40 DARWIN AND NATURAL SELECTION 



without the intervention of a directing power, 

 the riddle which animate nature presents to our 

 intelligence at every turn, and in face of which 

 the mind of a Kant could nndyio way out, for he 

 regarded a solution of it as not to be hoped for " 

 (p. 21), one is entitled to ask whether he has ever 

 heard of the series of difficulties enumerated, for 

 example, by Driesch, and later on to be dealt with 

 more fully and, if so, how he proposes to get over 

 these difficulties by the aid of selection. The real 

 explanation of Weismann's attitude appears (not 

 for the first time by the way) in another part of 

 the same article, where, after admitting that " we 

 cannot bring formal proofs of it (selection) in 

 detail" he goes on to say that " we must accent it 

 because the 'phenomena of evolution and adaptation 

 must have a natural basis and because it is the only 

 possible explanation of them " (p. 61 ; the italicized 

 words are so printed by the author). It is now 

 nearly twenty years ago since Weismann's con- 

 troversy with Herbert Spencer on the All-Suffic- 

 iency of Natural Selection. In the course of that 

 discussion Weismann very clearly explained why 

 he believed in natural selection, and we must leave 

 it to our readers to decide whether the grounds 

 upon which he founded his belief were solid and 

 unassailable. " We must assume," he wrote,* 

 " natural selection to be the principle of the ex- 

 planation of the metamorphoses, because all other 

 apparent principles of explanation fail us, and it is 

 inconceivable that there should be another capable 

 of explaining the adaptation of organisms without 



* Contemporary Review (1893), italics again the authors. 



