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Flowers and their friends

Chapter 38: CELLS.
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About This Book

A children's natural-history guide uses vivid, approachable vignettes about familiar garden and wild blossoms — morning-glory, geraniums, hyacinths, nasturtiums, and jewelweed — to teach how flowers are built and function. Clear explanations of stamens, pistils, pollen, nectaries, leaves, roots, cells, and chlorophyll are paired with stories of insect visitors and pollination, seed and fruit formation, and plant life cycles. Practical observation tips and a glossary help young readers explore how floral structure, nectar, and color serve reproduction and attract animal helpers.

STORIES ABOUT ALL SORTS OF THINGS

NECTAR GUIDES.

The bee is always in a hurry. She flies from flower to flower as fast as she can.

She sees the flowers far off and comes straight to them, choosing the brightest. She has learned that the bright flowers hold much honey and often have guides to the nectary, so that she does not have to hunt about, but, alighting on a flower, follows the bright guide. Sometimes it is a spot in front of the nectary and sometimes a line leading to it. It leads her at once by the shortest path to the nectar, and since she is in such haste, the nectar guides are her good friends, helping her to save time.

CELLS.

Cells are a matter of importance.

To be sure there are cells and cells, and some are much more important than others.

For instance, there are prison cells, more’s the pity, and anther cells and honeycomb cells and ovary cells and many more like them. All these are small, hollow spaces with walls around them.

But there is another kind of cell, more important than all these others put together, and they are not hollow and do not always have a wall.

Perhaps you are not very much interested in cells, but you had better be in these we are going to talk about, for they have a great deal to do with football games and dancing and going to parties and picnics. In fact, without them there could be no football and no dancing and no parties nor picnics.

All these things depend upon cells. So we may as well begin at once to find out what they are.

These cells that we are going to talk about are alive. They are made of protoplasm. You do not know what protoplasm is? I can tell you it is time you did then, for if it had not been for protoplasm you would not be in the land of the living. The protoplasm made you; so if you are not interested in it, I think you ought to have been a cabbage or a squash or a liriodendron or some other thoughtless vegetable not expected to be interested in protoplasm.

Like a good many other interesting things, protoplasm cannot usually be seen by the naked eye; it is in such small quantities that it takes a microscope to find it. And when you have found it, so far as its looks are concerned, it would hardly seem to pay for the trouble, for to the eye it is nothing but a colorless, jelly-like substance. It looks more like the white of an egg than anything else. But remember it is not safe to judge protoplasm or people by looks alone.

Napoleon was small, and he was not handsome; yet if you had seen him, you would have seen the greatest man living in the world at that time.

So when you look at protoplasm you see something very much more wonderful than it seems. In fact, the great Napoleon himself owed his physical life to protoplasm, as did also Shakespeare and Plato, and every person who has ever lived, for protoplasm is the only living matter in the world.

You cannot understand that all in a minute, but you begin to see that protoplasm is rather important, and as well worth knowing about as the latest fashion in bicycles or sleeve patterns.

Sometimes a bit of protoplasm lives all by itself. It is just a little speck of colorless, jelly-like substance. Yet it can do a number of things. One little creature, which is only a bit of protoplasm, has a name much larger than itself. We call it “Amœba.”

Rather a pretty name, on the whole, and very uncommon. I doubt if you know a single person by that name.

It is a name, too, that everybody ought to know.

Well, as I told you before, and shall probably tell you a great many more times, for I do not want you to forget it, the amœba is only a bit of protoplasm.

Yet it can go about. You watch it some fine day under your microscope and see it travel. It runs out a little, thin bit of its body, so and then the rest of the body sort of pulls itself up to that. In this way, by putting out little finger-like projections and drawing the rest of the body up to them, it can move quite a distance if you give it time enough. You can imagine so changeable a creature as the amœba can scarcely be found twice of the same shape, and how its friends recognize it is more than I can tell. Suppose you were in the habit of changing your shape whenever you moved, being long and thin one minute, short and thick another, having fourteen arms one day and none the next? How could you expect people to know you when they met you?

But perhaps the amœba has an unsocial nature and does not care whether it is recognized or not.

Because it changes its shape so often the amœba has received its pretty name. For “amœba,” you must know, comes from a Greek word meaning “change.”

It is sometimes called “Proteus” for the same reason. Of course you know all about Proteus, the sea god who lived at the bottom of the ocean and paid homage to the great god Neptune, who was ruler of the seas. Proteus took care of the sea calves, and he had a queer way of changing his shape whenever he chose. He used to go to sleep on the rocks while the calves were sunning themselves, and because he was very wise and could help people who were in trouble, they used to go there and catch him. But he was not as friendly as he was wise, and would never tell anything unless forced to; and when he found himself a prisoner, he would at once change his form, and so try to escape by frightening his captors. He had a pleasant habit of all at once changing into an enormous serpent and opening a mouth full of frightful teeth; then, if that did not frighten badly enough, he would all at once turn into a bull or a raging fire or a fierce torrent. He has been known to change into a dozen dreadful things in as many minutes, so no wonder his name has come to mean “something that changes.” And no wonder the amœba is called “proteus,” not that it indulges in any such outrageous transformations as the sea god, for it never does anything worse than change the shape of its own little jelly-like body.

Although it can move along, I do not think it would amount to much in a race, as it only moves a few inches in the course of a day; still that is a good deal, considering its size.

A great deal depends upon size in this world.

You could go as far in ten seconds as a snail could in as many hours. The distance would not count for much as far as you are concerned, but it would be a good day’s work for the snail. So when an amœba travels a few inches, that counts for as much in its life as a long day’s walk of a good many miles would in yours, or as a few hundreds of miles on a railway train.

The amœba can do more than travel. If you touch one it will shrink together, showing that this little bit of protoplasm has a sort of feeling power.

When it is hungry it eats. For an amœba can get as hungry as anybody.

Hunger does not depend upon size. You can get as hungry as an elephant, although you cannot eat as much. You would starve to death, too, as soon as an elephant, perhaps sooner. An amœba no doubt gets as hungry as you do, and it certainly would starve to death if it did not have something to eat.

How can it eat without a mouth? Just as easily as it can travel without feet. You do not know protoplasm if you think it cannot eat when it is hungry. Very likely the reason it travels about is because it wants to find something good to eat. It does not care for roast turkey and cranberry sauce, nor for apple pie and plum pudding.

That is not what it is looking for. It is looking for some tiny speck of food smaller than itself.

It lives in the water, of course. It would dry up if it were out in the air. You should think it would melt in the water? Well, it does not, any more than a jellyfish melts. When it comes to some little speck of dead plant or animal, or, for all I know, to some living speck small enough, it proceeds to eat it.

It glides over it in the way you know about, and wraps the food speck up in its body. Then it draws out all the good part of the food into its own substance and goes on, leaving behind the waste particles.

Do you not think that is a good deal for an amœba to be able to do? But it can do more than this; it can divide itself in two and make two amœbæ out of one.

The little amœba is called a “cell.” After awhile you will see why. The whole amœba is just one cell.

As to whether it is a plant or an animal you will have to ask the amœba, for I cannot tell you. Some think it is a plant and some say it is an animal.

I do not think it makes much difference which you say it is.

A bit of protoplasm living by itself is called a “cell.”

Many plants and animals have, like the amœba, only one cell. Very often the little one-celled being has a thick outside wall. The protoplasm changes part of the food into a hard substance, that is, it builds itself a wall.

Very often cells live together in colonies instead of living alone. In such cases, the first cell divides into two cells, but the two stay together instead of entirely separating. Then each of these two cells divides again, and the four cells stay together, and so it goes on until a large body is built up of many cells.

The truth is, plants are only collections of cells which have agreed to work together. Where there is but one cell, it has to do all sorts of work; but where there are many, some do one kind of work, some another,—just as Robinson Crusoe, living all alone on the island of Juan Fernandez, had to do all sorts of things for himself: make his own shoes and clothes, get his own food and cook it, build his own house, and gather his own wood. But in a town one set of men makes shoes, another chops wood, another raises vegetables and grain, another grinds the grain, and another bakes the bread; then they all exchange with each other, and everybody has enough—or ought to have.

So in the plant made of many cells. One set of cells makes hard walls to protect the plant. Another set draws up water from the earth for all the cells in the plant, for living things require a great deal of water. Another set takes gas from the air and changes it into food. Another set makes tubes for the sap to flow through. Other sets do other things. Each set of cells does something for the whole plant.

If you look at a leaf or a bit of skin from a stem under a microscope, you will see they are built up of cells, as a house is built of bricks. Only the cells are not placed regularly like the bricks in a house, and they are not solid like bricks. The walls of these cells are sometimes hard and sometimes soft, sometimes tough and sometimes tender; but the walls were all built by the protoplasm that lived in them. Sometimes the protoplasm leaves the little house it has built and goes somewhere else.

Then the empty, wall-surrounded space is left like a cell of honeycomb before the honey is put in, or an anther cell after the pollen has fallen out and left nothing in it.

Before microscopes were as perfect as they are now, these empty spaces with their surrounding walls were discovered. Even where the cells contained protoplasm the microscope was not strong enough to reveal it, so only the cell walls were seen.

Some of the cells in one plant.

It was soon known that plants were built up of these little compartments, and because they resembled cells in being small and shut in by walls, they were called “cells.” After awhile it was discovered that the living part of the plant was the colorless, jelly-like protoplasm which lived in the cells. Yet later, particles of wall-less protoplasm were found building up plants and animals. What were these soft little protoplasmic atoms to be called?

The plant was really built up by them, and only part of them had walls, so they were called by the name the people had already given to the walled spaces which they supposed built up the plant, and so got the name of “cells,” which is not at all an appropriate name.

There is nothing quite so easy as to be mistaken, you see, and the botanists, having seen that the plant was built of little compartments, and never suspecting the presence of the living protoplasm lurking in some of them, had called the compartments “cells”; later, when the protoplasm was discovered to be the real builder, the old name was kept. So you see how the amœba came to be called a “cell.”

There are a great many different kinds of cells in one plant.

But every living cell has very much the same powers as the amœba, though in many of them some one power is developed at the expense of all the rest. In this way different sets of cells are able to perform different kinds of work, and do it very well indeed.

The amœba is not the only single-celled creature. There are a great many different kinds of single-celled plants or animals, and some of them take very curious and beautiful forms, with streamers floating about them.

Such are not protean, like the amœba; they do not change their shapes.

Plants are not the only things that have cells. Animals, too, are built up of them. Animal cells are usually softer than plant cells, because they very often have no hard walls. Bone cells of course have hard walls, and there are others, but most of the animal cells are without walls.

So you see all living things are built of cells, and the living part of the cells is the protoplasm.

You yourself are built up of millions of cells, and without the help of protoplasm you would not be living, for protoplasm made your cells, and protoplasm is the only thing in you that is alive. Your muscles are made of muscle cells, and the protoplasm in them moves, and when the muscle cells all move together, that moves your arm or your leg or your head or some other part of your body.

Since your muscle cells devote themselves to moving, they do not try to do much else; so other cells digest the food which the blood carries to the muscle cells. Yet other cells build a good thick skin to protect the soft muscles, and yet another set of cells thinks for the muscles, and tells them where and when and how to move. Each set of cells has its own work.

Your brain is made up of nerve cells, and the protoplasm in them in some way enables you to think and feel. Your bone cells are hard and resisting, your sinew cells strong and flexible. So each part of your body is made up of different kinds of cells.

But what has all this to do with football and parties and picnics you would like to know?

Why, a great deal, to be sure. If it were not for cells and protoplasm there would be no people.

And how could you have football games and picnics without people, I should like to know?

POLLEN CELLS.

In the dark little dungeon cells of the anthers, the pollen grains lie. Hundreds, and sometimes thousands of them, are packed in there as closely as they can be. But they do not mind it, not in the least. They grow and get ripe, and as soon as this happens, their prison door opens and out they pour.

They are funny little things, not at all what they seem to be. For you would think they were just little specks of dust of almost no shape at all. But that is your fault, or rather the fault of your eyes.

You see your eyes were not meant to look at things so tiny as pollen grains. You can see a common ball or even a small shot very well indeed; but when it comes to pollen grains you are as blind as a mole. You will have to put on your spectacles to see that, I can tell you, and very powerful spectacles they will have to be, too. The best spectacles for you to look through are the ones we call a microscope. Just put your eye to that tube and you will see what you will see, for there are pollen grains at the other end—pollen grains from several kinds of flowers; there are some in the corner from our friend the morning-glory. And now you know what I meant when I said you could not see a pollen grain; for those little specks of dust have all at once become large and important objects. Some are round and some are not, and all are creased or pitted or ridged or covered with little points or marked in some other way. Now you see why they stick so easily to the hairs on the bee or the butterfly or whatever comes visiting the flowers for nectar. They are not smooth, but all roughened over by these ridges and points.

And this is not the end of it. You have not yet seen a pollen grain. You have only seen the outside of one.

For it has an inside. You think it is too small to have anything inside of it?

I can tell you things much smaller than that have something inside of them. The truth is, these things seem so small because we are so large. If we were as small as they, they would not seem small at all. They would seem a very ordinary size indeed, and we would expect them to have an outside and an inside.

The truth is, pollen grains are hollow. They are as hollow as the baby’s rubber ball. But they are not empty. The baby’s rubber ball is not empty; it is full of air. These pollen grains are not full of air. If you were to see what is in them, you might not think it very important, but that would be a great mistake, for they are full of—protoplasm!

The truth of the matter is, the pollen grain is a cell; it has a wall outside and is made of protoplasm inside.

Protoplasm, you remember, is the material out of which every living thing is made. You are made from protoplasm yourself; flowers are made from it, too, and leaves and birds and everything that lives.

So you see if a pollen grain is filled with protoplasm, that is rather a serious matter.

This pollen grain, small as it is, has a tough outer skin. It is not as tough as leather, but it is tough for so small a grain, and is strong enough to keep the protoplasm from running out.

The protoplasm in the pollen grain is what the ovule needs to nourish it and make it able to grow. The ovule, too, is a cell filled with protoplasm, and the protoplasm of the pollen and of the ovule must somehow come together before the ovule can do any more growing.

You know how the bees and butterflies and all sorts of insects carry the pollen from flower to flower and dust the stigmas with it. You may think that when a pollen grain is safely landed on a stigma then the rest is easy enough. But if you suppose the pollen grain can pass through the style you are very much mistaken. It cannot even pass through the stigma. It is true, the tissues of both style and stigma are rather loose, and that the style is sometimes hollow. But, as far as I know, the pollen never passes through. Small as it is, it is too large to get through the tiny openings in the stigma, and then, you know, the stigma is sticky and holds it fast.

Here is an interesting state of affairs! The ovule cell is waiting for protoplasm, and the pollen cell is anchored safe and fast at the stigma.

But you may be sure there is a way out of this difficulty.

To begin, the pollen grain has two coats, a tough outer one and a delicate inner one. There are openings, or at least weak places, in the outer coat, and after the pollen has lodged on the moist stigma, the protoplasm inside swells and comes bulging through these weak places. The inner coat is forced out, as though some extremely small fairy had stuck her finger through the wall from the inside and pushed out a part of the inner lining. Well, this finger-like part that comes through the wall does not break open, but begins to grow. It grows longer and longer until a tube is formed, a tube so small that only the microscope can enable us to see it.

This tube pushes its way through the stigma into the style; there it continues to grow like a long root, only it is not a root, and it is hollow; and the protoplasm from the inside of the pollen grain runs down this tube.

You can guess what happens next. The tube grows and grows; it finds plenty of nourishment in the tissue of the style, which is made of material suitable to feed it. Of course, it grows down the style into the ovary, because the style opens into the ovary.

When it reaches the ovary it finds its way to an ovule, and goes in at a little door which the ovule keeps open for it.

Now, you see, there is an open path between the pollen grain and the ovule, and the protoplasm from the pollen grain which has run down the tube enters the ovule. Here it passes out of the tube by breaking through the delicate wall, and unites with the protoplasm of the ovule.

Thus the ovule is fertilized. It is nourished and strengthened, and at once begins to grow into a seed.

Meantime the shell of the pollen lies on the stigma, a little dried-up, empty thing. Its work is done. Thanks to the bee or the butterfly or some other flower-loving friend, it has been taken to the right place, and all that was living in it, its protoplasm, goes on living in the little ovule.

The pollen grains the bees carry home have a very different fate. They are crushed and soaked and kneaded with honey and fed to baby bees.

But the flowers are willing the bees should have some to live on, and so each flower makes thousands more than it needs. You see, if it did not give the bees something to eat, they would not come and they could not live on honey alone; they, too, need the protoplasm in the pollen to nourish them.

Some kinds of flowers use their own pollen. They do not need the bees and do not want them. So they keep their pollen shut up tightly and do not make any honey to coax the bees to come. But nearly all flowers wish to have other pollen than their own. And this they can only get by the help of other people’s wings, as they have none of their own.

THE POLLEN.

What does the pollen do?

It helps the ovule change to a seed.

It feeds the bees and the wasps and the flies.

But above all, it helps the ovule change to a seed.

THE ANTHERS.

Anthers, anthers, full of pollen,
Cunning cupboards of the bee,
Stamen flour amply hiding,
What have you for me, for me?
What have you for me?
Pollen have I, plenty of it,
Pollen for my darling bee;
Pollen every day I blossom
For my bee, but none for thee,
For thee, none for thee.

OVULE CELLS.

You will be glad to know that the little ovules at the heart of the morning-glory and of all other flowers are single cells.

They have an outside wall and are filled with protoplasm.

When a pollen cell is formed from the inside of the anther, it separates and is no longer connected with anything. This is not the case with the ovule. It is fastened to the ovary by a little stem, for it will stay there and grow; and it must have a way to get food from its parent plant. It gets the food through this little stem.

You know what happens when the flower opens.

The bees bring pollen, and the protoplasm of the pollen joins that of the ovule. As soon as this happens the ovule begins to change. We say it grows. It gets the food to grow on from the mother plant through the little stem which is fastened to the inside of the ovary.

The protoplasm in the ovule first divides and makes two cells instead of one. These two cells do not entirely separate from each other. They stay together to do their work. Soon each of them divides into more cells. These cells again divide, and this continues until a great many cells are formed. Meantime the ovule has increased in size as well as complexity, and its cells do several different kinds of work. In the morning-glory, for instance, some build a hard outer wall about the young plant; this is the seed-case. Other cells form two little leaves; others make a little stub of a stem. So the change goes on until the single-celled ovule becomes a many-celled seed with a young plant rolled up under its walls. If you open a morning-glory seed you can see this little baby plant, only you will have to soak the seed first to soften the food that is stored about the young plant.

The cells made this food to nourish it, and it stays dry and hard until the rain moistens it in the spring, when it gets soft, like boiled starch, and is then ready for the little plant to use. When the ovules grow on one plant and the pollen comes from another, the seeds will contain the protoplasm of two different plants.

Now protoplasm remembers the plant it came from, and tries to make the new plant like it.

The ovule protoplasm tries to make the seed remember the plant it grows on, and the pollen protoplasm tries to make the pollen remember the plant it comes from.

So if the pollen comes from a plant bearing white flowers, it wants the seeds to grow into white-flowered plants. But if the ovules which fertilizes it grow on a pink-flowered plant, they try to make the seeds grow into pink-flowered plants. Now what happens? Very likely some of the flowers will be white and some of them pink. Some will take after the plant the pollen came from and some after the one the ovule came from. But sometimes the flowers will be a mixture of both plants and will be pink and white.

The ovule is the mother part of the plant and the pollen is the father part, and sometimes the seed-children take after the mother, sometimes after the father, and sometimes after both.

This is very strange and we cannot quite understand it. How can the protoplasm remember the exact shade and color of the plant it came from? How can it make seeds that grow into plants just like the old plants?

Protoplasm, you are a great, a very great mystery!

By knowing about pollen and ovules we are able to help form a great many lovely new flowers and fruits.

We get variegated flowers by fertilizing a flower of one color with pollen from a flower of another color.

When we do this we must cover over the plant with a piece of netting just before it blossoms, so the bees and butterflies cannot get ahead of us and fertilize the plant. Then we must put a bit of pollen from one flower on the stigma of the flower we want to experiment with.

We must always use the pollen from the same kind of a plant, however.

It would be of no use to put nasturtium pollen on a morning-glory stigma, for instance, for it could not affect the ovule in the least. The protoplasm knows in some way its own plant and will not fertilize any other.

This is a very good thing, otherwise we might have a funny mixture of all sorts of plants.

Many delicious fruits have been produced by fertilizing one plant with pollen from another.

New varieties of grapes and berries are constantly obtained in this way.

If you live on a farm or have a garden, you might try to develop some new kinds of berries or fruits. You might not succeed, but it would do no harm to try.

CHLOROPHYLL.

Chlorophyll is plant green.

That is what the word means.

We are so used to seeing green leaves that we think very little about it.

It probably never has occurred to most of us that the green coloring matter of plants can be of much importance. Yet it is one of the most important things in the world.

Like many other things, it is not what it seems. It is not merely a dye as one might suppose, but much more than that.

We cannot really see what it is without a microscope, and when we look at a piece of green leaf through the microscope we are surprised to find the leaf is not green at all.

It is colorless like glass, but in the cells just behind the skin cells we see little roundish green bodies packed away. These are the chlorophyll grains, and when there are a great many of them close together they show through the skin and make the whole plant green.

The skin protects them, you see, and yet it is transparent and allows the light to get to them, which is a matter of great importance to the chlorophyll grains, for they are hard workers, but cannot do a single thing without sunlight.

Chlorophyll grains lie just behind the skin cells in all parts of the plant that look green. The cells they lie in are often long with their short ends towards the skin. Leaves contain several layers of chlorophyll cells. The inner ones are not long like the outer ones, and do not contain so many chlorophyll grains. In the illustration, a, a represent the upper and lower skin and b the cells containing chlorophyll. The under side of a leaf usually has fewer chlorophyll grains in its cells, for the light is not so bright there, and chlorophyll needs plenty of light.

Sometimes the cells in the middle of a leaf, that is, halfway between the upper and lower surfaces, have no chlorophyll at all.

Now what do you suppose is the work the chlorophyll grains have to do?

You never could guess, so I may as well tell you at once. If it is not making sugar, it is something very like it. To begin at the beginning, which is a long way from sugar, but which will certainly bring us to it, I must tell you that these little round green chlorophyll people have a strong attraction for carbon dioxide, which you know is a gas and is always found in the air. You know, too, we breathe it out as an impurity. Probably you did not know it had anything to do with sugar, but it has a very great deal to do with it.

The chlorophyll grains attract carbon dioxide as strongly as a magnet attracts bits of iron. The carbon dioxide in the air goes through the pores in the leaf skin, right through everything to the cell where the chlorophyll lies. You know carbon dioxide is made of carbon and oxygen. The plant needs a great deal of carbon, for nearly all its hard parts are made of it. Wood for one thing is nearly all carbon.

As soon as carbon dioxide comes where chlorophyll is, the chlorophyll, which of course is chiefly made of protoplasm, tears it to pieces. It pulls the carbon away from the oxygen and the oxygen rushes out through the pores back into the air. But the carbon stays behind.

You see oxygen is a gas and carbon is a solid. When carbon and oxygen unite in a certain way, they make another gas, our carbon dioxide.

It is very queer that carbon should have the form of a gas when united with oxygen, and I cannot explain it here. You must just remember that it is so.

When the oxygen flies away into the air again and leaves the carbon behind, the work of the chlorophyll has but just begun. Raw carbon is of no use whatever,—no more use than carbon dioxide, which we know is good for nothing to the plant or else the chlorophyll would not tear it to pieces.

But if the chlorophyll can only get a little water, something worth while will happen. This it can always do, as the roots take good care to send it plenty.

Water, you know, is made of two gases, hydrogen and oxygen, united together.

Here, you see, gases unite and make a liquid. Well, chlorophyll has a way of its own of uniting the carbon it took away from the carbon dioxide with the hydrogen and oxygen it gets from the water and forming a solid, which the plant cannot live without.

Now what do you suppose this new solid is? Probably you never could guess.

It is starch, just starch!

Chlorophyll makes starch out of carbon, hydrogen, and oxygen.

Sometimes it makes sugar and oil out of them, but its work is most generally starch-making.

The carbon, you remember, it gets from the carbon dioxide of the air, and the hydrogen and oxygen from the water the roots send it.

The strangest thing about all this is, chlorophyll is the only thing that can make starch.

Perhaps you do not think starch worth making such a fuss about. But wait a moment.

There is more to starch than you ever dreamed of. Really and truly, if it were not for starch you would not be alive to-day, and I would not,—in short nobody would.

All our lives depend upon starch. So when we come right down to the truth, our lives depend upon chlorophyll, because that makes all the starch there is in the world.

You do not think our lives depend upon starch? Wait and see.

Chlorophyll makes starch. Never forget that as long as you live. Forget your own name if you want to, but do not forget that chlorophyll makes starch.

You see starch is the raw material of which plants are made.

After the chlorophyll has made starch, the starch is dissolved, or melted you would likely say, and so is carried all over the plant in the sap. Some parts of the plant change the starch into sugar; for sugar is made of the same things as starch, only in it the carbon, hydrogen, and oxygen are put together a little differently, just as you can make several kinds of cake from flour, butter, sugar, milk, and eggs by stirring them together differently and mixing them in different proportions.

You cannot make cake without flour, sugar, eggs, and milk, and usually butter. But if you have these ingredients you can make a great many kinds of cake.

Starch is the material of which the plant makes a large part of its substance.

Some parts of the plant that need sugar make it from the starch, and we find more or less sugar in all plants. There is, as you know, a great deal in the nectar of flowers, but other parts of the plant need it too, so sugar is a matter of importance to plants as well as to people. But sugar, remember, is made generally from starch, no matter in what part of the plant we find it.

The sweet sap in the sugar maple is made from starch; so is the sweet juice of the sugar beet and of the sugar cane. All the sugar we use, excepting that in homeopathic pills, is made from starch. The sweet juice of fruits, berries, apples, peaches, oranges, contains sugar, which the plant has made from starch. In green fruit the starch has not yet been changed into sugar, so it is not pleasant to the taste.

Some parts of the plant need thick walls, like wood or bark, and these are made by the protoplasm from starch; they are not sugar, however, but a very tough, firm substance so unlike sugar that you wonder how it can be made of the same materials. But it is, for starch is the substance from which both are made.

There are other things in the plant besides starch, and there are things which are not made from starch; for instance, there are acids and minerals of different kinds and there is protoplasm, but the greater part of every green plant is formed from starch.

Some plants make more starch than they need at once, so they store it away for future use, just as people raise extra supplies of wheat and corn, and store them away until they want them.

The potato plant, for instance, stores a large quantity of starch in the potatoes underground. A potato is nearly all starch, and the sweet potato stores up sugar as well as starch in its underground parts.

The potatoes have a reason for this, and, if let alone, would use up the starch and sugar another season; but we do not let them alone, as you know. We too need starch, and so we dig up the potatoes and eat them instead of leaving them for the plant.

A great many plants store up starch in their seeds that the young plant may have food enough to start growing. All our grains do this. Wheat, rye, oats, barley, rice, corn, and all other grains are only the seeds of plants which have been stored full of starch. Peas and beans are also starch-filled seeds. Cabbages store food made from starch in their big thick leaves. Beets store sugar and other starch-food materials in their thick roots; so do carrots and parsnips and turnips. Onions store it in their bulb leaves underground.

You begin to see now how important starch is to our lives. Nearly all the vegetables and grains and fruits we eat are composed almost entirely of starch or the materials of starch. Even meat is made from starch, for what do the animals we kill for meat live on?

Why, plants of course, and chiefly the starch they find in plants.

So now we are just where we started,—we see we really do owe our lives to starch, and we owe starch to chlorophyll, so of course, we owe our lives to chlorophyll. I wonder if we shall think of this next time we look at the green leaves everywhere in the fields and woods.

I wonder if these green leaves will not look more beautiful than ever when we think of the work they are doing.