Elementary anatomy

Front matter

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Chap. Copyright No.

UNITED STATES OF AMERICA.

Preface

No field of school instruction has in recent years undergone a more radical change in the method of presentation than that of the natural sciences. This change has been a progressive one, and each year has recorded some advance. In all nature work in the grades as well as in all natural science work in the secondary schools and colleges the pupil is brought into contact with the material studied. This is effected either through demonstrations before the class or through laboratory or field work in which the individual pupil, under the direction and inspiration of the teacher, observes or experiments with the material.

Physiology is a most important branch of the biological division of the natural sciences. Besides making a large part of both botany and zoology, it is set apart as a science by itself, devoted to the discussion of the functions of living matter. The nature work of the lower school grades leads naturally and logically to physiology, for which it forms a necessary basis.

The subject of human physiology is the most important part of the nature study of the schools. It introduces the pupil to the physical house in which he must abide while he lives in this world and, with hygiene, to the essential conditions of highest attainment.

With these principles in view, the subject of human physiology has been introduced with a brief treatment,

6 PREFACE

largely experimental and practical, of the phj^siology of a growing plant. Through this means one can best show the interdependence of plant and animal kingdoms, and the unity and harmony of nature.

Attention is called to the experiments suggested and described in the text. The appliances and material suggested are readily procurable; and the experiments described may easily be performed by any bright and energetic teacher. Taught in this way physiology becomes a living and intensely interesting science. The problems given for solution by the pupils will tend to fix indelibly the hygienic principles involved in them.

Especial attention is called to the lessons on Domestic Econoiny, This work has never failed to arouse the interest not only of the pupils, but of parents also, their feeling being that the school work in physiology is being made practical as life itself is and must be. This chapter and that on plant physiology is the work of Mrs. Winfield S. Hall.

The author is indebted to Professor Wilson of Columbia University, to Professor Piersol of the University of Pennsylvania, and to Professor Williams of the Universit)^ of Buffalo for several valuable figures. Acknowledgment is due also to Messrs. Lea Brothers, Philadelphia, for permission to reproduce several figures from the author's Text-hook of Physiology^ of which they are the publishers.

WINFIELD S. HALL.

Chicago, June, 1900.

CONTENTS GENERAL PHYSIOLOGY

CHAPTER PAGE

I. Plant Physiology — How the Plant lives and grows . 11 II. The Cells, Tissues, and Organs of the Body ... 27

III. The Nervous System — How the Different Organs are

made to work in Harmony 46

IV. Narcotics — Their Nature, their Classes, and their Gen-

eral Action upon the System 58

SPECIAL PHYSIOLOGY y. Nutrition — How the Body is nourished .

VI. Circulation — How the Nourishment is distributed

VII. Respiration — How the Blood is purified

VIII. How the Food is used in the Body ....

IX. How the Waste Materials are thrown out of the Body

76 126 164 196

X. The Skin — How it is made and what it does — how to

take care of it 211

XI. The Special Senses — How one knows what is going on

about him 225

8 CONTENTS

CHAPTER PAGE

XII. The Nervous System — The Brain, the Spinal Cord, and

the Nerves 237

XIII. The Muscles — How the Body moves .... 251

XIV. The Skeleton — The Framework of the Body . . . 263

PHYSIOLOGY AND HYGIENE

Physiology is one of the Natural Sciences. It tells how plants and animals live. It tells just what each part of the living being does, and how all of the parts work together. For example, it tells how the stomach digests the food we eat ; how the food is absorbed and distributed to all parts of the body by the heart and blood vessels, and how each part of the body is nourished by the food tlius brought.

Hygiene tells how to take care of the body. Every one wishes to have a healthy body. There are many things that injure the body, and many other things that make the body grow large and strong and healthy. Hygiene tells first, what is proper for the body, and second, what will injure it, and what should therefore be avoided.

Physiology treats not only of man, but of all other animals, as well as of plants. Animals could not live upon the earth if the plants did not prepare food for them. One might think that man could live upon milk and eggs and meat if there were no plants to furnish vegetable food ; but a second thought makes it plain that the animals which furnish us w4th milk, eggs, and meat live upon vegetable foods, such as grass and grain. Thus we are all dependent finally upon plants.

If one understands something of how plants live, that is, of Plant Physiology^ it is much easier to understand Animal Physiology and Human Physiology, We shall begin our study of physiology by the study of how a plant lives and grows; then we shall study how the cells and tissues, of which the human body is built, live and grow, and the part which they play in bodies. This part of the general science of physiology is called Greneral Physiology,

GENERAL PHYSIOLOGY

Chapter I.— Plant Physiology— How The Plant Lives And Grows

1. THE PLANT AND ITS NEEDS

Here is a kernel of corn that is dry and hard, and here is another which has been in water for a few days. Notice what a change has taken place in those few days. The little dried-up kernel has become large, full, and soft.

Fig. 1. — a, a dry kernel of corn, h, a soaked kernel, c, soaked kernel from which a thin slice has been cut. cZ, soaked kernel cut through along the line ah, (6). e, soaked kernel cut through along the line cd, (5). The skin of the kernel is peeled up and one can see the plantlet lying in its little bed of food.

Inside the change is still greater. If one opens a dry kernel, he will see in the midst of the white part a softer, yellow part which, in the soaked kernel, has become much larger and is plainly a little plant (Fig. 1).

Here is still another seed that has been in the wet earth in a warm place for five or six days, and in this we see the perfect little plant partly within and partly without the kernel (Fig. 2, a). What suddenly started this little plant to growing after lying asleep all winter ? What waked it up ?

It could not have been the water alone, for the kernels which Avere put in damp soil or water and set in a cold place showed no sign of life. Nor could it have been

Fig. 2. — The corn plant growing from the kernel, a shows the size of the plant at one week, h shows the size at ten days, and c at two weeks.

heat alone, for those that were put in a warm window without water still slept on. But when we gave them both heat and moisture, they awoke and began to grow. The growth, however, would soon stop if the plant had no food, so nature has put the food where the plant can get it most easily.

The white part and the yellow part of the kernel are all the food which the plant needs until it is old enough and strong enough to earn its own living. But even with all the moisture and heat and food which it needs, a plant cannot be healthy without one thing more.

You have seen a potato growing in a dark cellar, and have noticed its sickly, yellow color and long, weak shoots ; perhaps, too, you have seen a spot on the grass where a board has lain for several days and which Avhen removed showed the grass with yellow blades instead of green ones.

Without light there could be no green color in the leaves nor strength and vigor in the plant ; without food the plant could not grow, and after living for a time upon its own tissue, it would die ; without moisture the plant would wither and dry up ; without warmth, the light, food, and moisture could not do their work.

After the plant has started to grow, it grows in two directions, one part pointing up and becoming the stem, and the other pointing down and becoming the root, and whichever way the seed is planted, the stem will turn upward even if it has to make a complete turn to get started in the right direction.

If we look at the seed after the plant has been growing for two weeks, we shall find there is little of the seed left within the shell, for the plant has eaten all the stored-up food (Fig. 2, 0.

2. THE PLANT AIN'D ITS NEEDS {continued)

We have seen that a plant needs food and drink, heat and light, but we have said nothing about another need that is quite as great ; that is, the need of the oxygen of the air.

A plant not only eats and drinks, but it breathes. All plants breathe oxygen by day and by niglit. In plants that have leaves, the leaf is the organ of breathing ; in other plants the breathing is done by means of the body of the plant.

Before we can understand the use of the oxygen we must know something further of the food and the work of the plant. A plant cannot eat solid food. It must take its food either as a liquid or as a gas. The liquid food is taken from the earth through the roots, and the gases are taken from the air through the leaves. At least half of the solid part of a plant body is carbon, and the plant must have a continuous supply of carbon to satisfy this need.

There are several forms of solid carbon, such as coal or plumbago, but plants cannot eat solid foods, so that these forms cannot be used. The plant must take carbon in the form of gas, and this gas is called carbon dioxide. The plant can absorb this through the leaves and use it as a food. The most important food of a plant is carbon dioxide, which is absorbed from the air by the leaves.

Carbon dioxide is composed of carbon and oxygen. Carbon when alone is a solid like coal, or coke, or plumbago. Oxj^gen when alone is a gas. The air is composed of a mixture of gases, of which oxygen comprises about one fifth of the whole amount. When oxygen and carbon are joined together they make a gas which is called carbon dioxide gas. Carbon dioxide forms a very small part of the air. The leaves absorb the carbon dioxide, and if the plant is in the sunlight, the green coloring matter in the leaf separates the carbon from the oxygen. The carbon remains in the plant as a part of the plant, while the oxygen escapes from the leaves as a gas. All of this wonderful process is a part of the plant's eating.

To understand the way in which a plant breathes, we must study the subject of oxidation. Have you noticed that a fire which has been given plenty of coal will stop burning if we close the draught? If the draught is not perfectly closed, the fire will burn slowly ; but if quite closed, the fire will go out. It is plain that the fire needed something which it did not get. It had no oxygen. The coal cannot burn without the help of oxygen. This burning we call Oxidation,

You have seen copper become tarnished and iron become rusted when exposed to the air. In both cases they have become oxidized. When the coal became oxidized, it was a quick process which we call rapid oxidation, but when the iron became oxidized it was by slow oxidation.

Oxidation always produces heat. Rapid oxidation takes place in a short time with a great heat, while slow oxidation gives little heat during a long time.

Heat may be used for warming houses, for cooking, or for producing power to move machinery.

In the plant oxidation is used principally for power to do the work of the plant. The plant work is to push itself upward and to carry food from the ground to the highest point, and later to form the seed. It is the union of carbon and oxygen that gives the plant power to grow and to feed itself, and to make a ncAV plant.

As the leaf is the organ for inhaling, it is also the organ for exhaling. This is done by means of the cells in the surface of the leaves. Let us remember, then, that every plant has work to do ; that to get the power to do this work it must oxidize its own substance with the oxygen of the air. Remember that oxidation of the substance of a living plant or animal is hreathing. All living things breathe in oxygen, which combines with the carbon and other substances to form carbon dioxide and other combinations, such as water. After the carbon dioxide is formed it is ahvays thrown out of the animal body, but the plant leaves can use it for food when the sun shines.

3. THE PARTS OF A PLANT

We found the first need of a plant to be warmth and moisture, and found, too, that for days the plant could live upon nothing more than the food in the seed, with the water which it took in through the roots and the oxygen absorbed by the leaves from the air.

We can easily understand from this that a large part of a young plant and some part of all plants is fluid.

The fluid is in every part of the plant, and Avhen it is mixed with the food it becomes the sap. If you have tasted maple sap, you will remember that it was not like water, but was thicker and tasted sweet. That is because it has taken up the food of the plant, which it must carry to every part.

Besides the liquid part the plant has another part, and this part we call the tissue, just as we call the substance of your dress or coat, the material, the fabric, or the tissue. As tlie tissues have different uses, we call them by different names. Those that are active and do the work of the plant, we call active tissues; those that support the active tissues we call supporting tissues^ and those that cover and protect we call protecting tissues. Let us see if by thinking a little we can find which tissues belong to each division.

We know that the work of this plant is done by the leaves, the root, and the stem.

In all of these organs we find the living substance of the plant, which is called protoplasm. In the leaves it is green protoplasm, and in the stem and roots it is white protoplasm. All of the active tissues of the plant contain protoplasm, and are in the leaves, in the stem, and in the root. Most of the leaf is active tissue, but only a small portion of the stem and root is active tissue. The delicate root hairs contain protoplasm and represent active tissue.

If you hold a leaf up and look through it toward the light, you will see the branching veins of the leaf. These veins serve a double purpose in the leaf ; (1) they support the active tissue of the leaf ; (2) they serve as a circulatory system along which the sap of the plant flows. The stem is made up almost wholly of supporting tissue, the only active tissue being the inner bark in the case of trees and shrubs. What is true of a stem of a tree is also true of a root.

Protecting tissue is found upon every plant. The delicate, transparent skin which covers the little corn plant is its protecting tissue. The thick bark which covers the trunk and branches of trees and shrubs is their protecting tissue. Seeds have protecting tissue. The transparent skin so easily peeled off from a soaked kernel of corn is its protecting tissue. A nut has a hard, woody shell outside and a delicate brown skin inside, to protect it as it lies upon the ground all winter, waiting for the warm spring sunshine to wake it up.

4. THE pla:n^t organs

The tissues are but the materials of which the working part of the plants is made, and these working parts we call Organs,

18 rHYSIOLOGY

We have already spoken of the leaf as the organ of breathing. On its surface both above and below are cells through wliich the oxygen passes. The leaf is formed of the three kinds of tissue. Inside is the living part or protoplasm, kept in place by the supporting tissues, the veins, and the whole leaf covered by the protecting tissue or skin.

The work of feeding is shared by two organs, the leaf Avliich gets the gaseous food from the air, and the root, which gets the liquid food from the ground. This organ is composed of all three tissues. In large plants the main part of the root is supporting tissue, whose work is to hold it upright and firmly fixed in the ground ; but each large branch of tlie root has a thin coat of active tissue under its bark. In small plants like the little corn plant, the main part of the root is active tissue, composed of fine rootlets and root hairs, all filled with protoplasm and sap, and held in form and made strong by the cellulose, and covered and protected by the skin.

The stem with its branches is the organ of form, and gives to the plant its shape. Without this part the plant could not grow tall, nor send out arms, nor have any of the beautiful forms which plants now take. It would lie flat and formless.

The little corn plant which we have been studying has no other organs than the root, stem, and leaf, but in a mature plant there is still anotlier organ, the flower, to wdiich is given the highest work of the plant. The flower often adds beauty, color, and fragrance, but these things are not its real work. Its work is the making of a new plant of the same kind as the parent plant, and this is the crowning work of the whole plant. During the entire summer the leaves breathe in oxygen, the roots take in food, the veins carry it all over the plant body, all to give the plant strength to form the seed, which holds the sleeping plant for the following year. This work of making the seed and storing up within it the food for the young plant is so hard that it requires the help of the whole plant. But, as upon the seed depends the future good of the plant family, so each plant gives its work for the family good.

It is so important that the plant prepare this seed and ripen it that if it cannot get the proper food and drink for growth and seed making, instead of using what it does get for its own growth, it sacrifices its growth and hastens to form the flower, which in turn will produce the seed and insure the next year's plant.

5. THE SEED AND WHAT IT CONTAINS

We have talked about the young plant and its needs; the growing plant and its needs ; the material from which the plant is made ; and the organs of the plant and their work. The most important organ we found to be the flower, and its most important work the making of the seed. Now we will talk about the seed and its material. Let us look first at the outside. Here is a seed that has been in water for three or four days (Fig. 1, page 11). If you use a penknife or a pin, you can loosen the outside part or skin. Look at it and see how tough it is. When it was on the kernel, it looked yellow, but when it is taken off, it looks colorless, and we now know that the color showed through and that the skin itself is transparent. Did you notice where the skin stopped? If you look carefully enough, you will see that the point of the seed is not covered. This is where the kernel is fastened to the cob. The skin is entire over the seed except over this point.

Now we have taken off the skin and can see the body of the kerneh Look at the soaked kernel in which the parts have become swollen and are more easily seen. Now the little plant or germ can be loosened from the other part which is the plant food. In this seed that has been in the warm earth for five or six days the parts of the germ can be seen : the point which grows upward called the jjlumule, and the point which grows down called the radicle. Notice that what was a groove in the dry seed has filled out in this soaked seed, and in the seed that has been growing for a week we can see the root growing down- Avard from the pointed end of the seed, and the plumule growing upward from the middle of the side of the kernel in which the germ lay. Notice that on one side of the kernel there is a little bed of soft yellowish substance, in the midst of which the germ lies. This soft yellowish substance forms the first food of the little plant when it wakes up or sprouts in the spring.

It will be interesting to find of what the seed and the germ are composed.

The germ itself is composed largeh^ of protoplasm within thin cellulose walls and covered with a thin skin. Around this tender germ is a layer that is nearlj^ all protoplasm or proteid, and around that layer is the main part of the seed, which is starch. On each side of the kernel is a yellow part which contains the oil mixed with starch, and besides these materials are some minerals, such as salt and lime.

EXPERIMENTS

Get five cents' worth of iodine from the drug store. Dilute a part of this with water to a light brown color. Make a thin paste of laundry starch boiled with water.

1. Put some of this paste in a drinking glass. Pour into the starch a little of the dilute iodine, and notice that the starch instantly tnrns to a beautiful blue color. This is called the iodine test for stai^ch.

2. Put a little piece of lean meat in some of the strong iodine and notice that the meat turns brown. This is the iodijie test for proteid (see page 85).

3. Cut some thin slices across a soaked grain of corn ; put them into any little shallow dish like a watch crystal or a butter dish, and notice that the white part of the kernel turns blue, showing the presence of starch ; and that the yellow part around the germ turns brown, showing the presence of proteid there. The germ itself turns brown becanse its protoplasm is one kind of proteid.

4. Remember that the kernel contains the first food of the plant ; that this food is composed of starch, of proteid, and of oil ; that iodine turns starch blue and proteid brown.

6. PLANT DIGESTION

We know that as plants eat thej^ must have food, and that it must be in a form in which the plants can use it. As they can take no solid food, they must take all of their nourishment in the form either of gas or of liquid, and as many foods are not soluble in water, there must be some other process which changes them to a liquid form. This change is called digestion.

Plant digestion is of two kinds, the digestion of the seed food^ which takes phice within the seed when the germ first wakes up and is feeding upon the food stored for it by the parent plant ; and the digestion of the soil food^ which the roots take up from the ground.

It often hapjjens that both kinds of digestion are going on at the same time ; for example, when the wakened germ is living mainly upon the seed food, but has sent out one or two roots which bring in new material from the ground. As the roots can take only liquid food and the leaves only gaseous food, all changes in the food — or digestion — must take place outside of the plant body. Therefore the plant has and needs no digestive organs, but it does have digestive fluids, which it sends out to dissolve mineral matter or to change it into a liquid that can be taken up.

We found a large part of the kernel of corn to be starch ; but if you were to examine the plant itself, j^ou would find no starch at all, and yet the germ plant lives upon that stored-up starch. It is evident then that some change must have taken place in the food.

The foods that are found in seeds are either sugar, starch, oil, proteid, or cellulose, and all of these excepting the sugar must be digested before they can be used by the growing germ, and must be digested by some ferment.

Do you know what is meant by a ferment? If you put corn or beans to soak in water for several days, 3^ou will find that the water becomes cloudy and has tiny bubbles on top ; that shows the work of a ferment. The same ferment will not digest all the kinds of food which seeds contain, but it requires one kind of ferment for oil, one kind for proteid, and another for starch and cellulose.

Knowing that the food cannot be digested without a ferment, we naturally want to know where this ferment comes from and what it does.

Let us go back to our first lessons, and we shall find that the plant germ sleeps in the seed until it is wakened by the action of the heat and moisture working together. If the germ has only water or only heat, it sleeps on, but when it has both in the right amount, it wakens.

Bears and some other animals sleep during the winter in some warmly covered, dark place, neither eating nor drinking, and breathing but slightly. In the spring they waken and are so hungry that when we wish to express great hunger we say '^ as hungry as a bear."

The germ within the seed also sleeps during the winter and wakens in the spring '^ as hungry as a bear." The mother plant had prepared for this hunger, and right at hand the wakening germ finds food. When the protoplasm is wakened, it forms a ferment out of its own substance, and this ferment digests the different foods. One kind of ferment digests the starch and cellulose, another kind digests the oils, and still another the proteid matter. After the food has been acted upon by the ferment it is ready for the plant to use in building up new parts.

All the seed foods are digested in this way; but when the plant becomes old enough and strong enough to put out roots and to produce root hairs, then the plant uses another kind of digestion. The young plant carries on first the ferment digestion and then both kinds of digestion at once until the seed food is all used up.

From the soil the plant takes up mineral food, of which it could get very little from the seed.

A plant must have mineral matter to make it strong enough to stand upright.

The minerals of the soil are solid, and are not soluble in water. If they were, the rains would wash them away, as they have washed the soluble salt, into the sea.

Before minerals can be used as plant food they must be dissolved, and water will not do it. A way has been provided by means of the root hairs. These root hairs make an acid whicli dissolves the grains of mineral matter which are held close to the root by the close-growing root hairs. As soon as the mineral is dissolved it is taken up by the root hairs, forms a part of the sap, and thence is carried all over the plant, where it is built up into the growing tissues, giving it that firmness which only mineral food can give. Some of the minerals used are quite common to us, as the lime and salt, but others quite as useful to the plant are not so well known to us. Some plants require more of one mineral, and others more of another kind, and this is one reason why different plants require different soils, and why it is better not to grow one kind of grain on a field year after year, but to change each year, thus having '' a rotation of crops."