DARWINISM'S PRESENT STANDING. 385 



and too obvious to play the role of the Great Desideratum, 

 a causal factor of variability. 



When one attempts to picture the process of the making 

 of a new individual, and follows the complex phenomena of 

 fecundation, of embryology, and post-embryonic develop- 

 ment, is it not impossible to conceive of the production of 

 two identical individuals ? In all the course of this develop- 

 ment, from the first cleavage of the fertilised egg-cell on, 

 it is practically impossible to repeat processes absolutely 

 identically, hence to produce absolutely identical organs, 

 parts, cells. Now the germ-cells have their very origin in 

 a repeated complex process, mitotic cell division ; they are 

 produced as nearly alike as possible, but it is not possible 

 to make them absolutely identical. 



Development, whether largely epigenetic or largely evo- 

 lutionary, depends at least partly (probably largely) on the 

 physical, i. e., structural, character of the germ-cells. Slight 

 differences in the germ-cells then would lead to considera- 

 ble differences in the fully developed organ. If the differ- 

 ences in the germ-cells happened, as would occasionally or 

 rarely be the case, to be considerable, then the differences in 

 the adults would be very considerable (mutations, sports, 

 monsters, etc.). We know enough of the complex and 

 epigenetic character of ontogeny to see plainly that identity 

 among individuals, even of the same brood, is impossible. 



Variation, then, seems the necessary, the absolutely un- 

 avoidable outcome of the conditions to which the developing 

 individual is exposed. Indeed, all the individuals of a 

 species might start (as fertilised eggs) exactly alike, and 

 yet I cannot see how any two could come out alike. The 

 inevitable slight differences in position, and hence in nutri- 

 tion, in the results of the host of dividing and folding, in- 

 vaginating and evaginating processes, the relations of each 

 individual, whether in the mother's body or out of it, to 

 everything else outside of itself all these are conditions 



