THE FIRST LIVING THINGS
stuff can do nothing; it is of no use to the plant, and is only a burden to it. Indeed, if plants are cut off from sunlight altogether, they die at once, or, at any rate, lose all the green stuff in them. I t is the Sun that makes the green stuff in the plant, and the green stuff's only use is to help the plant to profit by the Sun. Now this is just a tremendous fact, and we should make a very great mistake if we went on to talk about what the green stuff does without making quite sure that we understand what the Sun does. Without the Sun there would be no life at all upon the Earth: No Light, no Life. The green stuff, then, though necessary for life; is only an instrument, some-
as we must now see, is that most plants are specially good at doing something which is just the opposite of breathing, something which no animal can do, and which every animal depends upon plants to do for it. The plants that do this wonderful thing that we are going to talk about are all green plants, or, at any rate, if they are not green, like grass, they are brown, like seaweed. But the little difference in colour does not matter, for the stuff that makes the seaweed brown is really the same as the stuff that makes grass green. This stuff is so important that we must think of all plants in the world as divided into two great kindsthose which have this green or brown stuff,
ONE
OF THE FIRST OF ALL LIVING ,THINGS-THE SEAWEED. IN THE SHALLOW WATERS WHERE LIFE IS SUPPOSED TO HAVE BEGUN
and those which have not. The first kind we shall call green plants. Very nearly all plants are green plants, but we have already mentioned one or two that are not-such, for instance, as the mushroom. The green stuff of all other plants is really one and the same everywhereeven when it is brown, as in some seaweeds. It has the long name 速f chlorophyll, but we may just call it green stuff. This green stuff is most important because of what it enables the plant to do, and that is what we must now talk about. But we must begin at the beginning-and that beginning is not the green stuff itself, but the Sun, the great and glorious Sun. By itself the green 201
thing the light uses to make life. If the Sun were to go out all the green stuff in the world would not help us at all, and all the plants and animals would soon die. Yet though we have learnt how important the Sun is, we can still look at the green stuff of the green plant with an interest, since it is the means by which light can produce life. This green stuff is to be found in other parts of plants besides the leaves. We know that the stalk of a rose is green. But most of the green stuff of plants is found in their leaves, and it is for the sake of the green stuff that leaves exist at all. The leaves of a plant are its tools for using the green stuff. Directly we think of a leaf we see that it is mnde in a particular way.