GERMINAL SELECTION. 37 



the individual produces. And since there is no more 

 reason for excluding irregularities of passive nutrition, 

 and of tlie supply of nutriment in these minute, micro- 

 scopically invisible parts, than there is in the larger 

 visible parts of the cells, tissues, and organs, conse- 

 quently the descendants of a determinant can never all 

 be exactly alike in size and capacity of assimilation, but 

 they vvill oscillate in this respect to and fro about the 

 maternal determinant as about their zero-point, and will 

 be partly greater, partly smaller, and partly of the same 

 size as that. In these oscillations, now, the material 

 for further selection is presented, and in the inevitable 

 fluctuations of the nutrient supply I see the reason 

 why every stage attained becomes immediately the 

 zero-point of new fluctuations, and consequently why 

 the size of a part can be augmented or diminished by 

 selection without limit, solely by the displacement of 

 the zero-point of variation as the result of selection. 



We should err, however, if we believed that we had 

 penetrated to the root of the phenomenon by this in- 

 sight. There is certainly some other and mightier 

 factor involved here than the simple selection of per- 

 sons and the consequent displacement of the zero- 

 point of variation. It would seem, indeed, as if in 

 one case, videlicet, in that of the Japanese cock, the 

 augmentation of the character in question were com- 

 pletely explained by this factor alone. In fact, in this 

 and similar cases we cannot penetrate deeper into the 

 processes of variation, and therefore cannot say a 

 priori whether other factors have or have not been in- 

 volved in the augmentation of the character in ques- 

 tion — other characters, that is, than the simple dis- 

 placement of the zero-point. There is, however, an- 

 other class of phyletic modifications, which point 



