THE AMERICAN BOTANIST. 113 



It is quite true that roots and leaves together are 

 essential to the building process, and that their growth 

 and extension are correlated ; but the roots are merely 

 providers of more or less raw material for the actual 

 builders — the leaves — which, drawing upon the supply of 

 water, and the simple salts dissolved in it, fashion, w^ith 

 the aid of the carbonic acid gas absorbed from the air and 

 the all-essential vital influence of the sunbeam, both their 

 OAvn fabric and that of all the rest of the tree, plus the 

 chemical constituents which it ma\" contain, and the 

 flowers and fruits which are its ultimate aim to perfect. 



A tree in point of fact is less an individual than a 

 gigantic community, the leaf being the individual proper ; 

 a little on the lines of the coral polyp, in so far that during 

 its existence it adds its mite to a more permanent growth 

 which long survives it. We have been careful to say "a 

 little on the lines," because there are material differences 

 in other directions. The coral poh'p simply builds up its 

 quota of the edifice in situ, while the leaf, when its ow^n 

 structure is complete, fashions through its chlorophyll, 

 and the action of the sunbeam thereupon, a contribution 

 of sap to the general fund as it were, and with this pre- 

 pared material a myriad busy cells beneath the bark of the 

 trunk and branch, build up the annual ring of wood and 

 so strengthen the fabric more and more as its branches ex- 

 tend abroad and exercise a greater strain. 



In vegetation below the rank of trees, i. e., devoid of 

 obvious trunks and branches, we have the leaf; but, ex- 

 cept in the fungi, the essential, vital work is always done 

 directly or indirectly, by the green chloroph3dl granules. 

 In herbaceous plants the surplus energy, which in the tree 

 would thicken its timber, goes to build up, in addition to 

 its seed, a root-stock, bulb, corn or tuber, stored with 

 nutriment sufficient to give the plant a fair start when the 

 next growing season sets in, preciselj^ as in the autumnal 

 buds of the tree there is a reserve for the same purpose. 

 In annual plants, where no such provision is made, there 

 is a correspondingly greater profusion of seed, which 



