First Course in Biology

Part I.

For three half-year courses, all the parts may be covered in full.

If the course in biology begins in the fall (with the school year), it may be well to study plant biology two days in the week and animal biology three days until midwinter; when outdoor material becomes scarce, human biology may be followed five days in the week; in spring, plants may be studied three days and animals two days.

If the use of the book is begun at midyear, it will probably be better to follow the order in the book consecutively.

If it is desired to take only a part of the plant biology, Chapters VI, XIV, XX, XXIII, XXIV may be omitted, and also perhaps parts of other chapters (as of X, XII, XIII) if the time is very short. The important point is to give the pupil a rational conception of what plants are and of their main activities; therefore, the parts that deal with the underlying life processes and the relation of the plant to its surroundings should not be omitted.

If more work is wanted it is best to provide the extra work by means of the study of a greater abundance of specimens rather than by the addition of more texts; but the teacher must be careful not to introduce too much detail until the general subject has first been covered.

The value of biology study lies in the work with the actual things themselves. It is not possible to provide specimens for every point in the work, nor is it always desirable to do so; for the beginning pupil may not be able to interest himself in the objects, and he may become immersed in details before he has arrived at any general view or reason of the subject. Great care must be exercised that the pupil is not swamped. Mere book work or memory stuffing is useless, and it may dwarf or divert the sympathies of active young minds.

Every effort should be made to apply the lessons to daily life. The very reason for knowing plants and animals is that one may live with them, and the reason for knowing oneself is that he may live his daily life with some degree of intelligence. The teacher should not be afraid to make all teaching useful and practical.

In many cases a state syllabus designates just what subjects shall be covered; the topics may be chosen easily from the text, and the order of them is usually left largely to the discretion of the teacher.

Finally, let it be repeated that it is much better for the beginning pupil to acquire a real conception of a few central principles and points of view respecting common forms that will enable him to tie his knowledge together and organize it and apply it, than to familiarize himself with any number of mere facts about the lower forms of life which, at the best, he can know only indirectly and remotely. If the pupil wishes to go farther in later years, he may then take up special groups and phases.

CONTENTS

PAGE

GENERAL INTRODUCTION I xi

Part I. Plant Biology

CHAPTER

I. NO TWO PLANTS OR PARTS ARE ALIKE P 1

II. THE STRUGGLE TO LIVE P 4

III. SURVIVAL OF THE FIT P 7

IV. PLANT SOCIETIES P 9

V. THE PLANT BODY P 15

VI. SEEDS AND GERMINATION P 20

VII. THE ROOT--THE FORMS OF ROOTS P 32

VIII. THE ROOT--FUNCTION AND STRUCTURE P 38

IX. THE STEM--KINDS AND FORMS--PRUNING P 49

X. THE STEM--ITS GENERAL STRUCTURE P 59

XI. LEAVES--FORM AND POSITION P 73

XII. LEAVES--STRUCTURE AND ANATOMY P 86

XIII. LEAVES--FUNCTION OR WORK P 92

XIV. DEPENDENT PLANTS P 106

XV. WINTER AND DORMANT BUDS P 111

XVI. BUD PROPAGATION P 121

XVII. HOW PLANTS CLIMB P 129

XVIII. THE FLOWER--ITS PARTS AND FORMS P 133

XIX. THE FLOWER--FERTILIZATION AND POLLINATION P 144

XX. FLOWER-CLUSTERS P 155

XXI. FRUITS P 163

XXII. DISPERSAL OF SEEDS P 172

XIII. PHENOGAMS AND CRYPTOGAMS P 176

XXIV. STUDIES IN CRYPTOGAMS P 182

Part Ii. Animal Biology

I. INTRODUCTION A 1

II. PROTOZOANS A 10

III. SPONGES A 17

IV. POLYPS A 22

V. ECHINODERMS A 34

VI. WORMS A 42

VII. CRUSTACEANS A 51

VIII. INSECTS A 63

IX. MOLLUSKS A 97

X. FISHES A 109

XI. BATRACHIANS A 126

XII. REPTILES A 139

XIII. BIRDS A 150

XIV. MAMMALS A 184

Part Iii. Human Biology

I. INTRODUCTION H 1

II. THE SKIN AND KIDNEYS H 16

III. THE SKELETON H 28

IV. THE MUSCLES H 39

V. THE CIRCULATION H 51

VI. THE RESPIRATION H 70

VII. FOOD AND DIGESTION H 89

VIII. THE NERVOUS SYSTEM H 117

IX. THE SENSES H 142

X. BACTERIA AND SANITATION H 158

GENERAL INDEX i

GENERAL INTRODUCTION

=PRELIMINARY EXPERIMENTS=

These experiments are inserted for those pupils who have not had instruction in chemistry and physics, to give them a point of view on the subjects that follow. At least a general understanding of some of these subjects is necessary to a satisfactory elementary study of biology.

=Elements and Compounds.=--The material world is made up of elements and compounds. An element is a substance that cannot be separated into two or more substances. A compound is formed by the union of two or more elements. All the material or substance of which the earth and its inhabitants is composed is formed of the chemical elements; this substance taken all together is known as matter.

Carbon and iron are examples of elements. Compare a bit of charcoal, which is one form of carbon, with a new iron nail. Which is brighter? Heavier for its size? Tougher? More brittle? Harder? More readily combustible? Resistant to change when left exposed to air and dampness? There are two other forms of carbon: graphite or black lead (used in pencils and stove polish); and diamond, which occurs in crystals and is the hardest known substance. Iron does not have varied forms like carbon. Sulfur is another element. What is its color? Has it odor? Taste? Will it dissolve in water? Is it heavy or light? Will it burn? What is the color of the flame? Of the fumes? Phosphorus, another element, burns so readily that it ignites by friction and is used in matches. Rub the tip of a match with the finger. What is the odor of phosphorus? Phosphorus exists in nature only in combination with other elements. Lead, tin, silver, gold, copper, zinc, nickel, platinum, are elements.

There are less than eighty known elements; but the compounds formed of them are innumerable. Carbon is found in all substances formed by the growth of living things. That there is carbon in sugar, for example, can easily be shown by charring it on a hot shovel or a stove until its water is driven off and only charcoal is left. Part of the starch in a biscuit remains as charcoal when it has been half burned.

=Oxygen and the Air.=--The great activity of pure oxygen in attacking other substances can be shown by passing into a fruit-jar a lighted splinter, a piece of lighted magnesium ribbon, an old watch spring (or a bit of picture wire), the end of which has been dipped in sulfur and lighted. About one fifth of the air is oxygen and about four fifths is nitrogen and other inactive gases. Pure nitrogen will quickly extinguish a lighted splinter thrust into it. It is the oxygen in the air that supports all forms of burning. Less than one half of one per cent of the air is an inactive gas called carbon dioxid, a compound of carbon and oxygen. It is formed not only when wood or coal is burned, but also by the life processes of animals and plants.

=Favorable and Unfavorable Conditions for Evaporation.=--Pour the same quantity of water (half a glassful) into three saucers and two bottles. Place one saucer near a hot stove; place the other two in a cool place, having first covered one of them with a dish. Place one of the bottles by the stove and the other by the remaining saucers. After some hours, examine the saucers and bottles and compare and record the results. Explain. State three conditions that are favorable to evaporation. State three ways in which evaporation may be prevented or decreased.

=Tests for Acid, Alkaline, and Neutral Substances.=--For acid tests, use sour buttermilk (which contains lactic acid), or hydrochloric acid diluted in ten parts water, or strong vinegar (which contains acetic acid). Has the acid a characteristic (“sour”) odor and taste (test it only when very dilute)? Rub dilute acid between the fingers; how does it feel? Is there any effect on the fingers? Obtain litmus paper at a druggist’s. Dip a strip of red litmus and of blue litmus paper into the acid. What result?

For alkaline tests, dissolve in a glass of water a spoonful of baking soda or some laundry soap; or dissolve an inch stick of caustic soda in a glass of water. Test odor and “feel” of last solution as with the acid; likewise test effect of alkaline solution on red and blue litmus paper. Record results. Alkalies are strong examples of a more general class of substances called bases, which have the opposite effect from acids.

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