On tke Mechanical Conception of Nature. 68 1 



in so far as these authors refer the " universal 

 individual dissimilarity " to dissimilar external 

 actions, I differ from Darwin in this, that I do not 

 see an essential distinction between the direct 

 and indirect production of individual differences, 

 if by the latter is meant only the unequal in- 

 fluencing of the germ in the parental organism. 

 Haeckel is certainly correct in referring the 

 " primitive differences of the germs produced by 

 the parents " to the inequalities of nutrition to 

 which the single germs must inevitably have been 

 exposed in the parent organism ; but another 

 dissimilarity of the germs must evidently be added 

 a dissimilarity which has nothing to do with 

 unequal nutrition, but which depends upon un- 

 equal inheritance of the individual differences of 

 the ancestors, a source of dissimilarity which 

 must arise to a greater extent in sexual than in 

 asexual reproduction. Just as in sexual propaga- 

 tion there occurs a blending of the characters (or 

 more precisely, developmental directions) of two 

 contemporaneous individuals in one germ, so in 

 every mode of reproduction there meet together 

 in the same germ the characters of a whole suc- 

 cession of individuals (the ancestral series), of 

 which the most remote certainly make themselves 

 but seldom felt in a marked degree. 



The fact of individual variability can in this way 

 be well understood ; the living organism contains 

 in itself no principle of variability it is the statical 



