170 THE SURVIVAL OP THE UNLIKE. [vL 



which the others were also contending. Man's cultiva- 

 tion is, fundamentally, the same as nature's. He has 

 devised means to augment or emphasize the processes, 

 but the ultimate aims of both are to increase the food; 

 and all this increase beyond the mere point of sustain- 

 ing the plant in the condition in which man found it 

 goes into the production of variation in one form or 

 another, — for mere increase in bigness is itself a most 

 important departure from the tjpc, and it is usually 

 the primary result of domestication. 



I believe that the second important cause of variation 

 amongst domestic plants is the effects of change of 

 climate. It is known that every different or peculiar 

 climate has its own type of plants, showing that, in 

 some way, there has come to be a modification or 

 adaptation to the environment. The same process of 

 adaptation begins with domesticated plants the mo- 

 ment man takes them to climates differing from that 

 in which he found them. These changes arc, cliiclly, 

 reduction of stature and shortening of form when tin- 

 transfer is to shorter, colder seasons ; increase in in- 

 tensity of colors of flowers and fruits, and often of 

 saccharine contents, in the nortli : the (liitiiimtioii of 

 evaporating surface, — of leaves and stt-ius, — in dry 

 climates ; the tendency to develop aromatic qualities 

 in arid regions; the shortening or lengtliciiiii^' of lia- 

 bitual periods of growth ; the increased or decii astd 

 sensitiveness to the progress of the seasons by wliicli 

 plants bloom and expand their leavrs r<l,itively earlier 

 in the north and later in the south ; the modification 

 of constitution by which plants become hardi* r or 

 tendciTi- : the tendency of plants to become annuals 

 or to develop a resting period in regions of severe 



