HOW PLANTS EAT. 39 



The plant has often many hundred leaves, that 

 is to say, many hundred mouths and stomachs. 

 Why do plants need so many when we have but 

 one? Because they cannot move, and because 

 their food is a gas, diffused in minute quantities 

 through all the atmosphere. They have to suck 

 it in wherever they can find it. And what do 

 they do with the carbonic acid when once they 

 have got it? Well, to answer that question, 

 I must tell you a little more about what the 

 ordinary green leaf is made of, and especially 

 about the green-stuff in its central cells. 



Now what is this green-stuff? It is the true* 

 life-material of the plant, the origin of all the 

 ImngTna/Eter in nature. You and I, as well as the 

 plants themselves, are entirely built up of living ?' 

 jelly which this green-stuff has manufactured 

 under the influence of sunlight. And the mate- 

 rial that does this is such an important thing in 

 the history of life that I will venture to trouble 

 you with its scientific name, CHLOROPHYLL. 

 When sunlight falls upon the Chlorophyll ^>r 

 green-stuff in a living leaf, in the presence of 

 carbonic acid and water, the chlorophyll at once 

 proceeds to set free the oxygen (which it turns 

 loose upon trie air again), and to build up the 

 carbon and hydrogen (with a little oxygen) into 

 a material called starch. This starch, as you 

 know, possesses jwergy that is to say, latent 

 light and dormant' 1TB9F" and rribvement, because 

 we can eat it and burn it within our bodies. . 

 Other materials, hydro-carbons and carbo-hy- 

 drates, as they are called, are made in the same 

 way. The main use of leaves, then, is to eat 



