VI.] AUGMENTATION OP FOOD. 169 



it, as capable of producing a new form or varietj- of 

 promise, if once the conditions under which it grows are 

 made to vary in given or ascertained directions, and if he 

 determines the means by which he can "fix" the varia- 

 tions or make them to become somewhat permanent, or 

 can even augment or "improve" the initial divergence; 

 and he should know, also, that it is impossible to suc- 

 cessfully submit a plant taken from the wild to the 

 conditions of cultivation unless the plant adapts itself 

 to the new conditions by means of variation. In a 

 word, the whole structure of the cultivation of plants 

 and, therefore, of agriculture, is impossible without 

 variation and evolution. 



Now, let us endeavor to put ourselves in nature's 

 place, if such a conception is possible, and to briefly 

 follow an outline of her methods with plants. We shall 

 find that variation is largely the result, so far as we can 

 see, of excess of food -supply. The seedsman knows 

 that heavy lands make his seed-crops "break " into non- 

 typical forms, and he therefore prefers, for most plants, 

 a soil not very rich in nitrogen or growth -production. 

 Heavy soils make the dwarf peas "viney," and bud- 

 sports of curious leaves and flowers are wont to appear 

 upon over- vigorous shoots. In short, the whole philos- 

 ophy of the amelioration of plants rests upon excess of 

 food -supply ; for what other object have tillage, irriga- 

 tion, fertilizing of the land, thinning of the plants, prun- 

 ing, and thinning of the fruit, but to supply more food 

 to the plants or to the parts which remain? Darwin has 

 clearly shown that great numbers of the variations in 

 nature come as the result of this general law, — the plant 

 which gets the better of its fellows generally does so be- 

 cause it has appropriated the food or air or sunlight for 



