I.] Darwin's philosophy. 27 



cause of unlikeness, however, since sex itself was at first 

 a variation induced by environment or other agencies, 

 and its present perfection, in higher organisms, is the 

 result of the process of continuous survival in a conflict 

 of differences. 



The recent rise of Lamarckian views seems to have 

 been largely the result of an attempt to discover the vera 

 causa of variations. Darwin's hypothesis of natural 

 selection assumes variability without inquiring into its 

 cause, and writers have therefore said that Darwin did 

 not attempt to account for the cause of variations. 

 Nothing can be farther from his views. Yet some of 

 our most recent American writings upon organic evo- 

 lution repeat these statements. Cope, in his always 

 admirable "Primary Factors of Organic Evolution," 

 writes that " Darwin only discussed variation after it 

 came into being." Yet Darwin's very first chapter in 

 his "Origin of Species" contains a discussion of the 

 "Causes of variability," and the same subject is gone 

 over in detail in ' ' Variation of Animals and Plants 

 under Domestication." Dai-win repeatedly refers the 

 cause or origin of variation to "changed conditions of 

 life,'' which is essentiallj^ the position maintained by the 

 Lamarckians, and he as strenuously combats those who 

 hold that definite variation is an innate attribute of life. 

 "But we must, I think, conclude * * *," writes 

 Darwin in the latter book, "that organic beings, when 

 subjected during several generations to any change what- 

 ever in their conditions, tend to vary." He discussed 

 at length the particular agencies which he considered to 

 be most potent in inducing variability, and enumerated, 

 amongst other factors, the kind and amount of food, 

 climate, and crossing. "Changes of any kind in the 



