THE GARDEN PRIMER 



form the foundation of all soil. Among these rocks 

 and stones, in many of their large and small interstices, 

 will be decaying pieces of plant roots and stems and 

 other organic matter, which appear very much like 

 logs and pieces of logs rotting among masses of rock 

 and gravel. All of this organic substance will be 

 dripping with water like a soaked sponge, while all the 

 stones and rocks have a layer of water over their 

 surfaces. And finally, in all the spaces where there 

 is nothing else, there is air — ^indeed nearly half the 

 volume of the whole cubic mile is air. 



A plant root coming down into this magnified 

 cubic inch of soil would be of course an enormous 

 thing, pushing its way among the rocks and stones and 

 decaying matter with a great, tireless, steady, resist- 

 less pressure that would move the biggest of them. 

 Near the tip of this ever extending and down-reaching 

 growth, small hollow tubes — root hairs — would be 

 seen reaching out and feeling this way and that, suck- 

 ing the water from the surfaces of the rocks and from 

 the dripping, spongy masses among them, by drawing 

 it through their thin and delicate walls. 



In this water is the mineral food, dissolved off in 

 the minutest particles from the "rocks" — and it is 

 somewhat staggering to note, by the way, that in 

 order to produce one pound of growth in dry matter — 

 that is in branch and leaf, flower and ixmt—from joo 

 to 800 pounds of water must be taken in by a plant's 

 roots, drawn up through its stalks and branches, and 

 discharged or "transpired" by its leaves. Think of 



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