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. [Illustration: [Leaves]] 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.