68 THE STORY OF THE PLANTS. 



That is the question we shall have to consider 

 in the present chapter ; and I shall answer it in 

 part at once by saying beforehand that, though 

 plants do grow for the most part out of the car- 

 bonic acid supplied by the air to the leaves, they 

 also require certain things from the soil, less 

 important in bulk, but extremely necessary for 

 their growth and development. What they eat 

 through their leaves is far the greatest in 

 amount ; but what they drink through their 

 roots is nevertheless indispensable for the pro- 

 duction of that living green-stuff, chlorophyll, 

 which, as we saw, is the original manufacturer 

 and prime maker of all the material of life, either 

 vegetable or animal. 



Plants have roots. These roots perform for 

 them two or three separate functions. They 

 fix the plant firmly in the soil ; they suck up 

 the water which circulates in the sap ; and they 

 also gather in solution certain other materials 

 which are necessary parts of the plant's living 

 matter. 



The first and most obvious function of the 

 root is to fix the plant firmly in the soil it grows 

 in. Very early floating plants, of course, have 

 no roots at all ; they take in water and the 

 dissolved materials it contains, with every part 

 of their surface equally, just as they take in 

 carbonic acid with every part of their surface 

 equally. They are all root, all leaf, all flower, 

 all fruit. But higher plants tend to produce 

 different organs, which have become specially 



