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MANUAL

OF

EXPERIMENTAL BOTANY

BY

l"M

FRANK OWEN PAYNE, M.Sc.

i

ASSISTANT IN BIOLOGY, HIGH SCHOOL^ OF COMMERCE
NEW YORK

NEW YORK •:• CINCINNATI •:• CHICAGO

AMERICAN BOOK COMPANY

COPYRIGHT, 1912, BY
FRANK OWEN PAYNE.

ENTERED AT STATIONERS' HALL, LONDON.

PAYNE'S BOTANY.
w. p. i

PREFACE

THERE is something in an experiment which appeals to the
mind of the young. The innate desire to find out what is in a
toy, how it works, and why various things happen, is largely
responsible for this.

Chemistry and physics owe their great popularity to the
fact that they have been taught by experiment. Zoology and
botany have always been less popular because they have often
been taught without experimentation.

In the days when morphology was the summum bonum of
botanical study, there could be small room for experiment.
But in these later years, when the science has been taught
more along physiological lines, the use of experiment has
come into more general vogue.

It is the purpose of this little book to teach botany by ex-
periment. Plants yield themselves very readily to experiment.
Being alive, they respond to all external influences most ad-
mirably, and there is no reason why such work with plants
should not prove as interesting and as useful as similar exer-
cises with levers, lenses, vibrating pendulums, and cords.

It is hoped that something may be found in this book which
will remedy the inadequacy which exists in the laboratory in-
struction of many schools.

The work is not entirely physiological in character, but it
has been thought wise to present the morphological part also
in the form of experiments.

3

4 PREFACE

In a number of places, several experiments have been intro-
duced to demonstrate the same truth. It is not intended, how-
ever, that all such exercises be undertaken by the same class
in any one term. They are offered so that the courses from
term to term can be varied, using alternative experiments.

This gives variety to the work and will make the use of old
laboratory notebooks less likely.

It is also expedient often to assign for home experiment such
exercises as are omitted in school. Field work should be
undertaken wherever possible; but as real field work is out of
the question in large cities, much reference work can be done,
and a certain amount of it ought to be required.

Reference work will include the looking up of topics in
libraries, and visits to museums and parks.

Written reports on assigned topics should be expected. A
certain number of common plants should be known by name.
This can be accomplished by requiring pupils to bring in
specimens. These collections may be arranged for exhibition
where all may see them and learn to recognize them.

Walks about streets and parks to identify trees and shrubs
should be made from time to time, and their leaves should be
collected as a means of recognizing them. The same method
is recommended for ferns and garden flowers.

If the boy or girl who studies this book comes to realize that
plants are alive as we are alive, — that they eat, digest, grow,
and reproduce their kind as truly as we perform these func-
tions; that they respond to outside influences as we do;
that they are in a way our brothers ; that they are necessary
to us and we to them, — my object will be fulfilled.

To Dr. Walter Hollis Eddy, of the High School of Com-
merce, New York, for his many helpful suggestions of material
and method of presentation ; to Mr. Frederick L. Holtz of the
Training School for Teachers, Brooklyn, who has read the

PREFACE 5

manuscript and has given it most careful criticism ; and to my
colleagues in the High School of Commerce, Messrs. Matthew-
son, Barbour, A. II. Lewis, Sprague, and Hahn, who have ren-
dered substantial assistance in the preparation of this book, —
I desire to express my sincerest thanks.

The following texts have been freely consulted : Bailey,
Principles of Agriculture, Plant Breeding, and Botany; The
Cornell University Bulletins; Osterhaut, Experiments with
Plants; Percival, Agricultural Botany ; United States Depart-
ment of Agriculture Bulletins, and the botanical textbooks of
Andrews, Atkinson, Bergen, Coulter, Barnes, and Cowles, Dana,
Goff and Mayne, Goodale, Gray, Hunter, Leavitt, and Sharpe.

CONTENTS

I. PRELIMINARY EXPERIMENTS. —1. Oxygen. 2. Carbon. 3. Carbon di-
oxide. 4. Hydrogen. 5. Nitrogen. 6. Acids, bases, and salts . . 9-18

II. FOOD MATERIALS AND HOW TO DETECT THEM. — 7. Protein. 8, 9. Starch.
10. Sugars. 11. Grape sugar. 12. Oils and fats. 13. Water. 14. Amount
of water. 15. Mineral salts 19-2!)

III. DIFFUSION AND OSMOSIS — 16-18. Diffusion. 19-22. Osmosis 30-35

IV. SOIL AND SOIL PREPARATION. — 23-26. Contents of soils. 27-30. Char-
acter of soils. 31, 32. Effect of tilling 36-44

V. FIELD WORK OR REFERENCE WORK. — I. Fertilizing. II. Tilling.
III. Planting. IV. Cultivating. V. Harvesting. VI. Marketing. VII. Flower
gardening 45-48

VI. SEEDS. — 33. Parts of a seed. 34,35. Effect of soaking. 36-37. Seeds
exert pressure. 38. The embryo. 39. Comparative structure. 40. Seeds
with food inside the embryo. 41. Seeds with one seed leaf . . 49-57

VII. GERMINATION OF SEEDS. —42, 43. The water factor. 44. The heat
factor. 45-47. The air factor. 48. Relation of depth to germination.
49. Respiration. 50. Heat from germination. 51. Effect of light. 52-54. The
fate of cotyledons. 55, 56. Effect of mutilation .... 58-71

VIII. GROWTH OF SEEDLINGS. —57-60. Growth (germination). 61, 62.
Growth (force exerted). 63, 64. Growth (effect of light). 65. Growth
(effect of obstacles) . 66. Growth (rapidity) 72-78

IX. SEED TESTING.— 67. Purity. 68. Weight. 69. Color and odor.
70. Form. 71. Germination capacity. 72. Percentage of germination.
73. Germination speed 79-84

X. ROOTS. — 74-85. Roots (structure and growth). 86-88. Roots (artificial
propagation). 89-97. Roots (functions). 98. Commercial fertilizers. 99,
100. Roots (light and heat effects). 101. Roots (plant foods) . 85-108

XI. STEMS. — 102. Location of growth. 103. Upward growth. 104-106. Stems
(effect of light on growth of stems). 107. Stems (parts of a typical stem).
108, 109. Structure. 110-112. Twigs. 113-115. Sap circulation. 116. Sap

7

8 CONTENTS

pressure or root pressure. 117. Budding. 118. Grafting. 119, 120. Prun-
ing. 121. Girdling. 122. Repairing wounds. 123-127. Turgor . 109-141

XII. LEAVES. — 128. Leaves (parts). 129, 130. Leaves (gross structure).
131, 132. Leaves (sap flow). 133-135. Leaves (effects of light). 136-144.
Leaves(transpiration). 145. Leaves (excretion of oxygen). 146. Stomata.
147. Cells. 148-150. Leaves (photosynthesis). 151. Leaves (effect of clos-
ing the stomata). 152, 153. Leaves (respiration). 154. Leaves (fall of
leaves) 142-172

XIII. PLANT IRRITABILITY. — 155. Phototropism or response to light. 156,
157. Sleep of plants. 158-161. Response to contact . . . 173-179

XIV. FLOWERS. — 162. Flower structure. 163-164. Sex organs of flowers.
165. Pollen. 166-169. Pollination 180-196

XV. SPECIAL EXERCISES ON TYPICAL FLOWERS. — 170. Trillium. 171. Iris.
172. Evening Primrose. 173. Buttercup or Anemone. 174. Strawberry,
Geum, or Potentilla. 175. Mustard or any other crucifer. 176. A Lily or
Amaryllis. 177. Jack-in-the-Pulpit or Skunk Cabbage. 178. Lilac, For-
sythia, or Privet. 179. Sweet Pea, Locust, or Lupine. 180. Violets.
181. Toad Flax or Butter and Eggs. 182. A Mint. 183. The Sunflower,
Asters, or Goldenrod. 184. The Dandelion, Chicory, or Hawkweed.
185. Indian Corn 197-21!)

XVI. EXPERIMENTS WITH FLOWERS. — 186. Function of the perianth.
187. Effect of light. 188. Effect of heat. 189. ReSj iration of flowers.
190. Flowers give off heat 220-223

XVII. TYPICAL FRUITS. — 191. Core fruits. 192. Stone fruits. 193. Pulpy
fruits. 194. Dehiscent fruits. 195, 196. Seed dispersal. 197. Sap flow in
fruits 224-232

XVIII. CRYPTOGAMS. — 198. Algae. 199. Reproduction in pond scum.
200. Pleurococcus. 201. Vaucheria or green felt. 202. Bread mold.
203-207. Molds. 208, 209. Fungi. 210. A moss plant. 211. Mosses.
212, 213. A fern. 214. Yeast and fermentation. 215-220. Yeast. 221-
225. Bacteria. 226-228. Protoplasm 233-269

EXPERIMENTAL BOTANY

I. PRELIMINARY EXPERIMENTS

What is an Experiment ?

AT the outset it may be well to consider what an experi-
ment is. An experiment is often called a question asked
of nature ; really it is a trial or test, made to learn some fact
of nature. For example, it is desired to know whether some
particular substance will burn or will dissolve.

To make the experiments it is necessary to have certain
accessory things called apparatus. In the first case, a
match or lighted candle would be the apparatus. In the
second case, the apparatus would be water or some other
liquid, a funnel, filter paper, and an evaporating dish.

The result of trying to ignite the substance or of shaking
it in the liquid will be nature's answer to the questions we
have put to her, and thus the conclusion or interpretation
follows; that is, this substance is or is not inflammable or
it is or is not soluble. In recording an experiment let the
following order be observed : —

(1) Object. — A statement of what is to be found out.

(2) Apparatus. — Names of articles used in making the
experiment and drawings of them where possible.

(3) Method and Results. — A full statement of what was
done step by step, with result of each step.

(4) Conclusion. — The interpretation of the results.

9

10

PRELIMINARY EXPERIMENTS

1. OXYGEN

Object. — To prepare oxygen and to learn some of its
properties.

Apparatus. — An ignition tube, a small portion of red oxide of
mercury, a Bunsen burner, and a splinter of pine.

Method. — Place the mercuric oxide in the ignition tube
and heat it in the flame as in Figure 1. Note any change
of color. What collects on the inside of the tube ? How do

you recognize this
substance ? Remove
some and examine it.
Plunge a charred

'.mercury

.Red .oxide

splinter into the upper
end of the tube, be-
ing sure that there
is a glowing spark on
the end of the splinter.
What happens? Re-
peat the experiment
several times. What
must there be coming
from the oxide besides
what collects on the
tube?

FIG. 1. — Preparing oxygen. This is Oxygen.

What color or other properties has this gas? What two
substances came from the oxide?

Conclusion. — Oxygen is , - — , - — , and supports

combustion.

Note. — An alcohol lamp will seldom give sufficient heat to pro-
duce oxygen gas in any considerable quantity. In schools which

PRELIMINARY EXPERIMENTS 11

are not supplied with gas, a gasoline stove or a kerosene vapor
stove can be used for experiments where considerable heat is re-
quired.

An ignition tube is better than a test tube, since it resists the
heat. Test tubes in this experiment will often melt, and the oxide
will escape through a hole in the bottom.

Definitions. — An element is a simple substance. It can-
not be separated into any other substances.

A compound is a substance that is composed of two or
more elements chemically combined. It can be separated
into its elements.

In Experiment 1 the mercuric oxide is a compound con-
sisting of oxygen and mercury. By heating we separated
this compound into the elements oxygen and mercury.

This process of separating a compound into its elements
is called analysis.

2. CARBON

Object. — To learn some of the properties of the element
carbon.

Apparatus. — Charcoal, coal, coke, gas carbon, graphite, soot
(a diamond may be shown). A lamp, test tube, and a small quan-
tity of limewater.

Method. — Examine the various forms of carbon, but
confine the experiments to charcoal. Determine the color,
taste, smell, softness, brittleness, etc., of charcoal. Notice
its structure. What does this reveal as to its source ? Pul-
verize a little and shake it up in water. Is it lighter or
heavier than water ? Does it dissolve in water ?

Hold a slender piece of charcoal in the lamp flame. What
occurs? Describe the color of the flame. Does it give

12 PRELIMINARY EXPERIMENTS

off smoke ? If so, its color and amount. Describe the ash,
its color, and amount.

Put a small quantity of limewater in a test tube and shake
it. Does any change occur? Now ignite the charcoal
stick, and while it is glowing red-hot plunge it into the tube
of limewater, but not down into the limewater. Withdraw
the charcoal, and holding the thumb over the mouth of the
tube, shake it. What change takes place? This is the test
for carbon dioxide.

Through a straw or piece of glass tube, breathe into a tube
of fresh limewater, letting the breath bubble through the
liquid. What is the result?

Conclusion. — State properties of carbon. What forms
when it burns ? How is the presence of carbon dioxide
detected ? What proof that it is contained in our breath ?

Note. — Limewater is made by placing a considerable quantity
of water on slacked lime, shaking it well, and allowing it to settle.
The clear liquid on top is limewater.

Definition. — Combining two or more elements to form
a compound is called synthesis.

In burning charcoal, the element carbon united with the
element oxygen in the air to make the compound carbon
dioxide.

Changes like these are known as chemical changes because
the original substances lose their properties and new sub-
stances are formed having new properties.

Thus the blackness, brittleness, etc., of the carbon disap-
peared and the different properties of carbon dioxide ap-
peared.

Query. — In what respects does the experiment with lime-
water demonstrate a chemical change ?

PRELIMINARY EXPERIMENTS

13

3. CARBON DIOXIDE

Object. — To learn some characteristic properties of car-
bon dioxide.

Apparatus. — A flask fitted up as in Figure 2, some broken marble,
two wide -mouth bottles, a little hydrochloric acid, and the appa-
ratus used in Experiment 2.

Method. — Place the broken marble in the flask, close
it with the rubber stopper, and add the hydrochloric acid.
Note the result. Col-
lect some of the gas in
a wide-mouth bottle
and test it with lime-
water. Result? Plunge
a burning stick into the
bottle of carbon di-
oxide. Result ? Select
two wide-mouth bottles
of equal size. Test
each with limewater.
Fill one jar with carbon
dioxide and leave the

— -Thistle Tube

____ Delivery Tube
..-..Stopper

.Hydrochloric Acid
.marble

FIG. 2. — Preparing carbon dioxide.

other full of air. Now

invert the jar full of carbon dioxide over the other. After
a few moments test the contents of each bottle. Which
one now contains the carbon dioxide?

What does this show as to the weight of this substance
as compared with the air ?

Let carbon dioxide bubble through a test tube of pure
water for a few minutes. Taste of the water. .What pecul-
iarity has the taste?

Conclusion. — State briefly what you have learned about

14 PRELIMINARY EXPERIMENTS

carbon dioxide, giving its color, taste, smell, test, weight,
and effect on burning.

Note. — The weight of carbon dioxide and its power to put out
fire are well shown by filling a large wide-mouth bottle with the gas
and then pouring it into an inclined trough in the bottom of which
several short bits of lighted candle have been placed. The gas
will flow down, and, as it meets the candles, will extinguish them one
by one.

Another device may be made by placing bottles of equal weight
in opposite pans of an ordinary balance. When they are exactly
counterpoised, hold the delivery tube of a flask over one of the
bottles, and the greater weight of the carbon dioxide will imme-
diately cause it to sink.

Query. — What causes limewater to become covered with
a scum of white substance whenever it is exposed for some
time to the air?

What are some of the sources of carbon dioxide in the
atmosphere? Explain the construction of a chemical
fire extinguisher. On what properties of carbon dioxide
does it depend?

Before going down into a deep well, how would you test
the air to find out whether there is carbon dioxide present ?
If present, how can it be removed before you go down
into the well ?

Why are the laws so strict regarding ventilation of schools ?

4. HYDROGEN

Object. — To prepare hydrogen and to learn some of Us
properties.

Apparatus. — Some granulated zinc or zinc scraps, dilute sul-
phuric acid (1 part acid poured into 5 parts of water), test tubes,
Argand lamp chimney, ,and a flask fitted as in Figure 3.

PRELIMINARY EXPERIMENTS

15

Method. — Place the zinc in the flask (a), adjust the stop-
per (c) , and add the weak sulphuric acid through the thistle
tube (6). Note the
result. Hold an in-
verted test tube over
the delivery tube
(/) and remove it,
keeping it inverted.
Touch a match to the
open end. Result?

Repeat the experi-
ment several times.
When you are sure
that there is no air
left in the flaskrtouch
a match to the end
of the delivery tube.
It is well to shield
the face when doing

FIG. 3. — Preparing hydrogen.

this with a fan or piece of pasteboard.

Note the color of the flame of burning hydrogen.

Hold a bit of wire in the hydrogen flame. Note the heat.
Hold a piece of cold earthen plate over the hydrogen flame.
What forms on the plate?

Now place an Argand lamp chimney over the burning
hydrogen flame and move it slowly down. What happens?
Try tubes of various sizes over the flame.

Conclusion. — Mention some properties of hydrogen.
What substance forms when hydrogen burns?

Note. — If a bit of pipe stem or a platinum tip is used, the hydro-
gen flame will be found to be colorless. The yellow color seen when
glass tips are used is due to the sodium in the glass.

16 PRELIMINARY EXPERIMENTS

With students it is always safest to interpose a wash bottle (e)
between the generator and the flame so as to prevent damage in
case of an explosion. If potassium permanganate is put in the
wash bottle, impurities will be removed.

5. NITROGEN

Object. — To learn something of the preparation and
properties of nitrogen, and the composition of air.

Apparatus. — A small piece of phosphorus, forceps, a cork float,
a large vessel of water, a bell jar, a support for the bell jar, and
several wide-mouth bottles. '

Method. — Place a crumb of phosphorus upon the cork
float, using the forceps for handling it. Dry it with a piece
of blotting paper, but under no circumstances let it touch the
skin.

Let it ignite spontaneously if there is time. Otherwise,
ignite it with a burning splinter, and immediately invert
the bell jar over it.

Note the color of the flame and smoke, the behavior of
the water, and the height to which it rises in the bell jar.
-Why does it rise only about \ the height of the jar? What
has been consumed ? How much oxygen must there be in
a given amount of air? What becomes of the white fumes
which come from the burning phosphorus?

After all the white fumes have disappeared and the con-
tents of the bell jar have become clear, the gas may be re-
moved into wide-mouth bottles and tested. To remove the
gas into a bottle, fill the bottle with water, invert, keeping
the mouth beneath the surface, and tilt the bell jar so that the
bubbles of gas can escape upward into the bottle. Test the
nitrogen thus obtained, with burning a stick, with limewater,
and by tasting and smelling.

PRELIMINARY EXPERIMENTS 17

Conclusion. — Describe nitrogen, giving its odor, color,
taste, effect on limewater, etc. Does it burn, support
combustion, or put out fire ? Is it heavy like carbon dioxide
or light like hydrogen?

Note. — The greatest caution should be observed in handling
phosphorus, since it ignites spontaneously and its burn is very dan-
gerous.

6. ACIDS, BASES, AND SALTS

Object. — To learn the characteristics of acids, bases,
and salts, -and what is meant by neutralization.

Apparatus. — Hydrochloric acid, vinegar, lemon juice, caustic
soda, ammonia, limewater, test tubes, evaporating dish, and litmus
paper.

Method. — (a) Acids. Put a few drops of hydrochloric
acid or vinegar or lemon juice in a test tube and add an inch
of water. Examine the mixture to determine the taste,
smell, and feeling. Put in a strip of neutral litmus paper or
a drop of litmus solution and note the change of color.

(6) Bases. Add water to a few drops of caustic soda,
ammonia, or limewater, as in (a), and examine in the same
way.

(c) Neutralization. To a test tube containing dilute
hydrochloric acid add dilute caustic soda drop by drop, and
test with litmus until it does not change color.

If in adding the caustic soda you get too much so that the
color becomes blue, reverse the process and add the acid
until the solution has no effect on litmus.

Instead of using litmus paper, a drop of litmus solution
may be used to color the acid at the start, then when it
becomes lavender, or just between red and blue, the solution
will be at the neutral point.
EXP. EOT. — 2

18 PRELIMINARY EXPERIMENTS

This process of combining an acid with a base is called
neutralization.

Now taste the contents of the tube. Is it sour like acids
or bitter like bases? Does it have the roughish feel of an
acid or the slippery feel of a base ? Has it the sharp pungent
odor of hydrochloric acid or the soapy smell of caustic soda ?
What does it taste like ?

Conclusion. — State (a) the characteristics of acids, (6) of
bases. What -is meant by neutralization? What results
from neutralizing hydrochloric acid with caustic soda ?

Definition. — A salt is a substance which results from
neutralization of an acid with a base.

Suggestions. — Test limewater, ammonia, fruit juices,
milk, soap, saliva, molasses, etc., and determine which are
acid, which are neutral substances, and which are bases.

H. FOOD MATERIALS AND HOW TO DETECT
THEM

Nutrients

A nutrient is a chemical compound capable of nourishing
the body. Foods are good for us because they contain one
or more of these chemical compounds.

The nutrients are proteins, carbohydrates, fats and oils,
water, and mineral salts.

Proteins always contain carbon, hydrogen, oxygen, and
nitrogen, and they may also contain a few other elements,
such as sulphur, phosphorus, iron, etc. Since they all
contain nitrogen, they are often known as nitrogenous foods.

Carbohydrates are mostly composed of carbon, oxygen,
and hydrogen. Sugars and starches are the principal carbo-
hydrates. Fats and oils are rich in carbon and hydrogen.

Water forms a large part of most foods. Common salt
is the principal mineral salt entering, into food, but there
are also compounds of lime, sulphur, phosphorus, and many
other elements in various articles of diet.

The following experiments will teach how to detect the
presence of various nutrients in any kind of food.

7. PROTEIN

Object. — To learn how to detect the presence of protein
in food.

Apparatus. — White of egg, lean meat, nitric acid, ammonia,
Millon's reagent, biuret reagent, lamp, and test tubes.

19

20

FOOD MATERIALS AND HOW TO DETECT THEM

Method. — (a) Physical tests. Put a small quantity of
the egg in a test tube, add a little cold water, and shake the
mixture vigorously. What happens? Stand the tube in

a test tube rack for some time.
Compare this tube with a tube
containing clear water.

Heat a small portion of
white of egg in water until it
boils. What change does it
undergo ?

Burn a small piece of white
of egg or lean meat and note
the odor of the smoke. This
peculiar smell is characteristic
of nitrogenous substances.
Name some other things which
emit this odor when burning.
(6) Chemical tests. The yellow test (xanthoproteic) . To
a small portion of white of egg add a few drops of dilute
nitric acid and heat the mixture. How does the nitric acid
affect the raw albumin ? What change of color follows heat-
ing ? Now neutralize with ammonia. What is the final color ?
The red test (Millon's). To another portion of egg
albumin add a few drops of Millon's reagent and warm
gently over a lamp. What change of color occurs ?

Note. — Heat gently at first, or this test is not likely to work.

The violet test (biuret). To a small amount of soluble
protein, for example, albumin or milk in water, add a little
of the biuret reagent. What change occurs ? Repeat this
test, using only a drop of the egg solution in a very large
quantity of water. This will show how delicate this test is.

Biuret. Xanthoproteic. Millon's.
FIG. 4.

FOOD MATERIALS AND HOW TO DETECT THEM

21

Conclusion. — State briefly in not more than four sentences
what are the tests for protein.

Suggestion. — Repeat these tests, using meat, cereals,
flour, cheese, milk, bread, potatoes, and other articles, and
determine which give the best tests for protein.

Note. — Millon's reagent is made by mixing one part mercury
by weight with two parts nitric acid (concentrated commercial).
When the mercury is all dissolved, dilute with twice the volume of
water.

Biuret reagent is made as follows : to 1000 cc. of a 10 per cent
solution of caustic soda in water, add drop by drop 10 cc. of a 3 per
cent solution of copper sulphate, stirring constantly while the solu-
tions are combining. The same test is obtained if the substance is
first treated with strong caustic soda and then very dilute copper
sulphate.

Another Protein Test

To a substance to be tested, add a drop of saturated cane
sugar solution in water. Then add a drop of pure sulphuric
acid. If proteins are present, the substance will assume a
deep red color.

8. STARCH

Object. — To learn how to detect
the presence of starch.

Apparatus. — Laundry starch, flour,
potatoes, solution of iodine, test tubes,
lamp, etc.

Method. — Place a little starch in
a test tube with water. Shake it
vigorously. Does it dissolve? Does
it froth as the egg did? Filter and
allow the filtrate to evaporate. Is
there any starch residue?

IP

fir

Starch. Test. Iodine.

FIG. 5.

22 FOOD MATERIALS AND HOW TO DETECT THEM

Heat the test tube gently over the flame. What change
takes place in the color and general appearance of the starch ?

Now add a drop of iodine solution to the starch paste.
What happens? Heat. What happens? Cool again. Does
the color return ?

Test potatoes, flour, and other things mentioned, also
milk, meat, eggs, etc. Which ones contain starch and which
do not?

Conclusion. — State in one sentence how starch may be
recognized.

9. STARCH (optional)

Object. — To find out something of the appearance of
starch grains-

Apparatus. — Various kinds of starch which can be obtained
from corn, wheat, rice, cannas, potatoes, etc., a compound micro-
scope, and a razor for cutting thin sections.

Method. — Mount a drop of water containing starch of
any sort and examine with a low power. Note the shape
and structure of a grain. Draw starch grains.

In a similar manner mount and examine other kinds of
starch. Wherein do these starches differ ? In what respects
do they agree ? Cut thin sections of potato tubers and mount
them in water. Note the starch grains packed in the cells.

Place a drop of iodine solution on the slide at the edge
of the cover glass. Watch the solution as it works under
and note the effect as it comes in contact with the starch
grains.

Note. — Canna rootstocks contain very large starch grains.

Suggestions. — Scrape as finely as possible one or two
large potatoes. Put the potato pulp in a large bottle with

FOOD MATERIALS AND HOW TO DETECT THEM 23

cold water and shake it vigorously. Set it aside for a day
and note the sediment on the bottom of the bottle.

Pour off the water and remains of potato pulp and examine
the deposit on the bottom of the bottle. What is its color?
Take out a little and boil it in a test tube of water. How
does it change in color and consistence? Add a drop of
iodine solution. What is the result ? What is the substance
obtained from the potato ?

Add a teaspoonful of water to a heaping tablespoonful
of flour and mix them thoroughly. When the water has
taken up all the flour possible, remove the dough and wash
it by holding it under a dripping faucet. Test the water
which washes the dough. What does it contain? When
the dough has been reduced to a grayish mass, test it for
protein. Burn a little. Result?

Note. — In both these exercises, the separation can be hastened
if the potato pulp or dough is placed in a cheesecloth bag and washed
in clear water. In the first case, the pulp of the potato will remain
in the bag while the starch will come through. In the second case,
the starch will come through and the gluten, a protein, will be
left in the bag.

Note. — Iodine solution is made by dissolving a teaspoonful
of potassium iodide in a tumbler of water and then adding a few
crystals of iodine. The solution should be of a rich wine color.
Bottle the solution for future use.

10. SUGARS

Object. — To find out how to recognize (a) cane sugar
and (&) grape sugar (glucose) in foods.

Apparatus. — Cane sugar, glucose, raisins, figs, maple sugar,
hydrochloric acid, Fehling's solution or Benedict's solution, tubes,
lamp, etc.

24

FOOD MATERIALS AND HOW TO DETECT THEM

Method. — (a) Put a few crystals of cane sugar into a
test tube and add concentrated hydrochloric acid to the depth
of | inch. Heat the mixture and notice the change of
color.

(6) Place a raisin, a fig, or a small piece of glucose in water
in a test tube and dissolve the sugar by shaking the mixture.

Cane sugar. Test.

Hydrochloric
acid.

Grape sugar. Test.

Fehling's
solution.

FIG. 6.

To a little of this solution add a drop of Fehling's solution
or Benedict's solution and heat it. What change occurs ?

Conclusion. — In two sentences state the test for these
two kinds of sugar.

Suggestion. — Test molasses and candies and find out
which contain cane sugar and which contain grape sugar.

Test starch for grape sugar. Result? Test saliva for
grape sugar. Result ? Place starch paste and saliva in a test
tube and set it aside in warm place for \ hour. Then test the
mixture for grape sugar. Result? What does this indicate
as to the action of saliva in digesting starch in food?

FOOD MATERIALS AND HOW TO DETECT THEM 25

Note. — Fehling's Solution. In a bottle labeled " Fehling's
Sol. A " put 34.65 grams of cupric sulphate dissolved in 500 cc. of
water.

In another bottle labeled " Fehling's Sol. B " put a solution of
125 grams of potassium hydroxide or sodium hydroxide and 173
grams of Rochelle salt dissolved in 500 cc. of water. Keep solu-
tions " A " and " B " separate until ready for use, then mix equal
portions.

Benedict's Solution. " With the aid of heat dissolve 173 grams
sodium citrate and 100 grams sodium carbonate in about 600 cc.
water. Filter into a glass graduate and make up to 850 cc. with
water. Dissolve 17.3 grams copper sulphate in 100 cc. water and
make up to 150 cc. with more water.

" Pour the carbonate-citrate solution into a large beaker and add
the cupric sulphate solution slowly with constant stirring.

" The mixed solution does not deteriorate on long standing." -
Hawk's Practical Physiological Chemistry.

11. GRAPE SUGAR

Object. — To demonstrate the action of diastase in
starch to grape sugar.

Method. — Prepare a small quantity of very dilute
starch paste. Add water until there is no appearance of
starch, but on testing with iodine solution a clear blue is
seen. Fill the test tube f full of the starch. To one add a
small quantity of diastase. Put both tubes in a warm place
for 24 hours.

Now test both tubes for starch and for grape sugar.
Result? Chew a bit of cracker or bread for three minutes.
What change in taste takes place ?

Note. — A substance which like diastase can act upon insoluble
substances and change them into different soluble substances is
called an enzyme.

26 FOOD MATERIALS AND HOW TO DETECT THEM

12. OILS AND FATS
Object. — To learn how to recognize oils and fats in foods.

Apparatus. — Olive oil, beef fat, butter, flaxseed meal, castor
beans, nuts, unglazed paper, ether, and an evaporating dish.

Method. — Oils and fats may be recognized by the fact
that they make a grease spot on unglazed paper. They do
not all yield their oil at once, and some require special treat-
ment to extract it.

(a) Contact. Place a drop of olive oil on a piece of un-
glazed paper. Result?

(6) Heat. Place some flaxseed meal on the paper and
heat it over a lamp or in an oven. Result ?

(c) Pressure. Place some flaxseed meal or corn meal on
the paper and apply considerable pressure. Result?

(d) Solution. Place any of these substances in a test
tube, add ether, and shake the mixture. Then strain the
filtrate and put it in an evaporating dish. Allow it to stand
until the ether has evaporated and try the residue on paper
for grease spot. On account of its great inflammability ether
should not be brought near a burning lamp.

Note. — A grease spot often looks like a wet spot. To tell one
from the other, hold the paper over a flame. If it is a grease spot,
the spot will spread and remain; but if a wet spot, it will dry out
and disappear.

Some nuts are so rich in oils as to burn like a candle. This
is particularly true of the Brazil nut. If the shell is removed and
the kernel is held with one end in a lamp flame, it will take fire and
burn for a long time, giving a clear white flame and very little smoke.
Removal of grease spots from clothing by pressing with hot flat
irons on brown paper is an application of a, 6, and c, and the use
of gasolene in " dry cleaning " is an application of d.

FOOD MATERIALS AND HOW TO DETECT THEM 27

The Soudan III Test

Directions. — Make a grease spot on a piece of filter paper,
using any substance which contains fats or oils. Saturate
the paper with Soudan III and then wash it with alcohol.
What occurs?

Repeat, using paraffin, beeswax, cocoa butter, vaseline, etc.
How may oils be detected ?

Note. — Soudan III is a stain used as a reagent in microscopic
work.

Suggestion. — Make a list of oils and fats and the plants
or animals which produce them.

Find out at least one use for each and any interesting
facts concerning their manufacture.

To a test tube half full of water add a few drops of oil.
Do they mix? Shake the tube vigorously and note the
result. Add a few drops of caustic soda and shake the tube.
•Result ? Examine a drop of milk under a cover glass, using
a low power of the microscope. Draw.

Select several articles of food such- as bread, cereals, meat,
cheese, potatoes, etc., and test each for protein, starch,
sugars, and fats. Which contain most of each nutrient?
Tabulate your results.

The Alcanna Test

Make a solution of alcanna root in 95 per cent alcohol.
Filter it and add an equal bulk of water. This solution
gives a deep red color to oils and fats.

Suggestion. — Make very thin sections of castor bean
or Brazil nut and examine for oil globules. Run a drop of
the alcanna solution under the cover glass and watch the oil
globules as they take up the color.

28 FOOD MATERIALS AND HOW TO DETECT THEM

13. WATER

Object. — To detect the presence of water in a food.
Apparatus. — Various substances, such as cereals, meats, etc.,
test tubes, and a lamp or Bunsen burner.

Method. — Place the substance to be tested in a dry test
tube and hold it over the flame for a minute. What collects
on the inside of the tube ? Continue to heat the tube, turn-
ing it in a slanting position.

Conclusion. — The presence of water may be detected
by what means?

Note. — The steam which comes off at first is clear and condenses
into water, but the water that comes off later is stained more or less
by the products of destructive distillation of the substance used.
To prove that it is actually water that comes off, put a drop of it
on a little copper sulphate that has been heated until it has lost
its blue color and become white. The copper sulphate will return
to its former blue color. This test is not necessary in ordinary ex-
periments.

Note. — Some mineral substances are destitute of water. Such
substances are known as anhydrous, a word which means without
water. Such substances are very rare. When a substance is
deprived of its water, it is said to be dehydrated. Most such sub-
stances, if left to themselves, tend to absorb water and become
hydrated. This is illustrated in the behavior of lime when it be-
comes slaked.

14. AMOUNT OF WATER

Object. — To find out the amount of water in different
articles of food.

Apparatus. — A slow oven, and any article whose water content
is to be determined, such as potato, radish, leaves of cabbage, etc.

Method. — Weigh *the article carefully, then chop it
fine and put it in an evaporating dish. Set it in a slow oven

FOOD MATERIALS AND HOW TO DETECT THEM 29

and keep it there until all water has been driven off. To
determine this, weigh from time to time, noting decrease
until the weight becomes constant.

How much water does each article contain ?

Note. — Care should be taken not to heat the substance so hot
as to set it on fire. The substance should be dried and not charred.

15. MINERAL SALTS

Object. — To prove that there is mineral matter in food
stuffs.
Apparatus. — Same as in Experiment 14.

Method. — After the water has been driven off as in the
preceding Experiment, continue the heat until no gases come
off. Then increase the heat and burn up the contents of
the tube. If nothing remains, it is a sign that no mineral
matter is present ; but if ashes are left in the tube, it is an
indication that mineral matter is there.

Substances like alcohol, ether, chloroform, benzine, gaso-
line, etc., leave no ash, therefore they are said to contain
no mineral matter.

Conclusion. — State in one sentence how the presence of
mineral salts is detected in foods.

m. DIFFUSION AND OSMOSIS

16. DIFFUSION

Object. — To learn what is meant by diffusion.

Apparatus. — A tall jar or bottle, some crystals of copper sul-
phate or potassium bichromate or any other highly colored salt
soluble in water.

Method. — Place a few crystals of the salt in the jar and
carefully cover it with water, letting it run down the side
of the jar very slowly, and do not shake or stir the mixture.
Let it stand for some time. What is the result? This
tendency of substances to mix is called diffusion.

Conclusion. — State in a sentence what is the meaning
of diffusion.

Note. — Gases also have this property and diffuse much more
rapidly than liquids.

17. DIFFUSION
Object. — Same as in Experiment 16-

Apparatus. — A U-tube, gelatin, litmus solution, hydrochloric
acid, caustic soda, potassium bichromate.

Method. — Soak the gelatin until it is soft and melt it
over a lamp. Add a drop of potassium bichromate to render
it insoluble, then add the litmus solution till it acquires a
rich purple color. Pour it into the U-tube until it fills the
bend and leave it in a cool place until the gelatin has set.

30

DIFFUSION AND OSMOSIS

31

Now fill one arm of the U-tube with dilute hydrochloric
acid and the other arm with dilute caustic soda. As these
substances diffuse through the gelatin, they will color the
litmus blue or red as
the case may be, and
the progress of the
diffusion can be ob-
served. If the solu-
tion is kept in a cool
place, the potassium
bichromate need not
be added. FlG 7

NaOH

Ulmus'-fclue b
Diffused Nad

HOI

Litmus red by
diffused HCr

..Gelatin colored
with neutral Litmus

18. DIFFUSION

Diffusion may be shown in several other ways. It is not
advisable to make much of this phenomenon since it does not

enter very largely into elementary
study of plants. Some of these exer-
cises should therefore be optional.

I. Arrange a U-tube as in Fig-
ure 7. Fill the bend with gelatin
which has been rendered insoluble
by addition of potassium bichro-
mate. After the gelatin has set,
fill one arm with strong copper
sulphate and the other with potas-
sium bichromate or any other
highly colored salt. These liquids
will diffuse and the advance can
be observed as it goes on.
II. Fill a glass tube with gelatin to which a little phenol-
phthalein has been added. Stand the tube in a beaker con-

Phenolphthalein

Caustic
Soda

32

DIFFUSION AND OSMOSIS

taining any alkali in solution. As the alkali diffuses upward
through the gelatin, the phenolphthalein will take on the
characteristic crimson color (Fig. 8).

III. Repeat this exercise, using gelatin colored with dilute
acidulated litmus and alkali in the beaker. Neutralization
is well illustrated by using a U-tube as in Figure 7 and
filling the arms with acid and alkali, while the bend is filled
with neutral litmus in gelatin.

IV. If copper sulphate and potassium ferrocyanide are
used, they will meet and form a membrane in the midst of
the gelatin,

19. OSMOSIS

Object. — To learn what is meant by osmosis and
dialysis.

Apparatus. — Several collodion bags (see Note) or pieces of thin
animal membrane (such as sheep gut or fish air bladder), starch,
sugar, egg albumin, etc.

Method. — Suspend the bags in cups of clear water as
follows : A containing starch paste, B containing sugar

solution, and C a
mixture of starch
paste and sugar
solution (Fig. 9).

After a half hour,
test some of the
water outside of
each bag for the substance which was put inside. Which
ones have diffused through the membrane?
Diffusion through a partition is called osmosis.
Query. — Will starch, egg albumin, olive oil, sugar, or
salt diffuse through a partition?

DIFFUSION AND OSMOSIS 33

DIALYSIS

Test the liquid outside the bag C containing both starch
and sugar. Does only one or do both substances come
through the partition? In this way it is possible to separate
diffusible from non-diffusible substances by using a mem-
brane. This method of separation is called dialysis, and the
partition used is known as a dialyzer.

Conclusion, — State briefly the meaning of the terms
osmosis and dialysis.

Note. — A collodion bag is easily made by pouring collodion
into a perfectly clean, dry, cylindrical dish and then pouring off all
that will flow out. A thin film of collodion will thus be left lining
the vessel. It may be removed by carefully loosening the edge and
pulling it gently. To prevent tearing, a little water poured be-
tween the film and the glass will help to loosen it. Before trying to
remove the film, hold the dish in the hand to warm it. This will
hasten the evaporation of the ether contained in the collodion.

20. OSMOSIS
Object. — To prove that osmosis may produce pressure.

Apparatus. — An egg, a piece of glass tube, sealing wax, a
tumbler.

Method. — With the point of a knife blade, carefully pick
away the shell at the large end of an egg so as to expose the
delicate skin (membrana putaminis) which lines the shell.
But in no case let this membrane be ruptured.

Then pierce a small hole through the opposite end so as to
expose the white of the egg.

Place the glass tube (a) over the hole and fasten it with
sealing wax. Now arrange the egg in a glass of water so
that the membrane is in contact with the water (i) (Fig. 10).

EXP. EOT. 3

34

DIFFUSION AND OSMOSIS

Let the apparatus stand for a few
hours and note the result. How do
you account for this?

Conclusion. — State what you infer
from the behavior of the contents of
the egg.

The pressure which causes this rise
of the contents of the egg in the tube
is known as osmotic pressure.

Osmotic pressure may also be shown
... h by using a thin rubber bag connected
with a glass tube and filled with olive
oil. If it be immersed in a vessel
containing ether, the ether will pass
through the partition and the contents

FIG. 10.-a, glass tube; °f the ba§ ™11 rise verV raPidlv in the

The bag must be surrounded

b, sealing wax ; c, punc- tube.

tare; d shell ; e shell
lining ; /, contents of

egg ;&, glass; h, opening prevent its becoming distended.

in shell ; i, water.

a d()th b Q£ the game gize

21. OSMOSIS

Object. — To learn how the pressure due to osmosis
may be measured.

Apparatus. — A potato, cork cutter, cork, glass tube bent at right
angles, sugar, and a shallow dish.

Method. — Cut off the lower end of the potato and remove
the skin about one third of the way up to the top. With the
cork cutter, bore a large hole to within \ to f inch from the
cut-off end.

Now bore a small hole into the side of the potato above
the peeled area. Coat the glass tube with vaseline and force
it into the side hole so that leakage is impossible.

DIFFUSION AND OSMOSIS 35

Then fill the large cavity with sugar and cork the top
hole tightly.

Stand the potato in a dish and pour in water up to the
height of the peeled area. Let it stand for two or three hours.
What is the result? The height to which the liquid rises
will measure the osmotic pressure.

Conclusion. — State how osmotic pressure may be meas-
ured.

22. OSMOSIS

Object. — To show that osmosis may take place through
the skin of a leaf.

Apparatus. — A bell jar, a plate, a thick leaf of such a plant as
the begonia, and a piece of paper.

Method. — Lay the leaf upon the plate and beside it
place a piece of paper about the same size. Upon the leaf
place a little pile of powdered sugar and put a similar amount
upon the paper. Cover the plate with the bell jar and let
it stand for several days, looking at it from time to time.

What happens to the sugar on the leaf? What happens
to that upon the paper? Explain the difference. In view
of what has been learned from the preceding experiments,
how do you account for this ?

Suggestion. — (a) Cut sections of beet root and place
them in cold water.

(6) Boil sections of beet root and then place them in cold
water.

What is the difference in the results ?

(c) Immerse sections of beet root in wood alcohol, then
remove them and place them in cold water.

How do you account for these results ?

IV. SOIL AND SOIL PREPARATION

23. CONTENTS OF SOILS
Object. — To learn what substances are found in the soil.

Apparatus. — A trowel or shovel, a large pan or box, and a simple
magnifying glass.

Method. — Dig up a pan full of soil. Be sure not to go
too deep. Six or eight inches is about right for ordinary
top soil.

Examine the soil to notice the following points: Does it
break up easily? Is it lumpy? Does it contain stones?
How does it feel to the hand? Is it gritty or soft? The
color ?

Can you detect any organic remains, such as dead leaves,
decaying roots, etc., in it?

Now examine a small portion with the magnifier. What
can you discover ? Look for grains of sand, particles of clay,
and vegetable remains.

Conclusion. — State what you find in the specimen studied.

Suggestion. — Examine soils from other places in the same
way.

Query. — How does garden soil differ from forest soil,
roadside soil, meadow soil ? How does the soil near the sur-
face differ from that farther down ?

Examine the exposed surface where cellars or other exca-
vations are being made, and note how the soil changes in
color and make-up as the depth increases.

36

SOIL AND SOIL PREPARATION 37

24. CONTENTS OF SOILS

Object. — To prove that there is water in soil.

Apparatus. — Any kind of soil, scales, a pan or earthen dish for
heating.

Method. — Carefully weigh any convenient amount of
soil and place it in a pan or evaporating dish. Set it in a
slow oven and let it remain there for several hours. Weigh
it from time to time and continue the drying process until
the weight becomes constant.

Do not overheat the sample, for it is not desired to burn
up any of the organic constituents.

After the weight has become constant, find the difference
between the first and last weighings, and this will be the
amount of water contained in the sample examined.

Investigation. — Examine various soils in this way and
find which contain most water. How do woodland soils
compare with roadside soils and garden soils ? How do sandy
soils compare with loam and clayey soils in water content ?

25. CONTENTS OF SOILS

Object. — To find out the amount of mineral matter
and organic substance in a given specimen of soil.

Apparatus. — Same as in Experiment 24.

Method. — Proceed as before until all water has been
driven off. Then increase the heat so that all organic sub-
stances may be burned. When only ash and such other sub-
stances as will not burn are left, again carefully weigh the
specimen. The final weight will indicate the amount of
mineral matter in the specimen. How is the organic part
to be determined?

38 SOIL AND SOIL PREPARATION

Suggestion. — Mix the last residue with water and filter
it. Evaporate the filtrate to drive off the water. The re-
sulting material will show the amount of soluble mineral
contained in the soil. The soluble parts are of course the
plant foods. The insoluble residue will be left in the filter.

Compare different soils as in Experiment 24 to determine
which are richest in soluble mineral salts. The relative
fertility of a given soil can thus be determined.

For comparison, the following table may be made : —

1. First weight 16 oz.

2. Loss through drying

3. Amount of water

4. Loss through burning

5. Amount of organic material

6. Final weight

(mineral matter)

7. (a) Insoluble

8. (6) Soluble (plant food)

Note. — See action of roots in producing acids which dissolve
minerals not soluble in water (Ex. 84), thus changing them to liquid
form so that they may be absorbed.

26. CONTENTS OF SOILS
Object. — To show that there is air in soil.

Apparatus. — Straight glass vessels such as battery jars or grad-
uate glasses, soils of various kinds, and water.

Method. — Accurately mark with a rubber band or paster
a level one half the height of the jars. Fill the jars with
water to the mark and then add equal volume of soil slowly
to prevent slopping. Both soil and water should be meas-
ured first to insure accuracy. If the volume of the mixture

SOIL AND SOIL PREPARATION

39

is equal to twice the volume of each, the soil contains no air.
If less, the difference indicates the amount of air in the soil.
Suggestion. — Compare loose soils with compact soils.
Which contain most air? Compare plowed soil with un-
plowed soil. Result?

27. CHARACTER OF SOILS
Object. — To show what kinds of soil best retain water.

Apparatus. — A frame with lamp chimneys arranged as in
Figure 11. Each lamp chimney is closed with a perforated rubber

C D

FIG. 11.

stopper and has a short piece of glass tubing to carry off the water,
which drains into beakers.

Method. — Place various soils in the chimneys.

A, 100 grams of gravel.

B, 100 grams of sand.

C, 100 grams of roadside soil.

D, 100 grams of rich garden soil.

E, 100 grams of leaf mold from forest.

F, 100 grams of dry leaves pulverized.

In

40 SOIL AND SOIL PREPARATION

Pour 100 cc. of water into each chimney and note into
which beaker the most water flows. Which kind of soil
holds water best ? Which least ? Which is best for plants ?

Conclusion. — State the result of these observations.

28. ' CHARACTER OF SOILS

Object. — To find out something of the productiveness
of different soils.

Apparatus. — Samples of five or six different soils selected from
different localities and sifted (specimens from different neigh-
borhoods are preferable), a flowerpot for each sample to be tested.

Method. — Fill the flowerpots, each with a different sample
of soil, and label them.

Plant in each flowerpot the same number of seeds of the
same kind. Place the flowerpots in a location favorable for
growth and leave them until the plants mature.

Compare the plants in all the flowerpots. Have all grown
with equal vigor? Have all produced the same amount of
flowers, fruit, and seeds?

Conclusion. — What may be inferred as to the productive-
ness of the various soils tested ?

Query. — Do slopes of " hills and mountains furnish a
richer or a poorer soil than valleys ? Give reasons for your
answer. Has color any relation to fertility ? Fineness ?

29. CHARACTER OF SOILS

Object. — To show the benefit of drainage in soils.
Apparatus. — Two fruit cans, soil, and seeds.

Method. — With a nail punch several holes in the bottom
of one can. Fill both cans with the same soil, which has
been broken up very fine and soft.

SOIL AND SOIL PREPARATION 41

Plant the same number of beans, peas, or corn seeds in
each can and set them side by side in a favorable location
for growth. Water both cans daily with sufficient water
to keep the closed can saturated and the open one only
moist. Do not water too much, but be sure that each can
gets the same amount every day. At the end of two or
three weeks note the soil in each can. What is the result
in growth of each plant? Why?

Conclusion. — What does this teach us as to drainage in
soil?

30. CHARACTER OF SOILS

Object. TO show the relation of drainage to tempera-
ture of the soil.

Apparatus. — Fruit cans, soil, seeds, and a chemical thermometer.

Method. — Punch holes in the bottom of one can. Fill
both cans with the same kind of soil. Plant seeds in them
and water thoroughly so that the water comes to the top
of the earth in the unpunctured can.

Set both cans side by side in a sunny window.

From time to time thrust the thermometer bulb into the
soil about an inch below the surface and record the readings
of each can. If a piece of white paper is wrapped about
each can and fastened with a rubber band, the readings can
be recorded when made.

After a day or two compare the readings. Which shows
the higher temperature at the start? Which one later in
the day ? What happens in the drained can ? What is the
effect of drainage on the temperature of soil ? How do you
explain this?

Conclusion. — How does drainage affect the temperature
of the soil ?

42 SOIL AND SOIL PREPARATION

Query. — What effect on growth of crops has under-
drainage of a field? Does the color of soil have any effect
on its capacity for absorbing and holding heat ?

Note. — Where the amount of water in soil is excessive, the spaces
between the soil particles become filled with water to the exclusion
of air. Such a soil is said to be saturated. • It is unfit for cultiva-
tion of all ordinary crops. Rice is the only cereal which can be
grown in very wet soils.

31. EFFECT OF TILLING

Object. — To demonstrate the benefit of tilling the soil.
Apparatus. — Flowerpots, soil, and seeds.

First Method. — Fill a flowerpot with coarse lumpy so
and another with the same soil which has been crumbled fine.

Plant seeds of corn, squash, or other quickly germinating
seed. Water both alike and stand them in a favorable
location. In which does germination start first? Which
plants thrive best? How may this be explained? Why is
soil plowed and harrowed?

Conclusion. — What sort of soil is best adapted to the
germination and growth of young plants ?

Note. — Experiments in tilling the soil are better made in school
gardens when possible. Space in flowerpots is not sufficiently
large to present such exercises to the best advantage.

Second Method. — Put .equal weights of soil in two flower-
pots. Pack the soil down firmly in each flowerpot, then loosen
up about two inches depth of one. At the end of a week
weigh both flowerpots. Which has lost the greater amount
of moisture? Why? How does this exercise illustrate soil
tilling?

SOIL AND SOIL PREPARATION 43

If it is desired to illustrate this more graphically, the follow-
ing device may be employed.

Place a cube of loaf sugar in a beaker. Pile as much
granulated sugar on top as it will hold. Beside this place
another cube of sugar without any granulated sugar upon
it. Now add a small quantity of red ink to the dish and note
rapidity with which it rises through the sugar cubes.

In which does it rise more rapidly? Can you explain
why? Wherein is this exercise like the preceding? The
loose aerated stratum on the surface of tilled soil thus pre-
vents the too rapid loss of soil water through evaporation.
The sugar experiment is not precisely similar to what hap-
pens in soil, but the phenomena are analogous.

Suggestion. — To show that germination is hindered or
prevented by lack of air in the soil, fill two flowerpots
with heavy loam or clay soil and plant some seeds.

Leave the soil in one flowerpot loose, mellow, and moist;
but add enough water to the other to puddle it so that the
clay surface becomes packed while wet.

In which soil do the seeds germinate first ?

32. EFFECT OF TILLING

Objects. — To study the effect of worms on soils.

Apparatus. — Flowerpots of rich soil, one or two free from worms,
one or two containing two or three earthworms, and one or two with
five or six earthworms.

Method. — Plant tender seedlings in each flowerpot, water
them, and stand them in a place favorable for growth. After
several days examine the surface of the soil for worm casts.
Continue observations for several weeks, or until definite
results are apparent.

44 SOIL AND SOIL PREPARATION

Conclusion. — How do earthworms modify the soil ?
What is the effect on the growth of the plants?

Suggestion — Drainage. Study the soils about the school
or home. When it rains, what sort of soils absorb most
water? On what kind of soils do puddles accumulate?
After a puddle has dried up examine the bed of its pool and
find out what kind of soil covers it.

Fill several flowerpots with soils and pack them down
tightly. Then water them well and let them stand for
some time. Which soils let the water pass through most
readily? Which remain damp longest? Which crack in
drying?

From your observations what kind of soil is best for let-
ting air and water down to the roots of plants ?

Earthworms. Examine the surface of the ground early
in the morning and look for wormholes and worm casts
near these holes. How does the earthworm modify the soil ?

Look for bits of leaves that have been dragged into worm-
holes by the worms. Show how worms benefit the soil (a)
by opening holes in it ; (6) by dragging down trash from the
surface ; (c) by bringing up the worm casts and leaving them
above on the surface.

Farming. Why does the farmer sometimes sprinkle
sand or coal ashes over a clayey field before plowing it?
If you had a very sandy field, how might it be treated to
make it hold moisture better? Why? What effect on re-
tention of moisture would it have to spread leaf mold on
a field before plowing it?

V. FIELD WORK OR REFERENCE WORK

Exercise I. Fertilizing

(See also Experiments 95-98.)

Visit a farm in early spring or in autumn before the fall
plowing is done. What is the reason for fertilizing the soil ?
What are the chief substances used for this purpose ? Which
ones are of mineral origin? Which are of vegetable origin?
What ones are supplied by animals? What is meant by
rotation of crops? Of what advantage is this? Find out
what crops may be so rotated.

What crops exhaust the soil most rapidly? What kind
of fertilizers are best for corn, wheat, potatoes, tobacco,
cotton, and other staple crops ?

How are the fertilizers applied to the soil ? What precau-
tions must be observed in using fertilizers? What chemical
elements are supplied by using lime, • phosphates, bone fer-
tilizer, stable manures, wood ashes, and green clover? What
results if commercial fertilizers are used in excessive amounts ?
What fertilizers are best for gardens, for orchards, and for
lawns ?

Exercise II. Tilling

Describe a plow. How is it used? What is the object
of plowing? When is deep plowing used? When shallow?
How should the soil be turned ? Why should it not be com-
pletely inverted ? Find out three reasons for plowing. Why
is it best to pulverize the soil as much as possible in plowing?

45

46 FIELD WORK OR REFERENCE WORK

Describe a harrow. What is its use? What relation
have plowing and harrowing to aeration and moisture of
soil? What effect on heat of soil? Why is a roller some-
times used after plowing and harrowing?

Exercise III. Planting

Learn through observation in the field how the following
crops are planted : wheat, corn, potatoes, tobacco, and
cotton. Learn also how five principal vegetables are planted.
What crops are transplanted ? Of what use are cold frames,
hot beds, and forcing houses to the truck farmer? Why do
truck farms abound near cities, while staple crops are
grown farther away? What crops are sown broadcast upon
the prepared soil ? Describe a seeder, or planting machine.
What advantages are gained by seeders over the old hand
methods other than that of time and labor saving ?

Exercise IV. Cultivating

What implements are used for cultivation of crops ? De-
scribe a cultivator. Why is constant stirring of the soil an
advantage to the crop ? What necessary things are admitted
to the soil by this treatment? What objectionable things
are got rid of in this way ? Compare a field or garden which
,has been properly cultivated with one which has been neg-.
lected. How do, the plants compare in vigor and in the
amount of fruit produced? How does cultivation modify
the following crops : potato, corn, celery, asparagus, tomato,
rhubarb, and peanut ?

Exercise V. Harvesting

Note. — The gathering of any crops is known as harvesting.
The manner of harvesting depends upon the kind of crop. Thus

FIELD WORK OR REFERENCE WORK 47

cereals are harvested with great machines known as harvesters;
potatoes are harvested with a digging machine ; eggplants are cut
with knives ; and grapes are severed with shears.

Visit a wheat field at harvest time and observe the process,
making note of each step. If possible, visit a great wheat
field where the whole process is accomplished by one ma-
chine. Compare old methods — reaping, threshing, winnow-
ing, etc. — with the most recent way of doing this work.

Visit a truck farm at any time during the summer and
make note of the way in which the various small fruits and
vegetables are gathered and prepared for marketing.

Exercise VI. Marketing

Visit a commission merchant's place of business at any
season. Make a list of products by seasons, together with
the localities from which they come. In what form does each
product reach the market? What products come in baskets,
in barrels, in crates ?

Select ten fruits or vegetables and find out, by reading
or by inquiry, where and how they are grown, how cultivated,
harvested, and shipped, and how used by man.

Exercise VII. Flower Gardening

Visit a large city park and study the process of flower
culture as it proceeds from season to season : —

1. The forcing houses where seedlings and cuttings are
being prepared for outdoor bedding ;

2. The preparation of soil in the beds and setting out of
bulbs and other plants ;

3. The removal of early plants to make way for later ones,
for example, tulips and hyacinths making way for coleus
and geraniums;

48 FIELD WORK OR REFERENCE WORK

5. The harvesting of seeds for future use and the removal
of dead summer growths in order to set out bulbs for next
spring.

Note. — For city schools where the foregoing exercises cannot
be taken as field work, the same and similar topics can be worked
up through reference to libraries. The various publications of
the United States Department of Agriculture and the reports of
the state experiment stations will furnish abundant material for
reference.

VI. SEEDS

33. PARTS OF A SEED

Object. — To find out the parts of a seed.

Apparatus. — Beans, peas, squash seeds, castor beans, horse-
chestnuts, or any other large seeds.

Method. — Examine the seed and note its color, surface,
and markings. Look for a scar (the hilum) which shows
where it was attached to the inside of the fruit. Look
for a small swelling (the chalaza) which is sometimes seen
on the outside of seeds. Look for the ridge (raphe) which
runs around some seeds. Look for a tiny hole (micropyle)
which penetrates the shells of some seeds. Describe and
draw the outside view of each seed studied and name all
parts shown.

Conclusion. — In one sentence state the parts which you
find common to all the seeds examined.

34. EFFECT OF SOAKING
Object. — To find out the effect of soaking seeds.

Apparatus. — Several dishes or bottles, water, and an assortment
of seeds, as beans, peas, etc.

Method. — Examine the seeds, noting the size and feeling
of the testas. Then place them in bottles and cover them
with water. Examine from time to time for several hours.
What change first takes place? Where does this change
begin? How do you account for this ? How does it spread ?
EXP. EOT. — 4 49

50

SEEDS

FIG. 12. — a, hilum ; b, chalaza ; c, raphe ; d, micropyle ; e, cotyledon ;
/, hypocotyle ; g, plumule ; h, caruncle ; i, endosperm.

When the seeds have become soaked and fully expanded,
examine them again. What change has taken place in the

SEEDS 51

size of the seeds? Why? Pjnch the seed. Does any water
come out ? If so, where ?

Conclusion. — State what is the effect of soaking seeds ;
also what changes take place and where the water probably
gets into the seed.

35. EFFECT OF SOAKING
Object. — To study the effect of water on dry seeds.
Apparatus. — Seeds as in the preceding Experiments.

Method. — Weigh a given number of the seeds dry.
Then place them in a beaker and cover them with water.
Let them stand over night. Then remove them, dry them
with blotting paper to remove superfluous water, and weigh
them again. Have they increased in weight as well as in
size? How much?

Conclusion. — State what is the effect of soaking on the
weight of seeds.

36. SEEDS EXERT PRESSURE

Object. — To show that seeds in absorbing water exert
pressure.

Apparatus. — Bottles of any sort (the square or flat-faced bottles
of thin glass are very good for the purpose), beans or peas.

Method. — Fill the bottles with dry seeds. Add water
enough to fill up the spaces around the seeds in one bottle.
Leave the other as control. Cork the bottles and allow them
to stand. After three hours note the result. If the cork has
been pushed out or if the bottle has been broken, what does
the experiment show? If the bottle remains intact, remove
the cork and try to shake out the seeds by inverting it.

Conclusion. — Inference from this experiment.

52 SEEDS

Suggestion. — Repeat this experiment, using four bottles,
filling one pair with fresh live seeds and the other pair with
seeds which have previously been killed by heat in an oven.
Fill one of each pair with water as before. Cork them and
set them away to await results.

Does expansion occur equally in all preparations?

Is the result due to mechanical or to physiological causes ?

Give reasons for your answer.

37. SEEDS EXERT PRESSURE

Object. — Same as in Experiment 36.

Method. — Repeat Experiment 36, using flowerpots, bricks,
and wire as follows : Fill a flowerpot with dry seeds. Place
a brick over the top and wire it on firmly. Then immerse
the whole in a pail of water and leave it overnight.

Lift the flowerpot carefully out of the water and note
the result. If the brick has been fastened down firmly,
there will be something worth seeing. How can you account
for the result ?

Query. — Is this power of exerting force of any use to
the seed in getting started under the ground?

Note. — A piece of board may be used instead of a brick in this
experiment. In this case the board may be bent and the flower-
pot not broken.

An embryo is an immature or undeveloped plant or animal.
Every seed contains such a plant surrounded by one or more
coverings called seed coats, which serve to protect it.

There is also laid up within the seed a quantity of food
for the use of the embryo when it begins to grow. This
food is sufficient to nourish the plant until it has developed
root and leaf surface enough to manufacture food for itself.

SEEDS 53

38. THE EMBRYO

Object. — To find the embryo in a seed and to learn
liow it is protected.

Apparatus. — Beans, peas, or other large seeds used in the pre-
ceding Experiments.

Method. — Select a large soaked seed and carefully re-
move the outer covering (testa). What is found under this
outer coat? Remove all the coverings and examine each.

After all coverings are removed the kernel remains.
Examine the kernel (embryo) and find its three parts.
What are they ? Draw the kernel and name all parts found.
The bean clearly shows a thick pair of seed leaves, a pointed
stem, and a small bud consisting of two tiny leaves between
the seed leaves. (See Figure 12.)

Conclusion. — Name the parts of an embryo and state
how many coats protect it.

39. COMPARATIVE STRUCTURE

Object. — To discover what parts of a seed are essential
and the relation of certain structures to each other.

Apparatus. — Beans, peas, and other large seeds as in the pre-
ceding Experiment; also almonds, horse-chestnuts, squash, acorns,
peach pits, and seeds of pine, four-o'clock, and morning-glory.

Method. — Examine, study, and compare the several
sorts of seeds, part by part. Which have thick testas, thin
testas, smooth, rough, or wrinkled testas ?

Which have one coat? Which have two? In which is
there a third coat ? In which is there a raphe ? a caruncle ?
a chalaza? (Fig. 12.)

Compare the seeds, noting relative position of hilum and

54 SEEDS

micropyle. Remove the testas and compare the embryos part-
by part. Which have thick seed leaves? In which are the
seed leaves thin? (Dodder has none.) In which are there,
more than two? In which seeds is there an endosperm?
What relation seems to exist between the size and thickness
of seed leaves and the amount of endosperm? In which
is the plumule (first bud) large and distinct ?

Conclusion. — State what parts are found in all seeds and
the relation which exists between the size of plumule and
thickness of seed leaves.

40. SEEDS WITH FOOD OUTSIDE THE EMBRYO
Object. — To find out the structure of castor beans.
Apparatus. — Several large castor beans.

Method. — Study the outside of the castor bean as before.
Then carefully crack the brittle shell by giving it a little
tap with a pencil.

On removing the testa notice the thin inner skin which
covers the kernel of the seed, (a) Run a pin around the
edge, being careful not to penetrate too, far into the kernel.
Separate the two halves and find the embryo as it lies em-
bedded in the food (endosperm). (6) Select another seed,
and having removed its testa as before, cut it lengthwise
through the middle. Note the embryo as it lies buried in
the thick endosperm.

How many seed leaves do you find? Are they thick or
thin? Large or small? Find the pointed end. Can you
find a bud between the seed leaves ?

Examine the food (endosperm). Note its thickness.
Test it for oil by crushing on unsized paper.

Conclusion. — State in one or two sentences the peculiar-

SEEDS 55

ities of a castor bean, making mention of the number and
character of its seed leaves and the place where food is stored.
Suggestion. — Study seeds of morning-glory, four-o'clock,
and buckwheat. Soak them well, and study them, using
a magnifying glass.

41. SEEDS WITH ONE SEED LEAF

Object. — To learn the peculiarities of a /rain of corn.

Apparatus. — Several grains of corn (yellow or red field corn is
good, but the large Western corn is most desirable), an ear of corn.

Method. — Examine the corn grains after having soaked
them for at least twelve hours.

(a) Observe the hard, horny covering, the stump where
it was once attached to the ear, the lighter-colored depres-
sion called the dent, and the tiny scar near the tip of the dent
where the corn silk was once attached.

These points will be more plain if an ear of corn is used
for demonstration.

(6) Cut several sections of corn grains, lengthwise, cross-
wise, and flatwise, trying to cut exactly through the middle
of the dent each time. Examine the cut surface and find
the embryo surrounded
on three sides by a
starchy and oily mass

of food (endosperm).

rp j\ . FIG. 13.

1 o determine the

starchy part is easy because of its chalky appearance; but if
the sections are soaked in iodine solution, the parts will all
be seen very clearly (Fig. 13). Iodine colors the starch'
black or dark blue, and stains the embryo yellow or orange.
Make out all the parts and sketch the various sections.

56 SEEDS

Conclusion. — State the peculiarities of a grain of corn,
making mention of the number of seed leaves and the loca-
tion of the food.

Note. — All seeds are of one of two classes; namely, those^ having
two seed leaves (cotyledons), like bean, pea, etc., and those having
only one seed leaf, like corn. Some seeds, such as those of the
pines, have more than two cotyledons. Such embryos are said to
be polycotyledonous. The orange seed sometimes has from two
to seven cotyledons of unequal size; but this is a monstrosity.
Polycotyledons are regarded as dicotyledons whose seed leaves are
cleft into two or more parts. Dodder seeds are destitute of coty-
ledons.

Most seeds of monocotyle plants are so small that the single coty-
ledon is not always easily seen. It is therefore often a better plan
to leave this fact to be shown later, after germination.

Suggestion. — Study other large seeds, such as the date,
wheat, Brazil nut, etc., and notice the similarity. In what
remarkable respects does the coconut differ?

Food Materials in Seeds

Select any number of seeds and test each sort for the
various nutrients.

Find answers to the following: —

1. What nutrients are found in wheat? In corn, rye,
rice, barley, beans, peas?

2. Does an orange seed contain starch ?

3. Is oil found in apple and pear seeds ?

4. Do various nut meats, which taste so sweet, contain
sugar ?

Seed Extractives

Some seeds contain bitter or poisonous oils. These serve
to protect the young from destruction by animals. Vanilla,

SEEDS 57

tonka beans, opium poppy, castor oil, and croton oil are
well-known examples.

Taste the seeds of oranges, lemons, apples, peach pits,
and bitter almonds.

Caution. — Peach pits, orange seeds, bitter almonds, and
many other kinds of seeds contain prussic acid, a deadly
poison. Hence it is not wise to taste of unknown varieties.

Some seeds are commercially valuable on account of es-
sential oils contained in them.

Larkspur seeds furnish a poison used to kill lice.

Stramonium and belladonna are powerful poisons extracted
from seeds of two plants of the nightshade family.

The betel nut yields a narcotic used in the East.

Pepper, mustard, nutmeg, cola, cardamom, and many
other seeds are valued because of oils which yield flavors
or spices. .

Suggestion. — Visit a drug store and make a list of seeds
used for medicine, flavors, etc. Visit a grocery and make
a similar list of seeds used for food.

VII. GERMINATION OF SEEDS

42. THE WATER FACTOR

Object. — To find how to make the embryo plant begin
to grow.

Apparatus. — Three tumblers or wide-mouth bottles, sawdust
or blotting paper, and seeds.

Method. — Fill three bottles with sawdust and plant in
them equal numbers of seeds of any sort. Label the bottles
A, B, C.

Leave bottle A dry, using no water. Fill B with water
to wet the seeds and sawdust, and then lay it on its side until

all superfluous water has
drained away. The seeds
in B will therefore be
damp but not saturated.
Fill C with water. Place
the three bottles side by
side where they receive
the same air, light, and
heat and let them stand
for three days.

What result follows in
A, B, and C respectively?
Why?

Conclusion. — State the
effect of water on germination as shown by this experiment.
Query. — Why do dry seeds stored in a bottle not sprout?
Why do seeds when stored in damp granaries often sprout ?

58

Dry.

Damp.
FIG. 14.

Saturated.

GERMINATION OF SEEDS

59

What precaution should be observed in mills and grain
elevators to keep the seeds from sprouting?

Suggestion. — Visit a malting house and observe the pro-
cess of making malt. Procure some grain not yet malted
and compare it with that which has been malted. Test
both for starch and for grape sugar. How do they differ ?

Note. — It will be seen that starch changes into grape sugar
during germination. This is effected by a substance called diastase,
which is known as a ferment because it can cause fermentation.
This change is necessary to the plant, since the starch is not capable
of diffusing through the tissues of the plant. But by being changed
to sugar it can be carried to all parts of the plant.

43. THE WATER FACTOR

Object. — To find out wlwther all seeds require the
same conditions of water to grow.

Apparatus. — A shallow pan, a plate of glass 4 in. X 12 in., blot-
ting paper, and assorted seeds.

Note. — Small seeds, such as lettuce, clover, alfalfa, timothy, blue
grass, and the grains, are better than others for this experiment.

Method. — Cover the glass plate with one or two thick-
nesses of blotting paper and plant the seeds upon the paper

FIG. 15.

in straight rows from end to end. Then place the covered
plate so that one end rests on the bottom of the pan and

60 GERMINATION OF SEEDS

the other on a side, thus forming an inclined plane. Now
add water to the tray slowly so that it may be absorbed by
the blotting paper without the lower seeds floating off.
Gradually the water will pass up the paper by capillary
force and after a time the whole will become moist. But
the amount of water will vary with the distance from the
level in the pan, and thus the seeds upon the blotter will
receive varying amounts of water, depending upon their
nearness or remoteness from the water in the pan. Leave
the apparatus in a warm room for several days and note the
result. Do all the seeds sprout alike? Do the same seeds
sprout equally well at all distances from the water ?

Conclusion. — State what you infer as to the need of
water by growing seeds and whether all seeds are alike in
their water requirements.

Note. — The water in the tray should be kept at the same level
and the atmospheric conditions should be kept uniform if possible.

44. THE HEAT FACTOR

Object. — To find how to make the embryo plant begin
to grow.

Apparatus. — Three bottles arranged as in Experiment 42, or
three plates with blotting paper and cover glasses.

Method. — Prepare the seeds in damp sawdust (B, Experi-
ment 42), or plant them on wet blotting paper on plates
and cover them with plates of glass.

Now place the bottles or plates in three different localities
where they will be alike in all respects save amount of
heat.

Put A where it is very cold, as in a refrigerator if in summer,
or on the outside of a window sill if in winter. Place B

GERMINATION OF SEEDS

61

in a warm place, as upon a desk where the temperature is
never excessive. Put C upon a hot radiator or in an oven.

After five days bring
the preparations together
and compare the results.

Do the seeds exposed to
the cold grow ?

How about those in the
warm place and those in
the hot place ?

Now remove all three
preparations to the same
warm location and allow
them to remain for three
days longer. Do the seeds
in A and C grow? Does
the cold hinder growth or kill the embryos ?
kill or merely hinder?

Conclusion. — State your inference as to the effect of
heat in making seeds sprout, also the amount necessary
and the effect of extreme heat and cold on germination.

Query. — In buying seeds for planting is it advisable to
purchase " sun-dried " or " kiln-dried " seeds? Why?

45. THE AIR FACTOR

Object. — To find out how to make the embryo plant
begin to grow.

Apparatus. — Two wide-mouth bottles, sawdust, and seeds. One
of the bottles having a cork so that it may be tightly stoppered.

Method. — Plant the seeds in damp sawdust, packing them
in quite tightly to exclude as much air as possible. Then

FIG. 16. — Effect of heat.

Does the heat

62

GERMINATION OF SEEDS

FIG. 17. — Effect of air.

cork one bottle tightly, but leave
the other open to the air. Place
both bottles in a warm place
where the heat conditions are
just right. Thus the seeds are
exactly alike in their conditions
for germination except the sup-
ply of air. After five days note
result. Continue observations
for a month.

Conclusion. — State the result
of your observations as to the
effect on germination of shutting
off the supply of air.

46. THE AIR FACTOR
Object. — Same as in Experiment Jj£.
Method. — Arrange six bottles containing damp sand in
varying amounts as , in Figure 18. Plant the same number

3 4

FIG. 18. — Effect of air.

of seeds in each bottle. Obviously the amount of air will
also vary, bottle (1) having most air. Place the bottles
where the heat supply will be alike for all. Cork tightly

GERMINATION OF SEEDS 63

and after ten days note the result of growth. This result
indicates that some part of the air was used up. What is
it ? Test the air in each bottle, using a lighted stick. What
gas has been given off by the germinating seeds ? Test with
limewater. Result ? See also Experiments 45 and 49.

47. THE AIR FACTOR

Object. — To find out whether seeds can germinate
without oxygen.

Apparatus — Two wide-mouth bottles, glass and rubber tubing,
stoppers (perforated for two tubes), hydrogen generator, seeds.

Method. — Select several seeds which have already begun
to sprout, carefully remove their testas, and place an equal
number of seeds in each bottle. Now fill one bottle with
water which has been boiled to drive off the air, insert the
stopper, and push it down until the water rises to the top of
the short tubes (a) and (6). Now generate hydrogen as in
Experiment 4, and when you are quite sure that no air re-
mains in the flask (see Note), invert the bottle so that the
mouth is submerged, and connect (6) with the delivery tube.
The hydrogen will rise through the water and drive it out
through the tube (a). When all the water has been ex-
pelled, the seeds will be in an atmosphere of hydrogen,
which is harmless ; and as long as the mouth remains under
water, no oxygen can enter.

The other bottle is to be filled with air to act as a control
in this experiment.

After some days make observations on the two sets of
seeds and see which are in best condition.

Conclusion. — State what you conclude is the effect on
growth of depriving germinating seeds of oxygen.

64 GERMINATION OF SEEDS

Note. — To be sure that no air remains in the flask let the gen-
erator work for some time after several test tubes of hydrogen have
been taken and tested for hydrogen.

Suggestions. — 1. Make an assortment of seeds and ar-
range each kind in as many different positions as possible;
for example, hilum upward; hilum downward; hilum to right,
seed on edge; hilum to right, seed on side; etc.

Germinate the seeds. Make sketches representing the va-
rious turnings and twistings which the hypocotyl is compelled
to make in order to get into right relation to the soil.

2. Make another assortment, selecting seeds of various
sizes, and plant five or six of each size, varying the depths
of each. After one or two weeks observe results. Has
depth of planting any relation to the size of seeds ?

3. Compare old seeds with fresh ones of the same kind in
their ability to germinate. How does age affect vitality of
seeds ?

48. RELATION OF DEPTH TO GERMINATION

Method. — Arrange a series of flowerpots containing soil.
Plant seeds in them as follows : —
Pot I, five peas on the surface.
Pot II, five peas one inch deep.
Pot III, five peas two inches deep.
Pot IV, five peas three inches deep.
Pot I, five clover or alfalfa seeds on the surface.
Pot II, five ditto one inch deep.
Pot III, five ditto two inches deep.
Pot IV, five ditto three inches deep,
five ditto \ inch deep.

Pot V

five ditto | inch deep,
five ditto f inch deep.

GERMINATION OF SEEDS 65

Set the flowerpots in a locality favorable for growth
and water them well. From day to day observe results.
Which come up earliest? Which had most work to do in
order to come up? Which are the larger seeds? Is there
any relation between size of seeds and depth of planting ?
Of size to the early seedling? What sort of seeds does the
farmer sow? What ones are planted? Probable reason
for this?

The Pocket Garden

It is often desirable to have a means of constant observa-
tion on seedlings during germination. This is accomplished
by what is known as a pocket garden or pocket germinator.

Procure two pieces of glass of any convenient size. Lay
one on the table and cover it with four or five layers of
blotting paper or flannel. Colored paper or cloth is pref-
erable, since the delicate growths show most clearly on a
dark background.

Now lay four thin strips of wood along the edges. Cigar
box covers are of about the right thickness.

Moisten the blotting paper or cloth and sprinkle over it
a few small seeds, such as radish, mustard, oats, or canary
seed.

Cover the top with the other glass and bind the whole
together with strips of bicycle tape or with common cord.

Many observations can be made on seedlings germinated
in this way.

49. RESPIRATION

Object. — To prove that germinating seeds give off carbon
dioxide.

Apparatus. — As in Figure 19.
EXP. EOT. — 5

66

GERMINATION OF SEEDS

.germinating
seeds

...Limewater

FIG. 19.

Method. — In a wide-mouth bottle place a small vessel
of lime water and fill around it with germinating seeds.

Cork the bottle tightly to pre-
vent entrance of air.

After three days remove
the cork. Test the gas above
the seeds with a burning stick.
Result?

Examine the dish of lime-
water. What change has taken
place in it? Proof?

Conclusion. — What is given
off by germinating seeds ?
Note. — See also Experiment 46.

Note. — A device to show that germinating seeds use up the
oxygen of the air and set free carbon dioxide may be arranged as
follows : —

Germinate some oats, wheat, or other similar seeds by planting
soaked seeds between folds of wet flannel or blotting paper. When
the roots and shoots are well started, fill the large end of a thistle
tube with them and close it with a cork.

Now clamp it in a vertical position so that the small end will
rest in a beaker of strong potash water or limewater.

When the young plants have consumed the oxygen in the sur-
rounding air of the thistle tube, and given off the corresponding
amount of carbon dioxide, the liquid in the beaker will rise in the
tube. This is because caustic potash and limewater have a strong
affinity for carbon dioxide. If the liquid is colored with eosin, its
rise in the tube will be more apparent.

50. HEAT FROM GERMINATION

Object. — To find out whether germinating seeds give
off heat.

Apparatus. — Two thermometers, two flowerpots, and seeds.

GERMINATION OF SEEDS 67

Method. — Fill one flowerpot with dry seeds and the other
with soaked seeds of the same kind.

Compare the thermometers to be sure that they read alike.

Thrust a thermometer into the center of each pot and
stand them side by side, covering each flowerpot with a
cloth to prevent evaporation, but permitting the stems of
the thermometers to project above the covering.

After a few hours compare the readings of the two instru-
ments.

Note. — A differential thermometer can be used if one is at hand
and the comparative temperatures noted.

Note. — The heat in this experiment may not be entirely due
to the germination of the seeds. Bacteria of decay often cause
the evolution of considerable heat. If the seeds are moistened
first with a solution of 5 per cent formalin and then are thoroughly
rinsed off in clear water, they will be far less likely to become heated
through agency of bacteria and the experiment will be more exact.
For use in high schools, however, this precaution is hardly neces-
sary.

51. EFFECT OF LIGHT

Object. — To find out whether light has any effect
upon germination of seeds.

Apparatus. — Two tumblers, sawdust, seeds, and a dark box. To
make a dark box blacken a chalk box inside with ink or paint.
Cover the outside with one or two coats of black paper or cloth so
that no light can enter.

Method. — Prepare the seeds by planting them in damp
sawdust in the tumblers. Then put one tumbler in the
dark box and the other outside. Place both on a window
sill where they will receive the sunshine and move them from
time to time so that the uncovered glass shall have plenty
of light. Keep both tumbler and dark box close together

68 GERMINATION OF SEEDS

so that they may have the same heat conditions, and remove
the box cover at night or in a closet by day so that the air
supply may be ample. After three days notice the result.
These seeds have had the same amounts of water, air, and
heat. The only difference has been the light. Does light
stimulate or hinder growth of seeds ?

Conclusion. — State your inference as to the effect of
light on germination.

Note. — Another method of making this experiment is to plant
seeds in a pan. Invert a flowerpot over some of them, having first
closed the hole in the bottom of the flowerpot. Press the rim well
down into the soil to exclude light. Air will enter through pores
in the flowerpot. After the seeds outside have begun to sprout,
remove the flowerpot to note the difference.

52. THE FATE OF COTYLEDONS
Object. — To find out the fate of the cotyledons.
Apparatus. — An oblong box, soil or sawdust, and kidney beans.

Method. — Plant the beans in lots of three or four at inter-
vals of two days, beginning at one end of the box. Set the
box in a locality favorable for germination and growth.
At the end of three weeks make a careful study of the crop.
What has become of the cotyledons? How do the youngest
plants compare with the oldest ones in size and the appear-
ance of the cotyledons ? What does this prove as to the use
of cotyledons ?

Conclusion. — State the results of this experiment.

53. THE FATE OF COTYLEDONS
Object. — Same as in Experiment 52.

Method. — Repeat Experiment 52, using squash seeds
instead of beans.

GERMINATION OF SEEDS 69

Does the squash differ from the bean in the use of its
cotyledons to the plant (a) while germinating ? (6) later ?

Does the difference in shape, thickness, and character
of the cotyledon in these seeds seem to have any relation
to its future use to the plant?

Suggestion. — Repeat the experiment, using castor beans
and any other available seed.

54. THE FATE OF COTYLEDONS (optional)
Object. — Same as in Experiment 52-

Demonstration of the use of food by the young plant.

1. With a razor or microtome prepare some very thin sec-
tions of cotyledons of bean, or pea, and mount them in a
drop of water under the microscope. Note the cells or com-
partments of which the cotyledon is built up. Note the
starch grains with which these cells are packed.

Now place a drop of iodine solution at the edge of the
cover glass and watch the effect as it spreads over the starch
grains.

2. Make a similar section of a cotyledon taken from a
seedling which has been growing for some time until the coty-
ledon has begun to show wrinkles. Mount it as before,
examine, and again treat it with the solution of iodine. How
do these cotyledons differ from the fresh ones (a) in plump-
ness, (6) in amount of starch in the cells? How can you
account for the difference ? What has become of the starch ?

3. Make similar sections of the endosperm of corn and
castor beans, fresh and sprouted. Use iodine solution for
the corn. The oil in the castor bean needs no test to show
the difference.

Suggestion. — Germinate barley or any other cereal on
moist blotting paper. As soon as the first leaf begins to

70 GERMINATION OF SEEDS

appear, taste of the sprouted grain and also of an unsprouted
grain of the same sort.

How do they compare in sweetness? Crush a few
sprouted grains and test for starch and for grape sugar.
Make the same tests on unsprouted grain. Result?

Note. — See also Note, Experiment 42.

55. EFFECT OF MUTILATION

Object. — To learn the effect of mutilation upon growth
of seeds.

Apparatus. — Sprouting beans, peas, and squash seeds, a sharp
knife, cheesecloth, tumblers, and water.

Method. — Cover several tumblers with cheesecloth, hold-
ing it fast with rubber bands or cord.

Punch three small holes through each cheesecloth cover
and fill the glasses with water.

Carefully cut away one seed leaf from one seed and both
seed leaves from another.

Then place the seeds upon the cheesecloth with the root-
let of each projecting downward through one of the punc-
tures into the water. Each tumbler should have three seeds,
one whole, one with one seed leaf removed, and the other
with both removed. It is best to do this with at least three
kinds of seeds, such as bean, pea, and squash. Continue
the experiment for ten days, renewing the water from time
to time as it evaporates. Note the result. Which seeds
sprouted most rapidly? Which least rapidly?

Conclusion. — What is the effect of mutilation on growth
from seeds?

Query. — Is the result in this experiment caused by the
shock due to mutilation or to the removal of the food supply ?
Give reasons for your answer.

GERMINATION OF SEEDS 71

56. EFFECT OF MUTILATION

Object. — To learn the result of removing other parts of
seeds.
Apparatus. — Same as in the preceding Experiment.

Method. — Prepare tumblers as before or fill several
glasses two thirds full of damp sand and cover them with
glass.

Remove the tip of the first stem (hypocotyl) from beans
and peas. Carefully remove the first bud (plumule) from
a bean without breaking the seed leaves apart. Cut away
as much as possible of the endosperm from a soaked grain
of corn or a castor bean. Then place these mutilated seeds
on the cheesecloth or upon the moist sand and let them re-
main for ten days. Result in each case ?

Conclusion. — State your inferences as based upon these
observations.

VIII. GROWTH OF SEEDLINGS

57. GROWTH

Object. — To learn how the plant comes from the
ground.

Apparatus. — Several Lima beans or kidney beans, flowerpots,
soil or sawdust.

Method. — Soak the seeds and plant them and place the
flowerpots in a location favorable for growth. When the

seedlings begin to emerge from
the soil, note their position,
changes of position, etc., until
the shell is cast and the first
leaves are expanded. Note
what parts come above ground
first, also what parts remain
under the surface. Illustrate all
the stages by means of sketches.
Conclusion. — State briefly the
243 i steps until the first bud ex-

FIG. 20. — Germinating beana. pands.

58. GROWTH

Object. — To learn how the squash plant escapes from the
shell.

Apparatus. — Squash seeds, flowerpots of soil or plates covered
with blotting paper and covered over with glass plates to prevent
drying out.

72

GROWTH OF SEEDLINGS 73

Method. — Place the seeds in the soil in various positions
or lay them upon the blotters and wet them. When they
begin to germinate, note how they split the shell. What
special organs are developed for splitting the shell. Does

FIG. 21. — Germinating squash seeds.

the shell come up with the plantlet? If it does come up,
how account for it?

Conclusion. — State step by step how the squash plant
escapes from its shell.

59. GROWTH

Object. — To learn how the peaplant comes above ground-
Apparatus. — Peas, flowerpots of soil.

Method. — Plant peas and observe their way of coming
up. How do they differ from beans? squash? Why
do they not need a peg to help split open their shells ? By
what structure do they break ground ? Of what advantage
is the arch to the pea plant ? Compare the size of the first
bud with that of beans and squash.

Conclusion. — State how peas come up, telling what part
breaks through the ground.

74

GROWTH OF SEEDLINGS

60. GROWTH

Object. — To learn how a corn plant comes up through
the soil.

Apparatus. — Corn, flowerpot, and soil.
Method. — Plant the corn as in the preceding Experi-
ments. After a few days observe how this plant forces

its way through the soil
and into the air.

Conclusion. — State the
result of your observa-
tions.

Note. — The preceding
four Experiments have been
introduced to illustrate
three ways or types char-
acteristic of dicotyledon-
ous plants, and one way in
which monocotyl plants
come forth from the soil.
Thus the squash develops
an arch and peg by which it
forces the shell open. The
peg holds down the shell,
and the arch breaks through
the soil. The bean has no
peg, but the arch breaks
ground, dragging the cotyledons up backward. In the pea we find'
the cotyledons remaining underground since they can never function
as foliage, and the ground is broken by a very small arched plumule.
In corn and most other monocotyls there is no arch, but the plumule
consists of a leaf rolled up so closely as to be able to puncture the
soil. The onion seed, however, forms a fine arch in germinating.

Suggestion. — From visits to the woods, parks, or gardens
in early spring find out to which type of dicotyledons each

FIG. 22. — Germinating corn.

GROWTH OF SEEDLINGS 75

of the following belongs: the beechnut, peach pit, acorn,
chestnut, horse-chestnut, pine, and maple.

Suggestion. — Plant onion seeds on wet blotting paper
and observe their interesting germination.

Plant an assortment of seeds in pots of different soils
studied in the soil experiments. Is there any difference in
the time required for seeds in different soils ?

Plant fresh date seeds and compare their germination
with cereals and other monocotyledonous plants.

Visit a conservatory and look for germinating coconuts,
Brazil nuts, and vegetable ivory nuts. Some of these plants
are exceedingly interesting in their early growth.

61. GROWTH

Object. — To show that the young plant exerts force in
coming up.

Apparatus. — Seeds, flowerpots of soil, covers of baking powder
boxes or other small trays, and a quantity of shot.

Method. — Plant the seeds three inches apart and place
over each a tray or tin box cover containing shot. Vary
the number in different trays and let the flowerpots stand
for several days. Do the young shoots lift all the trays?
Account for this result. What happens if the weight is
too heavy to lift ?

Conclusion. — Inference from this experiment.

62. GROWTH
Object. — Same as in Experiment 61.

Apparatus. — Small vial, shot, large glass, and a seedling just
breaking through the ground. The vial should be small enough
to slide easily in the glass tube.

76

GROWTH OF SEEDLINGS

Method. — Place the tube around the sprouting plant.
Then insert the vial and add the shot. Mark the vial at
the top of the tube and watch for upward
motion. Vigorous seedlings will often be able
to lift many times their own weight.
Conclusion. — Same as preceding.
Suggestion. — Compare seedlings of pea, bean,
squash, etc., to determine which are strongest.

63. GROWTH
Object. — To show the effect of light-

Method. — (a) Plant two potatoes in flower-
pots containing soil. Place one flowerpot in the
light and the other in the dark. Leave them for
several days. Then place them side by side.
Observe the growth of the plants node for node.

(6) Plant potatoes, sweet potatoes, or beets in battery
jars or tumblers of water so that the lower surface dips
down into the water. Place some in darkness, some in
shade, and others in the strong sunlight. Result ?

FIG. 23.

64. GROWTH

Object. — To study the effect of light on direction of
growth of roots.

Apparatus. — Mustard seedlings, a cork disk, and a tumbler.

Method. — On a cork disk which has two or three perfora-
tions arrange some mustard seedlings so that their roots
pass through the holes. Float the cork disk in the glass of
water and set it in a light place, but not in the direct sun-
light.

GROWTH OF SEEDLINGS 77

After a day or two observe the plant and discover what
the positions of stem and root are with reference to the light.
How does the stem differ from the root as to its direction of
growth ?

Conclusion. — State the result and 'the probable cause.

65. GROWTH

Object. — To find out what happens if a plant meets
with an obstacle in the path of its growth.

Method. — Place bits of stone, wood, etc., where they will
interfere with the growth of (a) roots and (6) stems.

Suggestion. — This can be easily done by placing the
seedlings on damp blotting paper covered with plate glass.
The obstacle and the plant can thus be plainly seen at all
times.

Note. — See also Experiments 158, 159, 160, 161, on plant move-
ments due to contact.

66. GROWTH
Object. — To study the rapidity of growth.

Apparatus. — • The auxanometer is an apparatus designed
to show the rapidity of growth of a plant.

A simple form of this device is shown in Figure 24. It
consists of an upright fastened to a block for support. At
the top an arm extends in a horizontal direction and to it
is attached a quadrant which may be cut from white card-
board and marked off into ten or fifteen equal parts. At the
center of the quadrant is a pulley which may be made of a
cork centered on a stout pin about which it can freely re-
volve.

78

GROWTH OF SEEDLINGS

To the pulley a wire index is fastened. A cord is tied
about the stem of a plant very near to the terminal bud.

This cord passes over the pulley
and is held taut by a weight
which is just heavy enough to
move the pointer. Set the
pointer at zero.

As the stem elongates the
weight will drop, pulling the
pointer upward as the pulley
revolves. If properly adjusted,
a very slight growth of stem
will be indicated by a rise in

\" ' fet i the pointer.

\ Query. — What effect has fer-
tility of soil on growth? What

FIG. 24. — Auxanometer. „ ,

enect does water have on growth r

How do plants of desert regions compare in size with those
of moist regions ? Why are mountain plants diminutive in
size, while lowland plants of the same kind grow to greater
size?

IX. SEED TESTING

Seed Inspection

It is very useful to the farmer and gardener to know how
to test seeds in order to find out which are best for planting.
In this way the purchase of poor seed can be avoided.

When buying for planting, one does not wish any other
kinds of plants growing in the crop. " Tares among the
wheat " are proverbial, and mixtures of different varieties
of the same plant often render a crop unfit for market.

In grain elevators, mills, and malting houses great care
is taken to remove all foreign substances.

67. PURITY

Object. — To determine the purity of a given sample
of seed.

Method. — Examine the seeds in bulk, taking note of the
presence of foreign matters, such as dirt, chaff, leaves, chips,
and other kinds of seeds.

Measure out equal bulks of each sample under inspection
and sift them with a sieve having a smaller mesh than the
size of the seed. Dirt, dust, and much of the other impuri-
ties will be removed in this way. Now spread the seeds
evenly over the bottom of a shallow tray or plate.

Compare the different samples. Which has most dirt?
Which shows the greatest amount of other impurities?
Which is best for planting?

79

80 SEED TESTING

68. WEIGHT

Since the amount of food stored in a seed determines the
vigor and hardiness of the plant, weighing is an important
test in determining the value of seeds.

Object. — To determine the weight of a sample of seeds.

Method. — Weigh out equal quantities of different seeds
under inspection, having first removed any impurities.
Count the seeds in each portion. The sample showing
fewest seeds to a given weight will be the best.

Another method is to pick from each sample one hundred
seeds and carefully weigh them.

Note. — Weight is not always proportional to size. Large seeds
are sometimes found in which the kernel is missing or shrunken to
very small size.

69. COLOR AND ODOR
Object. — To study the color and odor of seeds.

Young seeds are of a bright, fresh color. Old seeds lose
their freshness and become dull colored, sometimes fading
and sometimes becoming darker in hue. Most fresh seeds
have an agreeable smell and some are truly aromatic. But
with age the oils in seeds are apt to become rancid, and so
there is often a disagreeable odor about old seeds. Damp
seeds also acquire a musty odor.

Method. — Procure various samples of fresh seeds. Com-
pare them with old seeds of the same sort, noting the dif-
ference in color and brightness as well as the difference in
odor.

Plant old and new seeds of the same sort under conditions
favorable for germination. Result?

SEED TESTING 81

70. FORM

'Seeds which have developed symmetrically are the best
growers. A seed which has been hampered or stunted in
its growth is handicapped owing to its lack of food or its
deformed embryo.

Object. — To learn whether form has any effect on ger*
mination of the seed andgroivth of the plantlet.

Method. — From an ear of corn select grains which grew
at the ends where they are misshapen. Select also the
same number of perfectly formed kernels from near the
middle of the ear. Plant both sets under conditions favor-
able for germination. Which kind are first to start? From
which kind do the largest number germinate? Which ones
put forth the healthier growth? After a month's time
which plants look most vigorous?

71. GERMINATION CAPACITY
Object. — To study germination capacity.

The following exercise is modified from Circular 96, U. S.
Department of Agriculture, 1910.

Method. — Make a shallow box about 2 inches deep
and about 23 X 15 inches. Fill it with sand, sawdust, or
soil. Then by means of twine lay it off into squares like
a checker board, making ten on the end and fifteen on the
side. This is the germinating tray. Choose ten ears of
corn and number them to correspond with each of the ten
rows in the tray.

From each ear remove five kernels from each row, reject-
ing kernels from the ends of the ears, and selecting those
in a spiral around the ear.
EXP. BOT. — 6

82 SEED TESTING

Plant the kernels in the row which represents the ear from
which they came. Push each kernel, point downward, just
far enough to be covered with soil and arrange them so that
there shall be one near each corner and one in the center
of each square. Saturate the tray with water and place it
in a warm place, keeping the plants moist until they are
one inch tall.

Examine the squares in regular order, noting, (a) the num-
ber of seedlings in good condition, (6) the number in poor
condition, (c) the number of squares in which there were no
seedlings, etc. (d) If any seedling failed to come up, carefully
remove the sawdust and find out the cause.

Tabulate the results.

72. PERCENTAGE OF GERMINATION
Object. — To learn the percentage of germination.

Method. — Make a seed tester by cutting several pieces
of flannel, felt, or blotting paper to fit a dinner plate.

Sterilize the cloths by boiling them in water for five min-
utes and arrange them as follows : —

Place a layer of cloth on the plate. Lay one hundred
soaked seeds upon it. Cover them with another cloth and
lay a pane of glass or an inverted plate over it. Remove
the cover from time to time to aerate the seeds and at the
same time remove all seeds which have begun to germinate.
When no more seeds will germinate, count the number of
ungerminated seeds and subtract it from the original number,
100. This will give the percentage of germination. Thus
if 15 out of the hundred failed to germinate, the percentage
of germination would be 85.

SEED TESTING 83

73. GERMINATION SPEED

Object. — To study germination speed

If in Experiment 72 the number which germinate each
day is recorded, and these results tabulated, it will be
possible to determine the relative speed of germination.
In choosing seeds for planting those which are quickest to
germinate are most to be desired, since the earlier the crop,
the better will be the market price.

.Method. — Procure packages of garden seeds, such as
radish, turnip, lettuce, cucumber, melon, peas, beans, and
cereals. Get them from different seedsmen and farmers.
Test them to determine their speed, capacity, and percent-
age of germination.

Query. — Why is it preferable to buy seed corn on the
ear ? Why are high-priced seeds not necessarily the dearest ?
Why is it not safe to plant seeds left over from past years ?

Vitality of Seeds

Plant seeds from immature fruits, using apples, cucumbers,
squashes, pea pods, etc.

Plant seeds which have been a long time in bottles. Keep
a record of the number which are planted and the number
which sprout. Result? Inferences?

Reference Work on Seeds

The following questions are inserted here as suggestive
of what may be done by pupils in finding out facts relating
to seeds.

How are seeds collected by the farmer for future planting?
How is a granary or corn crib built and why is it constructed
as it is? How is grain harvested? How shipped?

84 SEED TESTING

How is grain loaded and unloaded at mills and grain ele-
vators ? How is it elevated ? How cleaned ? How weighed
and bagged? What impurities are found in grain? De-
scribe the construction of a grain elevator.

How is grain ground in a mill? What is the object of
grinding? Of bolting? How does stone milling differ
from the roller process? Describe the bolt. How does
bolting cloth differ from other cloths ? Where made ?
Name some products made in a mill. What are bran,
shorts, middlings, Graham flour, gluten ? Name some . of
the breakfast foods made from wheat, corn, oats, barley,
etc.

What is malt ? How is it prepared ? What change takes
place in the grain during the malting process ?

What ingredients enter into the process of brewing?
How is beer manufactured? Of what use is yeast in the
process? (See Experiments 214-220.) Why? For what
are hops used? Where do they come from?

What liquors are made from rye, barley, corn ?

X. ROOTS

Root Structure

Suggestion. — Prepare a number of bean, pea, and corn
seedlings by carefully digging them up and washing away
any clinging soil particles ; or use a pocket garden. Find
the long main root (primary root). Of what is it the con-
tinuation? What is its normal direction of growth? Find
the other roots (secondary roots) which branch from the pri-
mary root. What is their normal direction of growth?
Account for the difference in direction between primary and
secondary roots. Find other branches (tertiary roots or
rootlets). What is the general direction of all the roots?
Is there any definite system of arrangement in the branch-
ing of roots? Have they any definite shape? Do they
seem to be limited in the length to which they grow? Look
for root hairs near the ends of young roots. Do they occur
at the very tip of a root ? Are they seen along the surfaces
of old roots ?

74. ROOTS

Object. — To find out the parts of a root.
Apparatus. — A parsnip or carrot, and a sharp knife.

Method. — Examine the root, first giving attention to
the external appearance. Afterward make sections length-
wise through the center and crosswise at different points
so as to see the gross structure.

85

86

ROOTS

IBd.
St.

1. Outside examination. Describe the outer covering
(epidermis or skki). What is its color, texture, thickness,
and general appearance? Find the bud. Where is it lo-
cated? Of what is it com-
posed? Find the depressions
which are found on the sur-
face. Is there any system in
rSec. Rt their arrangement? What is
seen projecting from some of
these depressions? (Secondary
roots.)

2. Interior examination. Of
how many regions is the parsnip
composed ? How does the cen-
tral portion (central cylinder)
compare in color and structure
with the part underlying the
skin? (Cortex.) What sepa-
rates the cortex from the cen-
tral cylinder?

Make very thin cross sec-

FIG. 25. -Structure of a parsnip i{QW ftnd 1(X)k th h them

root : a, skin ; 6, cortex ; c, sap
region ; d, central cylinder ; towards the light. Can yOU

T. Bd., terminal bud ; St., stem ; discover any system in struc-

Sec. Rt., secondary root.

tural arrangement ? When pos-
sible, compare a parsnip two years old with one of one
year.

Cut sections through the parsnip at the point where sec-
ondary roots are given off. Where is the origin of a secondary
root? Draw outside view, longitudinal and cross sections.

Conclusion. — Name the parts of a root and state where
each is located with reference to the others.

ROOTS 87

75. ROOTS

Object. — To find out where the sap circulates in a root.

Apparatus. — Two large parsnips, a battery jar, and a pint of
water in which a small quantity of eosin has been dissolved.

Method. — Cut off the tip of one parsnip and place it
standing in a jar containing eosin solution. Let it remain
for two or three hours. Then remove it and make a section
from end to end. What region of the root has become
stained ?

Dig out a cuplike hollow in the top of another parsnip
and fill it with eosin solution and let it stand. After three
hours rinse out the top and make a section as before.

Does the sap circulate both ways or only one? In which
region ?

Conclusion. — State where sap flows in a root.

Note. — If anilin of two colors is used, one color in the battery jar
and the other in the cuplike hole at the top, it will be seen that the
upward and downward circulation is not in the same set of tubes.

Beautiful sections can be made by using eosin and methyl green
as the anilin dyes.

To the Teacher. — If parsnips are treated in this way and then
sliced very thin on an ordinary cabbage cutter or with a carpenter's
plane, they may be dried under pressure between blotters and then
mounted between plates of glass and bound with passe partout
binding. Such mounts are useful in demonstrations and reviews.

76. ROOTS

Object. — To learn the direction of growth in a root.
Apparatus. — A plate of glass, blotting paper, germinated seeds.

Method. — Arrange the sprouting seeds upon a blotter
so that the roots point in the same direction. Cover them

ROOTS

with the plate of glass and bind with cord. Keep the blotter
damp and hold it in the original position until the roots

are a half inch long.
Then turn the plate
over on the side so
that the roots point
in a horizontal direc-
tion. Observe them
from time to time.
Do the root tips show
any response to the
change of position ?
How? (Fig. 26.)

After a day or two
turn the apparatus
Continue turning the plate as the

FIG. 26.

again on the next side,
roots continue to grow.

Conclusion. — In what direction
you give a probable reason ?

do roots grow? Can

77. ROOTS
Object. — Same as in Experiment 76.

Apparatus. — Bell jar, shallow pan, cork float, pins, seedlings,
and water.

Method. — Fasten two or three seedlings of equal size by
pins as in Figure 27, so that Bell-jar,

the sprouts point upward.
After a few hours note the
change of direction of growth.

Note. — The bell jar is used
to keep the seedlings in a moist
atmosphere. FIG. 27.

...Seedlings

....Corn.

.water
Tray.

ROOTS

89

.Flowerpot
'Seedling

-Soil
Box
.Water

78. ROOTS
Object. — Same as in Experiment 76.

Method. — Prepare a box of soil in the center of which is
placed an ordinary porous flowerpot having the hole in the
bottom closed with a cork,
and filled with water.

Plant seeds in soil a few
inches from the flowerpot.
The only moisture in the
soil is what comes through
the pores of the flowerpot.

After three or four days carefully remove a seedling and
note the direction in which it has grown.

Query. — Downward growth in ordinary earth is prob-
ably due to what?

79. ROOTS
Object. — Same as in Experiment 76.

Method — Arrange a cone of wood or a funnel as in
Figure 29. Fill the funnel with wax or paraffin and cover it

with a layer of blotting
^...seedlings

}..ist. position,
snd.

position

L Blotting paper

Jar

.... ..Water

FIG. 29.

paper. If the cone is of
wood or wax, the paper
may be fastened with a
pin or thumb tack.

Stand the cone in a ves-
sel of water so that the
lower edge of the blot-
ting paper will be below
the surface of the water,
in order that the whole
paper maybe kept moist.

90

ROOTS

Select seedlings whose roots are about \ or f of an inch
long, and place them as in a so that the root will project
outward.

Stand the whole apparatus in a shady place for a day or
two and then examine it. Account for this change of posi-
tion in the root.

Note. — Sachs has shown the turning towards water (hydro-
tropism) by an experiment like the following.

80. ROOTS
Object. — Same as in Experiment 76.

Method. — Prepare a box with a wire-netting bottom. An
ash sieve will do very well. Scatter sprouted peas all over

the netting. Fill the
sieve with wet sphag-
num moss or other
similar substance and
suspend it in an ob-
lique position. The
roots which project
downward will soon
show a tendency to
bend upward towards
the wet moss.

They will frequently
be found weaving themselves in and out among the wires of
the screen.

The root seems to be endeavoring to obey two influ-
ences: one, geotropism, which draws it earthward; the other,
hydrotropism, which causes it to turn towards the water
supply.

FIG. 30.

ROOTS

91

81. ROOTS
Object. — Same as in Experiment 76.

Method. — To show how a root obeys both gravity and
water in its direction of growth, place a triangular piece of
wood small end down-
ward. Cover it with sev-
eral layers of filter paper
and saturate it with water.
Fix a young seedling as
in Figure 31 so that its
roots hang down.

Leave it standing for a
few hours and note change
of direction.

Make a sketch to show
original position and with
a dotted line indicate any
change in direction of the
root.

Note. — See also Experi-
ments 42 and 64.

FIG. 31. — a, root in original position:
b, root in new position ; c, wood ; d, water.

Geotropism

It has been demonstrated in several experiments that
roots of a plant have a more or less definite tendency to
grow downward. This property is known as geotropism.

We say that roots are positively geotropic when they grow
downward towards the earth's center.

Stems may be negatively geotropic when they grow up-
ward or away from the earth. Stems which creep or lie

92

ROOTS

prostrate, and secondary roots which extend outward from
the main root, are said to be neutral, since they show neither
positive nor negative geotropism.

Many interesting experiments may be devised by the use
of an apparatus called a clinostat. This is a revolving sup-
port run by clockwork, and cap-
7/ able of being made to rotate at
any angle.

Glass,

Thistle
tube....

Water.

82. ROOTS

Object. — To measure the ra-
pidity of growth.

Method. — Arrange a thistle tube
or funnel as in Figure 32 and place
a seedling in position.

...Cork.
Thumb tacKS

.....Threads
;'...,, Seedlings

...,,-MarKed root

Jar

.....water

FIG. 32.

FIG. 33.

As the sprout pushes downward, mark its termination
from time to time by thread or mucilaged markers.

If conditions of heat, light, etc., are varied, the effects of
these agencies upon rapidity of growth can be noted and
measured.

ROOTS 93

83. ROOTS

Object. — To determine just where growth in a root is
most rapid.

Method. — Arrange an apparatus as in Figure 33, suspending
the seedlings by means of thread and marking the young
roots with the marker shown in Figure 38. After a few
hours examine the roots and discover whether the lines are
equally distant as at the start.

Where is the growth most rapid?

84. ROOTS

Object. — To show that roots give off acid in growing.
Apparatus. — As shown in Figure 34.

Method. — Fill the lower part of a funnel with gelatin
in which a little blue litmus solution has been dissolved.
When it has cooled enough to become firm below, insert
the root of a seedling. Cover the funnel with a glass plate

and stand it in a rack or bottle.

After a day or two note the change
in the color of the litmus. What
does this prove?

Suggestion. — Place young seed-
lings upon damp blue litmus paper. Ucelatin Litmus
Result?

Suggestion. — Place a slab of pol- FJQ 34

ished marble in a flowerpot so that

it is inclined towards the top. Lay a grain of germinated
corn or other seed near the top so that the roots when they
grow will lie upon the polished surface of the marble.

Now fill the flowerpot with soil, and water it well.

94

ROOTS

When the plant is full grown and shows sign of dying,
remove the marble slab and plant together, shaking off the
soil and washing the slab with clear water. An etching
will often be found showing where each tiny rootlet touched
the marble.

Account for this.

Prints of such an etching may be made by coating the slab
with a mixture of vaseline and lampblack and applying the
slab to paper.

Examine surfaces of rock over which roots have grown.
How can we account for the grooves in which such roots lie ?

85. ROOTS
Object. — To observe the production of adventitious roots.

Apparatus. — A bottle, water, a branch of willow, poplar, ivy,
oleander, or tradescantia.

Method. — Cut the branch with a sharp
knife and put it into the bottle full of
water. As the water evaporates add more.
When roots appear, note where they grow,
also the character of such roots and the
root hairs which cover them.

Repeat the same experiment, using
leaves instead of branches. The leaves
of English ivy and rubber plant are
specially good. The top of a pineapple
cut off and placed on top of a vessel of
water so that the under surface is wet
will produce roots in this way.

Conclusion. — How may adventitious
roots be made to appear?

FIG. 35.— Adventi-
tious roots in water.

ROOTS

95

86. ROOTS

Object. — To learn how plants may be propagated by
cuttings.

Apparatus. — Branches of plants named in the preceding Experi-
ment, also geranium, fuchsia, or begonia. Flowerpots of clean, sharp
sand.

Method. — Make the cuttings with a sharp knife. Remove
nearly all the leaves. Thrust each branch into a flower-
pot of sand. Dampen it, cover it to prevent drying out,

FIG. 36. — Rooted cuttings.

and set it in the shade for one week. Remove one cutting
and examine it. Look for a scab or callus where the cut-
off end is healing. Examine the cuttings from day to day
to study the formation of roots.

Conclusion. — How may plants be propagated by cut-
tings ?

Query. — Of what practical value is this knowledge ? Of
what commercial importance is this to the florist and gar-
dener ?

96 ROOTS

87. ARTIFICIAL PROPAGATION

The propagation of plants by cuttings was presented in
the previous Experiment. There are other ways of pro-
ducing plants artificially.

Object. — To learn how plants may be propagated by

layering.

Method. — Select a shrub growing in the garden. Rose

bushes and currant bushes are good for the purpose. Choose

a long branch which
can be bent over
without breaking and
remove a portion of
bark from the lower
side where it will
touch the ground.

Lay the wounded
EIG. 37. — A layer.

surface upon the

ground, put a small amount of soil upon the branch, and
place a stone upon it to hold it in place. Pegs or staples
may also be used for the purpose.

After a few weeks cut the connection between the layer
and the parent plant. If examined, roots will be found
about the wound, and the layer will have become a separate
plant.

In a similar way plants may be layered from one flower-
pot to another. Periwinkle, which is propagated with dif-
ficulty by cuttings, can be easily grown in this way.

Queries. — How does the creeping buttercup propagate
itself?

How does witch grass spread ? Why does cutting off
such plants with a lawn mower not exterminate them?

ROOTS 97

How do you account for the fact that willows usually grow
along streams? How does the strawberry plant spread?
How does the grower of small fruits make use of this pecul-
iarity of the strawberry plant? Examine the long shoots
of a black raspberry bush late in the summer. What has
taken place where these long shoots have touched the
ground? Examine a plant of " Old-hen-and-chickens."
How does it spread? Find out what are runners, stolons,
and offsets. What plants propagate themselves in each
way?

88. ARTIFICIAL PROPAGATION

Object. — To learn how plants may be propagated by

offsets.

Apparatus. — Some sets of onions or the little black bulblets
of the tiger lily, soil, etc.

Method. — Examine the offset. What does it look like?
Plant it in a flowerpot of damp soil and cover it to prevent
drying.

Conclusion. — How may onions and tiger lilies be propa-
gated?

Note. — Late in summer examine the stems of the cinnamon
vine and find the little tubers resembling potatoes by means of
which that plant propagates itself.

89. ROOTS

Object. — To discover the use of the shin to a root.
Apparatus. — A parsnip root and a dish of water.

Method. — Allow the parsnip to lie in a warm, dry place
for some time. After it has become quite soft and flexible
EXP. EOT. — 7

98 ROOTS

immerse it in the water for about an hour. Remove it and
note the change.

Conclusion. — How does this experiment show that the
skin absorbs water?

Note. — This exercise does not prove that all the absorbed water
comes in through the skin alone. There may be holes where root
branches were broken off through which the water may also enter
the root.

Query. — Why do roots wilt when removed from the
soil? How may they be revived? A grocer sometimes
puts vegetables which have been exposed to the sun and air
on his vegetable stand into a tub of fresh water. Why is
this done?

To show that roots absorb water from the soil, fill two
flowerpots of equal size with equal weights of dry soil. Set
a plant in one. Water both flowerpots equally and set
them aside in a location favorable for growth. After three
or four days examine both flowerpots. Which contains
the drier soil ? What has become of the water ? How did
it escape from each?

90. ROOTS

Object. — To discover the use of the skin of a root-
Apparatus. — Two parsnips of nearly equal size and weight.

Method. — Carefully peel the skin from the larger pars-
nip until they are of the same weight.

Put them in a dry place and weigh them from time to
time, or place them in opposite pans of a balance.

What change takes place in the weight of these roots?
Which loses more rapidly? Why?

Conclusion. — What are two uses of a skin on a root ?

ROOTS 99

91. ROOTS

Object. — To learn how a plant increases the absorbing
surface of its roots-

Method. — Plant some radish seeds on moist blotting-
paper, and when the roots appear note their surface. Ex-
amine them with a hand magnifier. Repeat the experiment,
using oats or corn.

Visit a conservatory and examine the aerial roots of or-
chids. What takes the place of root hairs and why is this
modification beneficial to epiphyte plants ?

Suggestion. — Cut off a root tip of a germinating oat or
radish seed, mount it in a drop of water, and examine it
with a low power of the microscope. The character of a
root hair, the central cylinder, cortex, and root cap can read-
ily be made out. If a drop of eosin or methyl green is al-
lowed to follow under the cover glass, these structures will
be more easily seen.

92. ROOTS

Object. — To find whether roots absorb water.
Apparatus. — A wide-mouth bottle, cork, and a small plant.

Method. — Fill the bottle with water. Perforate the
cork and through the perforation pass the roots of the
plant. Insert the cork so that the roots are immersed in
the water and put some cotton around the stem to prevent
evaporation.

Does the water go down? If so, where has it gone?

Conclusion. — State the inference you can draw from this
experiment.

100 BOOTS

93. ROOTS
Object. — To find out where the water enters the plant.

Apparatus. — A young plant having root hairs plainly visible,
very dilute eosin solution.

Method. — Place the plant in the dilute eosin solution for
three minutes, then wash it thoroughly in clear water. What
parts become colored with the eosin ?

Conclusion. — State what special part of the roots absorb.

Note. — To distinguish between root and stem in very young
plants place them in weak solution of potassium permanganate.
The roots will become stained dark brown by the solution, but
the stem will remain white.

94. ROOTS

Object. — To find out whether light has any effect on the
growth of roots.

Apparatus. — Two sets of seedlings, soil or sawdust, a battery
jar, and glazed flowerpot.

Method. — Fill the two dishes with soil or sawdust and
plant the same number of similar seedlings in each, placing
them as near the sides of the dish as possible where those in
the battery jar will be sure to be exposed to light.

Now put both dishes in a sunny exposure. After several
days remove the seedlings from both dishes and observe
the size and position of the roots.

Conclusion. — From this exercise what do you infer to
be the effect of light on health of a root and direction of its
growth ?

Definition. — The behavior of a plant with reference to
light is called heliotropism. Turning toward the light is

ROOTS 101

called positive heliotropism ; the opposite is known as nega-
tive heliotropism.

Suggestion. — To show negative heliotropism of roots
plant seedlings on cloth over water in a tumbler or battery
jar. Cover the outside of the jar with black paper so as to
exclude light from the roots. Make a slit or small hole
through the cover paper so as to admit light at one point.
Keep the apparatus standing in the same position for sev-
eral days. (See Figure 40.)

Remove the cover and note the position of the root.

If the experiment has been carefully prepared, the root
tip will be found pointing away from the aperture where
light entered.

Suggestion. — Test carrots, parsnips, beets, radishes,
turnips, etc., for starch, cane and grape sugar, and protein.
Which are richest in starch? in sugar? Why do we eat
radishes raw, while potatoes must be cooked ?

Separate some of the cortex from the central cylinder
of several roots and test each tissue separately for the va-
rious nutrients. From the results of such tests what do
you conclude is the principal place of food storage in roots ?
Is there any relation between the size of a root and its food
contents ?

Reference Work. — Find out how beet sugar is obtained,
tracing the process from seed time to the manufactured
product.

95. ROOTS

Object. — To learn the effect of nutrient solutions upon
the growth of young plants.

Directions. — Select two young cabbage plants about
three or four inches tall and place them in two bottles,

102 ROOTS

suspending them by means of cotton wool, so that their
roots shall dip below the surface of the liquid in each
bottle.

In one bottle place distilled water or rain water; in the
other soil water. The latter may be obtained by thoroughly
mixing common rich garden soil with water and allowing
it to stand until all sediment has settled and the water has
become clear.

Place both plants for some time in a locality favorable
for growth. After a few days or even hours note any dif-
ference in appearance of the plants.

Which is the -more vigorous in its growth ? Why ?

Replenish each bottle with the kind of water which be-
longs in it, and note the result after several days.

Note. — If rain water is used, it should not be taken from cisterns
or rain barrels, since roof drainage frequently contains mineral and
organic matter which has gathered as dust on the house tops. If
distilled water is not at hand, melted artificial ice is an excellent
substitute.

9'6. ROOTS
Object. — Same as in Experiment 95.

Method. — Repeat Experiment 95, using various solutions
of saltpeter, making the solution in one bottle very weak
and the others much stronger.

After a short time examine the two plants. What has
been the result? If several such bottles are arranged, the
first containing distilled water only, the second having
but a drop of saltpeter in it, the third, fourth, and fifth hav-
ing greater amounts, the results will be more definite. This
will explain why the farmer does not give too much fertilizer
to his plants.

ROOTS 103

97. ROOTS

Object. — To discover why strong fertilizers are harmful
to plants.
Apparatus. — A potato, water, a knife, and saltpeter.

Method. — Cut the potato into thin slices. Make a
strong and a very weak solution of the saltpeter. Put some
slices of the potato into each solution and leave them for
an hour. Then remove them and examine them. How
do they differ? Why?

Explanation. — The weak solution, being good for the
plant, can be absorbed through its walls by osmosis ; but the
strong solution, being in need of more water, absorbs it from
the plant, so that the latter loses water instead of taking it up.

Note. — With very strong solutions there seems to be a sort
of toxic effect.

Field Work

98. COMMERCIAL FERTILIZERS
Object. — To study the effect of fertilizers.

Method. — Procure samples of as many different ferti-
lizers as possible and apply them as follows: —

Plant as many plants as there are fertilizers and an extra
one for control.

Treat each plant with one sort of fertilizer, being careful
to label each plant so that no mistake will be possible. Ob-
serve the growth during the season and compare results.

Are all fertilizers equally good for all crops ? In all soils ?

Talk with farmers and gardeners to find out what kinds
of fertilizers are best for each of the following crops: corn,
potatoes, tobacco, and wheat.

What is done with soils which are too acid ? Too alkaline ?

104 ROOTS

99. ROOTS

Object. — To study the effect of heat on the action of
roots.

Method. — Set a potted plant in a dish of ice water and
another of the same size in a dish of warm water so that the
flowerpots are immersed. Young radish, cabbage, tomato,
or coleus plants will do very well. Keep both plants in a
warm room where all other conditions are alike.

After an hour or two examine both plants, observing all
parts. How do they differ in appearance? Now reverse
the plants, placing the cold one in the warm water and the
other in the ice water.

After another two hours again observe the plants. Result ?

Conclusion. — State what may be inferred from this
experiment as to the most favorable conditions for root
action.

100. ROOTS

Object. — To shoiv the effect of mutilation of roots on
the growth of the plant.

Method. — Young cabbage or celery plants will do very
well. Transplant two seedlings about four inches high into
flowerpots of the same soil. With the first plant take care
not to injure the roots and press the soil carefully around
them. With the second plant grasp the stem carelessly
between the fingers and merely pull it up ; put it into the
flowerpot and scatter soil on the roots. After one week
compare the two plants. How do they differ ? Why?

Note. — To prevent mutilation of roots seeds are sometimes
planted in egg shells filled with soil. They can be transplanted
without being dug up. The shell and all may be planted in the
ground, and thus the roots will not be disturbed.

ROOTS

105

101. ROOTS
Object. — To study plant foods.

It is a well-known fact that plants will not thrive indefi-
nitely in the same soil : — •

1. The plant takes up from the soil those substances
which it needs for its nourishment so that in time the soil
becomes impoverished through loss of the food elements
which it originally contained.

2. The presence in the soil of harmful bacteria may render
it unfit for the growth of certain crops.

3. The presence of poisonous excreta which have been
thrown off by previous crops.

The loss of food content is by far the most important of
these causes of sterility of the soil.

The farmer, the gardener, and the florist meet these condi-
tions in several ways.

(a) Repotting and transplanting. When a plant shows
by its growth that it has exhausted the food supply in its
soil, it can be carefully removed from the flowerpot and
repotted into a larger one with a supply of fresh soil. It
can likewise be removed to another locality where the soil
has not become impoverished. But there is a better method
known as (6) fertilizing.

A fertilizer is any substance which contains materials
suitable for plant food. They may be of mineral origin,
such as phosphate earth, lime, plaster, or Chile saltpeter;
or vegetable matter, such as decayed vegetation, wood
ashes, or green growth plowed under; or they may be
animal matter, such as bones, sea shells, guano, and waste
from stables.

(c) Nutrient solutions are often made up, consisting of

106 ROOTS

various chemical salts dissolved in water. These are the
best for experimental purposes. A good nutrient solution
may be made by using the following formula : —

Calcium nitrate 6 g.

Saltpeter l|g.

Epsom salt l|g.

Neutral potassium phosphate . . . 1^ g.

Common salt l^g.

Dissolve the above in 600 cc. of distilled water and keep
it in a corked bottle in the dark.

When it is desired for use, shake it thoroughly and dilute
10 parts to 48 parts of distilled water.

To prove the value of the solution try it on seedlings,
cuttings, and potted plants. Prepare three tumblers as
follows: (a) full of distilled water, (6) full of well water or
hydrant water, and (c) full of distilled water, into which the
nutrient solution has been added according to direction
(10 parts to 48 of water).

^,ow carefully place some seedlings which have been
sprouted on blotting paper or cloth upon a cork float and
fasten them with a bit of cotton batting so that their roots
can be wet with the contents of the tumblers. Arrange
three sets of seedlings, one in each glass.

After a week which seedlings are growing best ? Why ?

Repeat the preceding exercise, using cuttings of willow,
poplar, or tradescantia which have been previously rooted in
water.

Water two potted plants of about equal size at the same
time every day, giving to one only distilled water and to the
other equal portions of a nutrient solution.

How do they compare in size, number of leaves, etc., at

ROOTS 107

the end of a month? What must be inferred from the re-
sults of this experiment?

Origin of Some Fertilizers

1. The commonest fertilizer in use is stable manure. It
is prepared by piling in heaps, where a sort of fermentation
takes place. When the mass has been reduced to a dark
color and heat has ceased to be generated, it is ready for
use.

2. Guano is a fertilizer imported from the rocky islands
on the Pacific coasts of South America. It consists of bird
manure, eggs, bones, decayed remains of fish, birds, etc.,
which have accumulated where the birds have their breed-
ing grounds. It resembles a grayish black soil and is a
very rich fertilizer.

3. Phosphate earth is classed as a mineral fertilizer, but
it is in reality of animal origin, being composed of the fossil
remains of fishes and other animals of long ago. The phos-
phate beds of the Carolmas are the principal source of this
fertilizer.

4. Chile saltpeter is a mineral found in many parts of the
earth, where it is mined. The greatest exporter of this sub-
stance is Chile, hence the name.

5. Wood ash, although obtained from plants, is a mineral
substance. It is rich in potash.

6. Lime is not itself a plant food, but it owes its chief value
to the fact that it decomposes many organic substances,
causing them to give up ammonia, which is a valuable ferti-
lizer. If a little lime is put into a test tube together with
any animal substance and heated, the familiar odor of
ammonia will be quickly detected.

A good nutrient solution for plants may be made by mix-

108 ROOTS

ing a small quantity of hen manure with two or three hun-
dred times as much water.

Stir it well and let it stand. From time to time, dip off
water from the top and use it for watering plants. As the
water is used up add more. This has been found to be an
excellent plant food, but it should not be used too frequently
or too strong.

XI. STEMS

102. LOCATION OF GROWTH
Object. — To find where young stems grow most rapidly.

Apparatus. — Young seedlings of bean, pea, squash, or any other
young shoots, a marking apparatus as shown in Figure 38. It is
cut out of pine and has
threads stretched across it
exactly one eighth of an
inch apart.

Method. — Wet the
threads of the marker
with India ink and touch
the young stem. This

Will make a series of FIG. 38. — Growth marker,

lines or dots on the stem one eighth of an inch apart.

After a day note whether the dots are the same distance
apart. Continue to make observations, until you know
where growth is most rapid. (See also Experiment 82.)

Conclusion. — State the result of this experiment.

103. UPWARD GROWTH

Object. — To learn something of upward growth of
stems.

Method. — Plant a seedling in a flowerpot so that it pro-
jects through the drain hole. Then suspend it as in Figure
39. After a few days observe the position of the stems.

109

110

STEMS

FIG. 39.

Sketch. After a week or two
carefully remove the plant
and notice whether the root
growth has been affected.

Query. — Why do corn,
wheat, etc . , tend to straighten
themselves when they have
been blown over by the
winds? How do you account
for lopsided trees which grow
at the edge of a forest ?

Why are the young trees
in the forest so tall and
slender ?

104. STEMS

Object. — To study the effect of sunlight on the growth
of stems (heliotropisrri).

Apparatus. — A dark box having one small hole for admission
of light, seedlings in a small flowerpot.

Method. — Place the plant in the dark box and leave it
there for several days. Notice the effect of darkness on
color and size of the stem. Observe the direction in which
the stem grows.

Compare a plant grown in the dark with one of the same
sort grown in the light. How do they differ in length, color,
size of the leaves, distance between leaves, etc. ?

Conclusion. — State in three sentences what you have
learned by this experiment.

Suggestion. — Place a potato in a glass of water so that
the under side is moist ; set it on the window sill where there

STEMS

111

is plenty of light. After the eyes have sprouted compare
it with another potato which has been sprouted in a dark
cellar.

How do you account for the difference?

105. STEMS

Object. — Same as in Experiment 104.

Method. — The growth of root and stem in obedience to
light and gravity may be shown by arranging an apparatus
like the one shown in Fig-
ure 40. First arrange a
seedling as in (a), having
the roots immersed in the
water of the test tube.

Wax well about the
top to prevent the water
from coming out.

Then invert the appa-
ratus and fasten it in a
clamp.

Observe the directions
taken by root and stem
(6). If placed where the
light comes from only
one side, notice the di-
rections in which both
stem and root turn.

Conclusion. — What do FlG 40 b

you infer from this as to

the effect of light on direction of growing roots and growing
stems ?

..Stem

...Stopper

Root

.Water.

Stopper.

Stem

112 STEMS

106. STEMS
Object. — Same as in Experiments 104 ana 105.

Method. — Prepare two sets of seeds by letting them ger-
minate in a box of good soil.

As soon as the sprouts peep above the soil, place the box
in a position where heat, water, and air supply will be favor-
able for growth, but not in direct sunlight. Now cover some
of the plants by placing over them an inverted flowerpot
whose drain hole is corked tight. Push the flowerpot down
far enough to prevent any light from getting in below. The
plants will thus be placed in exactly similar conditions
except light.

From time to time examine and measure length of nodes
and size of leaves. Note also the color of stem and leaves,
and the vigor of stem. Remove the inverted flowerpot and
exppse the plants to the light.

After three days look for changes in color, vigor, etc.

Turn over a flat stone or board which has lain for some time
on the ground. How have plants been affected where light
was excluded ?

Note. — The preceding exercises are equally good to demon-
strate the effects of light on roots.

Suggestion. — Cut off a stem of wheat or any other cereal
long enough to have at least one node. Pass it through a
cork into a flat bottle partly full of water and lay the bottle
on its side so that the cut end of the stem is under the sur-
face of the water. Stand the whole in a dark place for
several hours. What is the result? Why?

For city schools any of the common tall grasses found
growing in waste places are equally good for this work.

STEMS

113

Node.

internode.
Node.....

107. STEMS
Object. — To discover the parts of a typical stem.

Apparatus. — Portions of several different kinds of stems, such
as bamboo, Indian corn, maple, lilac, ailanthus, or beech.

Method. — Select the portion of stem included between
the leaf scars of any two consecutive leaves.

Study this region carefully and make out such facts as
color, texture, surface, covering, and appendages, such as
hairs, prickles, etc., if
they occur. Find a
node (joint). What
structures are found
at a node ? Do you
find these organs
elsewhere than at
the nodes ? (See but-
ternut, cherry, and
bitternut.) Measure
the length of an
internode (space be-
tween two consecu- FlQ
tive nodes). Do the

internodes vary in length or are they about the same in
length?

Now select another part of the same branch and examine
the same portion. Do the nodes and internodes sufficiently
resemble each other as to be recognized as being taken from
the same plant?

Of how many internodes does the branch you have con-
sist?

Study each of the other branches as you did the first.

EXP. EOT. — 8

..Node

Node

-.Mode

114 STEMS

Do they have nodes? How many leaves to each node?
How many axilLary buds to each node? How does maple
resemble lilac? How does maple differ from ailanthus and
beech? Which plants have prominent nodes ? Which have
least conspicuous nodes ?

Conclusion. — Of what unit does every stem consist ?

Note. — A stem may be considered as being made up of the sum
total of its nodes and internodes. The unit of plant gross structure
is the internode with one node.

Note. — When a seed is dissected, its embryo is found to consist
of a single internode (the hypocotyl) and one node bearing one or
more seed leaves with a growing point (the plumule) between them.

Growth therefore consists of the multiplication of these units
as the plant is built up.

Gross structure is resolvable into internodal units, just as fine
structure is resolvable into tissues and cells.

108. STRUCTURE

Object. — (a) To learn the gross structure and character-
istics of a cornstalk.

(6) To learn something of the ~*ine structure of a corn-
stalk.

Apparatus. — Some sections of cornstalk long enough to show
the joints or nodes.

(a) Method. — Examine the outside and note the rind
or skin which covers it, the prominence of the joints, and the
groove on one side which shows where a branch was.

Examine the cut-off end and note the compact region near
the rind, the loose pith which fills the bulk of the stem, and
the woody fibers which are scattered through it. Draw.

Cut a section lengthwise to see how these fibers run and
how a section at a joint differs from the other portions.

STEMS

115

Conclusion. — State the facts as to covering, joints,
amount and location of pith and wood.

Suggestion. — Compare cornstalk with bamboo, rattan,
straw, and the stems of grasses. Compare a cross section
also with that of a banana stem.

(b) Method. — Make very thin sections of stems of young
corn plants, using a sharp razor, and mount one in a drop

FIG. 42. — Transverse section of stem of monocotyledon (corn), showing
the " scattered " vascular bundles.

of water or glycerin on a microscope slide. Cover with
a cover glass and examine it with a low power. Move the
section slowly to and fro until all parts of the stem have been
seen. Notice the compact cells composing the rind, the loose
spongy cells which make up the body of the stem, and the
bundles which are scattered irregularly throughout the stem.

116 STEMS

Where are these bundles largest? Where smallest?
Where are they closest together ? What advantage is there
in this arrangement ? Draw one bundle magnified.

Note. — It will be remembered that the corn seed embryo had
only one cotyledon. Such a seed is called monocotyledonous, a
word which means having one cotyledon. All plants which spring
from monocotyledonous seeds are very much alike in the character
of their stems, leaves, and flowers. Such plants are known as
monocotyledons, or briefly monocotyls. Plants which produce seeds
of two or more cotyledons are dicotyl plants.

109. STRUCTURE

Object. — (a) To learn the gross structure of a, woody
(dicotyl} stem.

(&) To learn the fine structure of a woody stem.

Apparatus. — Twigs of woody plants one and two years old, also
a few sections of stems several years old in which the rings are easily
seen. Horse-chestnut, ash, and ailanthus are excellent for the
former; and oak, hard pine, ash, and chestnut are good for the latter.

(a) Method. — Follow the same general plan as in the pre-
ceding Experiment, making out as many answers to the fol-
lowing as possible: By what is the stem covered? What
scars and markings are to be seen? What is the cause or
meaning of each such scar or mark? Are the joints or
nodes conspicuous? Describe the buds and their covering
and protection. Where is the pith ? How much ? Its color
and other peculiarities if any? The wood? Its arrange-
ment? How may you tell the age of a stem? Find the
rays or lines which extend from the central pith outward
toward the bark.

How many layers of bark are distinguishable? How
many annual rings? In an old stem find the heartwood
and sapwood.

STEMS 117

Conclusion. — State the characteristics of the stem studied.

(b) Method. — As in Experiment 108 (6), make very thin
sections of dicotyl stems one, two, and three years old.
Mount them as before and study them with a low power.

By moving the section slowly across the field of vision,
every region will come into view and can be observed in

FIG. 43. — Transverse section of a three-year-old twig of Pinus aylvestris,
showing the small pith, the thick and compact vascular cylinder of second-
ary wood, and the cortex ; radiating lines through the wood represent the
narrow pith rays ; resin ducts in both wood (small) and cortex (large) ; to
the right is a branch gap in the cylinder.

detail. Compare bark with bast, cambium, and pith, making
note of the difference in size and shape of the cells and the
thickness of cell walls in the various tissues.

118

Study the wedge-shaped bundles out of which the first
annual ring is formed.

Note how the medullary rays arise from the pinching of
the pith between the expanding wedges of wood. Note
the difference between that part of the ring which is formed
in spring and the part which is a later growth. In which
part are the wood ducts larger? What is the probable
reason for the difference ? Draw a portion greatly magnified.

Read the chapter on woody stems in any textbook of
botany and endeavor to find as many structures as possible.

Note. — The study of the minute structure of monocotyl and
dicotyl stems is exceedingly difficult. The teacher's assistance is
demanded at every point, and the use of texts and charts will greatly
aid the beginner.

Prepared microscopic mounts are better than fresh material on
account of their greater thinness and the effect of staining reagents.

Exercise

Select good specimens of the two types of stem and
compare them part by part.

Cornstalk is the best common monocotyl stem, and some
thrifty dicotyl like the ailanthus is very good for comparison.
Tabulate your observations as follows : —

COHN STEM

AlLANTHDS

Covering

?

?

Joints

?

?

Pith

Where?

Where?

Pith

Amount ?

Amount ?

Wood

Arrangement?

Arrangement?

Wood

Amount?

Amount ?

New growth

Where?

Where?

Other facts

?

?

STEMS 119

Reference Work

What causes the grain in wood?

What is quartered oak?

How is it produced?

Visit a sawmill and see how logs are reduced to various
kinds of lumber.

Visit the woods when possible and see how timber is
gauged, cut, taken to mill, etc.

Collect as many varieties of lumber as possible and see
if you can find rings, rays, pith, bark, etc., in all. Find out
from a carpenter what kinds of wood are used for each of
the following parts of a house: frame, floors, roofs, clap-
boards, inside work, shingles; also what kinds of lumber
shrink and warp in seasoning.

Find out from observation and inquiry what kind of wood
is used for making violins, flutes, piano cases and sounding
boards, tubs, pails, baskets, barrel staves, hoops, and heads,
athletic goods such as dumb-bells, clubs, and bowling imple-
ments.

Why are hoe handles usually of ash and canoe paddles of
spruce?

110. TWIGS

Object. — To find out the parts and markings of a
twig and their meaning-

Apparatus. — Twigs of horse-chestnut at least two years old.
Forked twigs are greatly preferred since they show details not al-
ways seen on straight ones. A sharp knife is also required.

Method. — Carefully examine the twig and answer the
following questions regarding it: —

The Buds. — How are the buds arranged on the twig ?

120

STEMS

Which buds are largest? Which are smallest? Where are
those of intermediate sizes situated? With what are the
buds covered? The purpose of this covering? What addi-

...d formerly

lateral

FIG. 44. — Ailanthus and horse-chestnut: a, terminal bud; b, lateral axil-
lary bud ; d, leaf scar ; e, fibrovascular dots ; /, bud scale scar ; h, node ;
i, lenticel ; j, fruit scar ; k, bud scale ; I, bark ; m, wood ; n, pith.

tional covering do you discover? Its use? Cut open a bud
crosswise about the middle. What is found within the bud?
What is its purpose?

STEMS

121

Remove the bud scales as they come and lay them out
before you. How do they differ in size, shape, and texture
as they near the
center ? Draw. Cut
open another large
bud from top to
bottom through the
center. Draw.

What is found at
the very center ?
Examine the twig
and find scars where
the scales of former
terminal buds were

Shed. HOW does the FlG" 45' "~ Horse-chestnut bud expanding.

color of the bark differ on opposite sides of the ring of scars ?

Why ? These rings show the age of the branch. Why ?
How old is the branch you have? Cut off the lower end

smooth and count the
annual rings. Does
the number agree
with the number of
scale scar rings ?

In how many ways
may the age of a twig
be determined ?

Has this twig grown
the same amount each
year? Can you ac-
count for any differ-
ences in the amount

FIG. 46. — Horse-chestnut bud, dissected. of growth?

122

STEMS

The Bark. — Describe the bark, noting color, smoothness
or roughness, etc. Look for the lenticels (breathing pores).
Can you discover any system in their arrangement ? Is the
bark of the same hue on both sides ? If darker on one side
than on the other, how can you account for it ? Is there any

way of telling whether
the twig grew in a vertical
or a horizontal position
on the tree? Reasons
for your judgment.

Remove the outer layer
of bark and describe
what lies below it. How
many distinct layers can
be removed?

Scars. — How many
kinds of scars can you
find on your specimen?
What is the shape of
the leaf scars (traces) on
this twig? Draw a leaf
scar enlarged. What
scars are found in angles
between two forking
twigs ? Their cause ?
Do these scars show any dots like those seen in a leaf scar ?
Why not? Look for node lines (ridges joining opposite leaf
scars). Split a twig open through the center and observe the
structure at the region of a node.

Count the dots on several leaf scars and determine
whether the number is uniform or not. Account for these
dots.

FIG. 47. — Hickory bud, dissected, showing
modifications of bud scale.

STEMS

123

Conclusion. — State briefly what has been learned re-
garding buds, bark, and scars seen on this twig.

Suggestion. — Place several twigs in glasses of water,
and after the buds have expanded, make note of the changes
that take place. Note how the leaves are packed in the
bud (vernation).

n. «

FIG. 48. — Butternut, ash, and magnolia : a, terminal bud ; b, lateral axillary
bud ; c, accessory bud ; d, leaf scar ; e, fibrovascular dots ; /, bud scale
scars ; g, stipule scars ; h, node ; i, lenticels ; j, fruit scar ; I, bark ; m,
wood ; n, pith ; o, scar of leafstalk.

124 STEMS

Make a cross section of a woody stem several years old
which grew in a horizontal position. Make a similar sec-
tion of a vertical branch from the same plant. Compare
the thickness of the rings. How do you account for the
difference ?

111. TWIGS

Object. — Same as in Experiment 110.

Apparatus. — Twigs of ailanthus, beech, ash, or apple. Ailan-
thus is preferable on account of its rapid growth and the great size
of all its structures.

Method. — Study this twig in the same way. Its large
scars and conspicuous lenticels make it particularly good
for study.

Thrust a pin into the topmost bud and fasten a thread
to it. Then pass the thread spirally around the twig from
bud to bud until it has touched every bud on the stem.

How many buds at a node? Do you find any trace of a
node line? Select any bud and look down the stem until
another bud is found directly under it. Now count the
number of buds passed over by the thread between these
two buds. Also count the number of turns made by the
thread in traversing the distance.

Select any other pair of buds in the same way and count
the number of buds and turns of thread as before.

Is this ratio constant?

Do the same with beech, oak, ash, apple, or any other
tree. Compare them with scales on a pine cone.

Look for a scar at the extreme end of the ailanthus twig.

How does it differ from leaf scars, bud scale scars, and
fruit scars? What does this terminal scar show? Can
you find a terminal bud? Does this plant have definite
or indefinite annual growth? Reasons for your answer.

STEMS 125

What is the effect of this kind of growth on the form of
tree trunks ?

Compare the shoots with sumach, bramble, blackberry,
and raspberry shoots.

Conclusion. — As in Experiment 110.

Note. — When a plant makes all its annual growth in the spring,
it spends the remainder of the season in making preparation for
cold weather. This is accomplished by the production of woody
tissue in its stem to the very tip and by the development of bud
scales for the protection of future branches and flowers. Such a
plant is said to have definite annual growth.

Many plants, however, keep on growing all summer, and cold
weather finds the ends of their stems soft and tender. The first
frost kills the tender tips because no wood has had tune to mature
within them. Thus if warm weather continues into the autumn,
such plants will have long shoots. But should an early frost come,
these branches will be much shorter. Such a plant is said to have
indefinite annual growth.

112. TWIGS

Object. — Same as in Experiments 110 and 111.

Apparatus. — Twigs of catalpa.

Method. — As in the preceding Experiments. The catalpa
represents a different arrangement of leaves and branches.
What is it ? Are the leaf scars alike in size ? If not, which
ones are smaller? What does this show regarding the posi-
tion of the branch on the parent tree ?

Conclusion. — Similar to preceding.

Suggestion. — Collect twigs of as many common trees
as possible. Mount them on cards for comparison.

Which have opposite branching?

Which have alternate branching?

Which have whorled branching?

126

STEMS

Find some having more than one bud at a leaf scar. Find
some in which buds occur at unusual places. Find a branch
which has been wounded or bruised on which adventitious
buds have appeared.

Query. — In what two ways may the age of a given twig
be determined? Illustrate, using a twig of apple or horse-
chestnut three or four years
old.

By what external struc-
tures may one tell (a) when
fruit was produced ? (6) what
former seasons were favor -

FIG. 49. — Larch.
(Photographed by W. C. Barbour.)

FIG. 50. —Elm.
(Photographed by W. C. Barbour.)

able to growth? (c) in what position the twig grew on
the tree? How may the last two facts be revealed by the
internal characteristics ?

What natural habits of growth make the pine, the spruce,
and the fir tree produce unbroken (excurrent) trunks ? What
outside causes may modify these trees, causing them to pro-
duce more or less broken trunks?

STEMS

127

What natural habits of growth make it impossible for the
horse-chestnut, ailanthus, and catalpa to produce excurrent
trunks? Such trees are said to have deliquescent trunks.
Name forest trees which have trunks of this type.

Field Work on Trees

Make excursions into forests, fields, and parks. Study
trees growing in the open and compare them with trees of
the same sort which are found growing in groves. Make

FIG. 51. — White pine.
(Photographed by W. C. Harbour.)

FIG. 52. — Hickory.
(Photographed by W. C. Barbour.)

notes of differences in height, shape, position of branches,
etc.

Make lists of excurrent trees, deliquescent trees, and also
those which seem to be of an intermediate form. Find a
tree which is normally excurrent, as the pine, spruce, syca-
more, but which shows a forked trunk. Try to determine
the cause of the difference.

128 STEMS

Observe trees to note habits of position of branches.
Classify them as erect, arching, ascending, horizontal,
drooping, sagging, etc. Learn to identify, trees by their
leaves and general appearance, by their bark and by their
individual habit of growth. Thus the arching habit of the
horse-chestnut, the drooping twigs of weeping willow, the
erect shoots of Lombardy poplar, and the curious position of
pepperidge make them easily recognized in winter when
they are destitute of foliage.

Study the habitat of trees. Which favor moist soil?
Which thrive well on rocky hillsides? Which grow along
watercourses ?

Queries. — How does the bark of beech trees differ from
that of oaks, elms, and maples? What bark peculiarities
have the birches, sycamores, cherry, sassafras, hornbeam,
and cedar? How does the bark on young branches of
willow, osier, birch, and poplar compare in color and texture
with older branches of the same trees ?

How do the shape of the tree and position of branching
compare in Lombardy poplar, tulip tree, cypress, spruce,
white oak, and pepperidge ?

113. SAP CIRCULATION

Object. — To find out where the sap circulates in stems.

Apparatus. — Stems of corn and horse-chestnut or any other
woody plant freshly cut from the stalk, eosin or any other aniline
dye, bottle, and water.

Method. — Repeat the experiment for sap circulation
with roots, using the stems instead. Place them in light
for half an hour, make sections, and examine them as before.
What parts absorb the dye in cornstalk? In the other
stem?

STEMS

129

From this experiment can you discover any difference be-
tween monocotyl and dicotyl stems in location of sap-con-
ducting tissue ?

Conclusion. — State in a single sentence where sap rises
in each of the stems used.

Suggestion. — Make same experiment, using a potato
from which the lower end has been removed. Draw, indi-
cating with colored pencil the region of sap circulation.

114. SAP CIRCULATION

Object. — To show that sap also circulates downward in
stems.

Apparatus. — Twigs of willow or poplar, knife, and wide-mouth
bottle.

Method. — Place the twigs in water, having cut them
off smooth to prevent decay. After
the adventitious roots have appeared
and become at least one inch in
length, carefully girdle the twig
about two inches above the surface
of the water, removing a strip of
bark about one inch wide. Keep the
apparatus standing for about two
weeks and cover it with a bell jar or
coat the twig with vaseline to prevent
drying out.

What happens ? Where ? Why does
this prove that sap in the stem cir-
culates downward ? What becomes of FIG. 53. — Downward cir-
the first crop of roots ? Why ? culation of sap'

Conclusion. — State what evidence is here furnished that
sap circulates downward in a stem.

EXP. EOT. — 8

130 STEMS

115. SAP CIRCULATION
Object. — To demonstrate sap circulation in trees.

Method. — Bind a branch tightly by winding a wire about
it several times.

What is the effect on growth above the wire ?

What is the effect on growth below the wire ?

Give reasons for the result in each case.

Suggestion. — Procure twigs on which bagworms have
hung their cocoons and make an examination of the point
about which the web was fastened. How does it compare
with the portions on both sides of it? Cut such a twig
through the middle and examine the section exposed. What
does this show regarding sap circulation in the twig?

Examine a tree about which a wire clothesline has been
placed. How has its growth above and below the wire
been affected ?

What effect follows the use of shade tree branches as
anchorages for telephone, telegraph, and electric light poles,
etc.?

116. SAP PRESSURE OR ROOT PRESSURE

Object. — To measure the pressure due to the upward
flow of sap in a plant.

Apparatus. — A vigorous plant of hydrangea having a stem about
half an inch in diameter, a T-tube, a bent gauge tube, stoppers,
rubber connections, and mercury.

Method. — Cut off the stem of the plant about four inches
from the ground and quickly attach the T-tube before the
cut surface can become dry. Arrange the apparatus as in
Figure 54 and stand it in a favorable location. Water the
soil and await results.

STEMS

131

What happens to the mercury? Can you account for
this? How? What does this show?

Budding and Grafting

In Experiments 86-88 artificial propagation by cuttings
and layers was considered. In that method, the propagation
of new individuals is due
to the ability of a plant
to put forth adventitious
roots. But it is often
desirable to change a
plant in order to make it
produce a different sort
of fruit. This is accom-
plished by budding or
by grafting.

The following princi-
ples must be strictly ad-
hered to if this method
of propagation is to suc-
ceed : —

1. Only closely related
dicotyl plants can be en-
grafted upon one another.
Thus apples of different
sorts can be made to
grow upon other apples,

pears, quinces, crab apples, etc., but they cannot be made
to grow on peach, plum, or cherry stocks.

2. The union between the living tissues (cambium) of both
plants must be perfect. If the living parts do not actually
touch, they cannot unite and grow together.

FIG. 54. — Sap pressure : g, gauge tube ; st.,
rubber stopper ; m, mercury ; PL, plug ;
w, T-tube ; con, rubber connection ; PI.
St., plant stem ; Pt., flowerpot.

132 STEMS

3. Air must be excluded from the joint until the union has
become complete. If air should get into the joint, there would
be a loss of sap through leakage and evaporation; there
might be a chance for rain water to get in and dilute the sap ;
and there would be a liability for the entrance of germs of
decay which would prevent a healthy growth.

Definitions. — The plant whose fruit is to be changed is
called the stock. The buds or twigs which are to be engrafted
upon the stock are called the scions.

Note. — Budding and grafting are most successfully done in
early spring when buds are about ready to start. The scions may
be procured in the fall after the leaves have been shed, and the twigs
may be kept in damp moss through the winter in a cool place to
prevent growing.

117. BUDDING

Exercise. — With a clean sharp knife remove a bud to-
gether with a small portion of the attached bark. In sever-
ing the bud cut upward from beneath the bud to avoid
injuring it.

Cut a T-shaped slit in the bark of the tree on which you
desire the bud to grow and lift up the two right angles so
as to expose the cambium of the stock. Insert the bud so
that its cambium touches that of the stock. Push the bud
down and smear it around with grafting wax.

Grafting wax can be purchased of any dealer in garden
supplies. It is made of rosin, tallow, and beeswax melted
together. Cut off the branch of the stock above the bud.
This will increase the flow of sap to the bud and insure its
early growth.

First attempts are rarely successful, but a little practice
will enable one to do it very well.

STEMS 133

;. 118. GRAFTING
(a) SLIP OR SPLICE GRAFTING

Exercise. — With a clean sharp knife cut a twig from the
tree which is to furnish the scion. Trim it to a slender
wedge.

Cut off the end of a branch of the stock, split down the
bark on one side so as to expose the cambium; push the
scion down until its cut-off end fits firmly against the exposed
cambium. Bind firmly; cover with grafting wax.

(6) CLEFT GRAFTING

Another method is used when the scion is a larger branch.
Trim the scion to a chisel point and cut a wedge-shaped
groove in the end of the stock to fit it exactly. Insert the
scion into the stock in such a way that the bark and cam-
bium are in contact. Bind with cord ; wax as before.

Note. — There are many methods of cutting the scion and stock,
but any way which secures a perfect contact will meet the require-
ments for growth. See publications of the U. S. Dept. of Agr.

Suggestion. — Examine young fruit trees which are to
be planted. Find a swelling near the root. This is where
the plant was grafted or budded.

Query. — Why are we told to remove all branches which
spring from near the ground on all fruit trees ?

In planting fruit trees in a garden or orchard why are we
told to set them deep enough to cover the joint where they
were grafted? How do you explain the fact that we some-
times find more than one kind of fruit growing on the same
tree ? How is it possible for two different trees to become
united when they grow close together ?

134 STEMS

119. PRUNING

Object. — To learn the effect of pruning a plant.

Apparatus. — Any rapid-growing plant, such as geranium, fuch-
sia, or coleus, and a sharp knife.

Method. — Remove the terminal bud from a main branch
and after a week note the result on the growth of the plant.

In this way the shape of plants can be modified.

How does pruning affect the growth of hedges, ornamental
shrubbery, etc. ?

Observation. — Go into the woods after a heavy snow-
fall or violent wind storm. How has nature pruned the
trees ? Examine the trees which grow in the thickest shade.
Look for dead branches caused by overshading.

Examine poplar trees, which are common along city streets,
and willows growing in parks and lawns. Look for branches
which have died because of overshading by neighboring
branches. Trees in which this occurs are said to prune
themselves.

This pruning is probably due to the fact that the branches
which receive the most light do the most work and so demand
the most sap. The overshaded branches, being deprived
of their nourishment, gradually die and drop off.

A study of self -pruning will teach us many things which
will be of use in artificial pruning.

120. PRUNING

Object. — To learn the effect of pruning flowers.

Method. — From a plant which is beginning to bud re-
move all the flower buds but one and remove also all side
branches.

STEMS 135

When it blooms compare the flower with others from plants
which have not been so treated.

How has the pruning affected the flower?

Observations. — How do florists treat the American
Beauty and other popular roses? How do they produce
the splendid chrysanthemums and carnations?

Compare the fruit grown on an unpruned apple tree with
those which have been produced by a tree carefully pruned.

Which tree produces the greater number of apples?
Which one produces the largest and finest apples ?

Find answers to the following questions: 1. Why should
the branches be cut close to the main stem ?

2. Why cut with a sharp saw or knife ?

3. Why would you not prune an elm or a maple tree as
you would an apple tree or a pear tree ?

4. How would you prune so as to produce a bushy plant?

5. When is the best time of the year to prune? Why?

6. Find out names of trees that are pruned for each of the
following purposes : —

(a) To improve the fruit.

(6) To alter the shape.

Nature prunes in various ways. Wind storms and light-
ning rend the trees, causing the weird and grotesque forms
sometimes seen on mountains and sea coasts where the trees
are exposed to the elements.

Reasons for artificial pruning. — 1. Trees which grow
in the open develop a dense mass of twigs and interlacing
branches. (Why?) Such trees will produce great quan-
tities of fruit, but it will be small and of poor quality.
(Why?) By carefully removing such branches as will
interfere with the light of others, larger and better fruit will
be produced. (Why?)

136 STEMS

2. The struggle after light tends to make trees naturally
become tall. By removing those branches which are tallest,
the light is admitted to those farther down, and a tree of
lower habit is the result. This renders the harvesting of
fruit much easier.

3. Since different kinds of trees have different habits of
growth, it is necessary for the orchardist to study his trees so
as to be able to prune them intelligently. Many valuable
fruit trees have been injured through improper pruning.

4. Ornamental shrubbery is pruned to modify the shape.
Catalpa, mulberry, privet, box, bay, and osage orange are
familiar examples of plants which are pruned in this manner.

When to prune. — The time for pruning depends on the
object. Winter pruning is performed when wood production
is desired. Summer pruning leads to the production of fruit.
August pruning is practiced by orchardists. Hedges are
pruned in March before the spring buds have started.

How to prune. — The best implement for pruning large
branches is the saw. Smaller branches are removed with
pruning shears. After a tree is bearing, the terminal buds
can be pruned by merely pinching off in late summer.

In removing branches the cut should be made close to
the trunk. A stump should never be left projecting from
the main branch, for it furnishes a good place for decay to
set in. Suckers from the root should always be kept cut
away, since they often come from below the graft and hence
they would produce inferior fruit if left to grow. The freshly
cut surface of the stump should be painted over to exclude
decay germs. In case of splintered branches broken by
storms the boughs should be sawed off and painted. All
diseased branches should be removed to prevent the spread
of infection to other parts of the plant.

STEMS 137

Query. — Compare the number of strong, healthy buds
on any twig with the number of weak, small, and dormant
buds. How many of each?

What are the good results of pruning? What are the
bad results of overpruning ? Of insufficient pruning ? What
is the effect of pruning the lower branches ? How can prun-
ing cure a crooked tree? Why is the lilac shrub pruned
differently from the forsythia? Why do we pinch out the
terminal buds of coleus plant used in bedding ? How does a
plant cover its wounds ?

121. GIRDLING

Object. — To find out the effect of -girdling on a woody-
stem plant.

Apparatus. — Any common tree or shrub, and a sharp knife.

Method. — With a sharp knife carefully remove a strip
of bark two inches wide clear around the stem about three
feet from the end, and cut in deep enough to sever the living
part (cambium) which lies just inside the bark. Observe
the twig from day to day and make note of the result. How
does Experiment 114 explain the result?

Conclusion. — State the effect of girdling on the part
beyond the wound.

Note. — In girdling trees the incision is usually made deeper than
the cambium, for there is considerable sap in the outer rings (sap-
wood). The object is to cut off all upward flow of sap from the
root.

Reference Work

Directions. — Weigh two potatoes of about equal size
and carefully peel the heavier one until they weigh alike.
Now leave them lying side by side in a dry place where there
is free circulation of air for several days. Reweigh.

138 STEMS

Result? Why? Of what use to the potato is the skin?

(a) Remove a ring of outer bark one inch wide from a
stem. (6) From another stem remove a similar ring, but
cut deeper, going through the bark to the wood. How do
the results in (a) differ from those in (6) ? Why ?

Select any common woody-stem plant and with a sharp
knife cut from one side a wedge-shaped piece, cutting in
almost to the center. After some days examine the wound
and see how nature heals it.

122. REPAIRING WOUNDS

Object. — To learn how a plant repairs injuries.

Apparatus. — Growing plants, a saw, and a knife.

Method. — Cut off a branch of a plant, and after several
days examine the cut-off end and notice how it has healed.
Compare woody with herbaceous stems in this respect. Go
into an orchard where branches have been removed in pre-
vious years. Notice how the tree has healed and is gradually
covering up the wound.

If possible, cut a lengthwise section through the stump of
a branch which has been pruned and has partly healed over.
Where does the new tissue form in healing over an ampu-
tated limb?

Conclusion. — State how a tree repairs injuries and where
the new growth occurs.

123. TURGOR

Object. — To show the effect of turgor on rigidity of
young plants which have no mechanical tissues.

Method. — Remove a young bean or pea plant which has
been grown in sawdust. Immerse it in water for a few
moments until it has become quite stiff.

STEMS 139

Now transfer it to a 5 per cent solution of common salt,
and let it remain for a short time. Again note rigidity.
What has happened? Put it into water again and note
the result. Explain. Compare the behavior of these plants
with roots treated with strong fertilizers.

124. TURGOR

Object. — To show the effect of turgor on a dandelion.

Method. — Split a dandelion flower stalk into two or four
parts. What happens? Place it in clear water for five min-
utes. What occurs? Remove it and immerse in 5 per cent
salt solution. What happens ? Return it to water and note
the result. What causes these changes of curvature?

125. TURGOR

Object. — To show the effect of turgor on beet root.

Method. — Immerse some thin slices of beet root in water
and after ten minutes examine them. Now place some in 5
per cent salt solution and others in strong syrup of sugar.
After one or two hours examine. How do those in the salt
solution and those in the sugar solution compare with those
which have been left in the water ? Repeat this experiment,
using slices of cooked beet instead of raw beet. Is there
any difference in the results ?

Then place those which were in salt and those which were
in sugar again in fresh water. Examine again after half an
hour. What result? Why?

Query. — How are these experiments related to those
on osmosis? How do they tend to explain the recovery of
plants after a shower ?

140

STEMS

126. TURGOR
Object. — To illustrate turgor.

Method. — Fill a 30-cc. vial to the brim with a saturated
solution of sugar or very thick syrup. Tie over the top a

piece of fish air bladder or
sheep gut which has been
thoroughly soaked in water.
Be sure that no air is con-
tained in the bottle.

Immerse the whole in a
beaker of water and let it
stand for forty-eight hours.
Remove it from the water
and notice the condition of
the membrane. How does
it differ from its previous
FlG-55' condition? Why?

Now puncture the membrane with a fine needle. What'
happens when the membrane is punctured? Explain this.

127. TURGOR
Object. — To show the effect of turgor in an egg.

Method. — Place an egg in a cup. Cover with vinegar or
dilute acetic acid and let it stand until the shell has been
dissolved. If vinegar is used, this will require twelve hours.

Immerse the egg in a glass of water for one or two hours.
Remove it and examine the egg. Is it hard or soft? How
do you account for its condition? Now place the egg in a
saturated solution of salt and after two hours again examine
it. What difference ? Return it to the water. What result ?

STEMS 141

Food Storage in Stems

Suggestion. — Test various edible stems, such as potato,
onion, artichoke, asparagus, etc., for the various nutrients.
Which are richest in starch? Sugar? Protein?

Test stems of canna, Indian turnip (Jack-in-the-pulpit),
and any other plant having fleshy stems. Do they contain
food materials? If so, why are they not cultivated for food
by man?

Poisons in Stems

Cut a bit of Indian turnip corm and touch it to the tongue.
Describe the taste. Of what use are such substances to the
plant?

XII. LEAVES

128. LEAVES

Object. — To learn the parts of a simple leaf.

Apparatus. — Leaves of such common plants as elm, maple,
geranium, apple, and oak, with portions of the branch on which
they grow.

JBtethod. — Be sure to have the leaf entire. Examine
it. How many parts does it have ? A typical simple leaf

has three parts, blade or
lamina, leafstalk, and stip-
ules. One or two of these
parts may be wanting.
How many parts has each
of the leaves examined?
Examine many plants and
determine which have per-
fect leaves and which have
one or more parts lacking.
Draw one or more leaves,
naming all parts.

Conclusion. — Name the
parts . of a complete leaf
and state where each part

FIG. 56. — Parts of a leaf. is located.

Exercise on the Modification of Simple Leaves

Blade. — Compare leaves of willow, mullein, yarrow,
daisy, sunflower, nasturtium, water lily, thistle, dandelion,

142

LEAVES 143

maple, grape, etc., as to size, surface, outline, color, shape,
and any other differences. Which are broadest in propor-
tion to their width? Which are rough, smooth, glossy,
downy, etc.?

Make collections of leaves, ' press them, mount them on
cards, and label them for future reference.

Petiole or Leafstalk. — Compare leaves of poplar, cherry,
beech, burdock, tiger lily, tropaeolum, sycamore, pitcher
plant, water hyacinth, etc., as to length, shape, size, color,
appendages, etc. Why are the leafstalks of upper leaves
of maple and horse-chestnut shorter than those of the leaves
farther down the stem? Compare leafstalks as regards
special functions. Of what use is the caplike base of the
sycamore (platanus), the inflated petiole of the pitcher
plant, the swollen spongy petiole of the water hyacinth,
the grooved petiole of the burdock and celery, and the ten-
dril-like character of the tropaeolum and clematis?

Stipules. — Procure leaves of pansy, locust, sweet pea,
smilax, apple, rubber plant, tulip tree, red clover, rose bush,
etc. Be careful to secure the entire leaf. Stipules often
are so firmly adherent to the stem as to remain attached
when the leafstalk is broken away. Some plants also shed
the stipules when the leaf unrolls and are supposed to have
none when in reality these stipules have already been shed
(caducous or evanescent). Notice the modification of stip-
ules. Which help to climb? Which act as a means of
defense? Which are leaflike? Which seem to be solely
for protection of the bud?

Make sketches showing all forms of stipules seen. Which
ones fall off at the opening of the bud ? Which ones remain
permanently attached to the stem? Study the stem of a
rubber plant; sketch the terminal bud with its interesting

144

LEAVES

protecting scale (stipule). Note the stipular scars which
surround the stem at each node. Collect, press, mount, and
label a card of stipules.

129. LEAVES

Object. — To learn something of the framework of
leaves. (a] Parallel Veining, (b }Net Veining.

(a)
Apparatus. — Leaves of grasses, lilies, calla, canna, banana, etc.

Method. — Examine the leaves chosen and make out
the fact that the framework of these leaves is alike in the

general parallelism of the
veins. Arrange them in
two groups, according to
the direction of their veins,
lengthwise and crosswise.
To which group does the
onion belong ?

Tear one of these leaves
and observe that the tear
follows the direction of the
veins.

Conclusion. — How many
types of parallel veining are
there? How do they differ?

(*)

Apparatus. — Leaves of
apple, oak, or poplar. Any
firm-veined woody plant will
FIG. 57. — Parallel veining. do.

LEAVES

145

FIG. 58. — Net
veining.

Method. — Examine the leaves selected, giving special
attention to the under surface where the veins are more
prominent. The network is easily discovered
in most' leaves, but in cases of some leaves it
will be necessary to hold them between the
eye and the light. Fleshy leaves often do
not show their net veining because there is so
much pulp in them. Tear a leaf as in the
preceding Experiment and note how irregu-
larly it tears. Why? Study the general
plan of the veins and discover if possible the
general scheme of veining.

Conclusion. — How many types of net-
veined leaves can you find?

Note. — The veining of leaves usually indicates the kind of plant,
whether monocotyl or dicotyl.

Parallel veining is never found in dicotyl plants, and net veining
very rarely in monocotyl plants.

Such monocotyls as arrowhead (sagittaria), elephant's-ear
(caladium), and a few others seem to have net venation, but a close
examination will show that the veins run generally parallel with each
other and only the large ribs form a sort of network.

Leaf Impressions

For greater ease in studying leaves, the use of leaf impres-
sions is very helpful. They may be made in the following
manner : —

Apply a preparation of vaseline and lampblack to the under
surface of the leaf, using a dabber made of tightly rolled
cotton batting covered with chamois skin.

The leaf should be touched lightly all over its under sur-
face, and great care should be used not to have much of the
preparation on the dabber.
EXP. BOT. — 10

146 LEAVES

The leaf, coated with the preparation, is laid upon the
paper upon which the impression is to be made and placed
between two folds of cardboard. Run this through a
clothes wringer, and the impression will be complete.

A little practice will enable one to produce beautiful im-
pressions which surpass half-tones in delicacy and accuracy.

Note. — How to make the impression ink. Mix thoroughly
together a tablespoonful of vaseline with a teaspoonful of lamp-
black. Melt the mixture and stir it until it is uniformly black.

How to use it. Place a small portion of the preparation on the
middle of a plate of glass. What can be taken on the point of a
knife blade is plenty.

Spread this ink evenly over the glass by dabbing it with the dabber
mentioned in. the preceding exercise, and use the plate as long as
any ink remains upon its surface.

In this way there will be no unevenness in the blackness of the
impressions.

If carefully made, the finest details of veining, outline, and sur-
face features will be distinctly shown.

Skeleton Leaves

The framework of many leaves may be studied from their
skeletons. Skeleton leaves are very beautiful, are easily
made, and are useful for study. As permanent mounts under
glass they are an attractive addition to the school museum.

Skeleton leaves are made as follows : —

(a) Select leaves having a more or less firm framework,
such as oak, elm, apple, holly, and beech. The Judas tree
(cercis) is the easiest leaf to skeletonize.

(6) Place the leaves in a saucepan with enough water to
cover them and add a heaping tablespoonful of cleaning
powder. Set it over the fire and let the solution boil for
fifteen minutes. This cooks the pulp.

LEAVES

147

(c) Remove the saucepan from the fire, place the leaves
in a basin of clear water, and allow them to remain for a few
minutes. This removes the alkali.

(d) Place one leaf on a dinner plate and let water drip
on it. The leaf will spread out upon the white surface of
the plate, and the

water will remove the
pulp, leaving the net-
work clean.

(e) A little bleach-
ing powder can be
used if it is desired to
bleach the specimens,
and solutions of log-
wood or aniline dyes
can be employed if
one wishes to stain
them. But the natu-
ral color of the veins
is best.

(/) After the pulp
has been removed, the skeleton can be transferred to blot-
ting paper and laid in a book until thoroughly dry.

(g) Mounted under glass, they will keep indefinitely for
class use; and if placed between two glasses, they make
handsome transparencies. They may also be used in lantern
slides, where they are very effective.

Suggestion. — Mount a bit of skeleton leaf on a micro-
scope slide in a drop of water. Cover it with a cover glass
and examine it with a low power. If the skeleton leaf has
been carefully prepared, the terminations of veinlets will
be seen. Draw. Permanent mounts may be made by

FIG. 59. — Skeletonized leaf of Judas tree.

148

LEAVES

immersing the specimens in absolute alcohol for a short
time to remove any water which may be in them. Then
transfer them to xylol, after which they may be mounted
in a drop of Canada balsam.

Whole leaves skeletonized may be placed between plates
of glass, and passe partout tape or gummed paper may be
used to bind the plates together.

The Use of Blue Prints in Leaf Study

Lay leaves of all forms upon sheets of blue print
paper, arranging them with reference to . different forms

or other character-
istics.

This should be
done in a shady or
semidark room.
Cover them with a
glass plate and then
expose them to di-
rect sunlight for two
to five minutes. Then
remove them to a
shady place and wash
them thoroughly in
pure water for five
minutes.

These blue prints
can be dried between
blotters and mounted
while still damp or
kept unmounted for

FIG. 60. — Specimen of blue print work. reference.

LEAVES 149

Series of blue prints illustrating forms of apex, base, mar-
gin, shape, and any other conspicuous features may be so
prepared, also many flowers, flower clusters, and such deli-
cate objects as thistledown, milkweed seeds, and feathers.

Formula for Blue Print Paper

Solution I. Potassium ferricyanide . . 1 oz.

Water (distilled) 5 oz.

Gum Arabic 1 drachm

Solution II. Iron-ammonia citrate (green) 1| oz.

Water (distilled) 5 oz.

Gum Arabic 1 drachm

Directions for using — Mix equal parts. Coat paper in
the dark by use of oil lamp or yellow light. Dry the paper
quickly by heating and keep it in a dry, dark place. Select
by preference a paper which has a good sizing, such as fools-
cap. The mixed solution should have a wine color, and the
dry paper a lemon yellow. Print until the dark parts are
bronzed and wash the paper thoroughly in cold water.
Prints can be brightened by adding a trace of citric acid
to the last water.

Note. — No rule can be given for the time required for exposure,
since blue print papers vary in sensitiveness to light and the objects
used are so different in thickness. Thus the so-called " French-
satin-junior " paper is very sensitive, while many of the common
papers used by architects require a great deal longer time for ex-
posure. Objects like feathers, thistledown, and semitransparent
leaves may require but a minute, while old leaves may be exposed
for an indefinite time.

A little practice will show the experimenter how to get the best
results.

150

LEAVES

s

130. LEAVES

Object. — To find out the
relation of fomn to tlte
framework of leaves.

Apparatus. — Leaves of (a)
beech or elm, and (6) maple
or ivy.

Method. — These leaves
represent the two types of
net- veined leaves, known as
feather-veined and palmate-
veined.

Lay the leaves down and
compare their system of

FIG. 61. — Feather-veined leaf .

veining and the gen-
eral outline. How
many principal veins
has the ivy or the
maple? How many
points to the outline ?
Does the number of
principal veins corre-
spond in any way to
the number of lobes
of the blade? In the
beech and elm does
the shape have any

FIG. 62. — Palmate-veined leaf .

LEAVES 151

relation to the framework? Trace one of the main veins
to its termination. What do you find there? Is there
any relation between the feather veining and the outline?

Conclusion. — State the relation of form to framework
of leaves.

131. LEAVES

Object. — To find out where tl\e sap flows in a leaf.

Apparatus. — Stems bearing leaves or leaves with long leaf-
stalks, a bottle, and eosin solution.

Method. — Treat the leaves in the same manner as the
root was treated in Experiments 75 and 113. Where does
the leaf become stained? Cut off sections of the leafstalk
and see if you can tell where sap flows in that part. If this
experiment is made with large, coarse leaves like rhubarb,
burdock, celery, or cabbage, some very pretty results will
follow.

Conclusion. — State what part of the leaf furnishes a
channel for sap circulation.

132. LEAVES

Object. — To show that leaves exert an upward pull on
sap flow.

Apparatus. — A vigorous young shoot of ailanthus or other
equally strong plant, rubber tube, glass tube, beaker, retort clamp,
and mercury.

Method. — Cut off the branch under water to prevent
entrance of air at the cut surface.

Fit the piece of rubber tubing tightly about the stem and
insert the other end in the glass tube, fitting it air-tight.
Wax the joint as an additional precaution and fill the glass

152

LEAVES

FIG. 63.

tube with water which has been dis-
tilled or boiled to expel any air. Stand
the tube over the beaker of mercury as
shown in Figure 63.

After a few hours note what has oc-
curred. How do you account for the
result ?

Conclusion. — Your inference from this.

Note. — The effect of light on the root was
shown in Experiment 94 and its influence
on stems was seen in Experiments 103 and
104. We will now make similar experiments
and see how light acts on leaves.

133. LEAVES

Object. — To discover the effect of light
upon foliage.

Apparatus. — The dark box used in Experiment 51, also another
similar box having a small hole or window with an interior cut-off
so arranged as to prevent the direct rays from reaching the plant
within. Plant some young vigorous seedlings in small pots.

Method. — Place a plant in each dark box and also one
outside where it will receive plenty of light. Let them remain
for several days and then compare them.

Observe the following: —

(1) Color of each plant.

(2) Vigor or weakness of its growth as compared with
the others.

(3) Position of the plant in the box.

(4) Size of the leaves.

(5) Length of the internodes.

Conclusion. — What may be inferred regarding the effect
of light on foliage ?

LEAVES

153

134. LEAVES
Object. — Same as in Experiment 133.

Apparatus. — A vigorous potted plant, cork disks made by mak-
ing thin sections of an ordinary bottle cork, and pins.

Method. — Place the cork disks upon leaves so as to
cover opposite faces and hold them in place with a pin
(Fig. 64). Leave the disks in place
for three or four days, then remove
them and note the result (Fig. 65).
Conclusion. — What is the effect
of shutting off light from any part
of a leaf ?

Query. — Why do gardeners bank
up their celery? What is the
effect? What other crops are
bleached in this way?

Fold a piece of black felt or
thick black paper and punch or cut
a hole through both folds. Then
lay a leaf between the folds and pin it so that it will remain
in position. The leaf will thus be covered with only that
portion exposed which is under the hole.

Set the plant where it will be
exposed to strong sunlight and
leave it for three or four days.
When the covering is removed the
leaf will show a green spot where
the surface was exposed. All the
remainder of the leaf will be pale
or almost white (Fig. 66).
FIG. 65. Suggestions. — Select a plant of

FIG. 64.

154

LEAVES

FIG. 66.

erect habit and notice the position of the leaves with
reference to the stem on which they grow.

Now bend a branch over and
weight it so that it will occupy
as nearly as possible a horizontal
position.

After a few days remove the
weight and bring the branch back
into its original position. What
is the position of the leaves now?
How do you account for this
change ? Observe the same branch
again after another week. What is the position of the
leaves now ? (See Ex. 149.)

Compare erect with drooping branches on deutzia, snow-
ball, and other garden shrubs.

135. LEAVES
Object. — To study the direction of growth.

Select a young vigorous sunflower plant growing in a
flowerpot. A plant having four or five leaves is a con-
venient one for the purpose.

Lay the flowerpot on its side between two blocks. (1)
Make a sketch of the plant. (2) After an hour or two
observe the plant. Note any change of position in leaf or
stem and sketch it again. (3) Continue making observa-
tions and sketches until the stem has assumed a vertical
position.

Which responded to the change of position, leaf or stem ?
Which part of the stem was first to change its position?
What leaves were first affected? Which last? Which,
if any, not at all ?

LEAVES 155

Select a vigorous potted plant of sunflower or tropaeolum
and lay the flowerpot on its side. On a sheet of paper make
a diagram of the flowerpot and one or two fresh young leaves.
Let the flowerpot remain so for a day, then make a sketch
in dotted lines on the diagram, showing the new position of
the leaves.

Suggestion. — Observe a geranium which has been grow-
ing in a window box for some time. How do the plants on
the sunny side compare with those on the shady side as
to the position and number of their leaves?

Note. — Good examples of both negative heliotropism and nega-
tive geotropism are seen in such vines as climb by adventitious
aerial roots. In the trumpet creeper (tecoma) the climbing roots
project away from the sun and away from the soil. Prove this
by the following experiment: —

Choose a stem on which the roots are beginning to attach them-
selves. Turn the stem half round so as to get the roots into the
light. Fasten the vine to prevent its return to the former position.

After one week, observe it. Have the roots responded to the
change of position?

136. LEAVES

Object. — To show that plants give off water.
Apparatus. — As shown in Figures 67 and 68.

Method. — Cover a plant as in Figure 67, using rubber
tissue or waxed paper to cover the soil and a wide-mouth
bottle inverted over the plant. Or use a tumbler over a
leaf as shown in Figure 68, letting the petiole project through
a hole in the card which covers the battery jar, and plug
the hole around the stem with cotton batting.

When the plant has been arranged according to one of
these ways, stand it in a shady place or one where the sun-

156

LEAVES

shine does not fall strongly, and await results. After half
an hour what do you find forming on the inside of the glass
or tube ? How do you account for this ?

FIG. 67.

FIG. 68.

Conclusion. — State what this experiment proves.

Query. — If leaves are constantly giving off water, how does
it affect the air ? How do you account for its wilting when
a leaf is removed from its stem? Why does the United
States government encourage tree planting in the Western
states ?

137. LEAVES
Object. — To show that leaves give off water.

Apparatus. — Two tumblers, blotting paper, two leaves, and two
plates.

Method. — Line one tumbler with blotting paper and
dampen it, but do not have it wet enough to drip. Wipe
the other dry. Place a leaf in each tumbler and cover them
with the plates. After one hour remove both leaves. How

LEAVES 157

do they differ in appearance? Give the probable reason.
Do you find any moisture in the glass which was dry at the
start?

Suggestion. — Place a spray of hydrangea in a bottle of
water. Set it in one scale pan and balance it. What
happens after an hour or two? Why? How do you ac-
count for it?

Repeat the experiment, using a potted plant in a scale pan,
having first sealed the pot with paraffin paper. Then
counterpoise it.

Procure three test tubes or slender bottles of the same
size and shape. Fill them three fourths full of water and
mark the level with a thread or rubber band. Label the
tubes a, 6, and c. Now select from the same plant or from
plants of the same kind two branches of equal size and bear-
ing the same number of leaves.

Place them in two of the tubes thus : —

(a) Tube open, containing nothing but water.

(&) Tube open, but containing a branch from which the
leaves have been removed.

(c) Tube open, containing the other branch bearing all
its leaves.

After six hours note the level of the water in each tube.
Which tube loses most water? How do you account for
the difference?

138. LEAVES

Object. — To find out the relative amount of mineral
matter in leaves.

Apparatus. — Young leaves from new shoots and old leaves
fallen from the same tree, evaporating dishes, and Bunsen burner.

158 LEAVES

Method. — Dry the leaves thoroughly and burn them.
Which leaves contain the greater amount of ash? Account
for this.

Conclusion. — State whether young or old leaves contain
more mineral substance.

Note. — Compare the crust of lime left in a teakettle with the
mineral left in a leaf. What corresponds to the steam that comes
from the kettle ? Trace a drop of water from the soil through a
plant until it returns to the atmosphere.

How do you account for the presence of potash in wood ashes ?

139. LEAVES

Object. — To find tlw cause of wilting and recovery.

Apparatus. — Leaves of hydrangea or other similar plant,
tumbler, and water.

Method. — Cut off a leaf and let it lie upon the table in
the sunlight until it is wilted. Then place the leafstalk
in water. What happens? Repeat the experiment, put-
ting only the blade in water. Does it recover ?

Conclusion. — What causes a leaf to wilt ? What causes
it to recover? How does water get into the leaf? Where
does it go out?

140. LEAVES

Object. — To find out which surface of a leaf gives off
most water-

Apparatus. — Four leaves of hydrangea or other plant of similar
kind which wilts easily, vaseline, or olive oil.

Method. — Suspend the four leaves by threads so that all
surfaces will be equally exposed to the air.
No. 1. Leaves in natural state.
No. 2. Coat upper surface with vaseline.

LEAVES

159

No. 3. Coat lower surface with vaseline.

No. 4. Coat both surfaces with vaseline.

Also vaseline the leafstalk of each leaf. After a few hours
make observations on all the leaves. Re-
sult ?

Conclusion. — Which surface gives off most
water ?

141. LEAVES
Object. — Same as in Experiment 140.

Apparatus. — Two watch glasses, any plant
with large succulent leaves, and a rubber band or
other means of fastening the glasses in place.

Method. — Place the watch glasses on
opposite sides of the leaf and allow them
to remain there in a shady place for some
time.

In which glass does most of the dew
collect?

Conclusion. — Same as in Experiment 140. FIG. 69.

142. LEAVES

Object. — Same as in Experiment 140.
Apparatus. — Cobalt paper,1 leaves, and plates of glass.

Method. — Dry the cobalt paper over the flame of a lamp.
Lay a dry leaf between two pieces of the dried cobalt paper.
Place the whole between plates of glass which have been
wiped perfectly dry.

1 Cobalt paper is prepared by wetting filter paper with a solution
of cobalt chloride. Dry it thoroughly over a gas flame until it be-
comes blue. Dampness in air will cause the blue to disappear and
the paper will become red.

160 LEAVES

After ten or fifteen minutes note the result.
What occurs? Which paper changes color more quickly?
What may be inferred from this ?

Note. — Cobalt paper may also be used in the following manner:
If two bell jars are wiped dry and into each a piece of dried cobalt
paper is put, both will retain their blue color indefinitely because
the air remains dry.

But if a plant or branch from a vigorous plant is placed in either
jar, the cobalt paper will soon begin to turn red, showing the pres-
ence of moisture in the air. This moisture can of course come only
from the plant, since the other paper retains its blue color. Other
modifications of this experiment will readily suggest themselves.

Query. — Do thin leaves give off water more quickly or less
quickly than thick ones? Does a cactus yield moisture as
easily as spinach or lettuce ? Compare rhododendron leaves
with rhubarb, and houseleek with geranium.

143. LEAVES

Object. — To find how much water is given off by a
plant in a given time.

Apparatus. — A small, healthy potted plant having large leaves,
rubber cloth, and scales.

Method. — Weigh the plant after having watered it and
covered the flowerpot and soil up to the stem with the
rubber. The only exposed surface will thus be the stem and
other parts above ground:

After three or four hours weigh the flowerpot again and
note the loss. If the plant has been carefully covered, the
loss must be due to water transpired through the leaves.

Conclusion. — Answers will vary with kind of plant,
number of leaves, and conditions of moisture in the atmos-
phere.

LEAVES

161

Rate
oj transpiration.

144. LEAVES
Object. — To measure the amount of transpiration.

Method. — Magin's apparatus to measure the amount of
transpiration is shown in Figure 70. Push into one arm of a
U-tube a rubber stopper
through which a leaf or
branch has been passed.
Fill the tube with water
and into the other arm
push a stopper through
which passes a long piece
of glass tube bent at
right angles near the
stopper. The water
should not only fill the
U-tube but extend out
into the tube. As the FlG- 70-

plant transpires, the water contained in the tube will gradu-
ally move along the tube towards the U-tube. The rate at
which it moves along will indicate the rate of transpiration.

Suggestion. — Lay two large leaves like those of the hy-
drangea on a table in sunshine until they have begun to wilt.
Then place one with blade under water and leafstalk out
in the air. Place the leafstalk of the other in water with the
blade in air. After an hour or two what change has taken
place? Do both act alike? Account for the difference if
they are not alike.

What may be inferred from this experiment?

Do leaves absorb water from their surfaces ?

How are leaves of cabbage, mullein, caladium, and water
lily adapted to prevent wetting?
EXP. EOT. — 11

162

LEAVES

145. LEAVES
Object. — To show that leaves give off oxygen.

Apparatus. — Battery jar, funnel, test tube, and some water
plants, such as nitella or other submerged pond plants.

Method. — Place the plants in water in the battery jar,
invert the funnel over them, and fill the test tube with water

and invert it as in
Figure 71.

Set the whole ap-
paratus in the strong
sunlight. What hap-
. Battery jar pens? Remove it

to a shady place.
Result ? Again set
the jar in sunlight
and allow to remain
until the test tube
is filled with the
gas.

Remove the test
tube and test for
oxygen with a glow-
ing splinter as in
Experiment 1.

Conclusion. — State the result of your test.

Note. — If the water about the plants is charged with a little car-
bon dioxide before this experiment is made, there will be much
more oxygen produced than if ordinary water is used.

Generate the carbon dioxide with marble and sulphuric acid ;
otherwise proceed as in Experiment 3 and pass a little of the gas
through the water.

\0x\jgen bubbles
escaping.

.Water plant.

FIG. 71.

LEAVES 163

Sulphuric acid is preferable for two reasons : first, because it sets
the gas free less rapidly than does the hydrochloric acid; and
second, there are not so likely to be any acid fumes which might
injure the plants.

To Teachers. — It is sometimes preferable to charge the water
before the class-room experiment.

If the class is advanced, the charging had 'better be done during
the class-room experiment, but with young students the more
simple and direct the experiment, the better.

Suggestion. — Procure a branch of some water plant
such as potamogeton or other aquatic plant having stems
of good size.

Tie the branch to a glass rod and place it in a tall beaker
or battery jar of water so that it will be entirely submerged.

Now place the jar on the window ledge where it will
receive plenty of strong sunlight.

Observe the plant. Do any bubbles collect on the leaves ?
If so, what are they? Look at the cut-off end of the stem.
What occurs there? What is it? Give reasons for your
answer. Of what advantage are hollow stems to water
plants? Do the hollow stems of land plants like bamboo,
rush, etc., serve the same purpose? Reasons for your
answer.

146. STOMATA (optional)

Object. — To demonstrate the presence of stomata.

Method. — With a sharp knife peel off a strip of skin from
the under surface of any leaf and mount it in a drop of water
or glycerin under a cover glass. Examine it first with a low
power to see the cells of which the skin is made and note the
large number of kidney-shaped cells in pairs placed with their
concave sides together. These are the guard cells. Between
the guard cells will be seen a narrow slit, the stoma, through

164 LEAVES

which air is taken into the leaf and air and moisture are
given out.

Compare the upper and under surfaces of the same leaf.
How do they compare in number of stomata ? Do your
observations in this respect agree with the results of experi-
ments on transpiration ?

Note. — The epidermis of iris, lily, onion, houseleek, and fern
are easily removed.

147. CELLS (optional)

Object. — To demonstrate the cellular structure of
leaves.

Method. — Mount bits of skin of leaves or thin slices of
pith in water or glycerin and study the individual cells.
Make out the following points of cell structure : —
(a) The cell wall.
(6) The cell contents (protoplasm).

(c) The chloroplasts , or grains of yellowish green material
which are found in some of the cells.

(d) The nucleus, a sort of kernel or denser mass usually
near the center of a living cell.

If the nucleus is not clearly seen, place the section in
methyl green for a few minutes, and it will usually become
stained.

Make drawings of as many different forms of cell as you
are able to find.

Onion and lily epidermis have cells which are very unlike
those of fern. Pith cells are very unlike guard cells in shape.

Root hairs are epidermal cells of the root which are pro-
longed outward, increasing the absorbing surface of the
root (Ex. 91). Cells of endosperms (Ex. 40) contain
starch.

LEAVES 165

In Experiments 214-220 cells of yeast are considered.

Note. — For general consideration of the cell and protoplasm see
also Experiments 226-228.

148. LEAVES
Object. — To show that leaves purify the air-

Apparatus. — A healthy, freshly cut shoot of any vigorous green
plant, two tumblers and a shallow basin of water, vaseline, a piece
of glass or rubber tube ten or twelve inches long, and two. pieces
of plate glass three inches square.

Method. — Fill both tumblers with water to exclude the
air. Into one of them place the shoot, top down. Now
invert both glasses a b

under water so that
they stand as in Fig-
ure 72. By means
of the tube blow

into each tumbler

, ., ,, FIG. 72.

until they are com-
pletely filled with impure air from the lungs.

Set the tray containing the inverted tumblers in a sunny
window and leave it there for two or three days.

After two or three days grease the two glass plates lib-
erally with vaseline. Then very carefully slip them under
the tumblers so that they shut them air-tight.

Now with a burning stick test the contents of each tumbler.
Is there any difference in the way the stick burns in these
two glasses ? Both originally contained impure air from
the lungs. What is the difference between the contents of
these tumblers now? Can you account'for this?

Conclusion. — State what effect plants have on the air.

Query. — Give reasons why the planting of shade trees

166 LEAVES

is an advantage. Why are parks desirable in crowded cities ?
Why is the air in the country purer than city air ? Is it a good
thing to cultivate plants in the house ? Did this experiment
require light? If so, is there any reason why we should not
have large numbers of house plants in a sleeping room?

Suggestion. — Repeat this experiment, using gas formed
by burning a taper under the glass instead of using air from
the lungs.

With advanced students this experiment may be varied
by filling the glass with different gases. Will a plant re-
move hydrogen? Oxygen? Pure carbon dioxide generated
by action of acids on marble ?

149. LEAVES

Object — To show that leaves make starch.
Apparatus. — Green leaves, alcohol, lamp, and iodine solution.

Method. — Place any green plant in the strong sunlight
for a day. Then snip off a leaf and plunge it into boiling
water for one minute. Remove it from the hot water and
immerse it in alcohol. What is the effect of the heating and
alcohol upon the appearance of the leaf ?

Now add a drop of iodine solution to the bleached leaf
and after a minute remove it and rinse it in water. •

Examine the leaf to detect blue color due to the presence
of starch.

Or, scald in water leaves treated in Experiment 134 and
treat them as above with alcohol and iodine solution. The
exposed spot will take on the characteristic blue of the starch
test, while the remainder of the leaf will show no trace of
starch.

Conclusion. — State the result of these experiments as to

LEAVES 167

the relation of light to green coloring matter (chlorophyll)
in plants, also the relation of these to starch making.

Suggestion. — Repeat this experiment, using a leaf picked
from the plant early in the morning before the sun has
shone upon it. Does the leaf give the same starch tests?
How do you account for the difference ?

Note. — The color of green plants is due to the presence of small
green grains called chloroplasts. They may be seen with a low power
of the microscope if thin sections of leaves be examined in a drop
of water or glycerin. These small bodies have the power of making
starch out of water and carbon dioxide in the presence of sunlight.
In this process, called photosynthesis, oxygen is set free.

The leaf is a sort of factory in which water and carbon dioxide
are the raw materials, the chloroplasts are the machinery, sunlight
is the energy, starch and other substances are the finished product,
and oxygen is the waste product.

Only green plants are capable of making starch.

150. LEAVES

Object. — To prove that it is only in the green part that
starch is made.

Apparatus. — Spotted leaves of such plants as silver-leaf gera-
nium and some varieties of coleus, also &ny dicotyl albino plants,
and the same tests as used in the preceding Experiment.

Method. — Treat the leaves as in the foregoing Experiment
by boiling the leaves for a few minutes in water, then soak-
ing them in alcohol and adding iodine solution. Which part
of the leaf turns blue ? Inference ?

Conclusion. — State what kind of plants and what parts
of plants are engaged in starch making.

Suggestion. — Test mushrooms and other fungi, also red
or yellow plants like dodder, in the same way.

168 LEAVES

Also test monocotyl plants like ribbon grass, tradescan-
tia, etc., which have their leaves streaked with white. Do
the monocotyls give equally good tests for starch? How
do you account for the difference? Test the same plants for
sugar. Result ?

Query. — What has 'been shown in previous exercises as
to the necessity of light for growth of plants ? How does
light affect the direction of growth of stems ? The position
and arrangement of leaves? The vigor of plants? The
color and size of leaves? What substance do leaves absorb
from the air? Does this take place equally in the light
and darkness f What substances are given off by leaves ?
Give proofs for each substance mentioned. What sub-
stances are manufactured by leaves? Can these substances
be made in darkness? What part of the leaf makes the
starch? By what energy? Out of what substances?
What waste product is set free at the same time?

151. LEAVES

Object. — To observe the effect of closing up the sto-
m>ata of a leaf-

Apparatus. — Any healthy plant, preferably one of the common
deciduous plants, and vaseline.

Method. — Without removal from the stem coat both sur-
faces of a leaf with vaseline, being sure to cover all stomata.
After three or four days apply tests for starch and sugar.
What result?

Conclusion. — State whether air is needed by a leaf to
make starch.

Query. — How may this be explained ? What happens to
a leaf which has been coated with vaseline if allowed to re-
main attached to the stem ?

LEAVES 169

152. LEAVES

Object. — To show that leaves give off carbon dioxide.

Apparatus. — Two wide-mouth jars, two vials of limewater, and
leaves.

Method. — Put about one inch depth of water in each
jar. Into one jar put a number of vigorous leaves so that the
leafstalks are in water and their blades in the air of the jar.
Leave the other jar as a control. Place a vial of limewater
in each jar so that it does not mix with the water of the jar.
Cover both jars and set them away in a dark closet for a
day or two. Examine the limewater in each jar. Which
gives the better test for carbon dioxide ? Explain.

Conclusion. — What does this show concerning respira-
tion of plants?

Note. — There is a trace of carbon dioxide in the air. Hence
there will usually be a thin scale of carbonate on the surface of the
limewater in each vial.

153. LEAVES

Object. — To show that young buds respire and give
off heat.

Apparatus. — Same as in the preceding Experiment, a thermom-
eter, and several expanding leaf buds of horse-chestnut, hickory,
ailanthus, or maple.

Method. — Same as preceding. Test the temperature with
a thermometer from time to time and compare it with the
temperature of the air outside.

Make similar observations with the apparatus in the light.
Are the results alike in both cases ?

Conclusion. — What may be inferred from this experiment ?

170 LEAVES

154. LEAVES

Object. — To study the fall of a leaf.

Apparatus. — Any healthy deciduous plant such as maple, ash,
ailanthus, hickory, or horse-chestnut, a large black cloth or a dark
box.

Method. — Cover the leaves of one branch or cover one
leaf with the cloth, haying first dampened it, or place the
leaf in a dark box and stop up the aperture so as to shut
out light. Let the apparatus remain for at least a week,
then remove the coverings and note the result.

Note. — The leaf will usually drop off and its leaf scar on the
stem will be found as in autumn.

Conclusion. — How may this be explained ?
Query. — Why do leaves on a tree, where they are over-
shaded, turn yellow and fall during the summer ?

Food Storage in Leaves

It has been shown that green leaves manufacture foods.
In some plants the various food products are transferred to
other parts of the plant and stored there. The fleshy roots
and stems have been shown to be storage places for food.

In some plants the leaf is also used to store food.

In the foregoing experiments we have found starch in the
leaves after exposure to sunlight.

Suggestion. — Test leaves of lettuce, spinach, cabbage,
celery, etc., for starch by first soaking in alcohol to remove
the chlorophyll and then look for blue color after treating
with iodine solution. For sugar macerate the leaves in
water, filter, and test for sugar.

For oils and fats dry the leaves and treat them with
alcanna solution or with Soudan III.

LEAVES

171

Leaf Modifications showing Adaptation of Form to Function

MODIFICATION

FUNCTION

EXAMPLES

Foliage

starch making,

respiration,

transpiration, etc.

most plants

Spines

defense

cactus, barberry

Tendrils

climbing

pea, gourd

Thickened

food storage

houseleek

Thickened

water storage

agaves

Bulb scales

food storage

onion, tulip

Bud scales

protection of young

branch or flowers

deciduous plants

Floral parts

reproduction

flowering plants

(a) sepals

protection

(6) petals

protection and attrac-

tion of insects, birds,

etc.

(c) stamens

male reproductive

(d) pistils

female reproductive

Bracts

various

(a) as floral parts

dogwood

euphorbia

(6) as spathe

calla, Indian turnip

(c) seed dispersal

basswood

Dissected

various

(a) a light relation

yarrow, ferns

(6) a water relation

water buttercup

water milfoil

water parsnip

Inflated petiole

as a float on water

water hyacinth

Flytraps

capture insects

Venus's-flytrap

sundew

Pitchers

capture insects

pitcher plants

172 LEAVES

Protective Devices of Plants

I. Against transpiration and temperature changes.
By rolling of leaves — corn.
By folding and rolling in bud — all plants.
By hairs — mullein.
By gums, waxes, or resins — cabbage.
By position of stomata — under most leaves.
By protection of stomata — rubber plant.
By fleshy growths — agaves.
By " sleep " movements — legumes.
By absence of leaves — cactus.
By shedding leaves — deciduous plants.
By erect position — compass plants.
By varying position of leaf — rhododendron.
By hugging the ground — rosette plants.
By subterranean growth — tubers, bulbs, etc.

II. Against animals, including man.
By hairs or wool — mullein.
By prickles — rose.
By spines — cactus.
By thorns — honey locust.
By stinging hairs — nettle.
By bitter secretions — tomato.
By poisons — Jimson weed.
By flinty epidermis — grasses.
By hugging the ground — dandelion.
By subterranean growth — tubers, bulbs, etc.

Reference Work

Collect plants mentioned in the foregoing tables and
arrange them with reference to function. Draw.

XHI. PLANT IRRITABILITY

155. PHOTOTROPISM, OR RESPONSE TO LIGHT

Object. — To study the effect of light on the daily
movements cf plants.

Apparatus. — A vigorous young sunflower or sweet clover plant.

Method. — Make observations on the plant early in the
morning of a bright, sunny day, noting the position of the
stem as well as that of its crown of leaves.

From time to time during the day observe it and take
note of any change of direction. At evening, just before
sunset, again make observations and again note the direction
taken by leaves and stem. How does its morning position
compare with that at evening? How may this be ex-
plained ?

After sunset again make observations. Any new change ?

On a cloudy day make similar observations on the same
plant. Result ?

Conclusion. — What may be given as the probable cause
of these movements of plants ?

Note. — The term phototropism has been used here because it
is broader in its meaning than heliotropism. The former indicates
the response to light of any sort. The latter implies response only
to sunlight.

Where possible, experiments should be made with plants under
artificial light.

173

174

156. SLEEP OF PLANTS

Object. — To show the effect of light on the position
and motion of plants.

Apparatus. — Oxalis or clover plants in flowerpots. There
should be two of each sort. Young, healthy plants are preferable.

Method. — Place
one plant in the
strong sunshine for
half an hour and
the other in a dark
closet.

Remove both
plants to a shady
place and compare
their appearance.
Now reverse the
process, putting the
plant which was in
the light into the
closet and the other
in sunlight. After

half an hour again compare. Result? Why?

Conclusion. — State your judgment of the cause of these

movements.

157. SLEEP OF PLANTS

Object. — To study the so-called sleep movement of plants.

Apparatus. — Oxalis or any of the common leguminous plants,
such as clover, sweet clover, desmodium, or locust.

Method. — If the plant is potted, place it in strong sun-
light for half an hour. Observe the attitude of the plant.

FIG. 73. — Sleeping oxalis.
(Photographed by A. H. Lewis.)

PLANT IRRITABILITY 175

Then place it in a dark closet for half an hour and again
observe it. Notice the difference. If the plant is growing
in the garden, study it by day and again by night, using
a lantern. If the plant is large-leaved, like the locust, be
careful to note just where the bending or folding of parts
occurs.

Note. — Many plants have a swelling at the leaf base or petiole
foot. This organ is known as a pulvinus.

Movements of such plants are thought to be caused by variation
of sap pressure in the pulvini.

Suggestion. — Go into the field by night and study plants
by the aid of a lantern. Many of the most familiar plants
will be scarcely recognizable when seen in their sleeping
condition.

158. RESPONSE TO CONTACT

Object. — To learn something of the behavior of sensitive
plants.

Apparatus. — The best plant for this purpose is the greenhouse
sensitive plant, Mimosa pudica, but the wild sensitive plant, Cassia
nictitans, and the sensitive joint vetch may be used. The sundew
and the Venus' s-flytrap are too rare to be available.

Method. — Stroke a leaf lightly with a brush or the
ringer. Wait a minute and note the result. What happens?

If the mimosa is used, a very interesting result follows
if the terminal leaflet is pinched.

Does the motion follow instantaneously like a reflex ac-
tion in animals, or does it spread gradually through the leaf?
Look for pulvini. Do you see any explanation of these
phenomena?

Conclusion. — State what has been learned from this
experiment.

176 PLANT IRRITABILITY

159. RESPONSE TO CONTACT

Object. — To learn something of how tendrils respond to-
stimuli of contact.

Apparatus. — Any tendril-bearing plant, such as gourd, grape-
vine, or prickly cucumber.

Method. — Study the tendrils on a young shoot. Note
how they are coiled. Examine a fully expanded tendril
which has not yet come in contact with anything. Now
bring a piece of cord or slender rod so as to touch it. Re-
move the cord and look at the tendril from time to time for
ten minutes. If no change has occurred, repeat the experi-
ment and again look for a response. Vary the experiment
by hitting a fully expanded tendril two or three sharp taps,
and by placing a string where it will rub gently across a
tendril. Repeat the experiment with very young coiled
up tendrils and again with old ones. Examine a tendril
after it has seized a support. Note the spiral coiling. Is
this alike from end to end? Can you find any part of the
tendril which seems to be more sensitive than the remainder ?
If so, where is this special region?

Conclusion. — State in general terms what has been learned
in this experiment.

Suggestion. — Compare tendrils of sweet pea, smilax, grape,
pumpkin, and woodbine in order to find which respond
most quickly. Compare the leafstalks of tropseolum and
clematis with tendrils in the same way.

160. RESPONSE TO CONTACT

Object. — To find out something of the movement of
twining stems.

Apparatus. — Several twining vines, such as morning-glory, hop,
dodder, and cinnamon vine.

PLANT IRRITABILITY 177

Method. — Study the various plants selected. Observe
the direction in which they coil about a support. Do all
twist in the same direction? if not, which turn from right
to left, and which from left to right ?

Uncoil a stem several turns and try to make it twine in
the opposite direction. Result? See if you can make a
stem which has not yet begun to twist, coil opposite to the
way in which the other branches of the same plant tend to
coil.

Conclusion. — State in general what this experiment has
taught you.

161. RESPONSE TO CONTACT

Object. — To learn something of the irritability of sta-
mens of some flowers-

Apparatus. — Flowers of barberry, mountain laurel, and almost
any mint.

Method. — 1. Examine the position of the stamens and
pistil in a cluster of barberry flowers. Now thrust a pin
into the pistil and observe the result. Repeat the experi-
ment with the same flowers and with other flowers.

2. Examine a freshly opened flower of laurel. Note the
position of the stamens. Examine an older flower. What
is the position of the stamens? Touch the stamens of the
young flower. What happens? What would occur if
a bee should enter such a flower ? If possible, watch for a
bee to visit the laurel flowers. What happens ?

3. Study a mint flower in the same way. What move-
ments are to be witnessed here ?

Conclusion. — What may be inferred from these observa-
tions ?

EXP. BOT. — 12

178 PLANT IRRITABILITY

Suggestion. — If sundew plants are to be had, catch a
tiny insect and place it near the middle of one of the leaves.
The sticky hairs will hold it, and after a time the other hairs
will bend slowly Over and cover the insect. The Venus's-
flytrap quickly closes and entraps a fly which may alight
upon its surface. Sundews are not very abundant, but they
are found in peat bogs and sphagnum swamps. The fly-
trap is quite rare and is found only in the southern states.

Note. — For response to contact in roots see Experiment 64.

Find out by experiment : —

1. Do old parts respond to stimuli more or less readily
than young ones? Find out by experiments on young and
old tendrils.

Are very young tendrils sensitive? Are tendrils more
or less sensitive by day or by night ?

2. Study the young stems of a -twining plant. Select
two shoots of about equal size and vigor. Give one a cord
to twine upon and the other none. Measure each at equal
intervals of time. How do they compare in rate of growth ?
Measure one which projects beyond its support. Is there
any relation between the rate of growth and the presence
or absence of a support?

3. Test the sensitiveness of barberry stamens from fresh
and from old flowers. Is there any difference? Reason?
Do these stamens show sensitiveness in flowers not yet in
bloom ?

4. Select some fresh barberry flowers and place some in a
cold place, as a refrigerator, for half an hour. Remove them
and test the stamens immediately. What is the result ?

Make similar tests with tendrils.

5. Let a tendril coil about a large support, as a lead pencil.

PLANT IRRITABILITY 179

Count the number of coils. Carefully remove the pencil
and insert a small wire in its place. What change takes
place in the number of turns in the coil? What does this
show?

Note. — To observe automatic movement in a plant place it
under a bell jar or inverted battery jar, or support a plate of glass
above it just so that it does not touch the plant. With a wax
pencil used for marking on glass, and with the eye exactly above
the plant, sketch the position of the uppermost pair of leaves. The
sketch will thus become the orthographic projection of the leaves
drawn.

After an hour make another observation, and if any change of
position has occurred, sketch again as before. Continue observa-
tions and sketches until the fact has been established or disproved.

XIV. FLOWERS

162. FLOWER STRUCTURE
Object. — To learn the parts of a typical -flower.

Apparatus. — Flowers of almost any common plant. Large,
regular, simple flowers, such as those of the tulip, lily, rose, magnolia,
and hollyhock, are preferable.

A simple magnifier, a knife, and a pin are handy.

: Method. — Examine the

flower and note that it
is made up of one or
more circles of parts.
How many such circles
do you find?

Describe the outer-
most circle (calyx), its
color, number of parts
(sepals), and the shape
of each. (Such terms as
wheel-shape, cup-shape,
bell-shape, etc., will de-
scribe the calyx ; and
such terms as oval, spoon-
shape, boat-shape, etc.,
will apply to the sepals.)
Describe the second circle (corolla). Of how many parts
(petals) does it consist? Describe as before. These (petals
and sepals) are called the non-essential organs. They are

180

FIG. 74. — Water lilies.
(Photographed by W. C. Barbour.)

FLOWERS 181

for protection of the innermost parts and they often attract
insects.

Now find the two kinds of essential organs which are found
within the flower (stamens and pistils).

Conclusion. — State how many and what organs are
found in a typical flower, naming them from outside towards
the center.

Suggestion. — Find a flower in which one or more kinds
of organs are missing (incomplete). Find one in which all

Mil

i i » i »

FIG. 75. — Parts of a water lily.

parts are present and of the same number (symmetrical) or
a multiple of the same number. Find a flower in which
some petals are larger than others (irregular). Find flowers
in which the petals are grown together (gamopetalous) into
one piece.

Is there any relation between the number of petals and
stamens? (1) Make drawings of each flower studied, mak-
ing the drawings to scale. Remove one of each set of floral
organs, and (2) draw it enlarged, naming each part. (3)
Draw a plan of each flower, showing the number and position
of the various organs. (4) Draw a diagram of a length-
wise section through the center of each flower and show the
insertion of each part on the receptacle.

182 FLOWERS

Exercise

Procure a water lily, or a double tulip or rose, and care-
fully remove a part from each circle, laying the parts
removed down in the order of their removal. Note how, as
you proceed toward the center, the parts seem to change in
shape. Do you find petals with anthers or stamens which
are spreading out to form petal-like organs ?

Suggestion. — Place the series of floral organs in a book
and press them until thoroughly dry. Then mount them
on a card, cover them with glass, and passe partout them with
paper. Compare this series with similar ones of bud scales.
What is the inference from these form studies ?

163. SEX ORGANS OF FLOWERS

Object. — To learn something about the reproductive
organs of plants.

Apparatus. — Any large perfect flower, such as tulip, Easter lily,
wild crane's-bill, evening primrose, or hollyhock. If smaller flowers
must be used, a simple magnifier will be necessary.

Method. — Remove the outer floral circles (calyx and
corolla) and study what remains.

(a) Stamens. Remove a stamen from a fresh flower and
examine it. Of how many parts is it composed? Describe
it. Draw. Look for fine powder on the anther. This is
pollen. The stamen is the male part of a plant. Pollen
is the male or fecundating substance of the flowering plant.

(6) Pistils. Examine the organ which stands exactly
in the center of the flower. This is the pistil. Of how many
parts does a pistil consist? Some flowers have more than
one pistil. How many are found in the flower studied?
Draw a pistil, naming its parts ovary, style, stigma.

FLOWERS

183

From an old flower remove the pistil. Carefully
cut the lower part (ovary) crosswise. What is seen
within ? How many chambers (locules) ? What is con-
tained in the ovary? Note the partitions (dissepiments)
which separate the carpels and the place where the immature
seeds (ovules) are attached. This point of attachment is
called the placenta, and it is through this that sap from
the parent plant is conducted to nourish the ovules.

These young seeds or ovules will ripen and mature into
young plants.

The pistil is the female part of the plant. From it come
the young seeds. The ovary protects the immature seeds
until ripe and ready to be cast.

Conclusion. — What parts of the
plant are fitted for producing new
plants ?

FIG. 76. — Walnut flowers.

FIG. 77. — Willow flowers.

Note. — Stamens are the male part of a plant. They produce
a powdery substance called pollen, which is necessary to the develop-
ment of a seed. The pistils are the female part of a plant. They
produce the ovules. The ovules never mature unless they receive
the contents of the pollen grains from the stamens. Thus each little
seed is the result of the combination of pollen with an ovule. The

184

FLOWERS

parents of the baby plant or embryo are the stamens and pistils of

the plants which produced them.

The sign $ stands for the male plant
or animal and the sign ? indicates the
female. In the accompanying illustra-
tions are seen male and female flowers
of several common plants.

When a flower possesses both the
essential organs, it is said to be perfect.
If only one kind of sex organs is present,
the flower is said to be imperfect. If both
kinds of flowers (staminate and pistillate)
are found on one and the same plant, it
is said to be monoecious, but when they
occur on separate plants, they are said to
be dioecious.

To which class do ailanthus, pine,
corn, sheep-sorrel (rumex), ragweed, castor
bean, willow, hazel, alder, chestnut, hick-
ory, belong? Examine several flowers of
Jack-in-the-pulpit and find three varieties:
(1) all staminate, (2) all pistillate, (3) both
sorts (polygamous). Squash flowers also
are polygamous.

FIG. 78.— A, sedge; B, oak;
C, sugar maple.

164. SEX ORGANS OF FLOWERS
Object. — To learn what is meant by imperfect flowers.

Apparatus. — Sterile and fertile flowers of any direcious plant,
for example, a cone-bearing plant (pine or spruce), and a magnifier.

Method. — (a) The male flower. Examine the whole
flower (cone). Cut it open from end to end and note the
attachment of the scales and the position of the stamens.

Remove one stamen. Note its form and the number of
its pollen sacs. Where do these pollen sacs grow, on the
upper or under side of the stamen? Can you find where

FLOWERS

185

these pollen sacs split open for the casting of pollen ? Draw
two stamens, one with open and the other with closed anther.

Can you find anything resembling calyx and corolla ?

What can you say of the size of pollen grains ?

FIG. 79. — Corsican pine : a, pistillate flower ; b, pistillate cones one year old ;
c, pistillate cone two years old ; d, staminate cones.

(6) The female flower. Examine the cone and note the
shape, size, color, and arrangement of the scales.

Why do the outstanding edges of scales project as they do?

186 FLOWERS

Sketch the cone, showing the rows of scales as they stand.

Remove a scale and draw the upper and under views.
Look for ovules (two small elevations near the base of a
scale). Do you detect any means by which the pollen grains
could be caught? Do you find anything corresponding to
petals or sepals here ? pistils ?

Examine an older cone and determine the fate of these
ovules.

Dip an old cone in water. What happens? Dry it out.
What happens? What has the ability to open and close
to do with dispersal of the seeds?

Note. — On account of the difficulty of obtaining the staminate
flowers of pine trees the following plants may be studied equally
well for work on imperfect flowers : any other cone-bearing plant,
oak, willow, walnut, poplar, hickory, or chestnut.

165. POLLEN (optional)

Object. — To study pollen.

Method. — (a) Mount dry a few grains of pollen by shak-
ing a ripe stamen over a microscope slide, and examine them
with a low power.

Sketch a few grains as they lie scattered over the field
in various positions.

To some fresh pollen on a microscope slide, add a drop of
water. What effect does it have on the pollen grains ?

Examine as many kinds of pollen as possible, especially
that of dandelion, rose, tulip, pine, corn, milkweed, and
evening primrose, where these can be had.

Which have large grains? small grains? dry grains?
moist grains ? Which show special means of flight ? Which
have special means for sticking to insects? What colors
are most common in pollen?

FLOWERS

187

FIG. 80. — Pollen grains.

(6) Place fresh pollen in a Petri dish and add a few drops
of dilute sugar and water or honey. Cover it to prevent
evaporation and examine it from time to time with the micro-
scope. Look for very fine threadlike growths which come
from the pollen grains.
If a drop of eosin or
methyl green is added,
they will become more
readily seen.

These are pollen
tubes. When pollen
germinates on the
stigma of a flower of
the same kind, the
pollen tube penetrates
the stigma, forces its
way down through the spongy tissue of the style, until it
reaches the ovary, and at last penetrates the micropyle of
the ovule.

When this occurs, the living contents of the pollen grain
fuse with that of the ovule, and the latter is then said to
be fertilized. Hence this process is known as fertilization of
the ovule.

It is not until this has occurred that the ovule begins to
grow. With few exceptions, only fertilized ovules ever
develop into seeds.

Note. — Since different pollens require different strengths of
sugar, it is well in making this experiment to sow the pollen in
Petri dishes containing sugar solutions of from 1 per cent to 15 per
cent strength.

Definition. — In order that the ovules may grow they must
receive pollen from the stamens. This is called pollination.

188 FLOWERS

166. POLLINATION

Object. — To find out whether pollen is necessary to the
production of seeds.

Apparatus. — Any blooming plants having large flowers or
flowers whose stamens 'may easily be seen, a pair of sharp-pointed
scissors, and paper bags.

Method. — Carefully remove the stamens from some
flowers which are just opening, clipping off the anthers.
Then cover the flowers with a paper bag, tying it so that no
pollen can get in from any other flower and reach the stig-
mas. Treat other flowers in the same way, but do not cover
them with a bag. Thus the first flowers can receive no
pollen, while those of the second sort are open to the visits
of insects and winds. After ten days remove the bag and
compare the two flowers.

Conclusion. — What must be inferred as to the necessity
for pollen in the production of seeds ?

Note. — Experiments in pollination are seldom successful when
undertaken within the house. This is due to absence of insects and
to shelter from the winds. If experiments must be made in the
laboratory, pollination must be done by hand, and care must be
observed to get pollen which is just ripe and to place it on a stigma
which is ready to receive it.

All such experiments succeed much better when made in a garden
where winds and insects have free play.

167. POLLINATION
Object. — To illustrate pollination by insects.

Apparatus — Flowers of toadflax, four-o'clock, iris, cypripedium,
or honeysuckle. The experiment is best made in the field where
the plant is growing.

FLOWERS

189

Method. — Study the flower, making note of its color,
odor, and peculiarities of form. Hunt for nectaries and spe-
cial structures, such as
spurs, nectar guides,
etc., which aid insects
in their work of pol-
lination. Look for
special devices which
prevent the entrance
of unwelcome visitors. FlQ- 81.;— Flower and moth.

Take a position near the plant and await the coming of
an insect visitor. Observe what insects come, how they
alight upon the flower, how they enter it, and whence they

FIG. 82. — Pollination of Salvia glutinosa. 1, a stamen. The upright column
to the left of / is the filament, c, c, the connective, anther bearing above
and sterile below. 2 and 3, longitudinal diagrams of a young flower, show-
ing the anther in its natural position in 2, and pushed down by a bee by
pressing on the lower part of the connective in 3. 4, a bee visiting a
younger flower ; the anthers pushed down upon its back. 5, a bee visiting
an older flower ; the style having become elongated and pendent touches
the bee's back. After KERNER.

go on leaving it. Can a bee enter and leave a flower without
touching the stamens and pistils?

190 FLOWERS

Conclusion. — State how the flower studied makes it pos-
sible for pollen to be transferred from flower to flower.

Suggestion. — Observe butterflies, humming birds, and
hawk moths as they fly about. See if you can discover by
what means they reach into a blossom. .Examine goldenrod
in the field and look for various kinds of beetles which usu-
ally infest these plants.

How is the shape of the corolla of Jimson weed (Fig. 81)
fitted for insect visitors ? Is it adapted to pollination by bees ?

168. POLLINATION '

Object. — To learn how flowers are formed to permit
the winds to carry pollen-

Apparatus. — Flowers of grasses, corn, or plantain.

Method. — Study the flowers, making comparisons with
those in the previous lesson. Is there any conspicuous
color, odor, or nectar which is likely to attract insects?
Are the flowers open or closed? Do the stamens project,
or are they hidden deep in a corolla tube? Is there much
or little pollen, and is it sticky or dry? If the tassel at the
top of a cornstalk is shaken, a large amount of pollen will
usually be obtained.

Conclusion. — In a single sentence state how the wind-
pollinated plants differ from those pollinated by insects.

Suggestion. — Examine some pine pollen with a micro-
scope. How are the pollen grains specially fitted for flight ?

Note. — Some years ago, after a strong south wind, the streets of
Washington, D. C., were found covered with a yellow powder, which,
on examination, was found to be pine pollen. The nearest pine
forests from which it could have been wafted are in North Caro-
lina, several hundred miles distant.

FLOWERS 191

169. POLLINATION
Object. — To learn what is meant by self-pollination-

Apparatus. — Flowers of closed gentian, fringed milkwort, or
the common cleistogamous flowers of the blue violet.

Method. — Examine the flower to be studied. Cut open
the ovary and find the seeds. Does the plant receive pollen
from any other plant? If not, whence comes the pollen
which has made the ovules mature into seeds. If the
flower does not open, the pollen cannot have been borne
on the winds or brought by insects. From what source
must it have come?

Conclusion. — What is self-pollination ?

Suggestion. — (a) Look for cleistogamous flowers at the
root of violet plants. Notice that such flowers are lacking
in the color, odor, and nectar which are so abundant in the
ordinary flowers of the violet.

(6) Can a plant be pollinated artificially ? Hint : Having
removed the stamens from a freshly opened flower, fill a
camePs-hair brush with pollen. Gently brush it over the
stigma and then inclose it in a paper bag. This will pre-
vent any other pollen from getting on. After ten days
remove the bag and note the result.

(c) Make the same experiment, using pollen from other
kinds of plants. What result? Does it make any differ-
ence whether the pollen is fresh or old ?

(d) Is the stigma as receptive at one time as another?
Examine hollyhock flowers on the same spike. How do the
stamens of the upper flowers differ from those of the lower
ones ? How do the pistils differ ?

(e) Walk in a field or pasture where there is English
plantain growing, or observe any mint or mallow. Are all

192

FLOWERS

the heads alike? Select one from which stamens are pro-
jecting and tie a colored thread about it or otherwise mark
it. At the same time mark one from which the stigmas
are projecting. After a day return and examine each stalk
which has been marked. What change? If no change

is noted, come again
a day later and again
make observations.
What do you learn
from this regarding
pollination of plan-
tain? Can plantain
fertilize itself? Give
a reason for your
answer.

(/) Take your sta-
tion in a garden near
a bed of bright or
sweet-scented flowers
and make note of
what insects visit
these flowers. To-

FIG. 83. — Columbine. Pollinated by insects. Wards evening watch
(Photographed by W.C. Harbour.) ^ ft honeysuckle

or trumpet creeper. By what creatures are these flowers
visited? Catch a hawk moth and find its long proboscis
by means of which nectar is extracted from flowers.

Catch a bee and examine the legs to find pollen in the
pollen baskets.

Note. — Hybrids are formed by crossing plants, that is, by pollen
of one plant fertilizing the ovules of another plant. The new plant
may have the characteristics of both parents.

FLOWERS 193

Sometimes the offspring combines desirable qualities of both
parents, and sometimes undesirable qualities predominate.

In this way the plant breeder can improve his plants by a careful
selection of parent plants and a destruction of those which show
undesirable qualities.

Thus sweet corn and pop corn have been produced from the primi-
tive wild field corn of the Indian.

In recent years the seedless apple and many other new fruits
and flowers have been produced by crossing and selection.

Variation

Note. — Examine a large number of plants of the same sort
with a view to their points of difference. The leaves of dandelion
plants show very great differences in outline, and those of the arrow-
head are so different in form that there are seldom two leaves alike
on the same plants (hence the name Sagittaria variabilis) .

Exercise. — Select two plants which show as much dif-
ference as possible. The oxeye daisy and Indian corn are
good for this purpose.

(a) The Oxeye Daisy

Compare the two plants. Are they alike in size? Are
the leaves alike in size and shape? Make note of -any dif-
ferences in leaf outline. Compare the stems as to thick-
ness and strength. Look for differences in habit of growth.
Are there any differences in surface characteristics, such as
smoothness, roughness, pubescence, etc.? Compare the
flowers as to number of heads, size, number of ray flowers
to each head, and color and position of the floral parts. Try
to find two oxeye daisies which are exactly alike in all these
qualities.

What do you conclude as to absolute likeness among
flowers ?

EXP. BOT. — 13

194

FLOWERS

(6) Indian Corn

Procure several ears of corn and note the following

points: shape of the
ears, whether cylindrical,
tapering, blunt, etc. ;
color of the grains, size
of the grains, evenness
or regularity of arrange-
ment of the grains ; color
of the cob, etc.

Count the number of
grains to each row. Do
all ears agree in this?
How many rows to the
ear? Are all ears alike
in this? What is the
average number of rows
per ear ? Are all ears
from the same plant
alike in this ?

Compare ears of sweet
corn, pop corn, and dif-
ferent varieties of field

FIG. 84. — 1, seed ear of corn ; 2, 3. 4, types

of ears harvested. corn> and tabulate the

(Year Book, 1902, U.'.S. Dept. Agr.)

(c) Sports

Examine any large plant, such as a rose bush, or branches
from a large shrub or tree. Look for branches which are
different from the remainder of the plant. Such branches
will not often be found. They are known as sports.

FLOWERS

195

Many new forms of fruit and varieties of flowers have been
produced by propagating such sporting branches by means
of cuttings. Sporting
branches are common
on coleus plants,
which may be made
to produce some very
odd color effects by
making the cuttings
at the right time.

The famous and al-
ways popular Brides-
maid rose originally
sprang from a sport
in one of the rose
houses of Mr. Frank
L. Moore of Chat-
ham, N.J. From that
one branch have de-

tiG. 80. — Variation in size of cob and length

scended all the Brides- of kernels.

maid rOSeS nOW SO (Year Book, 1902, U. S. Dept. Agr.)

abundant in the rose houses. The seedless orange was
propagated from a sport.

Suggestion. — Study plants of the same kind growing
under different conditions of moisture, also plants having
submerged, floating, or aerial leaves.- How do they vary
in form ? Study plants in sun and shade. Study the effects
of rich and poor soils on character of foliage and habit of
growth.

(See tables of leaf modifications (pp. 171, 172), also dis-
cussion of fertilizers (pp. 105-108).

Queries. — From your knowledge of plant breeding how

196 FLOWERS

would one set about to produce a double daisy? A very
large daisy ? A large-leaved or downy-leaved daisy ?

How should one proceed in order to develop a variety
of corn having more or less than the normal number of
rows of grain to each ear? How might sweeter and larger
kernels be produced ?

How has the seedless apple been developed? How can
it be propagated when once produced ?

XV. SPECIAL EXERCISES ON TYPICAL FLOWERS

170. TRILLIUM

This is a particularly good flower for beginners, since its
structure is so simple and all its parts are so large and dis-
tinct. It may be found in damp, rich woods, in spring,
almost everywhere.

Method. — Procure if possible one entire plant, so as to
describe all parts. Does it spring from a rootstock or bulb?
Reasons for your an-
swer. Are the roots
fleshy or fibrous ?
Study the aerial por-
tion. Is the stem
monocotyl or dicotyl
in structure? Reasons
for your judgment.
What is the arrange-
ment of leaf? Num-
ber, veining, shape, FIG. 86. — Trillium.

and Outline Of leaves ? (Photographed by W. C. Barbour.)

Note length and position of the flower stalk. Of how many
sepals does the calyx consist? Their shape and color?
How many petals? Their shape, color, and size? How
many stamens? Describe them. Remove all parts and
study the pistil. Is it simple (consisting of only one carpel)
or compound (composed of several united carpels) ? This can
be told by the number of stigmas, styles, or lobes of the ovary.

197

198

SPECIAL EXERCISES ON TYPICAL FLOWERS

Make drawings as follows : —

1. The entire plant.

2. The plan of the flower.

3. A sepal, a petal, a stamen, and the pistil X 3.

171. THE IRIS

Blue flag is common along streams and marshes and fleur-
de-lis is abundant in gardens. Most of these flowers are to
be had only in spring, but the Tigridias may be cultivated in

gardens late in the
summer.

Method (Field). -
Study the plants in
the field, noting the
erect habit of growth,
shape, and position
of leaf, character of
the soil where they
grow. Procure an
underground part and
examine it. Is it root
or stem ? Reason for
your answer. Draw.
Note the way in
which the leaves over-
lap (equitant). Do these plants in general occupy any defi-
nite position with reference to the sun; that is, are they
in any way what are known as compass plants? If so,
account for it.

Method (Laboratory). — Study a bud. How do the floral
organs overlap in the bud ? Draw. Study a flower. How
many floral circles can you find?

FIG. 87. — Iris.
(Photographed by W. C. Barbour.)

SPECIAL EXERCISES ON TYPICAL FLOWERS 199

Describe each circle. (When the two outer circles are
alike in color, they are spoken of as a perianth instead of calyx
and corolla.) Of how many parts is the perianth composed?
How do these parts differ in position? In other respects?
What appendages are found on one set which are not found
on the other? Can you suggest any use for this? Note
the long, slender tube where the parts of the perianth are
united. Draw the flower.

Remove the perianth and study the essential organs.
Draw. How are the stamens placed relative to the stigmas?
Is self-pollination • possible in such a flower? Reason.
Where is the nectar secreted? Try to discover how pollen
can be transferred by bees from flower to flower. Where
is the ovary? Cut a flower lengthwise through the center.
Draw the section exposed.

172. EVENING PRIMROSE

Evening primrose may be found in dry fields, roadsides,
and waste places, and sometimes in gardens. It opens late
in afternoon about sunset and remains open all night, closing
next day about ten o'clock A.M. or earlier. It often remains
open longer if the day be cloudy. When opening, it often
makes a distinct sound like an explosion.

Its fragrance is peculiar, having a suggestion of black
pepper.

Method (Laboratory) . — Are the flowers solitary or in clus-
ters? If clustered, describe the cluster. Remove one flower.
Has it a stalk (pedicel)? If so, describe it. Describe this
flower, calyx, corolla, stamens, pistils, giving number, size,
shape, character of the pollen, and other characteristics.

Where do the old flowers grow? The buds? Can you
determine how many flowers will be borne on this cluster ?

200

SPECIAL EXERCISES ON TYPICAL FLOWERS

For study of pistil use the oldest blossoms, and for stamens
the buds which are about ready to burst.

Split open the long tube and see if you can find any trace
of nectar in its depths. Its object? Draw a flower, top
view, showing the arrangement and number of the parts;
also a view of the split corolla. Draw one stamen and a

Top —

PttHL.J

FIG. 88. — Evening primrose.

view of the ovary. Cut open a mature ovary crosswise
and make out the attachment of the ovule. Can you dis-
cover any lines or seams (sutures) where the fruit will split
when it becomes ripe ? Draw pollen highly magnified.

Method (Field). — Take your station near an evening prim-
rose plant just about sunset and listen for the explosions
which accompany the opening of the flowers. What insects
visit these flowers ? See if you can discover how they extract
the nectar.

Note. — For comparison study willow-herb (epilobium). Both
evening primrose and willow-herb are good for autumn as well as
spring classes, since they usually blossom until frost.

SPECIAL EXERCISES ON TYPICAL FLOWERS 201

173. THE BUTTERCUP OR ANEMONE

There are many species of buttercup, and they differ so
in habit of growth that no exact outline can be laid down
for their study. The leaf is very different in different
species and the stem may be bulbous, erect, creeping, etc.
But the flowers are all essentially alike.

What is the character of the stem? Is it erect, creeping,
bulbous, etc. ? Is it smooth or rough, silky or • downy ?
Are the leaves opposite or alternate? How are they di-
vided? Draw a leaf. Are the upper leaves like the lower
ones? If not, draw one of each sort. Study a flower and
draw one. Is it complete or incomplete? Describe each
kind of organ found.

How many sepals? Their shape? How many petals?
Their shape and any other characteristics? Remove a
petal and draw it. Look for a scale or nectary at or near
its base. Its use? How many stamens? How many
pistils? Describe one pistil. Has it all parts? If not,
which part is missing?

Are the petals opposite or alternate with the sepals?
Draw a section through a flower, showing all parts in posi-
tion. Draw a plan of the flower, showing each floral
circle.

In a bud or very young flower notice how the petals are
arranged with reference to each other. Are any of the petals
entirely outside the others (imbricate), or how are they ar-
ranged ? Indicate this on the floral plan.

Note. — The buttercup is the representative of a great family
of plants, the crowfoot family.

Suggestion — Study the flowers of clematis, anemone,
hepatica, columbine, and larkspur for comparison. Most

202

SPECIAL EXERCISES ON TYPICAL FLOWERS

of them are spring flowers, but clematis and larkspur can be
found blooming in autumn.

Make out a list of characteristics common to all these
plants.

174. THE STRAWBERRY, GEUM, OR POTENTILLA

The strawberry, like the buttercup and sweet pea, belongs
to a great family of very useful plants.

Leaflet

.Corolla
-Cal\|x

^.Receptacle
k ^Pedicels

racts

Pistil
9

V. Lni.

s

stamen

Section

FIG. 89. —The strawberry.

Plan.

SPECIAL EXERCISES ON TYPICAL FLOWERS 203

Roses, peaches, pears, cherries, and many other very
common plants are members of the same order.

Method. — How does the strawberry plant spread? Make
a sketch, showing a runner. Draw one leaf and name the
following parts: petiole, stipules, blades (leaflets). How
many leaflets are there?

Are the flowers solitary or in clusters? Is the inflores-
cence definite (ending in a flower) or indefinite (ending in a
bud) ? Examine a flower cluster (cyme) and draw a dia-
gram to show the kind of inflorescence.

This flower seems to have ten sepals, but such is not the
case. There is a whorl of five bracts just outside the calyx.
How many sepals? Petals? Are they separate or united?
How many stamens? Pistils? Remove a petal and draw it.
Remove a stamen and a pistil and draw them greatly en-
larged. Study the oldest flower in the cluster and see what
becomes of the pistils.

What is the origin of a strawberry? What part of the
plant is eaten? What are the little yellow points on the
surface of a ripe strawberry which give it its name ?

Make drawings of a section through a flower, a plan of
the flower, and a section of the fruit.

Suggestion — Compare apple blossoms and roses with
strawberry blossoms. Wherein are they alike? In what
respects do they differ? Compare raspberry flowers and
fruit with those of the strawberry in a similar manner.

175. MUSTARD OR ANY OTHER CRUCIFER

Mustard is a common weed which is a representative of a
very important family of plants. Radish, turnip, horse-
radish, cabbage, and many other food plants are related
to it.

SPECIAL EXERCISES ON TYPICAL FLOWERS

Method. — Draw the entire plant if it is not too large. If
it is too large, make drawings of basal leaves, stem leaves,
flowers, fruit, and inflorescence.

Draw one flower greatly enlarged. Dissect a flower and
draw one of each set of parts. How many sepals and petals ?
Are they alike in size ? How are they arranged when seen
from above? The plants of this order are called crucifers
(cross bearers). Why is the name appropriate? Are the
stamens alike in length? If not, how many are there and
how do they differ ?

Select an old ovary and cut it crosswise. Draw the sec-
tion, showing the attachment of the ovules. From a very
old pod find out how they break open and how the seeds are
scattered.

Taste of the seeds or green stems. Describe the peculiar
flavor.

Note. — In spring the cresses are abundant. During summer
horse-radish and mustard are very common in bloom. Sweet
alyssum, candytuft, and wallflowers may be found in gardens
and hothouses. Shepherd 's-purse is a common weed belonging
to the same family, but its flowers are too small to be studied
without the aid of a magnifier.

176. A LILY OR AMARYLLIS

Any liliaceous flower will do for this exercise. Tulips,
lilies, day lilies, yuccas, star-of-Bethlehem, and hyacinths
are common in gardens and are cultivated for ornament.

Onions, garlic, leeks, and asparagus are esteemed for food.

Method. — Study any of the above plants as in previous
exercises.

Some spring from rootstocks, others from bulbs. If from
the former, study and make out the nodes, roots, and re-

SPECIAL EXERCISES ON TYPICAL FLOWERS

205

duced leaves (scales). If from the latter, determine whether
the bulb is solid (corm) or scaly.

Study the stem, noting the smooth skin, rather prominent
nodes, and absence of annual rings (monocot) . Study the leaf.
Its veins are of what kind? What type? (See Ch. XII.)

FIG. 90. — Lilium superbum.
(Photographed by W. C. Barbour.)

What is the number of floral circles? How many parts in
each? Draw the whole flower, one of each of its parts, a
plan of the flower, and a section to show insertion of parts.

Make a cross section of the ovary, showing placentation.
Draw. From your observation, will the pod split (dehis-
cent) or remain closed (indehiscent) when it ripens? How

206 SPECIAL EXERCISES ON TYPICAL FLOWERS

many chambers (locules) in the ovary? Is the flower
symmetrical or unsymmetrical ? regular or irregular? per-
fect or imperfect? Give reasons for your answers.

Note. — A study of a liliaceous flower will give one more differ-
ence between monocotyl and dicotyl plants, namely — The floral
organs are always in threes or multiples of three.

Compare arrowwort, iris, spiderwort, and lilies in this respect.

177. JACK-IN-THE-PULPIT OR SKUNK CABBAGE

Method. — Following the same general plan as outlined in
the preceding exercise, answer the following questions : -

What is the habitat
in which this plant
grows ? What are the
form, position, and
venation of the leaf ?
What is the nature of
the stem (monocotyl
or dicotyl) ? Give
reasons for your
answer.

From what under-
ground part does the
plant spring ? De-
scribe it. Is it a
root or a stem ? Give
reason for your an-

FIG. 91. — Jack-in-the-pulpit. T-\ -L j.u

swer. Describe the

roots. Cut a slice from the corm (underground part) and
touch it to the tongue. Do not chew it or take any portion
into the mouth. Only touch it to the tongue. Describe the
taste. After having tasted it, what do you think of the

SPECIAL EXERCISES ON TYPICAL FLOWERS 207

common belief that this plant was eaten by the Indians?
Taste a corm after cooking it. Does heat have any effect on
it ? The name Indian turnip is often applied to this plant.
Test it with iodine and see whether starch is present.

Study the inflorescence. The flowers are situated at the
base of a club-shaped spadix and are surrounded by a broad
leaflike spathe which arches over the flower cluster. Turn
back the spathe and examine the parts within.

What is the color of the spathe ? Are all spathes colored
alike? Are the flowers perfect or imperfect? Have they
calyx and corolla?

Cut open a spathe, removing a part of the lower side so
as to expose the essential organs.1

Make drawings of (1) the plant, (2) a spathe, side view,
(3) front view, (4) the spadix with spathe removed.

Suggestion. — Observe the plant all through the season.
Of what use is the spathe? What becomes of the spathe?
What insects visit this flower ? What kind of fruit does the
ripened cluster of pistils become? When does it mature?
What is its color ? Gather some of the ripened fruit in Octo-
ber or November and plant them in damp soil in winter.
Their germination is very interesting.

Note. — Jack-in-the-pulpit corms may be dug in autumn and
planted in a window box where they will bloom in winter. For
other plants having a spathe and spadix study the common water
arum, skunk cabbage, golden club, and sweet flag.

They are all spring flowers. Many strange and beautiful spadi-
cious plants are to be seen in conservatories.

1 A study of many specimens of Jack-in-the-pulpit will discover
the fact that some are all staminate, others are all pistillate, and
some, by far the greater number, contain flowers of both sorts.
Plants having all three kinds are known as polygamous. See also
Note, Experiment 163.

208

SPECIAL EXERCISES ON TYPICAL FLOWERS

178. LILAC, FORSYTHIA, OR PRIVET

Method. — Make drawings of the flower, top view, show-
ing number, shape, and position of petals, and position and
number of stamens.

Draw side view so as to show the calyx, the corolla tube,
and the general shape of the corolla. Split open the corolla

between two of the
lobes and draw the in-
terior view, showing
the insertion of the
stamens, the anther
cells, and the lines
where they will split

Corolla
'....Stamens-

fCorollau
[ limb

.Corolla tube!
Stamens inserted

•Calvjx
.Pedicel

(Corolla aplirto

when mature.

Carefully pull off a
corolla and draw the
pistil as it stands in

—Stijmalshow stamens ,, n ,

c,txjie the calyx. Cut away

ilvjx one side of the calyx

petjjcej and show the ovary.

Answer the follow-
FIG. 92. — The lilac. jng questions : -

How many petals ? Are they free or gamopetalous ? How
many stamens? What is their position relative to the
petals ? How many stigmas and how many parts has the
ovary ?

This is a good example of what is known as a symmetrical
flower. It has sepals 4, petals 4, stamens 2, pistils 2, i.e.
one consisting of two carpels.

What renders this flower attractive to insects ?
Suggestion. — For comparison study flowers of forsythia,

SPECIAL EXERCISES ON TYPICAL FLOWERS

209

Virginia fringe tree, and privet. These shrubs are all mem-
bers of the same order of plants.

179. SWEET PEA, LOCUST, OR LUPINE

These plants belong to a great family of plants, the
Leguminosae, to which beans, clovers, medick, vetches,
mimosas, and many
other plants belong.

Method. — How does
the pea vine climb?
What is the shape of
its stems? Draw one
of its peculiar leaves.
How do its stipules
differ from those of
most plants ? How
are the uppermost leaf-
lets modified? For
what purpose ? Are
the tendrils sensitive?

Describe the flower.
Is it solitary or clustered? Of how many parts does
the calyx consist? Are they alike in size? Of how
many petals does the corolla consist? Is it regular
or irregular? Give reasons for the answer. Draw. Re-
move the petals one by one and arrange them in order.
Draw. How many stamens are there? What is peculiar
about the stamens? Draw the essential organs in place.
Draw a plan of the flower showing the position of the various
organs. Remove the stamens and expose the pistil. An
old flower or one which has faded will be best for this. Find
EXP. EOT. — 14

FlG- 93- — The sweet pea-

Plan.

210

SPECIAL EXERCISES ON TYPICAL FLOWERS

all parts of the pistil. What is peculiar about the position
of the style in relation to the ovary? Is the pistil simple
or compound? Give reason for your answer. Draw pistil.
Procure a ripened pod and compare it with a pistil. What
parts of the pistil persist ?

Note. — This form of corolla is often called papilionaceous, a
word that means butterfly-shaped. Why?

Query. — Is this flower regular or irregular? Symmetri-
cal or unsymmetrical ? Perfect or imperfect? Complete
or incomplete ? Give reasons for your answer.

180. VIOLETS

Violets are so well known and there are so many species
that it is well to have as many different species as possible
in the class.

Method. — - Draw a typical leaf. How are they rolled in

FIG. 94. — Blue violet.

SPECIAL EXERCISES ON TYPICAL FLOWERS

211

the bud ? Draw views of the flower, front and side, showing
all parts.

Dissect a flower. Find the spur. Is it a special part
or a modification of some petal? Reason for your answer.
Bite off the tip of the spur and taste the nectar. Find two

FIG. 95. — Yellow violet.

hornlike projections from the two lower stamens which
secrete the nectar.

Are the stamens united? Remove the stamens and draw
them showing their apparent attachment (syngenesious).

Do the stamens turn their anthers towards or away from
the pistil ?

Find flowers without petals down near the root of the
violet. These may be found all summer, developing in
great numbers and producing a vast quantity of seeds. See
Suggestion, Experiment 169.

212 SPECIAL EXERCISES ON TYPICAL FLOWERS

181. TOADFLAX OR BUTTER AND EGGS

Toadflax is a common weed of roadsides and fields. Its
bright color and curious two-lipped flowers are always
attractive to the student.

Method (Laboratory). — Make a drawing of the entire
plant, showing its strict habit of growth, position, and
shape of leaves on the stem, and kind of flower cluster
(spike).

Remove a flower and draw it enlarged. Notice the pe-
culiar shaped corolla (labiate or two-lipped). Of how many
petals is each lip composed ? Compare the upper and under
lips as to color, surface, and shape. Take the flower be-
tween the fingers and pinch it gently. What happens?
Look into the open throat of the corolla and see how many
stamens and pistils can be seen. Cut open a corolla, being
careful not to injure the essential organs. Draw. How
do the stamens compare in length ? Their number ?

From your knowledge of pollination, how is this plant
able to give and receive pollen? Examine the spur as was
suggested in the exercise, on the violet. Does it contain
nectar? Draw a bud, showing how the petals are folded
in the bud. Draw a stamen enlarged. Remove the corolla
and draw the essential organs, naming all parts shown.
Draw one of the fruits (capsules). Cut an ovary crosswise
and draw it, showing the placenta, seeds, ovary walls, par-
titions if any, etc. From a ripe or nearly ripe capsule,
remove a seed and examine it with a magnifier. What
peculiarity have they?

Method (Field). — Study toadflax in the field. What in-
sects visit this flower ? How do they enter it ? Are there
any special structures which aid a bee to get into the corolla ?

SPECIAL EXERCISES ON TYPICAL FLOWERS

213

Can a fly get in ? How about small insects like ants which
are fond of sweets? Having seen a bee enter a toadflax
blossom and come out again, examine a flower, paying
special attention to the position of stamens and pistils. In
the light of these observations, how are these flowers adapted
to insect pollination.

Note. — Other plants which resemble the toadflax are the
mulleins, gerardia, foxglove, turtlehead, and snapdragon. All
are good for laboratory exercises. Mullein is noted for its leaves,
which are covered with branching hairs. Foxglove is a beautiful
garden flower from which the poison digitalis is obtained.

182. A MINT

The characteristics of the mint family are so definite that
any of the following plants may be selected as typical:
catnip, peppermint,
spearmint, gill, skull-
cap, salvia, and heal-
all.

Method. — Study
the plant as a whole,
noting position of
the stem, whether
erect, creeping, etc.,
and shape of the
stem. What is the
leaf arrangement ?
Bruise a leaf and in-
hale the odor. What
is the flower arrange-
ment (inflorescence) ?

FIG. 96. — A mint.

Remove a flower and determine : —

1. Form of calyx and number of sepals.

214 SPECIAL EXERCISES ON TYPICAL FLOWERS

2. Form of corolla, number, attachment, and cohesion of
the petals.

3. Number, attachment, and other peculiarities of stamens.

4. Number of ovaries and stigmas.

Note. — All members of the mint family are alike in shape of
their stems, arrangement of their leaves, shape of their flowers, and
number of their ovaries. Their stamens differ in number, but
they agree in being unequal in length; that is, 2 long and 2 short
or 4 long and 2 short (didynamous or tetradynamous). Their
foliage is usually odorous, for example, peppermint, spearmint,
hoarhound, pennyroyal, catmint, and ground ivy. Among autumn
flowers the salvias of the gardens are good for study.

Suggestion. — Study any mint in the field as it is sug-
gested to do with toadflax. What insects visit it ? How is the
flower adapted to receive the visits of insects ? How are the
essential organs arranged for giving and receiving pollen ?

Note. — The splendid scarlet salvia of the parks and gardens
and the common coleus plants are good mints for any season from
May to November.

183. THE SUNFLOWER, ASTERS, OR GOLDENROD

The sunflower belongs to the largest of all families of
flowering plants. This family is known as the Compositae,
because their so-called flower is composed of many small
flowers closely packed together, the whole cluster resem-
bling one flower.

Method. — A sunflower should be examined as a whole,
noting, first, the circles of green leaflike organs (bracts)
which imitate a calyx; second, the single circle of yellow,
strap-shaped flowers which appear to be a corolla; and
last, the broad disk covered with the dark brown tubular
flowers where stamens and pistils are seen in simple flowers.

SPECIAL EXERCISES ON TYPICAL FLOWERS 215

Note which of the disk flowers are open and which are
still buds. How does the blossoming proceed, that is, from
circumference to center, or the reverse? Remove a disk
flower and a ray flower. Compare them and draw each
enlarged. Do you find any part that represents the pedicel ?
The calyx? Of how many petals is the corolla formed?
How may the number of petals in a ray flower be determined ?

Examine a flower just opened and find out how many
stamens it has. What is peculiar about their anthers?
Examine a flower nearer the edge of the disk. How many
stigmas has it? Are the ray flowers fertile (having essen-
tial organs) or sterile (without essential organs)? If ster-
ile, of what use are they to the plant ?

Gather a few grains of pollen on a microscope slide and
examine it dry with a low power. Draw a pollen grain.
From an old flower head remove one of the disk flowers
which has matured, and examine it. Find the calyx which
forms the teeth at the top of the ovary. Remove all the
flowers from the disk and find the small bracts (chaff) which
cover it. Can you determine how many such chaff scales
accompany each disk flower ? Study the naked disk, noting
the pits or scars where flowers and chaff were attached.

Note. — Other composite flowers are the daisy, aster, fleabane,
goldenrod, and black-eyed Susan. Most of these are autumn
flowers.

184. THE DANDELION, CHICORY, OR HAWK-
WEED

The dandelion is another plant whose flowers grow in a
composite head.

Method (Laboratory}. — To procure dandelion plants, the
student should be provided with a sharp spade with which

216 SPECIAL EXERCISES ON TYPICAL FLOWERS

to dig up the strong taproot which penetrates the ground to
a considerable depth. In addition to a whole plant, there
should also be a supply of buds, flowers, and ripened fruits.
A magnifying glass is a necessity.

How does the root adapt the dandelion to withstand the
cold and the efforts of the gardener to exterminate it?
Taste of the root. How does the dandelion withstand the
ravages of root-eating animals?

What can be learned of the stem f What advantages has
a so-called stemless plant ? What of the leaf arrangement ?
Account for the rosette form. How does this prove an
advantage to the dandelion? What effect does such a
growth have on other plants, such as grasses, which grow
close by? Break off a leaf. Describe the sap, its taste,
color, etc. Draw. Account for the shape and peculiar mar-
gin of the leaves.

Study a bud, making note of the many circles of bracts
which surround it. What is their position in a bud, in an
expanded head, in the withered flower, and in the ripe
fruit?

Examine the flower. Has it ray flowers and disk flowers
like those of the sunflower? Wherein does it differ? Re-
move a flower and study it with a magnifier. Find the
ovary, its crown of very delicate bristles (pappus), and the
other parts of the flower. Study and draw as in the preced-
ing exercise. Remove some pollen and examine it dry
with a low power of the microscope. Draw. Select a fully
expanded ball of ripened fruit. Blow it gently to see the
fruit (achenes) float away. Study a single fruit and draw it.
Examine the receptacle after all the fruits have been blown
away^ Note the pits where they were attached. Draw.
Compare with lettuce, chicory, and cynthia,

SPECIAL EXERCISES ON TYPICAL FLOWERS 217

Suggestion. — Find out what use is made of dandelion
root (taraxacum). How do gardeners exterminate this
weed ? Its use in spring as salad and greens is well known.

Method (Field). — Make observations on a dandelion plant
from day to day, taking note of the following points : —

(a) Character of soil where it grows.

(6) Variation in size and shape of leaf due to habitat.

(c) Leaf arrangement (rosette) affording large surface in
small space.

(d) Absence or shortness of stem affording protection from
browsing animals and from cold weather.

(e) Effect of the leaf arrangement in monopolizing space
to the exclusion of other plants.

(/) Behavior of the plant, especially the action of the
involucres in opening and closing the flower in different
stages and under different conditions of light and weather.

(g) Mark a bud which is about to open by tying a colored
thread about its peduncle (flower stalk). Note when it
opens and closes, also how many days it continues to open
and close.

(h) When the ball of fruit expands, observe the manner
of seed dispersal.

(i) Carefully dig up a plant and study the long, sturdy
taproot.

There is another group of composite plants whose flowers
are all tubular. The commonest ones are ironweed, the
thistles, and bonesets.

Suggestion. — Study a plant of burdock or thistle as in
the other exercises on composites. Draw a head, showing
the outer involucre of hooked or prickly bracts. Cut a
head lengthwise and draw the section exposed. Remove
a flower and draw it greatly enlarged.

218 SPECIAL EXERCISES ON TYPICAL FLOWERS

When the fruit has matured, draw one of the beautiful
tufted achenes of a thistle. If burdock is used, remove one
hooked bract and draw it enlarged.

185. INDIAN CORN

This plant is best studied in the field, but if corn can be
grown in a school garden, it will be equally good. If studied
in the laboratory, an entire plant is desirable, also young
and old ears, ripe ears, and a supply of fresh sterile flowers
from the tassel.

Method. — The great number and character of roots, the
aerial, adventitious, or so-called brace roots which spring
from the lower nodes for the purpose of supporting the plant,
are always seen. The smooth, jointed stem so character-
istic of monocotyls is not to be overlooked. The long parallel-
veined leaves also prove the monocotyl nature of the plant.

(a) Study the tassel as a flower cluster, then remove one
fresh flower and find its parts. Has it calyx and corolla?
How many stamens to a flower? Do you find a pistil?
Is there any organ where the pistil ought to be ? Draw one
flower, showing its pedicel and other parts. Name the or-
gans which resemble sepals (glumes}. Do the glumes stand
opposite each other, or are they overlapping? How many
glumes are there? Draw a stamen. Describe a stamen.
Shake a corn tassel. What can be said of the amount of
pollen? Is it dry or sticky? Examine it with a micro-
scope. Draw a pollen grain. How does it compare in shape
with other kinds of pollen ?

(6) Study a very young ear. By what is it covered?
How are the husks arranged? Cut an ear open from end
to end and study the arrangement of parts.

Examine an older ear from which the silk is beginning

SPECIAL EXERCISES ON TYPICAL FLOWERS 219

to project. Carefully strip back the husks and expose the
kernels without breaking off the silk. Trace one thread
of silk from end to end. From what does it come? Where
is it attached to the kernel ?

Examine the exposed end of a corn silk, using a magnifying
glass. Describe its surface.

Query. — How is a corn plant provided against self-
pollination? What advantage is there in having the stam-
inate flowers at the top? Why do corn flowers lack color,
odor, and nectar? Why are the tassel flowers open? Ac-
count for the amount of pollen. Do ears and tassels of the
same plant mature at the same time ?

Note. — Oaks, chestnuts, birches, alders, and sedges have the
sterile and fertile flowers on different parts of the same plant.

XVI. EXPERIMENTS WITH FLOWERS

186. FUNCTION OF THE PERIANTH

Object — To find out the function of the perianth of a
fiower-

Method. — From any large flower bud, carefully remove
the calyx and corolla, thus exposing the essential organs to
view. Do the same with a flower just opening. Mark both
with a tag or bit of colored cord. From time to time ob-
serve the flowers.

When fruit matures, note which if either produces the
most seed. Also which produces the best quality of seeds,
a mutilated flower or one which has been left intact.

Note. — Tulips and other large flowers are best for such experi-
ments.

Suggestion. — Find out whether the position of a flower
has any relation to seed production. Do this by selecting
some large irregular flower, as a nasturtium (tropseolum),
and carefully twist the stalk halfway round so as to bring
the upper petals below and the under petals above. A
pansy or papilionaceous flower is good for such experi-
ments.

Note (1) whether such flowers have the power to right
themselves, (2) whether insects visit them as readily as
those which have not been inverted, and (3) whether they
develop their seeds as well. Why or why not?

220

EXPERIMENTS WITH FLOWERS 221

187. EFFECT OF LIGHT

Object. — To demonstrate the effect of light on flowers.
Apparatus. — A blooming oxalis plant.

Method. — Place the plant in the sunshine. When the
flowers are wide open, remove to a dark closet for one hour.
Bring the plant out and examine the flowers. How do they
differ from their original condition.

Return the plant to the darkness and again note result.

Repeat the experiment, using artificial light.

Conclusion. — State the effect of light on oxalis flowers.

Suggestion. — Expose night-blooming flowers, such as four-
o'clock, moonflower, and evening primrose, to strong light.
Will they respond?

Query. — Why do night-blooming flowers usually remain
open during cloudy days? What relation can you discover
between the behavior of flowers and leaves at night.

Note. — The opening and closing of flowers cannot be attrib-
uted wholly to presence or absence of light. There are many
plants which open their flowers at night. Of such are the night-
blooming cereus, night-blooming water lilies, evening primrose,
four-o'clock and moon vine. Many other plants open their flowers
by day and close at night. But by far the great majority of flowers,
when once open, remain so until fertilized. Then they wither and
die.

The time of opening and closing seems rather to be a specific
characteristic.

188. EFFECT OF HEAT

Object — To demonstrate the effect of change of tem-
perature on flowers.

Apparatus. — Flowers of crocus, tulip, or star-of-Bethlehem, and
a thermometer.

222

EXPERIMENTS WITH FLOWERS

Method. — Select some buds which are about to open.
Note the temperature of the air. Put them in a cold place,
such as a refrigerator, or in a stoppered bottle which is
immersed in a pail of ice water. The latter is better, since
the light is not shut off- as it is in a refrigerator. Repeat

the experiment, using an open
flower instead of a bud. Remove
the bud to a warmer place and
note the result. Try the exercise
with different flowers. Are all
equally sensitive? Make the ex-
periment with only slight changes
of temperature. Procure, if pos-
sible, a flower of night-blooming

12° c- 22° c- cereus or any other night-bloom-

FIG. 97. — Star-of-Bethlehem. , ^ , c

ing plant. Cut the flower trom

the stem at night when it is in full bloom and transfer it
immediately to a cold dark place. It may be kept open
for a long time in this way. Flowers of Phyllocactus lati-
frons have been kept open for thirty-six hours in this way.

Conclusion. — State what is to be inferred as to the effect
of temperature on opening and closing of flowers.

Query. — From your observations, which do you think
is the more potent cause of these phenomena in flowers,
light or heat ? Give reason for your answer.

189. RESPIRATION OF FLOWERS
Object. — Tb find out what is given off by flowers.

Apparatus. — Some half-open flowers of such plants as dandelion,
daisy, or elder, two wide-mouth bottles, corks, and materials for
testing gases.

EXPERIMENTS WITH FLOWERS 223

Method. — Note first that there is nothing but air in the
bottles. Place the flowers in one bottle and cork tightly
for ten or twelve hours. Remove the cork and test the gas
with a burning stick, with limewater, etc., to determine
whether it is oxygen or carbon dioxide. Test the contents
of the other bottle which has been corked and kept as a
control. Result?

Conclusion. — State what is given off by flowers.

190. FLOWERS GIVE OFF HEAT

Object. — To demonstrate the evolution of heat by
flowers.

Apparatus. — Fresh flowers of dandelion, aster, elder, a wide-
mouth bottle, perforated cork, thermometer, sealing wax or par-
affin.

Method. — Fill the bottle loosely with the flowers. Pass
the thermometer through the cork and insert it in the bottle.
Close the opening with wax to prevent escape of air and set
it away for observation. Watch the thermometer. Does
the temperature rise or fall ? How can this be accounted for ?
In what way is the result of this exercise connected with that
of the preceding Experiment?

Conclusion. — State the result of your observations.

XVII. TYPICAL FRUITS

191. CORE FRUITS

Object. — To learn the structure of a core fruit.
Apparatus. — Two apples and a knife.

Method. — Study the outside of the apple. Find the
stem end, the blow

^^g^^^^BBQBB^^.

. ||H ^W end. What parts of

the flower are still
found attached to
the fruit?

Cut one apple
from stem to blow
end and examine
the section exposed.
Note the skin, flesh,
fibrous line, core, and

-^dp*" — - wall of nvn rv

placenta

Find also where and
how the seeds are

attached. Draw the
section, naming all
parts.

Cut the other apple crosswise through the center. Find
all parts mentioned above.

Conclusion. — Describe the structure of a core fruit,
naming each part from outside to center.

Suggestion. — Compare apples with pears, quinces, haws,
and the fruit of mountain ash.

224

peduncle

receptacle

dead esuential

organs
sepaJti

FIG. 98. — The apple.

TYPICAL FRUITS 225

192. STONE FRUITS

Object. — To learn the structure of a stone fruit.
Apparatus. — A peach and a knife.

Method. — Study outside as before. Then cut through
flesh to the pit and remove one half.

Note character of the flesh, the stone, etc. Remove the
stone and crack it. How many coverings has the seed?

Conclusion. — Describe a stone ^ — v

fruit as in preceding Experiment.

Suggestion. — Compare peach (A T^

with plum, cherry, apricot, date,
and olive.

193. PULPY FRUITS

Object. — To find out the char-
acteristics of a pulpy fruit
(berry}.

Apparatus. — A tomato and a
knife.

Method. — Study the outside as
in the two preceding Experiments.
Are there any remains of the
flower left on this fruit? How
can you account for the scar
opposite the stem ? What part of FlG" "' ~~ The peach"
the flower adheres to the stem? Cut a tomato crosswise.
Into how many sections is it divided? What can you say
of the number, attachment, and location of the seeds ?

Conclusion. — Describe a berry, having a tomato in mind
as a typical berry, stating what you can of the character
of the skin and the number and location of the seeds.
EXP. EOT. — 15

226 TYPICAL FRUITS

Suggestion. — Compare the tomato with the grape, goose-
berry, and currant, which are typical berries; also with the
orange, melon, etc., which are modified berries.

194. DEHISCENT FRUITS

Object. — To learn what is meant by dry fruits, and
how they scatter their seeds.

Apparatus. — Pods of beans, peas, locust, honey locust, catalpa,
or any other dry dehiscent fruit.

Method. — Study the fruits selected and determine how
they split. Some open on one seam only, others on two
seams, and still others in three or more places.

Examine several old pods which have split and note
whether they are still flat or twisted.

Do you see any advantage in having the valves twist as
they spring apart?

Hang up several ripe pods not yet open and let them re-
main for some time. When they split, note the result.
What becomes of the seeds ?

Conclusion. — State what a dry fruit is and how the seeds
are scattered.

195. SEED DISPERSAL

Object. — To learn some ways in which a plant scat-
ters its seeds.

Apparatus. — Maple keys, balsam or jewelweed plants in fruit,
and burdock or clotburs, desmodium, and milkweed.

Method.— (a) Study the maple key to get an idea of
the formation of its wing and the number of seeds it contains.
Throw one into the air and see how long it takes to fall to
the ground. Of what use is the wing? Compare it with
dandelion, milkweed, and ailanthus fruits.

TYPICAL FRUITS

227

(6) Select a branch of balsam or jewelweed having full-
grown pods. Touch one and note its behavior. How far
can the balsam pod throw its seeds. Compare it with
wistaria pods and with the so-called squirting cucumber.

(c) Examine the fruits of burdock and clotbur. How are
they fitted for being scattered? Throw one against a piece
of cloth. Result?

Compare them with sticktights, beggar-lice, and other
similar fruits.

FIG. 100. — A, maple ; B, ailanthus ; C, Ptelea.

(d) Study all the others in like manner, making out the
peculiar method of seed dispersal employed by each.

Queries. — How are geranium seeds scattered ? How does
the basswood tree scatter its seeds? How do you ac-
count for the distribution of such fruits as apples, peaches,
and edible nuts which have no wings or barbs or the explo-
sive power to expel their seeds?

228

TYPICAL FRUITS

Suggestion. — Examine the wool of a sheep or the tail
of a cow and find if any seeds are clinging there. After

FIG. 101. — A, sticktights ; B, sticktights, magnified ; C, burdock ;
D, cocklebur.

a walk through the woods in summer or early fall what
fruits will be found clinging to your clothing ?

196. SEED DISPERSAL

Object. — To demonstrate seed dispersal by explosive
fruits.

Apparatus. — Witch-hazel fruits which are ripe but not yet
bursting, wide-mouth bottles, damp sand or moss, and formaldehyde.

Method (Laboratory). — Gather the witch-hazel fruits and
place them in the bottles of damp sand or moss to which has
been added enough formaldehyde to prevent decay. A few
drops of 4 per cent solution is sufficient. When you desire
to show the phenomenon of seed dispersal by explosive

TYPICAL FRUITS

229

Q a

FIG. 102. — A, violet ; B, squirting cucumber ; C, cranesbill ; D, witch hazel.

action of fruit, take one of the specimens from the prepa-
ration jar and place it where it will dry out.

When dry the capsule valves will close up and the seeds
will be thrown to a considerable distance.

ii m

FIG. 103. — I, celandine ; II, pea ; III, jimson weed.

230

TYPICAL FRUITS

Table Showing Methods of Seed Dispersal

maple
1. By winged fruits.

Seed Dispersal

2. By winged seeds.

3. By hooked fruits.

4. By tufted fruits.

5. By tufted seeds.

6. By tailed fruits.

7. By explosive fruits.

8. By buoyant fruits.

9. By edible fruits.

10. By edible seeds

(by man)

11. By brittle stems.

12. By breaking of a falling

fruit due to force of
the fall

ash

elm

ailanthus

catalpa

trumpet vine

pine

clotbur

burdock

sticktight

thistle

dandelion

geranium

milkweed

cotton

althea

clematis

avens

anemone (patens)

witch-hazel

jewelweed

wistaria

coconut

balloon vine

bladder nut

berries

cherries

garden fruits
f nuts
1 cereals

Russian thistle

panic grass

" tumbleweeds "

Brazil nut

TYPICAL FRUITS 231

Method (Field)- — Go into the woods, fields, and parks and
make a collection of as many examples as possible to illus
trate seed dispersal.

Bring them together and mount, label, and classify accord
ing to the method of dispersal represented.

Make drawings of each type found and supplement speci-
mens with pictures.

Query. — How are poppy seeds scattered ? How can
you account for the occurrence of poison ivy along the
fences bordering country roads? How are cedar trees so
often found along roadsides at quite regular intervals as if
planted by man?

Suggestions. — (1) Test various common fruits for the
nutrients. Sugar will naturally be found in most sweet
fruits. Which fruits contain protein, starch, oils? Which
have the greatest amount of water?

(2) Test ripe and unripe fruits of the same sort such as
green apples and ripe apples. How do they differ in their
food content?

197. SAP FLOW IN FRUITS

Method. — Find out where the sap flows in a fruit,
by making an experiment similar to experiments on sap
flow in roots, stems, and leaves. Cut off and place with
the peduncle (stem or fruit stalk) immersed in eosin or methyl
green dye. After a few hours, cut open the fruit and see
what structures have become stained with the color. Does
it reach the seeds? What light does this exercise throw on
the use of the hilum of seeds ?

Note. — Cucumbers, gourds, okras, and other garden fruits when
unripe will give excellent results.

232 TYPICAL FRUITS

Reference work — (1) Do fruits require sunlight in order
to ripen?

Pick two of each sort of several unripe fruits. Place one
of each in a dark place and the other where it will receive
the sunlight. Temperature and other conditions must be
the same for both samples.

After a week's time, examine both fruits and note the
difference.

(2) Do fruits require air in order to ripen ?

Repeat the foregoing experiment, using fruits, some of
which have been previously coated with vaseline to close
the pores in their skins.

(3) What is the function of the fruit skin or epicarp ?
Compare peeled with whole fruits both ripe and unripe.

Does the removal of the skin have any effect on ripening ?
On retention of sap ? On hastening or retarding decay ?

(4) Examine fruit skins with a microscope. Do they pos-
sess stomata?

Query. — Why do gardeners often pluck unripe tomatoes
and lay them where the sun shines to ripen?

XVIII. CRYPTOGAMS
Introductory Note

The following Experiments on a few typical seedless plants
are added for the purpose of giving the student a general
idea of what is meant by the so-called flowerless plants.
Most of these Experiments are such as may be undertaken
without the aid of a compound microscope. The unaided eye
is able in most cases to see the structures alluded to, and a
simple magnifier is all that will be required.

As every well-equipped school is provided with at least
one compound microscope, the use of the latter is recom-
mended.

198. ALGAE (pond scum)

Pond scum (spirogyra) is one of the commonest water
plants, where it often abounds in still or slow-flowing
streams. It is easily recognized by its bright green, silky
threads, which form dense tangles. At times they throw
off great masses of gas which gives them a frothy appearance,
hence it is often 'called " frog spittle."

Object. — To study growing algae.

Method. — Place a mass of pond scum in a tall beaker
(a) or preparation jar and set it in the strong sunlight.

Place another (6) similar mass in darkness or diffused
light. After one hour place the jars side by side and com-
pare their contents. Where is the green alga in (a) ? In
(6)? Do you discover any reason for this? Change the
bottles, placing (a) in shade and (6) in strong sunshine for

233

234 CRYPTOGAMS

another hour. What change has now taken place in each
jar? Why?

Arrange an apparatus as in Experiment 145, putting the
pond scum below the funnel. Now place it in strong sun-
light. What comes from the plant? When a test tube is
full, remove and test with a lighted stick. Is it nitrogen?
Hydrogen? Carbon dioxide? Oxygen? Give reason for
your answer.

Now select a small portion of the plant. Remove it
with your fingers and place in a white earthen dish with
enough water to cover it. How does the plant feel?

Examine the threads of pond scum as they lie in the dish.
Of what do they consist? Do the threads branch or fork?
Examine with a magnifying glass and you will see that the
threads are built up of little cylinders placed end to end.
These are cells, and the fiber is made up of a string of such
cells. Try to find the end of one of the threads. Does this
end cell look like the others ? If not, how does it differ ?

To what is the green color due? In coarse plants the
arrangement of this coloring matter (chromatophores)
may be made out.

At certain seasons, one may find places where the threads
are of different color, and sometimes no green color will be
found for several cells. Two threads may also be found so
joined as to form a sort of ladder. Look for these things.

What effect does the presence of many such plants have
on the value of drinking water ?

Suggestion. — Mount a thread of pond scum in water
and examine with a low power. Note the cell wall, the clear
contents of each cell, and the green spiral within (Fig. 115).
Examine many such threads and search for the end cell.
Is it like all the others? If not, how different?

CRYPTOGAMS 235

Suggestion. — Extract the chlorophyll from a mass of
spirogyra by placing it in a beaker and covering it with
alcohol.

What change occurs in the color of the alcohol ? Remove
some of the plant and compare it with some which has not
been immersed in alcohol.

Refer to Experiment 149. Why is the color so different
here from what it was there?

Query. — Does spirogyra make starch ? Does it contain
starch ?

199. REPRODUCTION IN POND SCUM
Object. — To observe conjugation in spirogyra.

Method. — In autumn procure a supply of spirogyra and,
having placed some in a shallow dish, examine with a mag-
nifier in search of the parallel filaments which have formed
the ladderlike structures referred to in the foregoing Experi-
ment. Remove such to a slide, cover with a cover glass in
water, and carefully examine with a low power. Look for
the various steps in reproduction: —

1. The ordinary cylindrical cells with their spiral chro-
matophores.

2. Cells from separate filaments which have produced
knobs projecting towards each other.

3. Cells in which these processes have met but not yet
united.

4. Cells in which, the processes have united and their
dividing walls have ruptured to permit the contents of one
cell to flow into the other.

5. Empty cells whose contents have gone into the con-
jugating cell.

236 CRYPTOGAMS

6. Zygospores, or oval masses which have formed out of
the united contents of the two cells.

Notice the thickened wall which forms about the zygo-
spores.

Note. — Reproduction is effected in two ways in spirogyra:
(a) Asexually, that is, by pieces breaking off and continuing to
grow. (6) Sexually, that is, by the forming of zygospores through
the union of contents of neighboring cells. The process is known
as conjugation. The sex elements are different from those of
flowering plants in being alike in appearance.

200. PLEUROCOCCUS

This common alga is found on the north side of stone
walls, old fences, and tree trunks. It is usually more abun-
dant near the ground, but sometimes is to be found on old
roofs. It gives a green color to whatever it grows on, be-
coming brighter in damp weather.

Object. — To study the structure of pleurococeus.

Method. — Procure bits of bark or old wood showing
green color, note powdery appearance on dry surfaces ; place
in a damp chamber where they will remain moist. What
change of color follows ? Set in a warm place, preferably in
the shade. Remove some of the green material and mount
it in a drop of water. Examine first with a low power and
later with a higher (£" objective) noting: —

1. The shape of the cells.

2. Dividing cells as shown by pairs and clusters which
are still united.

3. Can you distinguish between the cell wall and cell
contents?

4. Can you determine the number, shape, etc. of chloro-
plasts?

CRYPTOGAMS 237

5. Can the nucleus be seen?

Let a drop of iodine solution flow under the cover glass.
Look for starch test. What effect does iodine solution have
on the nucleus? From observations on the plants, deter-
mine how reproduction is effected.

Note. — This method of reproduction is known as direct cell
division. The cell simply cuts itself in two by forming a partition
through the center. Each new cell is known as a daughter cell.
The original cell is called the mother cell. After cell division the
daughter cells remain loosely attached for some time while they
proceed to grow. Either one or both of the daughter cells will
again divide, thus forming groups of three, four, etc., in clusters-
Draw single plants, dividing cells, also any clusters which may be
observed.

201. VAUCHERIA OR GREEN FELT

This plant is most abundant in muddy pools and ditches,
where it forms in masses resembling felt. It is also found
growing on damp earth and on moist surfaces of flowerpots.

Object. — To study the structure of vaucheria-

Method. — Examine the pads noting the color, texture,
feeling, etc. Under the microscope make out the coarse-
ness of the filaments. Do they branch regularly or irregu-
larly? Do the filaments show any light relation? If so,
what? Is a filament uniform in diameter or does it vary?
Is the filament divided into cells by cross partitions? Is
the protoplasm uniformly colored?

Look for rhizoids, or colorless rootlike outgrowths, chloro-
plasts, oil globules, nuclei, and a central vacuole. Using
iodine solution, determine whether starch is present.

Look for sex organs, (a) the large oval oogonium con-
taining an egg. Look for the pore through which sperms

238 CRYPTOGAMS

can enter at fertilization. Where is this pore situated?
(6) The short bent antheridium or male reproductive
organ.

Let the material remain in a warm place and cover to
prevent drying out. Under favorable conditions the zoo-
spores or sperms will develop and may be studied under a
high power. They escape from the antheridium and swim
about by means of pairs of delicate cilia or lashes. A drop
of iodine solution is needed to show these organs.

Fertilization is effected when a sperm swims into the
pore of the oogonium and fuses with the egg.

Look for the ripened egg or oospore within the oogonium.
How do the walls and contents differ from that of an un-
fertilized egg?

This method of reproduction is known as heteroyamy,
because the sex elements are unlike, namely, eggs ( 9 ) and
sperms ( $ ) .

202. BREAD MOLD
Object. — To study the growth of bread mold.

Method. — Select two wide-mouth bottles. Mason fruit
jars with rubber rings and screw tops are best.

Place a piece of bread or banana skin or a cold boiled po-
tato in each jar, and leave it open to the air of a kitchen,
pantry, or cellar for five or ten minutes. Then screw on the
covers tight, after having added a few drops of water to
insure a damp atmosphere within.

Now plunge one jar into a kettle of boiling water and let
it boil for a few minutes. Remove it and stand both jars
in a warm place for several days.

Which jar first shows signs of mold? Why? How long
before the other jar shows mold?

CRYPTOGAMS 239

What does this teach us regarding the effect of heat on
molds ?

Why do canned fruits as a rule not become moldy? If
one should find mold in a fruit jar, what inference can be
made as to the method of canning? Open the jar in which
there is a good crop of mold and quickly plunge in a lighted
candle. Does it burn or go out ? What does this show as to
what is given off by molds ?

For laboratory work, lay a slice of stale bread or some
slices of cold boiled potato on a dish. Dampen or add a
sponge saturated with water and cover with a bell jar.
When a good crop of mold has appeared, remove the bell
jar and examine the colony of plants. Note color, size,
smell, and general appearance of the plants. Notice the
tiny threads (hyphse) which form a delicate network all
over and through the bread. Look for other hypha3 which
stand up at right angles to the surface. How do these up-
right threads terminate? (Sporangium.)

Observe these parts with a magnifier. How do the spo-
rangia differ in color ? How may old ones be distinguished
from young ones?

Make mold cultures of all manner of food stuffs and com-
pare them. See if you can grow bread mold on cheese or
meat. Also the reverse.

203. MOLDS

Object. — To show the development of different molds in
food materials.

Apparatus. — Several plates, bell jars or tumblers for covers,
and an assortment of foods, such as bread, cheese, orange peel,
banana, etc.

240 CRYPTOGAMS

Method. — Moisten each article and place it on a plate.
Cover it with the bell jar and set it aside in a warm, dark
place. Observe any changes which may take place from
day to day. When molds appear, examine them carefully.
Where color begins to show, the spores are beginning to
ripen. Examine them with a magnifying glass. How many
different species can you find? Do the different kinds ap-
pear on the same or on different substances ?

204. MOLDS

Object. — To show the mycelium of a mold.

Apparatus. — Test tubes, fruit juice, or any liquid culture me-
dium.

Method. — Partially fill the test tubes with the fruit
juice and drop into each a few mold spores taken with a
needle from a moldy substance. Set them in a place favor-
able for growth and make observations daily with a magnifier.
Note the minute threads which are sent forth from the
spores. These are called hyphce. Study the way in which
they spread outward and downward into the fruit juice.
The mass of branching and interlacing threads is called the
mycelium.

How do the parts above the surface differ from those
below? Which ones bear spores?

Mount the mycelium in a drop of water and study it with
a low power.

205. MOLDS

Object. — To demonstrate the presence of mold spores in
the air.

Apparatus. — Petri dishes, nutrient solution (see page 257) mak-
ing it slightly acid by addition of hydrochloric acid or fruit juice
until it gives litmus a red color.

CRYPTOGAMS 241

Method. — Expose the dishes in various places for two
or three minutes. Then cover them and set them away for
the molds to develop.

Make the exposures in different places, as cellar, pantry,
parlor, etc. Make some exposures out of doors and others
in the house.

After three or four days, what results are to be seen ?

Conclusion. — What does this show concerning the prev-
alence of mold spores in the air ?

206. MOLDS

Object. — To show that there are mold spores in dust.
Apparatus. — Petri dishes as before.

Method. — Over one Petri dish shake a dry dusting
cloth or feather duster. Over another, shake a damp dust
cloth. Over a third shake a rug. Into a fourth drop
a bit of dirt scraped from a crack in the floor.

Close all the preparations and set them away for develop-
ment of molds. After three or four days note the result.

Conclusion. — What may be inferred as to the occurrence
of mold spores in dust? From your experiment which is
better to use, a dry or a damp dust cloth? Why?

207. MOLDS

Object. — To learn some of the conditions favorable to
growth of molds.

1. Moisture. Place a piece of wet bread and a piece of
dry bread side by side on a plate and cover them with a bell
jar. After a week study the preparations. On which one
does mold develop best? Inference?

2. Temperature. Prepare three Petri dish cultures. Sow

EXP. EOT. — 16

242 CRYPTOGAMS

them with a liberal supply of spores, close them, and place
one in a very cold place, the second in a warm place, and
the third where it is quite hot. After one week, bring the
preparations together and compare results. Inference?

3. Light. Prepare two Petri dish cultures as before, placing
one in a dark or semidark place, and the other on a window
sill where it will receive direct sunlight. After one week
bring them together and compare. Inference?

4. Air Supply. Make two Petri dish cultures, placing one
under cover and the other where the air can freely blow over
it. After a week, bring them together and compare them.
Set a culture on which a fine growth of mold is growing
where the wind can blow over it. What result? What
may be inferred from this experiment?

Note. — The canning of fruit depends largely on exclusion of
molds. The heating of the fruit is designed to kill molds which
may have found access to the fruit. The cans are closed quickly
while the contents are still hot so that no spores can get in. The
sealing must be air-tight to prevent molds from getting in before
the fruit is eaten. In spite of all these precautions, sometimes
molds will find entrance and spoil the fruit.

208. FUNGI
Object. — To sturdy a mushroom.

Mushrooms may be found in rich woods, fields, meadows
— wherever there is abundant decaying vegetable matter.

These plants are saprophytes, that is, living on decaying
substances. They are important economic plants for the
reason that they aid in the removal of dead vegetation.

Method. — Draw the fungus after having studied it to
make out the following parts: the cap (umbrella or pileus),
the column (stipe or stalk), the gills or flat plates which extend

CRYPTOGAMS

243

FIG. 104. — Mush-
room.

(Photographed by A.
H. Lewis.)

from center to circumference underneath, the

veil or delicate membrane which stretches

across from the rim of the cap to the annulus

or ring which adheres to the stipe, and the

mass of rootlike fibers at the base of the

stipe called mycelium.

Cut a vertical section through the center

of the cap and down through the stipe.

Draw the section and name all structures

seen.

What is the color of the under side of a

mushroom? Are the young and the old

ones of the same color? Do all the gills extend from center
to circumference ? Are they attached to
the stipe?

Spore Prints. — Cut off the stipe of a
fresh young mushroom close to the pileus.
Lay it down upon a piece of white paper.
Invert over it a tumbler to prevent the
wind from blowing away the spores.

After a few hours, carefully remove
the tumbler and lift the pileus. What
do you find on the paper where the mush-
room lay? Beautiful spore prints may
be made in this way. Dark spore fungi
show up best on white paper, but pink
'c spores or yellow or white ones are best
seen on black paper.

To fix a spore print a fixative such as

FIG. 105.— Mushroom: is used" by artists may be employed, but

Z£S3£,t. the force with which an atomizer throws

stipe ; r, ring ; g, gills, the spray will usually spoil the print.

244

CRYPTOGAMS

A better way is to make the prints on very thin Japan paper
and float it on a dish of fixative or mucilage until the latter
penetrates the paper through and through. Then dry it and
mount it on a card for reference.

Another way of fixing is to spray a fixative over the paper
first and then get the spore prints while the preparation is
still moist.

Caution. — Too much cannot be said concerning the
danger of tasting unknown fungi. Beware of any fungus

FIG. 106. — Spore print and spore-bearing surface.
(Photographed by A. H. Lewis.)

which has a cup at its base. As a rule, any highly colored
or strong-smelling fungus or one having a milky sap is not
regarded as wholesome, although there are exceptions to
all these rules.

209. FUNGI
Object. — To study shelf fungi.

Procure as many different kinds of shelf fungi as possible.
They are always found growing upon the dead branches of
trees or upon fallen logs.

CRYPTOGAMS

245

Make a note of the kind of tree on which they are found
growing, and if possible secure a portion of the bark and
wood at the point where the fungus is attached.

In general three types of shelf fungus will be found. Their
chief difference will be the character of the under surface.
In some this surface will
be found covered with
minute pores, in others
there will be a beautifully
corrugated surface, and
in the third class this
region will be found cov-
ered with teeth or points.

Method. — Study the
specimen and determine
its color, feel, and texture.
Draw upper and under
aspects. Answer the fol-
lowing questions : On
what tree did the speci-
men grow ? What are its
color, texture, and smell?
Is there any way by which its age can be determined ? Is
there any system about the arrangement of the ridges, pores,
or teeth on its spore -bearing surface?

Cut a specimen from upper to under surface. How far
do the pores extend ? Draw a portion of the section. Does
the fungus grow continuously or by seasons? Give reasons
for your answer.

Examine the base where the fungus is attached and see
if you can find any roots or other connection with the tree.
Examine some of the wood and also a specimen of sound

FIG. 107. — Shelf fungi.
(Photographed by W. C. Barbour.)

246 CRYPTOGAMS

wood of the same kind. How do they differ in look, strength,
softness, and other qualities?

Note. — Fungi propagate by spores which are so light as to be
easily carried by the winds. When discharged from the parent
fungus, they float away on the winds. If any favorable locality
for growth is found, such as the exposed end of a broken branch
or a fallen tree, these spores promptly germinate and begin their
work of destruction. The tree becomes permeated with the fine
cobweblike fibers, and when mature, they produce the shelves.
Whenever a tree is seen to bear these fungi, it should be promptly
cut down and burned t6 prevent the spread of the disease.

Logs and old lumber which are affected with fungi ought to be
burned.

Suggestion. — Procure some fresh mushrooms with a por-
tion of the soil in which they are found growing.

Repeat Experiments 140-144 with them to find out if they
transpire water. Repeat Experiments 145 and 152 and 153 to
find out whether they perform the same work as green plants.

Examine a portion of the delicate skin covering of the
fungus with a microscope. Do you find stomata ?

210. A MOSS PLANT

Object. — To learn the characteristics of the spore-bear-
ing stage of a moss.

Apparatus. — Any moss when in fruit, a hand magnifier, a pin.

Method. — From a tuft of moss, carefully remove one
of the plants. If the specimens are dry, they may be fresh-
ened up by plunging them into hot water for a minute before
studying. Of how many parts does a moss plant consist?
Describe each. Examine one leaf with the magnifier. Do
you find any veins such as are found among seed-bearing

CRYPTOGAMS

247

u

plants? Have they leafstalks? Draw. Find the capsule

at the top of the stem (stipe). Does

this capsule spring from the end of the

stipe, or is it borne on the side ?

Find a capsule which bears on its top

a very loose and delicate cap (the calyp-

tra). This cap is often shed, but will
w ,'j surely be found on some

-d of the plants. Remove the
calyptra and sketch. Ex-
amine the capsule and
draw it greatly enlarged.
With a magnifier look
for the lid which fits like
a cover over the capsule.
Find an old capsule which FIG. 108. — Two com-
has shed its cover. The mon mosses-

lid over the opening at the top is called the
operculum. Draw it.

What may be seen surrounding the open-
ing after the lid is removed? Breathe on
the top of the capsule and quickly look
at it with a magnifier. What occurs?
The ring of teeth within the mouth of the
capsule is called the peristome. How do
the teeth behave when moist breath touches
them? Give reasons for this. Draw. Of
what use to a moss plant is this property
of the peristome ?

Note. — A moss leaf mounted in a drop of
FIG. 109. — A com-
mon moss plant water under the microscope is an excellent
(Polytrichum) . object for showing chloroplasts.

248 CRYPTOGAMS

211. MOSSES

Object. — To learn what is meant by alternation of
generations.

Method. — Prepare a shallow flowerpot by filling it with
soil to within an inch of the top. Dampen it and set it in a
saucer of water so as to prevent drying out. Crush several
moss capsules on a piece of paper to obtain the spores and
sow them by blowing them over the soil in the pot. Cover
it with a glass plate and set it away in a shady place.

When the spores have begun to germinate, examine a
portion with the magnifier and later with a low power.

1. The protonemata will show numerous branching fila-
ments. Look for buds, which will develop into leafy moss
plants. Look for rhizoids, which are delicate hairlike struc-
tures used as roots. With a higher power look for chloro-
plasts. Draw a protonema, showing all structures.

2. Procure specimens of Funaria, Mnium, or Polytrichum
in spring for use fresh, and preserve some in formalin, for
later in the year.

Remove a rosette from the tip of one plant and place on
a glass slip in a drop of water. With a pair of needles, tear
it apart and examine with a low power.

Look for flask-shaped organs, which will usually be found
floating in the water. These are the archegonia. Look
for club-shaped structures in like manner. These are
antheridia.

If a drop of weak caustic potash be allowed to flow under
the cover glass, the archegonia will become clearer and the
egg can be seen within.

If fresh antheridia be crushed and examined with a high

CRYPTOGAMS 249

power, the sperms will be seen swimming about in the
water.

Make drawings of all structures seen.

Reproduction in Mosses. — Mosses admirably illustrate
the phenomena of alternation of generations.

The life history of a moss plant may be described as fol-
lows : 1 . Spores are produced in the capsule of the plant
studied in the preceding exercise. The capsule, together
with its stalk (seta) is known as a sporophyte (spore plant).
Spores falling upon favorable soil germinate, forming a
delicate green plant called a protonema, which is made up of
numerous branching filaments.

2. The protonemata have numerous hairlike structures
resembling root hairs, which are called rhizoids. They also
bear tiny buds which ultimately develop into leafy moss
plants.

3. The leafy moss plant is known as a gametophyte, because
it bears the sex organs, or gametes, carefully tucked away
among the minute leaves forming the rosette at its top.

The male gamete is called an antheridium. The female
gamete is called an archegonium.

The sexes may be on the same plant (monoecious) or upon
different plants (dioecious) as among flowering plants.

Within the archegonia are egg cells and within the an-
theridia are numerous sperms. Fertilization is effected by
union of a sperm with an egg cell, whereupon the latter pro-
ceeds to develop into the spore-bearing plant (sporophyte),
thus making the life cycle complete. The sporophyte re-
mains attached to the leafy moss plant and grows upon it
like a parasite. Thus we have two alternating generations;
namely, the gametophyte which produces the eggs and
sperms, and the sporophyte, producing non-sexual spores.

250

CRYPTOGAMS

212. A FERN

Object. — To learn the characteristics of the spore-bear-
ing stage of a fern.

Apparatus. — Any common fern (one of the shield ferns (aspid-
ium) is preferable), and a magnifier.

Method. — Study the plant as a whole, making out its

roots, its under-
ground stem (rhi-
zoma), its leaves
(fronds) , and their
peculiar manner of
folding or rolling in
the bud (circinate).

Examine the frond
and make out its
venation. How does
the veining differ
from that of leaves
hitherto observed ?
Note the parts into
which the frond is
divided (primse, etc.).
Is the frond alike on
a both sides? If so,

FIG. 110. — A fern plant, a, fronds and root- u jg a s£erile frond,
stock ; b, fertile pinna ; s, s, sori ; c, cross sec-
tion of a stipe, showing ends of the fibro vascular rind a irond wnicn
bundles ; d, a cluster of sporangia, magnified ; has dots On the Under
e, a single sporangium still more magnified, . . _, ,, ,

shedding its spores. side. These are called

son'. Describe the

sori, their size, color, and arrangement on the frond. Make
a sketch of a portion of the frond, indicating as many

CRYPTOGAMS

251

of these details as can be made out with help of the
magnifier.

Some ferns have the sori covered with a shield (indusium),
others are naked, and still others are covered by a fold of
the frond. (Compare maidenhair and brake.)

With a needle, lift an indusium and find the spore cases
(sporangia) underneath. Have they stalks? Draw a sorus
covered by the indusium,
also one having the in-
dusium removed. Draw
one sporangium.

Spores. — Lay a mature
fern frond upon a sheet
of white paper. Cover
it with another paper
until it is perfectly dry.
Then lift the frond and a
considerable quantity of
black or brown dust will
be found where the fern
frond has been lying.

Suggestion — The following ferns are very common. As
each has a peculiar manner of bearing its sporangia, it is
suggested that as many of them be studied as possible.

Onoclea, the sensitive fern, shows marked differences
between the sterile and fertile fronds. It also has an inter-
mediate form which is interesting.

Pteris, the brake, covers its sporangia with a fold of the
frond like a hem.

Osmundas show three interesting modifications of fertile
fronds. In the cinnamon fern there is a beautiful brown
fertile frond. The royal fern has the fertile portion only

I II

FIG. 111. — Prothallium of a common fern
(Aspidium). I, under surface, showing
rhizoids, rh, antheridia, an, and arche-
gonia, or ; II, under surface of an older
gametophyte, showing rhizoids, rh, and
young sporophyte, with root, w, and leaf ,6.

252 CRYPTOGAMS

at the tip of the frond. There is another species, Clayton's,
in which the fertile portion is near the middle of a huge
sterile frond.

The ostrich fern, the walking leaf, the moonwort, are very
characteristic. The maidenhair, adiantum, conceals the spores
under the overlapping tips of the delicate leaves.

Aspidium, the shield fern, is easily recognized by the curi-
ous shields called indusia which cover the sporangia.

Gather as many different kinds of ferns as possible. Bring
them together and learn their names. Every one should
be able to recognize at least ten species of ferns. Reference
to almost any standard text will enable one to learn to iden-
tify them.

213. A FERN
Object. — To propagate ferns from spores.

Prepare a large glass jar or Wardian case with about an
inch of ashes or gravel on the bottom. Above this put a
layer of rich wood soil and sprinkle it with water. Let it
stand for a day or so to allow the soil to settle and drain
off all superfluous water.

Now crumble some fertile fern fronds fresh from the plant
over the jar so that there will be an abundant supply of
spores to fall upon the prepared soil.

Cover the jar with a plate of glass and stand it in a shady
spot where the temperature is proper for germination.

After from two to four weeks, small green bodies resem-
bling delicate leaves will be found here and there upon the
surface. These are the beginnings of ferns (prothallia).

When the prothallia are about a quarter inch in diameter,
remove one, place it in a dish of water, and examine it.

What is its shape? Examine both sides. Has it roots

CRYPTOGAMS 253

(rhizoids)? If so, where are they found ? If your magnifier
is very strong, you may be able to find minute protuberances
on the under side. They are the sex organs of the fern plant.

After a few days longer, observe the prothallia again, and
you will doubtless find tiny fern plants growing from them.

Where do these come from? Is there any advantage in
the shape of a prothallium? If so, what ?

Ferns like mosses show the phenomena of alternate gen-
erations. The sporophyte stage is the familiar fern plant.
The gametophyte stage is seen in the prothallium with its
archegonia and antheridia.

Note to Teachers. — In propagating ferns from spores, water
the soil well to begin with, before the spores are sowed. Keep it
covered with a plate of glass to prevent drying out. Do not water
the culture again until it is desired to have fertilization take place.
Prothallia will live indefinitely, and no fertilization occurs if there
is no water in which the sperms can swim. After watering, the
embryo fern plants will soon appear.

214. YEAST AND FERMENTATION
Object. — To study the growth of yeast.

Method. — Prepare two wide-mouth bottles. Fill each
one about half full of water in which a small quantity of
sugar has been dissolved.

Add to one bottle a small piece of yeast cake dissolved
in water or a teaspoonful of liquid yeast. Let the other
bottle remain as a control. Place both preparations in a
warm place and allow them to stand for several hours.

What change, if any, takes place in each bottle? How
do the contents of the first bottle differ from that of the
second? To what must this difference be due? Note the
smell, if any. Plunge a lighted stick into each jar and test

254

CRYPTOGAMS

the gas above the liquids. How do they differ? Test with
limewater by holding a glass rod on which hangs a drop of
limewater.

What gas is given off by substances in which yeast is
working ? Repeat this Experiment using a small portion of
bread dough.

215. YEAST

Object. — To prove that carbon dioxide is given off in
fermentation.

Apparatus. — Test tubes, limewater, perforated stopper, and bent
tube as shown in Figure 112.

Method. — Fit up an apparatus like that shown in Figure
112, filling one tube half full of the molasses preparation

mentioned in the preced-
ing Experiment. Fill the
other tube with limewater
and let the gas from the
fermentating sirup pass
through the limewater.
Result?

Conclusion. — What does
Molasses this show as to the gas
& Yeast, given off when fermenta-
tion takes place?

Note. — Alcohol also is produced in this experiment and re-
mains dissolved in the solution. Its presence can be detected by
the odor, and it can be obtained if the substance.is distilled. It is
hardly advisable, however, to take the time to distill it although
that is an interesting and instructive experiment.

Cider and fresh fruit juices may be substituted for molasses,

Limewater.

Coa

FIG. 112.

CRYPTOGAMS 255

216. YEAST

Object. — To determine conditions favorable to the
growth of yeast.

Method. — Prepare three bottles of sugar and water. Add
yeast to each and place one in a cold place, another in a
warm room, and the third on a radiator or other hot surface.

After several hours examine the three preparations and
note results. What conclusion can be drawn at this point ?

Now put all three bottles in a warm place and let them
stand for another period. Result? What conditions are
most favorable to yeast? How are these conditions ob-
served in bread making ? In brewing ?

217. YEAST

Object. — To discover the effect of extreme heat on yeast.

Method. — Prepare three bottles of sugar and water and
treat them as follows: After adding the yeast, heat one
bottle scalding hot and then set it away for observation.
Place the other two in a warm place until fermentation has
begun, then heat the second bottle scalding hot. Allow all
three bottles to stand for several hours longer. Then com-
pare the results.

Conclusion. — Why does fermentation not continue after
bread is baked ? Give reason for your answer.

218. YEAST

Object. — To find out what substance is necessary to
yeast.

Method. — Prepare bottles containing various substances
other than sugar and add yeast as before. Do all substances
ferment? Try starch paste, salt solution, fruit juice, flour,

256

CRYPTOGAMS

rice, etc. Try some of these which have been sweetened
and others plain. What may be inferred from these experi-
ments ?

From the foregoing Experiments, answer the following
questions : —

Under what conditions does yeast develop? What
effect has heat on the growth of the yeast plants? How
does cold affect their growth? What is given off by these
plants? On what substance does yeast feed? How may
fermentation be stopped ? How may it be hindered ? What
gas is produced by yeast? How do you account for the
frothing of liquids containing yeast? What causes bread
to rise? Will fermentation go on forever? If not, why
not? Reasons for your answer. How long will fermenta-
tion continue?

219. YEAST (optional)

Object. — To observe the form of yeast plants and their
manner of reproduction.

Method. — Mount a drop of liquid yeast or any substance
in which yeast is growing and cover it with a cover glass.
Examine it first with a low power and then with a higher

power objective. Note the oval
cells of yeast. Are all of equal
size ? Find cells which are joined.
Look for cells producing smaller
cells (buds). Sometimes several
cells can be distinguished, forming
chains or colonies. What is the
color of these plants? Can they
manufacture starch ? Give reasons
FIG. us. — Yeast plants. for your answer.

CRYPTOGAMS 257

220. YEAST

Object. — To demonstrate the result of desiccation on
yeast.

Method. — Mix a little fresh yeast with some corn meal
and a small quantity of sugar until it has the consistency of
stiff dough.

Spread it on a board to dry. When it is thoroughly dried,
put it away in a jar and keep it dry.

After a week or two, dissolve a little in a vessel of warm
sweetened water and keep it in a warm place. Does it
show signs of fermentation ? How do you account for this ?
Does drying kill or merely check the development of yeast
plants ?

Try other portions after a longer interval. Result? Can
yeast be kept indefinitely in a dry state ?

Why does the grocer sell dry yeast of any age, but only
fresh moist yeast ?

Bacteria

Bacteria are very minute plants, so minute that it requires
the highest power of the microscope to reveal them. Indeed
they cannot be seen clearly even with the microscope with-
out the use of various staining reagents.

As individual plants, therefore, they are not to be con-
sidered in a work of this character. They may, however,
be studied in a broad way, since it is possible to cultivate
them in various nutrient solutions, where they develop so
rapidly as to form spots resembling mold, which are colonies
of bacteria.

Culture Medium. — A standard culture medium is made out
of the following: —

EXP. BOX. — 17

258

CRYPTOGAMS

Agar, 5 g.
Beef extract, 5 g.
Peptone, 5 g.
Common salt, 5 g.
Water, 500 cc.

Directions. — Dissolve the beef, peptone, and salt in
water and neutralize with sodium carbonate if necessary.

FIG. 114. — Bacteria, a, from drinking cup; b, from lunch room; c, from
schoolroom ; d, on hairs.

CRYPTOGAMS 259

Dissolve the agar in boiling water and add the first solution,
stirring constantly until they are thoroughly blended.

Test with litmus and neutralize again if necessary with
sodium carbonate. Add water to make up to 500 cc. Boil
the solution and filter it hot through absorbent cotton.
Pour it into sterilized Petri dishes or test tubes as desired.

Sterilizing. — (a) Dishes, needles, tubes, etc., are sterilized
by being boiled for fifteen minutes in water in which wash-
ing soda has been dissolved, and then being thoroughly
rinsed in boiling or very hot water. They should be dried
in an oven or over a Bunsen burner or alcohol lamp
flame.

(6) Needles, platinum wires, etc., may be sterilized by
being held in a flame until red-hot.

(c) Absorbent cotton, used for the 'plugs in test-tube
cultures, is sterilized by being placed in an oven and heated
until it is on the verge of scorching. When the cotton
begins to assume a brownish hue, it should be removed
and placed in a sterilized fruit jar ready for use.

221. BACTERIA

Object. — To prove the presence of bacteria in the air.
Apparatus. — Petri dishes and a culture medium.

Method. — Having sterilized the Petri dishes, put a small
quantity of the culture medium in each. There should be
only enough to flow over the bottom of the Petri dish so as
to leave a thin, even layer when the agar sets.

Cover the dishes to exclude dust and set them away until
the material has become firm.

Examine the dishes and note the clear, transparent char-
acter of the culture medium.

260 CRYPTOGAMS

Set apart one dish for a control and label it A. Then
expose a second dish to the air for ten minutes. Close it
and label it B. Set it aside with A, in a warm place where
the thermometer reads 36° C.

Leave the preparations and examine them from day to
day until spots appear on the surface of the culture
medium.

Describe the color and any differences in appearance of
these spots.

Look for spots on the control dish. What does this prove
regarding the source of the spots ?

Conclusion. — How can you explain the presence of the
spots in the dish which was exposed if no spots appear in
the control dish?

222. BACTERIA

Object. — To demonstrate the fact that the air in some
localities is richer than others in bacteria.

Apparatus. — Same as in the preceding Experiment. Several
Petri dishes will be required.

Method. — Prepare dishes as before, setting one away as
a control. Then expose each of the remaining dishes for
ten minutes in different places, such as the cellar, pantry,
parlor, attic, and the street. Dishes may be exposed in
different houses and in different parts of the city, as streets,
parks, or public buildings.

Label each dish and bring all together with the control
in a place where the temperature is 36° C. and again make
observations from day to day.

Conclusion. — State what localities give most and what
ones the fewest colonies of bacteria.

CRYPTOGAMS 261

223. BACTERIA

Object. — To prove the presence of bacteria in water.

Apparatus. — Test tubes, culture medium, and sterilized cotton.

Method. — Fill two test tubes with the culture medium
to about i their depth. Pour into one about 10 cc. of
drinking water and close the mouth of the tube with a plug
of sterilized cotton.

Into the second tube, pour the same amount of water
which has been boiled. Plug the second tube as before and
place both preparations at a temperature of 36° C.

After several days, examine both tubes, making note of
any differences in color, odor, and reaction on litmus. What
effect has boiling upon the water used ?

Suggestion. — In like manner, try different samples of
water, such as that from wells, cisterns, streams, pools,
ditches, etc.

224. BACTERIA

Object. — To demonstrate the prevalence of bacteria.

Method. — Make several cultures, using such things as
tartar from the teeth, scrapings from the finger nails, phlegm,
pus, saliva, etc.

Make cultures, using money, articles of clothing, door
knobs, tool handles, and books as sources of bacteria.

Prepare Petri dish with sterilized culture medium and
let a fly walk over the surface and leave it for several days.
Touch a lead pencil which has been used to the agar in a
Petri dish. What result?

Make two cultures of any sort of bacteria and add a drop
of corrosive sublimate, formalin, carbolic acid, Platt's chlo-
rides, or any other disinfectant to one of them. Label the
cultures and set them away for observation. Result ?

262 CRYPTOGAMS

225. BACTERIA

Object. — To demonstrate the relation between soil bac-
teria and the growth of plants.
Apparatus. — Flowerpots, soil, clover seed or alfalfa.

Method. — Fill two flowerpots of medium size with soil.
Rich soil dug from a field where clover is growing is the
best for the purpose. Sift the soil to remove stones, roots,
and other coarse matter.

Heat one flowerpot in an oven for an hour. This will
sterilize the soil if the heating has been thorough.

Sterilize seeds of clover or alfalfa by rinsing them in a
very dilute solution (2 per cent) of formalin and then rinse
them in distilled or sterilized water.

Plant the sterilized seeds placing an equal number in each
of the flowerpots.

The seeds will then be placed in exactly similar conditions
with exception of the soil which in one flowerpot has been
freed of bacteria, while the other has not been sterilized.

Place both pots under conditions favorable for growth and
keep them so until the young plants have been growing for
some time.

What difference is noticed in the two plants? Compare
them as to height, vigor, number of leaves, and general
appearance. Keep the plants growing if necessary for a
month or six weeks before making the comparison. Remove
both plants from the soil by turning the flowerpots over so
that the roots will come out uninjured, and examine the
exposed roots. Are they alike? If not, what differences
are observable? Draw or make blueprints of the root of
each plant.

Conclusion. — What may be inferred as the difference

CRYPTOGAMS

263

between sterilized and unsterilized soil in supplying nourish-
ment to plants?

Note. — If a sample of soil should contain harmful bacteria,
sterilization would kill them and the soil would be better for the
plant than unsterilized soil, for then the plant could absorb such
mineral foods as might be present without interference from bac-
terial foes.

Leguminous plants, such as clover, alfalfa, beans, peas, etc.,
usually have swellings upon their roots which are the home of bac-
teria. These organisms perform valuable work by absorbing
nitrogen from the air, which they build up into nitrites and nitrates.
In this way, plant foods are formed. The process is known as
fixation of nitrogen, and such bacteria are called nitrifying bacteria.

Cells and Protoplasm

If the student refers to the various demonstrations with
the microscope (Exs. 54, 91, 108, 109, 146, 147, 198, and 215),
he will find that on close inspection all these plant structures

FIG. 115. — Spirogyra.

are built up of very small units called cells. In seeds of
the horse bean ( Vicia faba) the cells can be plainly seen with
the naked eye or with a simple magnifier.

If sketches of all the different forms of cells are made and
compared, they will be found to have three points of simi-
larity; namely, a very delicate sac or membrane, the cell
watt, containing a clear transparent fluid, the protoplasm,
and suspended somewhere within it, a tiny mass of slightly
denser material, the nucleus.

264

CRYPTOGAMS

Root hairs seen on young roots are
cells of slender tubular shape. Pali-
sade cells in the leaf are oblong and
contain many chloroplasts or green
corpuscles which carry on the work
of starch making. The delicate
threads of pond scum or spirogyra
are made up of short cylindrical cells
whose chlorophyll grains are arranged
in very beautiful spiral threads.
Guard cells of the stomata occur in
pairs and are half round or kidney-
shaped, and the cells of leaf epidermis
are very various in outline. Compare
also the sec-
tions of mono-
cotyl and di-
cotyl stems,

and various other cell forms will be

seen.
But no matter what the form may

be, all cells studied and most vegetable

cells will be found to agree in having

the three parts named — wall, proto-
plasm, and nucleus.

Mount thin sections of plant tissues,

root hairs, pollen grains, moss leaves,

etc., in water under cover glasses and

study them with low power ; and when Flo< 1 17. -Diagram of

the thinness of the section will permit, mesophyl cell of a leaf ;

examine them also with a higher c; chIor°Plast; n' m~

cleus ; 13, vacuole ; w, cell

power. waii.

FIG. 116. — Root hair of
wheat.

CRYPTOGAMS 265

The nuclei will not always be seen in this way, but a drop
of methyl green or iodine solution run under the cover glass
will often stain the nucleus so as to make it plainly visible.

If young onion root tips are prepared and properly sec-
tioned, the wonderful process of cell division known as
mitosis will be seen. This, however, requires careful prepa-
ration of the mounts. Prepared sections are preferable.

226. PROTOPLASM

Object. — To demonstrate the living contents of a cell.

Apparatus. — Microscope, slips, cover glasses, and a flower of
tradescantia.

Method. — Mount a fresh stamen in a drop of water and
examine the hairs which are found upon the filaments.

Note the cells of which these hairs are made. Watch
for some time until the eye is accustomed to the field. The
contents of the cell will be seen to be circulating inside the
walls. This slowly streaming fluid is the protoplasm. It
is alive. Does the protoplasm move about the nucleus or
does the nucleus also circulate in the stream?

227. PROTOPLASM

Object. — To contrast the behavior of living with dead
cells.

Apparatus. — A red beet root, knife, beakers, and water.

Method. — Slice the root in thin pieces and place one or
two of them in boiling water for five minutes to kill the pro-
toplasm. Now put raw slices in one beaker of water and
the cooked slices in another. Let them stand for ten
minutes and note result.

How do you explain the difference ?

266 CRYPTOGAMS

228. PROTOPLASM

Object. — To demonstrate automatic movement in plants.
(See also Exs. 155-161).

Apparatus. — Any twining plant of rapid growth, such as a hop
morning-glory, or cinnamon vine, a cardboard disk, and an upright
support.

Method. — Select a plant about six or eight inches high,
and examine it. Does it show any signs of coiling? Bring
it into contact with a slender upright cord or rod. Does it
respond ? If so, how ? When it begins to coil, note the direc-
tion in which it turns. Can it be made to revolve in the
opposite direction?

When it reaches the top of the support, leave it and
watch its revolutions.

Over the end of the stem slip a circular disk of cardboard
and fasten it to the support. Note the revolutions of the
stem and indicate the different positions on the disk. Note
the time of each position. Does the plant move in a defi-
nite period of rotation or not ?

Does the motion increase or diminish at night? Does
watering produce any change in rate of rotation ?

Protoplasm. — The living substance of which plants and
animals are made is called protoplasm, a word which means
first form. It differs from all other substances in being
alive. Chemically it consists of varying quantities of carbon,
nitrogen, hydrogen, oxygen, phosphorus, sulphur, and traces
of several other elements, and resembles a protein. But no
chemist can analyze it, for in so doing it must necessarily
be killed, and then it is protoplasm no longer.

The fact that it is alive gives to protoplasm several dis-
tinctive properties.

CRYPTOGAMS 267

1. Selective absorption is the ability to take or reject
those things which are needed. This is shown in the fact
that two plants, as corn and tobacco, growing side by side
in the same soil, will take up only those substances needed
by each. Again, the leaf takes into its stomata all the sub-
stances of the air, but selects only the carbon dioxide for
making starch and enough oxygen for respiration, giving
back what it rejects into the atmosphere.

2. Metabolism is the power of protoplasm to utilize the
absorbed materials and give off wastes.

3. Assimilation is the making of more protoplasm out of
the substances which have been selected and changed
(1 and 2).

4. Growth. Increase in size and weight naturally results
from the increase in the amount of protoplasm (1, 2, and 3).

5. Excretion. This is the ability to throw off waste
matters. This is seen in the excretion of water in transpira-
tion, in excretion of oxygen in photosynthesis, and in the
excretion of carbon dioxide in respiration of all living things.

6. Reproduction is shown in the power of plants and ani-
mals to propagate their kind.

7. Automatic movement. Protoplasm is the only form of
matter which can move of itself. It can contract, expand,
and move about from place to place. This is seen in the
streaming of sap, in the change in position of leaves, and
in the motions of animals from one place to another.

8. Irritability. This is the power to respond to outside
influences called stimuli. The behavior of tendrils, the
phenomena of hydrotropism, heliotropism, and geotropism,
all illustrate this property.

Cells. — A unit of protoplasm is called a cell or protoplast.
It is the smallest particle of protoplasm that can live alone.

268 CRYPTOGAMS

It is the physiological unit of the plant or animal body. The
plant or animal is the sum total of its cells. Every cell
consists of protoplasm and has a nucleus. Vegetable cells
usually also have a cell wall which is composed of a sub-
stance called cellulose, secreted by the protoplasm of the cell.
(See Ex. 147.)

Every living cell can select, change, assimilate, grow,
excrete, and perform all other functions of protoplasm.

They can reproduce other cells by a process of division
which can be seen in sections of young root tips and by bud-
ding, as we saw in yeast.

Growth of plants is increase in size due to an increase in
the number of cells.

Every living thing, whether plant or animal, begins its
existence as a single cell known as an egg. By a series of
cell divisions followed by corresponding growth the embryo
is at length developed and all later growth is due to increase
in number of the cells.

Adaptation of parts to function applies to cells as well
as to plant organs. Thus are developed all manner of cell
forms, such as root hairs, guard cells, palisade cells, piths,
pollen, wood, etc., each adapted to its own peculiar
work.

Tissues. — When cells are engaged in doing the same sort
of work, they assume similar form and appearance. Such
a collection of similar ceils is called a tissue. Thus we
have seen epidermis, cortex, and fibrovascular tissues in the
root. In the stem were pith, bark, bast, spiral, and many
other tissues. In the leaf were epidermis, palisade, spongy
parenchyma, etc. In like manner, animals have bony,
muscular, nervous, fatty, and many other tissues.

Organs. — An organ is a tissue or collection of tissues

CRYPTOGAMS 269

operating in harmony to do a special work. This work is
the function of an organ.

The root is an organ whose function is to absorb plant
foods, to anchor the plant to the soil, and to store food.
The stem is an organ whose function is to carry sap up and
down from root to leaf and back, to bring the leaves into the
light, and to store food. The leaf is an organ having many
important functions.

The entire plant or animal body, being composed of or-
gans, is known as an organism; and hence the substances
which come from plants and animals are distinguished as
organic substances.

A LIST OF APPARATUS AND REAGENTS RE-
QUIRED IN MAKING THE EXPERIMENTS

I. APPARATUS

Battery jars.
Beakers.
Bell jar.
Blotting paper.
Bottles —

wide-mouth.

narrow-mouth.

flat.

Corks (assorted sizes).
Cork cutter.
Cotton batting.
Cover glasses.

File.

Flask for gas generator.

Flowerpots.

Forceps.

Funnels.

Glass tubing.
Glass plate.

Ignition tube.
Insect pins.

Jars —
fruit,
tall,
graduated.

Knife.

Litmus cubes.
Litmus paper.
Lamp.

Magnifiers.
Microscope.

Needles.

Petri dishes.
Platinum wire.
Platinum foil.
Pins.

Rubber bands.
Rubber stoppers.
Rubber tissue.
Rubber tubing.
Ruler.

270

Sand.
Sawdust.
Scalpels.
Sealing wax.

Thermometers.
Thistle tubes.

APPARATUS AND REAGENTS

Thread.
U -tubes.

Watch glasses.

Whetstone.

Wire.

271

Absorbent cotton.
Acids.

sulphuric.

nitric.

hydrochloric.
Agar.

Alcanna solution.
Alcohol, eth.
Alcohol, meth.
Ammonia.
Aniline dyes.

Benedict's sol.
Biuret reagent.

Calcium nitrate.
Carbolic acid.
Carbon (charcoal).
Carbon (lampblack).
Cobaltic chloride.
Collodion.
Copper sulphate.

Diastase.

II. REAGENTS

Eosin.
Ether.

Fehling's sol.
Formaldehyde.

Gelatin.
Glycerine.

Iodine.
Iron filings.

Lime.

Limewater.
Litmus cubes.
Litmus paper.

Magnesium sulphate.

Marble.

Mercuric oxide.

Mercury.

Methyl green.

Millon's reagent.

272

APPARATUS AND REAGENTS

Phenolphthalein.
Phosphorus.
Potassium bichromate.
Potassium hydroxide.
Potassium iodine.
Potassium nitrate.
Potassium neutral phosphate.
Potassium permanganate.

Sodium carbonate.
Sodium chloride.
Sodium hydroxide.
Sodium nitrate.

Soudan III.
Zinc.

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