mouth is the most primitive of 
all the organs of the body, the place where animals take in 
food. In ourselves we realize still more the importance of 
the mouth when we begin to consider the result of not 
taking care of it. 
With a small hand mirror much can be learned about the 
mouth cavity. Open wide the mouth to the light and 
identify the teeth of the upper and the lower jaws, the 
incisors, the canines, the premolars, and the molars. Is the 
I. PARTS WITHIN THE MOUTH CAVITY 118 
THE HUMAN MOUTH 
tongue attached Io the upper or Io the lower jaw? When 
the mouth opens and closes which jaw moves? What parts 
form the side walls of the mouth cavity? Looking far back 
into the cavity, identify the passage into the pharynx, the 
uvula or soft palate, extending tremulously from above, and 
the red tonsils at the sides of the passage. 
What adaptations of structure to function can you 
discover in the arrangement of the parts in the mouth 
cavity? 
II. THE TEETH 
The teeth are a part of the digestive system. Let us see 
why they are so called. 
When you take a bite of food, which teeth cut off the 
piece? If the food is something that you pull or tear apart, 
which teeth are called upon to do most of the work? Try 
it at meal time and see. If you are eating nuts or other 
hard food, which teeth do the work of chewing? How many 
of each kind of tooth have you in upper and lower jaws? 
How is each kind of tooth adapted to the work it 
does? 
While you were looking at the teeth, did you notice any 
cavities, or did you see where any teeth had been filled? 
Have you lost any teeth? And do you notice whether any 
white food matter has collected about the bases of your 
teeth, or between the teeth? Where do most of the cavities 
occur in teeth? Why? What is the best way to brush 
the teeth? 
Write an account of the reasons for taking care of 
the teeth, and of how to do it. 
Close your teeth together, spread your lips away from the 
teeth as far as possible, and look to see if teeth of upper 
and lower jaws strike one another. If they do, you are less 
liable to have trouble in later years with receding gums or 
pyorrhea. If teeth do not strike their opposing teeth, try THE HUMAN MOUTH 
119 
to have an orthodontist (a dentist who sets teeth straight) 
adjust them for you. Remember the infection in pyorrhea 
is a result of receding gums, not a cause of receding. 
What may a good set of teeth have to do with good 
digestion? 
The tongue is composed of muscular tissue. On the 
surface near the tip are many delicate sense organs of 
touch. On top are many sense organs of taste. 
III. THE TONGUE 
1. Do you see any advantage in the location of these 
two sets of sense organs? 
2. How does the tongue aid in the work of the teeth? 
Sometimes the tongue is coated brown. This is an 
indication of indigestion. 
Do you know of other indications of indigestion, 
and do you know how indigestion may be avoided? 
IV. THE SALIVARY GLANDS 
Spread the jaws enough to permit the tip of the tongue to 
be extended out to the inner surface of the cheek muscles. 
Feel about until the tongue touches a noticeable lump, one 
on either cheek. These are the papillae on which one pair 
of salivary glands open, they are called the parotid glands. 
Two other pairs of salivary glands open beneath the tongue. 
When your mouth "waters" these glands are secreting large 
amounts of saliva. In the course of time tartar from this 
secretion collects about the bases especially of the lower 
front teeth. This is incidental to the chief work of the 
saliva. 
Under what conditions have you noticed your 
mouth " watering " ? 
What is the meaning of the watering? 
Try placing a strip of litmus paper into the mouth to 
ascertain the chemical reaction of the saliva. 120 
FOODS IN HEALTHFUL LIVING 
V. THE CONNECTING PASSAGES 
From the mouth cavity there are passages through the 
pharynx to the nostrils, and also to the middle ear cavities 
by way of the Eustachian tubes. 
Have you ever had experiences indicating that this 
statement could be verified? What were they? 
The pharynx may carry infection to the alimentary canal, 
as in typhoid fever. Or it may carry infection up the Eus- 
tachian tube, causing pus to collect in the middle ear, from 
which infection may extend to the mastoid bone behind 
the ears. 
What care can be taken at the mouth to prevent 
typhoid fever infection and the infection of the 
Eustachian tubes? 
Textbook, Chapter XXXIII. 
LABORATORY STUDY GO 
FOODS IN HEALTHFUL LIVING 
Food is our first necessity. We take it instinctively 
for continued existence, and along afterward, perhaps, 
think over the matter of why we do it, and under what 
conditions it should be done. Intelligent persons are anxious 
to give careful attention to a problem that is bound up so 
closely with their personal safety from day to day, and with 
their happy and efficient activity in a long life. 
I. FOODS THAT FURNISH THE NECESSITIES 
At first through experience, and later more definitely 
through scientific knowledge, we learn that there are im- 
portant classes of food which our bodies absolutely require. 
Without a little of all these classes we should not be able FOODS IN HEALTHFUL LIVING 
121 
to continue alive at all. They are the carbohydrates (sugars 
and starch), protein, fats, mineral salts, vitamins and water. 
Our laboratory study on the Tests for the Organic Nutrients, 
page 12, has made us acquainted with the means of detect- 
ing the presence of the first three. We know water, but 
less of mineral salts or vitamins. 
1. Let us add to our knowledge by testing for carbo- 
hydrates the following foods, if we have not 
already done so: potato, bread, carrot, cereal. 
2. Which of the following contain glucose (grape 
sugar): potato, carrot, apple? 
3. Do the following foods contain protein: beans, 
cheese, cereal? 
4. Is there oil in these: meat, some green vegetable, 
oatmeal? 
These are some of the many foods of which we consume 
a great deal. But we should know just why we eat them. 
Study of the textbook makes it clear that we derive energy 
for the body and its organs from the carbohydrates. 
In order to have a variety of sources of energy, let 
us make a list of five foods from which carbohydrates 
may be obtained (see textbook, pages 342, 343). 
We consume protein to have material for repairing the 
small amount of muscle and nerve tissue that is worn out 
each day. While we are growing, a considerable amount 
of the protein we eat goes directly to the building of pro- 
toplasm in the new living cells. One food containing an 
abundance of protein will supply this need. 
What foods would supply this protein (see textbook, 
pages 345, 346)? 
Fat is not turned into fat on being consumed and digested, 
but is oxidized for energy. 
What foods may supply this energy from fat {see 
textbook, pages 344, 345)? 122 
FOODS IN HEALTHFUL LIVING 
The other nutrients which have definite uses are mineral 
salts, vitamins and water. The mineral salts furnish bone 
material and substances useful in correcting the bodily 
functions. 
A list of the foods containing these nutrients should 
be given here (see textbook, pages 346, 347). 
The vitamins are the newly discovered essentials for 
healthful living. 
Make memoranda to show their uses and their 
origin {see textbook, pages 348-350). 
Water is present everywhere, and is needed to keep the 
protoplasm fluid and alive. 
II. AMOUNTS AND CONDITIONS FOR EATING 
Even a furnace lias to be supplied intelligently with 
burnable material. If you throw into the furnace, or into 
the human body, a considerable amount of material at once 
it will seem to be enough, when it really will not be. In the 
case of the furnace, and in the case of ourselves, we are 
deceived. 
1. What precautions in this matter will set us right? 
2. What other effect have you noticed resulting from 
rapid eating? 
3. What effect have you noticed from actual over- 
eating? 
4. Have you ever had experiences like those de- 
scribed in the textbook, page 383? If so, what 
would you suggest as a means to establishing 
good conditions for eating? 
Many persons are puzzled to know how much they should 
eat. It is difficult to estimate the amount to eat, on a 
mathematical basis. If the habit of eating three times a 
day oidy is established, and the habit of eating slowly, 
and chewing the food well, the appetite itself is a good leader. FOODS IN HEALTHFUL LIVING 
123 
A suggested limit on eating, however, is offered in the fol- 
lowing for the principal meal of the day: 
One dish rich in protein. 
One dish rich in starch. 
One dish rich in sugar. 
One dish rich in fat. 
One dish rich in mineral salts. 
One harmless beverage. 
Fruit. 
On this basis suggest a meal, and compare it with 
what you commonly eat. 
Food having been consumed under favorable conditions, 
and in suitable amounts, it is necessary that the digestion 
proceed under good conditions. Sometimes we have head- 
aches, dizziness, bad taste, foul breath and acute pains in 
the abdomen. Added to these the skin may appear sallow. 
These are signs of constipation or a clogging up of the whole 
digestive system. Fresh fruits are valuable aids in setting 
the digestive system right in difficulties of this kind. 
III. THE HYGIENE OF DIGESTION 
1. What actual experience have you had bearing on 
these points? 
2. What have you noticed in your experience to be 
the effect of vigorous exercise on the satis- 
factory completion of digestion? 
3. Have you ever planned to avoid the necessity of 
complaining about your digestion, a misfortune 
of many older persons? 
Textbook, Chapters XXVIII, XXIX, XXX. 124 
THE DIGESTION OF STARCH 
LABORATORY STUDY 67 
THE DIGESTION OF STARCH 
We learned in the study on Osmosis, page 8, that starch 
cannot pass through a membrane. In the same study we 
learned something about the solubility of various substances. 
We realize from these studies that the change in the chemical 
composition of foods is a necessity before living things can 
make use of them. The process by which these changes are 
brought about is called digestion. It is a fundamental 
process for all animals and all plants. 
I. DIGESTION IN THE MOUTH 
Have several clean test tubes ready. Set out some 
Fehling's solution for the glucose test and some iodine 
solution for the starch test. 
To see what happens to soda crackers on being chewed, 
chew a piece for two or three minutes. Place a small portion 
in each of two test tubes with a little water. Into two 
other test tubes containing water drop pieces of dry cracker. 
Apply the starch test to the contents of a tube containing 
the dry cracker, and to the other dry cracker apply the 
glucose test. 
What is the result in each case? 
Next apply the starch test to one lot of chewed cracker, 
and the glucose test to the other. 
Describe the results in these cases, and state what 
seems to be proved. 
But may it be that the saliva itself may be giving some 
reaction to one of these tests? Therefore, rid the mouth of 
cracker, and test some saliva for starch and for glucose. 
What is your final conclusion from all these tests? THE DIGESTION OF PROTEIN 
125 
II. DIGESTION IN THE SMALL INTESTINE 
The pancreas, a digestive organ lying under the stomach, 
by the first fold of the small intestine, has very important 
functions. Prepare some pancreatin solution from the 
manufactured product of an animal's pancreas. 
Place a piece of soda cracker in a test tube and pour in 
some pancreatin solution. Set in an incubator or an oven 
of about 100° Fahr, for twenty-four hours. 
Carry out the glucose test on the cracker in the 
test tube, and also on some pancreatin solution, and 
state your conclusion. 
III. DIGESTION IN PLANTS 
Plants, of course, contain starch; they also contain glu- 
cose. Let us see if there is digestion of starch in plants. 
Cut some soaked grains of corn lengthwise and apply the 
starch test. Also to other specimens apply the glucose test. 
Describe what happens in each case. 
Next take from the laboratory stock a few corn seedlings 
with stems three or four inches high. Remove stems and 
roots. Section longitudinally and test two of these seeds 
for starch and two others for glucose. 
Describe the results and state your conclusion. 
Textbook, pages 250, 343. 
LABORATORY STUDY G8 
THE DIGESTION OF PROTEIN 
In the experiments under Osmosis, page 8, we learned 
that white of egg, a typical protein, will not pass through 
a membrane. Therefore, protein cannot be absorbed from 
the intestine of an animal eating the white of egg. 126 
THE DIGESTION OF OIL OR FAT 
Cut pieces of cooked white of egg and drop into four clean 
test tubes. Prepare cotton plugs for closing the tubes. Into 
the first tube pour water to cover the egg, into the second 
pour a solution of fresh saliva, into the third, a solution of 
prepared pepsin, and into the fourth a solution of prepared 
pancreatin. 
Close the test tubes with cotton. Place the four test 
tubes in a warming oven of about 100° Fahr., and look for 
changes indicating progressive dissolving of the egg. 
1. Record results daily for four to six days. 
2. According to these results, where in the digestive 
system does protein digestion begin, and where 
is it completed? 
Textbook, pages 384-385. 
LABORATORY STUDY 69 
THE DIGESTION OF OIL OR FAT 
We now know that oil or fat occurs in small or large 
quantities in a great many foods. Like other organic nutri- 
ents it can be digested, and for the same reason it must be. 
Set up four test tubes with a small lump of butter in each. 
Into the first pour water, into the second pour saliva, into 
the third a solution of pepsin, and into the fourth a solution 
of pancreatin. Place all in an oven of about 100° Fahr, 
for two or three days. 
1. What happens in the several tubes? 
2. Supposing that you know the source of pan- 
creatin, where in our digestive system would 
fat or oil be digested? 
Textbook, pages 384, 385. THE BALANCED MEALS OF A DAY 
127 
LABORATORY STUDY 70 
THE BALANCED MEALS OF A DAY 
Even thoughtless persons will not deliberately try to make 
a meal on a single kind of food, except under necessity. No 
single food contains what we need in the ratio satisfactory 
to man. 
I. THE BALANCING WORKED OUT IN HUMAN EXPERIENCE 
There are certain food combinations which we eat from 
long habit, like meat and potatoes, bread and butter, etc., 
etc. 
Name five other natural combinations, and tell 
what organic nutrients are brought together in the 
balanced ration. 
II. WHAT SCIENCE HAS ADDED IN COMPLETING THE 
BALANCE 
Although it appears to be natural for children to adopt 
the balanced rations, bread and butter, meat and potatoes, 
and others, it is not natural for them to like another class 
of food which science has shown to be necessary. This is 
green vegetables. 
1. What is the scientific basis for the advice to eat 
green vegetables {see textbook, pages 347, 349, 
350)? 
2. What green vegetables were you yourself obliged 
to learn to like? 
III. THE DAILY BALANCE 
There is considerable variation in the needs of adults in 
the daily supply of food; some hard-working men require 
three times as much as other men. Among children and 
adolescents, however, the actual needs are similar for each 128 
THE CIRCULATORY SYSTEM 
age group. And the amount required by a young person 
in school is not very different from the amount needed by 
a grown person working at a profession. 
Experience has shown that at breakfast our needs are 
not as great as they were thought to be at one time. The 
menus given on pages 356, 357 in the textbook are said on 
competent authority to be enough. 
1. Take up the breakfast menu suggested, and tell 
what nutrients this would provide for the con- 
sumer. 
2. Do the same with the menu for lunch. 
3. Do the same with the menu for dinner. 
Textbook, pages 356-3G0. 
LABORATORY STUDY 71 
THE CIRCULATORY SYSTEM 
The circulatory system of man is a good example of a 
system of organs that has closely connected relations with 
several other systems. Among these are the digestive 
system, the nervous system, the respiratory system and the 
excretory system. A way of stating the importance of the 
circulatory system is to say that it stands in a key position 
in metabolism, the whole series of chemical and physical 
processes which the living body carries on 
I. THE EXTERNAL PHENOMENA OF THE CIRCULATORY 
SYSTEM 
The best known of the external activities of the blood 
system is the "pulse." There are several places on the 
surface of the body where the rate of beat of the heart can 
be determined by counting the pulsations in an artery. 
The easiest point at which to locate the pulse is perhaps THE CIRCULATORY SYSTEM 
129 
the small artery that runs in front of the ear (see textbook, 
page 390). 
1. Let each member of the class count his pulse for 
one minute while remaining seated. 
2. Count again while standing. 
3. Let the members of the class hop up and down 
rapidly for one minute and then count again. 
4. Rest two minutes, and count once more, and count 
until the normal standing rate is recovered. 
5. Compare the rapidity of recovery of normal stand- 
ing rate among the members of the class. 
The most superficial blood vessels are veins. Note the 
distribution of some of the veins on the inner surface of 
the forearm. Grasp the right arm with the left hand at a 
point above the elbow. Press down until the veins swell 
to considerable size. 
1. What causes the swelling of the veins? 
2. When the pressure is released what happens? 
3. Is there a pulse in the veins? Explain. 
One of the most important conditions of the blood system 
to know about is the blood pressure. It is now within the 
power of nearly everyone to have this information about 
himself. The information may be obtained by means of 
the sphygmometer (pulse measurer). This instrument con- 
sists of a syringe pump which in the hands of an operator 
forces air into a rubber bag bound about a person's arm. 
The pressure exerted by the blood is checked against the 
pressure exerted by the pump, and is indicated by a column 
of mercury, or by a dial gauge. If the blood pressure is 
high it means that the body is using a large amount of energy 
to carry blood through arteries that have become inelastic, 
probably as a result of chronic constipation or of the excessive 
eating of food. 
1. What would seem to be the risk involved in per- 
mitting the blood pressure to become high? 
2. What can be done to prevent high blood pressure? 130 
THE CIRCULATORY SYSTEM 
II. THE INTERNAL PHENOMENA OF THE CIRCULATORY 
SYSTEM 
The center of the circulatory system is of course the 
heart. Its periodic contraction and relaxation is in the 
control of the autonomic nervous system (see textbook, page 
423), but the rate of contraction is adjustable to needs in 
other systems. 
1. What systems especially are supplying increased 
needs during an athletic contest? 
2. To what organs are these needs transported? 
3. Study the work of the red blood corpuscles, and 
state their function {see textbook, page 394). 
To understand another function of the circulatory system 
we must consider what is likely to happen to the food the 
digestion of which is being completed in the intestine. The 
blood vessels penetrate the wall of the intestine, and lie 
on one side of membranes on the other side of which is 
digested food. 
Recalling the experiments on Osmosis, page 8, 
what now happens to the digested food? 
In a later study we shall find some of this food stored in 
the liver, and some of it will be distributed over the whole 
body, a little to be stored in the muscles, a little to be used 
up at once to supply energy, and some to be transformed by 
assimilation into protoplasm of living cells. 
1. By what process would certain portions of the food 
be used up to supply energy? 
2. Study the connection of the lymph system (see 
textbook, page 395) and give your idea of the 
way digested food reaches the cells, and the 
wastes are carried back into the circulatory 
system. 
3. On page 394, textbook, you will read the interest- 
ing story of the white blood corpuscles. Tell RESPIRATION 
131 
what each person can do to give these " eating 
cells " their best support in protecting us. 
Textbook, pages 328-330 and Chapter XXXIV. 
LABORATORY STUDY 72 
RESPIRATION 
Respiration or breathing is a function that brings every 
animal and every plant into contact every second with the 
most generally present substance in existence, - air. Thus, 
respiration and its attendant process, oxidation, become in 
an important sense the most fundamental process in life. 
I. HOW RESPIRATION IS FUNDAMENTAL 
We are accustomed to saying that plants breathe in what 
we breathe out. This is a contradiction in the meaning 
of the term, breathing. The word is used scientifically to 
apply to the process of taking in oxygen and giving out 
carbon dioxide, and to nothing else. But plants also use 
carbon dioxide as described in the study of Leaves (page 
95). 
We found in the study of Oxygen and Oxidation (page 3) 
that oxygen will combine with any one of several elements. 
1. What element or elements are present in the 
bodies of plants and animals that may combine 
with oxygen? 
2. What is the source of these elements? 
Borrow from the chemical laboratory the carbon dioxide 
generator. Fill it with blocks of marble and dilute hydro- 
chloric acid. Collect a quantity of the carbon dioxide ob- 
tained from the splitting up of the lime in the marble, and 132 
RESPIRATION 
mix it with clear lime water. Take note of the milky pre- 
cipitate (sediment) formed. 
For comparison blow your own breath through a 
glass tube into another glass of clear lime water, and 
say what you think the result means. 
Next take two large glass-covered jars of equal size. Put 
into each equal quantities of moistened filter paper and 
small open vessels of lime water. Into one of the jars place 
a number of fresh cuttings from a coleus or other conven- 
ient "fleshy" stem and leaves. Keep the other jar without 
leaves as a check. Cover both jars carefully. 
In twenty-four hours note results, and tell what 
they mean. 
We found also in the study of Oxygen and Oxidation that 
energy is set free during oxidation. 
1. Is there evidence that energy is set free in the ani- 
mal body? If so, what kind or kinds of energy? 
(Remember that any kind of work being done is 
evidence of the manifestation of energy.) 
2. Do plants show evidence of energy being set free? 
II. THE HYGIENE OF BREATHING 
We realize the importanee of the lungs in providing oxygen 
for the body in quantity sufficient to maintain all bodily 
functions. In the average person the amount of air entering 
the lungs is about one eighth of their entire capacity. 
"Shallow" breathers, careless folk, have no more than one 
half this amount of what is called tidal air. Thus, the red 
blood corpuscles carry from the lungs only a portion of the 
oxygen they could carry. 
1. What is bound to be the effect of the reduced 
supply of oxygen on the degree of activity of 
the organs of the body? VENTILATION 
133 
2. 
By taking in a large amount of tidal air, what organs 
and tissues of the body may be directly benefited? 
How? 
Colds are traced to mucous membranes of the throat and 
lungs that are weakened and made susceptible to the attacks 
of bacteria. 
Why may a person who lives indoors most of the 
time have more colds than one who spends his days 
out of doors? 
Textbook, pages 251, 259, 336, 401. 
LABORATORY STUDY 73 
VENTILATION 
We live immersed in an ocean of air. But sometimes we 
appear to have difficulty in getting enough air to breathe. 
Why this should seem to be so is certainly worthy of study. 
The first thing to do in dealing with a problem that appears 
to be difficult is to try to analyze or take apart its elements. 
Let us, therefore, examine the air. We find, as already 
noted in the textbook (page 407), and from the studies on 
Oxygen and Oxidation, and on Nitrogen (pages 3, 6) that 
air is composed of oxygen one-fifth part, and of nitrogen 
nearly four-fifths part, a little carbon dioxide and about 
one per cent of argon, and other little known gases. 
1. In a body of air from day to day, and in different 
localities, what other substances are there 
present in air? 
2. How would temperature affect the amount in the 
air? 
It used to be thought that the amount of carbon dioxide 
given off from the lungs of a number of persons in a close 134 
VENTILATION 
room is the cause of the discomfort noticed. Scientific 
experiments have shown that this inference was incorrect. 
The familiar bad odor has also been shown not to be the 
cause of the discomfort. In order to trace the source of the 
discomfort, let us imagine ourselves in the open air on a 
warm day. 
1. Are the days on which we suffer most in the 
summer the days that show the highest tem- 
perature? 
2. Do we suffer most when we have the most per- 
spiration on the skin? 
3. How is it that on certain days when the tempera- 
'ture as shown by the thermometer is high we 
seem to perspire little? 
4. How does the humidity of the air as shown by the 
weather reports relate to this situation? 
Now let us return to our ill-ventilated room in order to 
find out what to do about it. Evidently the moisture in 
such a room has some relation to the discomfort we feel. 
1. What is the source of the moisture in this case? 
2. What is the effect of an amount of moisture present 
in the air of a room on additional moisture sent 
out into it? 
3. When water is evaporating from a boiling pot, or 
from your own skin, what goes out with the 
water? 
4. Why is it when water (perspiration) escapes into 
the air readily you feel more comfortable than 
you do when it passes off slowly? 
5. What, then, should be done with an ill-ventilated 
room? 
Textbook, page 407. EXCRETION 
135 
LABORATORY STUDY 74 
EXCRETION 
Through the biological process of excretion materials that 
have been a portion of the body are sent out as waste. 
Since the foods that animals consume are in general com- 
plex, the wastes produced by a breaking down process are 
relatively simple in chemical composition. Plants, too, 
give off as waste simple compounds. These are few in 
number. 
I. ORGANS OF EXCRETION 
For human beings the chief organs of excretion are the 
kidneys, the liver, the lungs and the skin. The same organs 
serve the function of excretion in all the vertebrate animals 
down to the Amphibia, for a part of their existence. The 
skin of the thick-shell reptiles, however, is impervious to 
gases and liquids. 
The organs of excretion in plants are the stomata, minute 
pores on the leaves and on the younger portion of the bark. 
What explanation occurs to you for the existence of 
the greater number of kinds of excretory organs in 
animals? 
The function of the kidneys is to separate from the 
blood the wastes of urea, uric acid, minerals and water. 
This waste passes from the kidneys through tubes to the 
bladder from which it is expelled from the body. 
The liver has several functions, two of which are con- 
nected with excretion. In the first place, it takes some of 
the waste products of the protein substances in the body 
and builds them up into a less dangerous product, urea. 
The blood carries the urea finally to the kidneys where it 
is separated from the blood. The other function in excre- 136 
EXCRETION 
tion is the separation from the blood of the broken down 
red corpuscles, which are sent into the secretion, bile, later 
to be expelled into the intestine. 
It has already been explained that the lungs excrete 
carbon dioxide after the process of oxidation is finished. 
The skin excretes perspiration which contains water, urea 
and mineral salts, with a minimum of urea in health. Inci- 
dental to the elimination of perspiration excess heat is given 
off. 
The functions of the stomata of plants is the elimination 
of carbon dioxide after oxidation, and the elimination of 
oxygen after photosynthesis. Excess water is also sent out 
from the stomata 
What systems of organs in the body seem to be 
connected with building-up processes while the ones 
mentioned in this study are removing wastes? 
II. THE HYGIENE OF THE ORGANS OF EXCRETION 
It is worth while to note that the heathfulness of every 
organ of the body is promoted if the general health is good. 
This is just as true of the deep-seated excretory organs, 
the liver, the kidneys and the lungs as it is of the skin. 
But the kidneys and the liver are especially susceptible to 
injury from over-eating. Both organs are much stronger in 
persons who eat a small amount of meat and plentifully of 
green vegetables and fruit, and exercise in the open air in 
loose clothing. Jaundice, a disease of the liver, comes from 
the clogging up of the bile wastes. 
1. On the basis of what has been said, give advice 
for the hygienic care of the lungs and the skin. 
2. Knowing the functions of the skin, can you say 
what part baths play in its hygiene? 
3. From your own experience, what are the effects 
of warm and cold baths on the general tone of 
the body? 
Textbook, pages 266, 329-330, 372, 399, 401-403, 405. THE HUMAN EYE 
137 
LABORATORY STUDY 75 
THE HUMAN EYE 
Our eyes are rightly considered the most important of our 
organs of sense. This is true chiefly because the eyes make 
things outside ourselves seem real. Without the power to 
see few things, except what we feel, would appear to exist. 
I. THE PARTS OF THE EYE 
You will notice that everything about the eye is marvel- 
lously adapted to particular uses, and that the protection 
of the eye is the outcome of all these adaptations. 
1. What is done by the eye-lids and the eye-lashes 
that bears on this point? 
2. Examine the human skull and tell how it is adapted 
to protecting the eye. 
3. Compare the convex surface of the cornea of the 
eye with the convex surface of a reading glass, 
and tell what each does with the rays of light 
that pass through. 
4. With a mirror watch the change in the blue, gray 
or brown iris of the eye on first awaking in 
the morning, or on coming from a dark room, 
and explain what you see. 
II. WHAT THE EYE DOES 
We don't have to think much to make the eye do its work. 
For the most part, the activities of the eye are carried on 
by reflex action (see page 415), and in accordance with 
certain laws of light. Rays of light reflected from surfaces 
enter the pupil of the eye, and are brought to a focus on the 
retina at the back of the eye by the corneal lens in front of 
the iris and the crystalline lens back of it. The optic nerve 138 
THE HUMAN EYE 
on the retina transmits the stimulus to the optic lobes of 
the brain - and we see. 
1. What must the eye do to see things at one side, 
or in looking from one object to another at a 
different distance? 
2. Try closing each eye alternately while looking at 
an object with angular sides a few feet away, 
and tell the advantage two eyes give you. 
3. When you have been using your eyes for a long 
time, where do you feel pain? What is the use 
of this information? 
III. THE CARE OF THE EYES 
Sometimes in cases of serious eye trouble the sufferer 
may feel pain or weakness apparently having no connection 
with the eyes. Thus, information on the condition of the 
eyes must be secured from time to time by means of certain 
tests. Among these are the tests easily provided by the 
"Snellen Cards." 
1. While looking at an object first with one eye and 
then with the other, do your eyes see differently? 
If so, what does this mean? 
2. If one holds a book close to the eyes what is the 
trouble, and what can be done about it? 
3. Have you known of persons whose lines of vision 
for the eyes seem to cross at times? What is 
the meaning of this, and what can be done? 
4. Why should we not read in weak light, or with the 
light falling into our eyes? 
5. What general principle of health is involved in 
practicing with our eyes before a Snellen Card, 
covering our eyes with the palms of the hands 
for some minutes, and looking at various letters 
without straining? 
6. What are the possible uses of the eye-cup in 
caring for and protecting the eye? 
Textbook, pages 435-437. THE HUMAN EAR 
139 
LABORATORY STUDY 76 
THE HUMAN EAR 
Next to the eyes, the ears are probably the most important 
of our sense organs. It is difficult to calculate the depriva- 
tion a person suffers who loses the sense of hearing. 
I. THE STRUCTURE OF THE EAR 
The ear is made up of three parts, the convoluted outer 
ear, which collects the waves of sound and permits their 
passage along the short canal to the tympanum or drum, a 
membrane cutting off the outer ear from the middle ear. 
In the middle ear are three small bones, which carry the 
waves of sound across to the nerve endings in the inner ear. 
The auditory or hearing nerve transmits the stimulus to the 
brain which gives us the sensation of hearing. 
In our study of the Mouth, page 117, we came upon the 
term Eustachian tube which is the name of the passageway 
connecting the pharynx at the back of the mouth with the 
middle ear. 
1. Through which organ, the eye or the ear, may in- 
formation reach the brain the more quickly? 
Explain. 
2. Propose an experiment, or describe one already 
tried, which shows how long it may take for 
sound to reach the ear. 
3. How accurate is the ear in locating sound? Blind- 
fold a person and hold a watch in different posi- 
tions above, behind, in front, and at both sides 
of the head. 
Have you ever passed through a tunnel under a river, 
or have you been carried to a great height suddenly, and, 
II. SOURCES OF TROUBLE IN THE EARS 140 
THE HUMAN EAR 
in the process, have you felt uncomfortable pressure in the 
ears? If you have not had either of these experiences, per- 
haps you have had the same feeling during the time you 
have suffered from a cold in the head. 
Can you suggest an explanation of these sensations? 
You may know the cases of men who have belonged to the 
army and have difficulty in hearing. 
What is the cause of the difficulty? 
In childhood especially a great many persons have had 
trouble with "running ears." In all such cases the ear drum 
has burst because of inflammation in the middle ear and the 
collection of pus. 
1. How may the middle ear have become infected? 
2. What may a person do to avoid at least some of 
the trouble from this source? 
Sometimes a person passing through an attack of measles 
"catches cold.'' Inflammation develops in the middle ear, 
and the inflammation may extend through the mastoid bone 
behind the ear. Through this and other colds mastoiditis 
may develop, in which case a serious operation is imperative. 
Frequent examination of the ear drum by a physician may 
help in avoiding mastoiditis. 
1. What does an earache mean, and what should be 
done if the earache is continuous? 
2. What harm may a person do in trying to " pick " 
his ears? Have you tried cleaning the dirt out 
with a thick absorbent cotton swab on the end 
of a blunt stick? 
Textbook, pages 436, 437. THE CARE OF THE BONES 
141 
LABORATORY STUDY 77 
THE CARE OF THE BONES 
There are more things to concern ourselves about in the 
care of our bones than to see that we do not break them. 
Consider the skulls of the Flathead Indians, flattened down 
by a board in babyhood, the crippled feet of the old-time 
Chinese ladies, and the cramped ribs of our own American 
ladies of the era of 1880. Have we stopped such foolishness? 
For answer, examine the picture in the textbook on page 
441. Besides, we must feed our bones. 
I. THINGS TO WATCH 
The bones of young persons and adolescents are quite 
hard, and cannot easily be pressed out of their natural 
shapes. But the pads of cartilage at all the movable joints 
may be compressed. Wrongly applied pressure on the 
cartilage will force the bones out of place. 
Observe the habits of your neighbors, as well as 
of yourself, and note down the things you see which 
in your opinion may induce physical defects in the 
skeleton. 
II. THE PHYSICAL PROTECTION OF THE SKELETON 
Perhaps you have noticed that most of the avoidable 
troubles that persons have with their skeletons is in the 
trunk of the body. That being the case, it is economical 
of time and thought if we can find a remedy that is fun- 
damental and easy to apply. Try to take a deep breath, 
and see what happens. Up goes your head, shoulders and 
entire trunk. Inhale and exhale several times at the rate 142 
THE CARE OF THE BONES 
of about eight times a minute for the whole process - no 
faster. 
1. How do you feel? 
2. Write a list of the things probably happening now 
in your body that were not happening well when 
you began this exercise. 
There is one point that you may overlook in this study 
unless attention is called to it. Bad posture is not due 
entirely to carelessness. It may be due to weak muscles. 
The muscles may have become weak through carelessness. 
Probably lack of use has something to do with it. 
What can be done to strengthen weak muscles? 
But no matter how much we exercise in the open air, 
incidentally breathing deeply because we cannot avoid it 
then, we cannot correct defects as long as we are carrying 
around with us the cause of more trouble, such as tight 
clothing and heels narrow and more than one inch high. 
Mention other foot troubles, and tell how to correct 
them. 
Have you wondered how a small animal like the clam 
or mussel could surround itself with so much hard protective 
material? All this lime compound must come from the food 
which the animal consumes. Similarly, the lime and phos- 
phorus compounds must be set aside by the protoplasm of 
the human body and organized as framework. This is a 
chemical process of great complexity. 
III. AVOID STARVING THE BONES 
Have you noticed children with bent legs? Are 
they little or large for their ages? 
These troubles of little children are due to lack of food 
containing sufficient quantities of lime and phosphorus ATHLETICS 
143 
compounds and also to lack of vitamins (see textbook, 
page 348). 
Examine the statement made on pages 348-350 and 
say whether in all particulars you are doing full duty 
to your bones and to your general growth. 
Textbook, pages 348-350, 440-442. 
LABORATORY STUDY 78 
ATHLETICS 
Athletics are new activities in our civilization, although 
men have always amused themselves in games in which one 
matches his wits and muscular prowess against the skill of 
another. But today physical exercises as games are highly 
organized and varied, and constitute an important phase 
of our education. 
I. KINDS OF ATHLETIC ACTIVITY 
At first athletics were developed only for boys and men. 
But now we have organized physical activities for girls and 
women. 
1. What are the athletic activities most popular in 
this country for boys and for girls? 
2. What countries were represented in the last 
Olympic Games? 
3. Which of these countries showed supremacy in the 
various branches of athletics? 
4. What benefits of any kind can be traced to the 
Olympic Games? 
5. What forms of athletics are adaptable to persons 
of widely different ages? Why? 
II. WHY ATHLETICS ARE POPULAR 
Athletics are popular everywhere. A great deal of time, 
money and organizing energy go into the work of providing 144 
ATHLETICS 
opportunity for boys and girls to take part in athletic 
games 
1. Consider an athletic contest you have witnessed, 
and tell why you enjoyed being there. 
2. Consider a form of athletics that is not usually 
engaged in before large audiences, and tell why 
you think the game is liked. 
III. THE PRACTICAL VALUE OF ATHLETICS 
An enterprise which is merely popular might even be 
injurious. In athletics we find wise and experienced persons 
giving time and money to the development of athletics. 
There must be a practical reason for this. 
1. Do you see any practical value in athletic contests 
to persons who do not actually engage in them? 
2. Have you known cases in which some bodily weak- 
ness or lack of development has been corrected 
through athletic exercises? If so, tell about it. 
3. How does athletic exercise improve the bodily 
functions of circulation, respiration and the 
removal of wastes? 
4. Is there a practical advantage in being proficient 
in a number of athletic activities? If so, what 
is it? 
Textbook, pages 445-447.