BIOLOGY FOR BEGINNERS TRUMAN J. MOON GIFT OF From the collection of the z n z m o Prelinger v Jjibrary p San Francisco, California 2006 CHARLES DARWIN 1809-1882 BIOLOGY FOR BEGINNERS BY TRUMAN J. MOON MIDDLETOWN, N. Y. HIGH SCHOOL NEW YORK HENRY HOLT AND COMPANY - COPYRIGHT, I Q2 I BY HENRY HOLT AND COMPANY PREFACE THIS text is an attempt to present the fundamental facts of elementary biology as clearly and briefly as a reasonable scientific accuracy will allow. Three years' use in manuscript form has dictated the topics included and the arrangement followed in order that the book may be easily taught and readily understood. The course emphasizes the fact that biology is a unit science, based on the fundamental idea of evolution rather than a forced combination of portions 0f botany, • zoology and hygiene. Emphasis has been placed upon a logical arrangement within the chapters, so that it is easy for the pupil to study, outline, and remember each lesson. A larger proportion of pages is devoted to outlines, tabulations, and diagrams than in any other similar text. This means that the pupil has less text matter to cover, and more help to assist him in doing it. No laboratory work is included. Any laboratory manual can be used with the text, however, as it covers much more than the required ground. It is thought that a separate manual will allow the teacher to emphasize in the laboratory, those subjects which he considers most important. Experience has indicated that the "vocabularies" save the pupil much time and confusion. Particular care has been taken to keep the vocabulary of the text as simple as possible. Careful explanations are made where this seems advisable. The definitions in the text are not complete, but, for the sake of clearness, are purposely limited to those meanings which fit the use in the chapter concerned. In any science subject collateral reading is highly important. To facilitate this, lists of references have been placed at the ends of the chapters, covering such books as should be available in a well-equipped school. This outside reading should be encouraged. v 462251 vi ACKNOWLEDGMENT The large number of line drawings is intended to simplify matters of structure for the beginner who would have difficulty in selecting the essential points of a more detailed drawing or photograph. Since the object of illustrations in an elementary text is to call attention to essential facts, the simple diagrammatic outlines and complete labeling found in this book are worthy of notice. It is hoped also that a reasonable use of line drawings will help the pupil in his own work by affording models which he can easily approximate. The economic applications of biology have been given very full treatment, especially as to their bearing on agriculture and civic problems. The scope of the matter presented is broad enough so that the teacher can select what seems most important, and still be sure of covering any requirement in any elementary biology syllabus. On the other hand the attempt has been made not to burden the pupil with matter required for advanced biology only. ACKNOWLEDGMENT IN offering this text book to the public, recognition is due to many sources of aid and information. The lists of references appended to the various chapters fulfill the double purpose of indicating some of the authorities which have been consulted and of telling the student where fuller in- formation may be obtained. The cuts, in so far as they are not original, are credited to the proper sources in each case. In many cases, these are changed in some degree, to conform to the uses of the text. The author is especially indebted to the cheerful assistance of his wife in the laborious task of reading and correcting the manu- script and proof, and to his fellow teacher, Miss C. E. Reed,* for many helpful suggestions as to content and arrangement. If there be aught of use or value in this book let it be to the credit of the authorities consulted and the help received; for its many shortcomings the author alone is responsible. T. J. MOON CONTENTS PAGE CHAPTER I. INTRODUCTION 1 Definition of Biology. Reasons for study. Organic things. In- organic things. Familiar biology. CHAPTER II. THE LIKENESS OF LIVING THINGS 5 Processes common to organic things. CHAPTER III. ELEMENTS, THE ALPHABET OF LIVING THINGS 9 Oxygen and oxidation. Occurrence, properties and uses of other common elements. CHAPTER IV. COMPOUNDS, BIOLOGY'S BUILDING MATERIALS 18 Water; — Carbon dioxide; — Proteids; — Fats; — Carbohydrates; — Method of testing. CHAPTER V. PROTOPLASM, THE "Bios" OF BIOLOGY 25 Protoplasm, its composition and properties. Cell, Tissues, Organs, System. Adaptation. CHAPTER VI. THE STRUCTURE OF SEEDS 31 Parts of typical seed. Bean and Corn seeds as examples. CHAPTER VII. GERMINATION 41 Conditions necessary. Stages hi germination. Corn and Bean. CHAPTER VIII. ROOTS 49 Characteristics. Structure. Functions. Adaptations. CHAPTER IX. ABSORPTION AND OSMOSIS 58 Use of water to plants. Turgescence. Osmosis, definition and essentials for. Root hairs. Geotropism. Hydrotropism. CHAPTER X. STEMS, THEIR FORMS AND FUNCTIONS 68 Characteristics. Functions. Kinds of branching. Forms of stems. Buds. CHAPTER XI. STEM STRUCTURE 75 External structure. Grafting. Internal structure, dicot. and monocot. types. CHAPTER XII. LEAVES AND LEAF STRUCTURE 86 Functions. General structure. Minute structure. Adaptation. Modified forms. Fall of leaves. vii viii CONTENTS PAGE CHAPTER XIII. LEAF FUNCTIONS . . ^.^ 96 Photosynthesis. Digestion. Assimilation. Respiration. Transpi- ration. CHAPTER XIV. FLOWERS: POLLENATION AND FERTILIZATION 108 Structure and function of flower parts. Adaptations for pollenation by wind and insects. Pollen; Ovule; Fertilization stages. CHAPTER XV. FRUITS AND THEIR USES 118 Definition; — Types of fruits; — Functions. Dispersal. Economic importance. CHAPTER XVI. SPORE-BEARING PLANTS 127 Classes of plants. Representatives. Fungi as type of spore plants. CHAPTER XVII. BACTERIA .' 133 Kinds. Method of study. Useful and harmful forms. Natural and artificial protection. Antiseptics. Disinfectants. History. CHAPTER XVIII. PROTOZOA 146 Relation to higher animals. Amoeba and Paramoecium as types. Life functions compared. CHAPTER XIX. METAZOA 154 Development. Specialization. Classification. CHAPTER XX. WORMS 161 Representatives. Structure. Adaptations. Economic importance. Parasitism. Earthworm. Trichina. Hookworm. Tapeworm. CHAPTER. XXI. ARTHROPODS 172 Characteristics. Classification. Scientific classification explained. CHAPTER XXII. CRUSTACEA, A CLASS OF ARTHROPODS 179 Characteristics. Crayfish as type. Structure and adaptations of crayfish. Homology. Life history. CHAPTER XXIII. INSECTS, A CLASS OF ARTHROPODS 192 Characteristics. Grasshopper as type. Structure of grasshopper. Adaptations. Life History. Economic importance. CHAPTER XXIV. INSECTS; — BUTTERFLY, MOTH AND BEE 205 Structure and adaptations of each. Communal life and specialization of bee. Economic importance. CHAPTER XXV. INSECTS AND DISEASE 220 Structure and Life History of Fly and Mosquito. Relation to dis- ease;— how proven. Means of prevention and control. CHAPTER XXVI. THE VERTEBRATES 234 Classification of animals. Development. Classification and types of vertebrates. CONTENTS ix PAGE CHAPTER XXVII. FISHES 239 Structure, external and internal. Life History. Adaptations. Economic value. CHAPTER XXVIII. THE FROG AND ITS RELATIVES. . .' 252 Characteristics of the amphibia. Structure of frog. Adaptations. CHAPTER XXIX. THE AMPHIBIA; — LIFE HISTORY AND HABITS 267 Metamorphosis of frog. Toad, Salamander and Frog compared. Economic importance. CHAPTER XXX. REPTILES 273 Representatives. Characteristics. Adaptations. False ideas. Poisonous snakes. Treatment. CHAPTER XXXI. BIRD STRUCTURE AND ADAPTATIONS 281 Characteristics. Adaptations for flight. Adaptations for active life. Adaptations of beaks and feet. CHAPTER XXXII. BIRD HABITS 294 Food. Nesting. Eggs. Migration. Economic importance. CHAPTER XXXIII. MAMMALS 310 Characteristics. Adaptations of limbs, teeth, and body coverings. Special adaptations of rodents, ungulates, carnivora and primates. Man's place in the group. CHAPTER XXXIV. THE DEVELOPMENT OF MAN 321 . Relation to other animals. Idea of evolution. Evidences of evo- lution. CHAPTER XXXV. THE METHOD OF EVOLUTION 326 Antiquity of the idea. Lamarck's theory. Darwin and Natural Selection. Summary of the theory; — its conclusions. CHAPTER XXXVI. THE DEVELOPMENT OF CIVILIZED MAN 333 Ancient records. Primitive man. Stages in development. Imple- ments used. Results of higher mentality. Present races. CHAPTER XXXVII. FOOD 342 Necessity. Definition. Functions of various food stuffs. Measure- ment of values. Proportions. Balanced ration. Digestibility. Cost. Cooking. Lipoid. Vitamines. CHAPTER XXXVIII. NUTRITION 363 Digestive changes. Digestive organs. Mouth. Teeth. Stomach. Intestine. Glands. Absorption. Assimilation. CHAPTER XXXIX. RESPIRATION 382 Development of organs, in lower forms. Structure and adaptation of nose, trachea, lungs, diaphragm. Changes in air and blood. Venti- lation. CHAPTER XL. CIRCULATION 392 Function. Blood, its composition and use. Heart. Arteries, Veins, Capillaries. Lymph circulation. x CONTENTS •. PAGE CHAPTER XLI. EXCRETION 403 Source of waste. Organs of excretion. Kidneys, Lungs, Skin. Heat regulation. CHAPTER XLII. THE NERVOUS SYSTEM 408 Location and functions of cerebrum, cerebellum, medulla, . spinal cord, sympathetic system. Regions of control for various activities. CHAPTER XLIII. THE SENSE ORGANS 415 Irritability. Touch. Taste. Smell. Hearing, structure of ear, care of ears. Sight, structure of eye, care of eyes. CHAPTER XLIV. BIOLOGY ,AND HEALTH 425 Hygiene of Muscles, of Digestion, Breathing. Bathing. Care of eyes, teeth, feet. Posture. Sleep. CHAPTER XLV. Civic BIOLOGY 440 Food control. Sanitation. Disease prevention. Housing conditions. Food laws. Medicines. CHAPTER XL VI. ECONOMIC BIOLOGY OF PLANTS 446 General uses. Harmful forms. Plant uses in detail. CHAPTER XLVII. ECONOMIC BIOLOGY OF INVERTEBRATES 467 General uses of animals. • Harmful forms. Importance of each group in detail. Harmful insects and their treatment. CHAPTER XL VIII. ECONOMIC BIOLOGY OF VERTEBRATES 480 Fish. Amphibia. Reptiles. Birds. Mammals. CHAPTER XLIX. BIOLOGY AND AGRICULTURE 486 Soil formation. Plant breeding and protection. Animal husbandry. Bacteria on the farm. CHAPTER L. ECONOMIC IMPORTANCE OF FORESTS 495 Value of forests. Enemies of forests. Protection. Timber structure. Street trees. CHAPTER LI. TOBACCO AND TABLE BEVERAGES . 508 Tobacco, physical and social objections to its use. Tea, Coffee, Cocoa, and Chocolate. CHAPTER LII. ALCOHOL IN RELATION TO BIOLOGY . . 514 Composition and kinds of alcoholic liquors. Physical effects. Not a food. Alcohol and disease. Waste of resources. CHAPTER LIII. SOME GENERAL BIOLOGIC PROCESSES . . 524 Osmosis in life processes. Oxidation. Circles in Nature. Evolution of life functions. CHAPTER LIV. HISTORICAL DEVELOPMENT OF BIOLOGY . . Biologic development. The work of Pasteur, Roux, von Behring, Lister, Carrell, Flexner. Darwin, Huxley, Mendel, Burbank. INDEX.. •• 549 BIOLOGY FOR BEGINNERS CHAPTER I INTRODUCTION The student should make sure that he understands every term used in his Biology lessons. This book will include vocabularies like the following, but in addition, a good dictionary should be consulted frequently and derivations studied. As is shown in the first paragraph on this page, a great deal can be learned about the meanings of scientific terms by looking up their deri- vations. Vocabulary Domestic, tamed, as applied to animals and plants used by man. Biology, the science of living things. Organic, pertaining to living things. Inorganic, things which have never been alive. Biology is a study of living things. The dictionary tells us that this term comes from two Greek words, " Bios " which means " life," or " living things," and " ology," a word-ending meaning " the science or study of." The two parts thus make a perfect definition of biology, which is, truly, " The science of living things." Classes of Things. All things in the world can be divided into two classes; those which are, or have been alive, and those which have never lived. The former are called organic substances, and the latter inorganic. Organic things include both plants and animals, together with all substances derived from them. Inorganic things include the members of the mineral kingdom such as stone, glass, or iron, as well as water, carbon dioxide, oxygen and similar substances. Biology is the science which deals with the study of organic things, as its derivation shows. Words as Tools. Since three new words have been used already — biology, organic, and inorganic — it may appear that the subject 1 BIOLOGY FOR BEGINNERS "is to :be -made -diffieuk because of many hard and strange terms. There need be no alarm at the prospect if we will consider each new word as a tool which will enable us to do our work better, more accurately, and more easily. It is simpler to say " organic substances " than to say, " sub- stances which are or have been alive." It is also more accurate, and furthermore we have increased our vocabulary by the addition of this new tool. We should think a carpenter very foolish who cut all his lumber with a jack knife because he thought it too much trouble to learn to use a saw. Students in their school life are workmen, and their most important tools are words. Each subject taken up, like different kinds of carpenter work, requires the use of a certain number of new tools (words). These must be learned before the student can do his work efficiently. On the other hand a carpenter would be foolish to load up his chest with a lot of tools which he rarely used, and so, in our study, we have included only those new names and terms without which we could not possibly get along. If we learn to use them, we will not have to " cut off our board with a jack knife." Sciences Included in Biology. . Although biology is a single and closely united science based on the study of all things that are or have been alive, it is so broad in scope that it includes many special branches. Some of these are already familiar, such as botany, which deals with plants; zoology, which deals with animals; hygiene, which concerns the care of the human body; physiology, which is the science of the use or function of living organs; and many others. Familiar Biology. To begin with, each one of us has studied biology already by observing the things of nature about us. Is this not true? We know some plants and trees by name. We know how to cultivate gardens, what will help plants grow, the names of many flowers. All of us buy and use fruits, grain, and vegetables. We also know something about the care of animals, and, most important of all, are anxious to learn all that we can about the care and use of our own bodies. INTRODUCTION 3 Reasons for the Study of Biology. Biology is a required study in many schools, and we have a right to ask why it is considered so important that we are obliged to study it. In the first place there are few subjects that add so much to ANIMAL PLANT . FIG. 1. Diagram to show the relation of General Biology to the biological sciences. From Calkins. general culture by increasing the number of things in which we. are interested and about which we should have information. Few people really see very much of the things about them — accurate observation is a very rare but valuable trait, and biology will greatly increase the powers of observation. 4 BIOLOGY FOR BEGINNERS Mere observation of facts is not enough, however, for one should be able to draw correct conclusions from what he sees. This ability to think and reason is one of the chief aims of the laboratory work in biology or any other science. Although these reasons for the study of biology are by far the most important, others can be mentioned which may seem more practical. Tt is the foundation of farming, gardening, and forestry and upon its laws are based the care and breeding of all domestic animals and plants. In even a more personal way, biology deals with the health and care of our own bodies — hygiene. It also includes the study of the cause and prevention of disease, the work of bacteria, and means of maintaining healthful surroundings — sanitation. One-half of all human deaths are caused by germ diseases and at least half of these could be prevented by proper knowledge and practice of hygiene and sanitation. This in itself is sufficient reason for interest in the study of biology. SUMMARY Biology, a study of living things. 1. Derivation: Bios, Logos. 2. Definition. 3. Classes of things. Inorganic (meaning and examples). Organic (meaning and examples). Plants: Animals. 4. Words as tools. 5. Sciences included. 6. Familiar biology. 7. Reasons for study. Adds to culture. Cultivates power of observation. Teaches to think and reason. Importance in many industries. Relation to health. Hygiene. Sanitation. CHAPTER II THE LIKENESS OF ALL LIVING THINGS Vocabulary Similarity, likeness. Assimilation, " to be made the same," that is, the process by which food stuff is made into tissue. Nutrition, all the processes by which food is prepared and assimi- lated in the body. Excretion, the passing off of waste matter from plant or animal. Biology, then, is the study of organic, or living things, and living things include both plants and animals. At first one would say that plants and animals have very little similarity and that it would be difficult to study them together, but let us see if this is true. Nutrition. First, both plants and animals are alive and grow in size and that means that they both need food. A cat, for instance, has to eat, and a geranium has to have earth, in order to live. The cat uses organic food and the plant inorganic. The cat obtains its food by means of its claws and teeth, while the food-getting of the plant is done largely by the roots. They are both dependent on food. After they get their food, both plants and animals have to put it into liquid form in their bodies. We call that process digestion. Then the digested food undergoes a change by which the milk or meat actually becomes part of the cat, while the plant foods be- come part of the geranium. This is a very wonderful process and is called assimilation. (Look up this word in the dictionary and see if you can tell why it is used in this way.) Food-getting, digestion, and assimilation together make up the process of nutrition (getting nourishment). The animal and the plant have this process in common. 5 6 BIOLOGY FOR BEGINNERS Respiration. Another point in which our two examples are alike is that they both breathe. If we keep either one in an air-tight box it will die. The cat breathes by means of its lungs and it is easy to see the muscular movements involved. The leaves of the plant breathe too, although our eyes cannot detect the way in which this is done. The process of breathing is called respiration in both cases. Excretion. Both cat and geranium use the food that they assimilate to build up their bodies or to give them energy, and both throw off from their bodies unused and changed food materials by a process called excretion. The animal does this by means of the lungs, skin, intestines and kidneys; the plant by means of the leaves. Motion. Another way in which all living things are alike is in the power of motion. It is easy to see the cat move, but few observe how the geranium turns its leaves to the light and its roots to the water. Though animals usually have greater freedom of motion, plants do not lack it altogether. Sensation. In a general way, all plants and animals have the power of responding to touch, heat, light, and other forces outside of themselves. This is sensation, and may vary in its expression, from the mere turning of leaves toward light to the delicate opera- tion of a wonderful sense organ like the human eye. Reproduction. Both plants and animals reproduce others like themselves. Kittens are born and grow to be cats, and the plant bears seeds which will produce other plants like itself. By this wonderful provision of nature, although all organic things die, others like them are left to take their places. The processes of reproduction and nutrition are the two most important charac- teristics of all living things. Likeness of all Living (Organic) Things. The cat before the fire and the geranium on the window sill, though apparently different, are really alike in all of the necessary processes of life. It is, therefore, possible and easy to study plants and animals together. Biology is not merely botany plus zoology, but a study of the life processes of all living things. THE LIKENESS OF ALL LIVING THINGS 7 Difference from Inorganic Things. The points, in which all living or organic things are alike, are also the points in which they differ from inorganic things. A stone and a piece of iron are familiar examples of inorganic matter. We cannot imagine a stone taking food or growing, or a piece of iron moving or reproducing its kind. Our study of biology is thus sharply separated from inorganic things. To be sure, plants can take inorganic matter and by certain wonderful processes make it into the living plant as we have mentioned. But it then ceases to be inorganic and becomes a part of the plant. Plant and animal are alike in all essential ways and they also differ in these ways from all inorganic substances. SUMMARY Organic things (Plant and Animal). 1. Live, grow, and move. 2. Obtain food. 3. Digest and absorb food. 4. Assimilate food as part of themselves. 5. Excrete waste. 6. Reproduce. Inorganic things can perform none of the above processes. Organic and Inorganic things resemble each other in the following points: 1. They are composed of similar elements. 2. They contain, use and produce similar compounds, such as carbon dioxide, water, etc. 3. They have characteristic shapes and weights. 4. They undergo chemical changes. 5. They liberate energy. Organic things differ from Inorganic, in the following points: 1. They have organs for various functions. 2. They are composed of cells. 3. They always contain protoplasm. 4. Their growth is from within. 5. They respond to their surroundings (irritability). 6. They follow a " life cycle." 7. They depend upon oxidation for life. BIOLOGY FOR BEGINNERS PROCESSES IN WHICH ORGANIC THINGS ARE ALIKE Process i In plants is per- formed by In animals is per- formed by Food-getting Roots, leaves Teeth, claws, etc. Digestion Ferments in the tissues Stomach, intestines, glands, etc. Absorption All live tissues Intestine, stomach, etc. Assimilation « • U « All live tissues Respiration (oxidation) Air spaces and tissues Lungs, gills, etc., all tissues Excretion Leaves Kidneys, skin, etc. Motion Flowers, leaves, ten- Legs, wings, fins, etc. drils, etc. Sensation Leaves, tendrils Nerves, sense organs Reproduction Seeds, slips, etc. Eggs, live young What evidences can you give of any of these processes, in either plants or animals? Since both plants and animals perform similar processes, what might you expect about the stuff they are made of? COLLATERAL READING General Biology, Sedgwick and Wilson, pp. 1-19; Applied Biology, Bigelow, pp. 10-22, 122-132; Practical Biology, Smallwood, pp. 1-10; Essentials of Biology, Hunter, pp. 26-30; Elementary Zoology, Galloway, pp. 36-54, 72-97; Biology, Calkins, pp. 6-15; General Zoology, Pearse, pp. 25-36. CHAPTER III ELEMENTS, THE ALPHABET OF ALL LIVING THINGS Vocabulary Individual, separate. Innumerable, very many. Oxidation, the union of any thing with oxygen. Combustion, rapid oxidation, producing light and heat. Restrain, to hold back. All the words of our language are made from less than thirty letters. If we think of our big dictionaries we realize what an enormous number of different combinations can be formed from a few letters. Elements and Compounds. In something the same way, all the matter in the world is composed of about eighty individual substances called elements. These we might think of as the letters in a chemical alphabet which spell all the substances — both organic and inorganic — that are in existence. When elements unite, they form all the innumerable things that compose the world around us. -These substances, formed by the union of two or more elements, are called compounds. For example, iron is an element. Oxygen in the air is also an element. When these two unite, they form a compound which we call iron rust. Organic substances utilize only about ten elements, but when we stop to think of the thousands of kinds of plants and of animals, and of all the different substances of which they are made, we see that ten elements are enough to make a wide variety of compounds. What to Learn about Them. The complete study of these elements and their compounds is called chemistry, but for the present we need to learn only four things about the elements which compose organic substances: (1) their names, (2) where 9 10 BIOLOGY FOR BEGINNERS they are found, (3) enough of their characteristics or properties so that we can recognize them, and (4) their use to living things. OXYGEN Where it is Found. We already know that oxygen (O) is part of the air, but it is also a part of water, sand, soil, rock, and many other things. It may be hard to understand how a gas, like oxygen, can be a part of a liquid, like water, or of a solid like wood, but this is true. Oxygen is found in all plant and animal substance. In fact it is the most abundant element in the world, and is itself one-half of the solid material of the earth. Properties. We shall see oxygen prepared in the laboratory, and shall discover that it is a colorless, odorless, and tasteless gas. It is heavier than air, will dissolve slightly in water, and most curious of all, though it will not burn, it nevertheless makes other things burn very rapidly. Iron, copper, and many other substances which do not seem to burn at all in the air will do so in oxygen, while sulphur and wood, which do burn in air, burn very fast in oxygen. Test. It is the only substance which will cause a glowing splinter to burst into flame. This fact is utilized in testing whether a gas is oxygen or not, and is therefore called a test for oxygen. Oxidation. When anything unites with oxygen, the process is called oxidation, and the compound formed by the substance and the oxygen is called an oxide. Oxygen may unite with substances rapidly, as when a stick burns, or slowly, as when iron rusts. An oxide is always the product, and there is always a more important product, namely, heat energy. Both plants and animals use oxygen. Heat energy is necessary for all life. All plants and animals therefore depend on oxygen which they take into their bodies by breathing, as we have seen in CKapter II. As the living tissues become oxidized they produce heat and energy, leaving a residue of oxides and other material to be thrown off as waste. The food assimilated as tissue contains the vital energy which oxidation releases. THE ALPHABET OF ALL LIVING THINGS 11 Live and Dead Engines. A living organism is often compared to a steam engine. Both need a supply of food (fuel), and both must have oxygen to unite with (oxidize) the food and set free its energy. In both, heat is produced by this oxidation and then changed into motion, and in both there are waste products which have to be removed. But an engine is only an inorganic thing. It cannot get" its own food, it does not assimilate or grow, it does not excrete its waste products, or reproduce. Really the only way in which it resembles a living thing is that it depends on energy which is released from substances by uniting with oxygen, and turns this energy into motion. RESEMBLANCES A living organism A steam engine Requires Food Fuel To unite with Oxygen Oxygen By means of Respiration Draft To produce Heat and energy Heat and energy Leaving waste Unused food Ashes Carbon dioxide (in Carbon dioxide (in chim- breath) ney gas) DIFFERENCES A living organism . A steam engine Is alive Grows in size Repairs wear Reproduces Is not alive Does not grow Wears out Cannot reproduce Similarities based on oxidation, differences based on functions of the protoplasm. Other Uses of Oxygen. Oxygen has many other uses in nature. It causes combustion from which we get heat and power. It also causes rusting, oxidation, and decay. Its myriad compounds are 12 BIOLOGY FOR BEGINNERS absolutely necessary as food and drink. But its chief importance in biology is that, by uniting with the substance of both plant and animal, it sets free the energy which keeps them alive. Without oxygen, no life can exist. NITROGEN Where it is Found. Nitrogen (N) is another important element. It makes up four-fifths of the air. It is found combined with several minerals in the soil and exists in the living tissue of all organic things. Properties. Nitrogen resembles oxygen in being colorless, odor- less, and tasteless, and in that it will not burn. It is less soluble in water and lighter in weight. It is the exact opposite of oxygen in its behavior, for it will not cause combustion, nor will it combine readily with other elements. Its compounds decompose easily. Uses. It is found in the active living substance of all plants and animals and is essential to their life. Its various compounds are our most necessary foods. All fertilizers which we use for plants, as well as meat, milk, eggs, and many other animal foods contain very important com- pounds of nitrogen. If the air were pure oxygen, fires could not be controlled and things would oxidize too rapidly. Thus, another important use of nitrogen is to restrain the activity of oxygen and make the at- mosphere suitable for life. HYDROGEN Where it is Found. Hydrogen (H) occurs combined in water, plant and animal tissue, wood, coal, gas, and all acids. Properties. It resembles both nitrogen and oxygen in being colorless, odorless, and tasteless. It does not dissolve much in water and it will not cause things to burn, but unlike either nitrogen or oxygen it burns readily and even explodes when mixed with air and brought into contact with fire. It is the lightest substance known and, because of this fact, is used to fill balloons. THE ALPHABET OF ALL LIVING THINGS 13 Uses. Hydrogen is important to the biologist because it unites readily with oxygen and forms water. It also combines with both oxygen and carbon (another element) and forms a whole series of compounds called fats, sugars, and starches. It is an essential ingredient in all organic tissue. CARBON Carbon (C) is an element with which we are more familiar; coal, charcoal, and wood are common forms. Lead-pencils do not really contain lead at all but another form of carbon called graphite. Strangest of all, the diamond is carbon, too, though not a common form. Properties. Carbon is (except in the diamond) a black solid, not soluble in any thing. At ordinary temperature it is very inactive. When heated, however, it unites readily with oxygen, (that is, it burns) and forms an oxide which is called carbon dioxide — a compound very necessary to plants, as we shall see later. Uses. Carbon's importance to biology is due to the fact that it is a part of all organic substances, combining with hydrogen, nitrogen, and oxygen and other elements to form all plant and animal tissues and many of their foods. We know that if any plant or animal substance is partly burned a black solid is produced. This, in every case, is carbon. We also know that if the burning is continued the carbon will disappear. This means that it becomes oxidized into carbon dioxide, which is an invisible gas. Plants alone have • the power to obtain their carbon from the carbon dioxide of the air. Animals depend entirely on plant foods for the carbon compounds which are necessary for their life. SULPHUR Sulphur (S) is a yellow solid element, which (like carbon) will not dissolve in water, but can be dissolved in other chemicals. Sulphur itself has no odor, but it readily unites with oxygen, even at low temperatures. It also burns readily, producing in 14 BIOLOGY FOR BEGINNERS both cases an oxide of sulphur (SO2) with the familiar, suffocating odor which we wrongly associate with sulphur itself. Its importance in biology is due to the fact that it is a part of the living substance of all organic things though in smaller amounts than any of the preceding elements. Mustard, onions, and eggs will blacken silver dishes. This is due to the sulphur compounds which they contain; but sulphur, in smaller quantities, is found hi all plants and animals. PHOSPHORUS Phosphorus (P) is a light yellow, waxy, solid element. Like sulphur, it dissolves in several other liquids, but not in water. It also resembles sulphur in that it unites readily with oxygen. In fact it unites with oxygen more readily than does sulphur, for, if exposed to air, it will take fire and burn fiercely, forming an oxide of phosphorus. It has to be kept covered with water to prevent it from burning and is a dangerous and poisonous element. It seems strange that such a substance should be a necessary ingredient of our bodies and, in fact, of all living things. To be sure it is present in small amount but is absolutely essential, being especially abundant in bone and nerve tissue. You have probably heard plant fertilizers called " phosphates." This is because they contain phosphorus compounds. IRON Iron is another element. We are familiar with it as a heavy, solid metal; and we know it unites slowly with oxygen forming iron oxide (rust). This is about the last thing we would think to be of use in the bodies of plants or animals. However, iron is absolutely necessary in the green coloring matter of plants and in the red blood of animals. Later we will learn the remarkable services which its compounds perform in these substances. THE ALPHABET OF ALL LIVING THINGS 15 SODIUM, POTASSIUM, AND CALCIUM Our list of elements important to organic life will end with three similar ones — sodium, potassium, and calcium. These are light, metallic substances which burn when put in water and are there- fore very dangerous to handle. Potassium compounds must be in the soil if plants are to thrive, while sodium and calcium com- pounds are necessary for the blood and skeleton of animals. Nitrogen, sulphur, phosphorus, iron, sodium, potassium, and calcium are all obtained from their mineral compounds in the soil; animals use salt (a sodium compound) directly, while they get the other elements from plant foods. Plants in turn obtain them from the soil. By themselves, all these elements are inorganic substances, but in the wonderful process of assimilation, plants and animals can combine them to form the living stuff of which their tissues are made. On the other hand, by the processes of oxidation, death, and decay, the complex organic compounds are broken up into simpler forms, and return to the soil or air as inorganic compounds or elements, to be used over again by organic things. Here is an estimate of the composition of the human body, which may give an idea of the comparative amounts of the different elements in animal tissue. 16 BIOLOGY FOR BEGINNERS A person weighing 154 pounds would be composed of; Oxygen 97.2 pounds Carbon 31.1 " Hydrogen 15.2 Nitrogen 3.8 " Calcium 3.8 Phosphorus 1.75 " Sulphur .27 " Chlorine .25 " Fluorine .22 " Potassium .18 " Sodium .16 " Magnesium .11 " Iron .01 " Oxygon 97.2 Carbon 31.1 Hydrogen 15.2 Nitro- gen 3.8 a Iron .01 D Magnesium .11 D Sodium .16 D Potassium .18 D Fluorine .22 Chlorine .25 Phosphorui 1.75 Calcium 3.8 FIG. 2. Elements composing a human body weighing 154 pounds. (Figures express pounds.) COLLATERAL READING See index of any text book in Elementary Chemistry. Applied Biology, Bigelow, pp. 5-9; Elementary Biology, Peabody and Hunt, pp. 5-13; Essentials of Biology, Hunter, pp. 17-25. THE ALPHABET OF ALL LIVING THINGS 17 _ M* 0) ll W5.2 ij l! S) co W ,S g 3 S-e ^ ill Rji: •c.i 11 1 .2 fa g „- •fl -al o I I So c/5 q^ «a G. rt a .