xxvn] ADAPTATION 333 



stringent ordeal of Natural Selection, to which they would have 

 been subjected in the feral state. 



But Natural Selection is, after all, merely a negative force. 

 That in the struggle for existence the less fit go to the wall, is 

 a truism which all must admit ; but, curiously enough, we do not 

 seem to possess many records among aquatics of this process 

 having been observed in actual operation. It has been noticed, 

 however, that, in the lake district of Pico in the Azores, Potamo- 

 geton polygonifolius is playing the part of an aggressive species 

 and is ousting such plants as Littorella and Isoetes from the 

 ponds 1 . Possibly the chief work of Natural Selection consists in 

 sorting out species into the environments most suited for them ; 

 it has, for instance, suffered plants which can tolerate aquatic 

 conditions to embrace that mode of life, while annihilating 

 any others, with a constitution unfavourable for the purpose, 

 which may also have attempted it. In the same way a Labour 

 Exchange may distribute men into appropriate situations, and 

 may also be responsible for the elimination of the unfit, by 

 setting some of them to tasks not within their capacity, but yet it 

 has no claim to be the originator of any skill which they display 

 in their respective crafts. 



If we can no longer whole-heartedly accept the facile Dar- 

 winian explanation, we must be content to confess that adapta- 

 tion remains one of the outstanding mysteries of biology. It 

 seems impossible to arrive at any glimmer of a comprehension 

 of its nature, without accepting, in some form, the notion of 

 the inheritance of acquired characters, with which the inherit- 

 ance of unconscious memory is probably bound up. Many 

 biologists to-day seem disposed, at the best, to regard the in- 

 heritance of acquired characters as both unproven and im- 

 probable, but it seems to the present writer to be an almost 

 inevitable article of belief, if it is understood in a broad and 

 general sense. Whether the offspring of a mutilated Guinea-pig 

 derives abnormal characters from its injured parent, is quite 

 beside the point. If we suppose that the whole organic world 



