INTERPRETATION AND QUALIFICATION. 473 



has a share in determining the proportion between the 

 amount of matter that goes to Individuation and the amount 

 that goes to Genesis. Whether the interests of the species 

 are most subserved by a higher evolution of the individual 

 joined with a diminished fertility, or by a lower evolution of 

 the individual joined with an increased fertility, are ques 

 tions ever being experimentally answered. If the more- 

 developed and less-prolific variety has a greater number of 

 survivors, it becomes established and predominant. If, con 

 trariwise, the conlitions of life being simple, the larger or 

 more-organized individuals gain nothing by their greater size 

 or better organization ; then the greater fertility of the less 

 evolved ones, will insure to their descendants an increasing 

 predominance. 



But direct equilibration all along maintains the limits 

 within which indirect equilibration thus works. The 

 necessary antagonism we have traced, rigidly restricts the 

 changes that natural selection can produce, under given con 

 ditions, in either direction. A greater demand for Individua 

 tion, be it a demand caused by some spontaneous variation or 

 by an adaptive increase of structure and function, inevitably 

 diminishes the supply for Genesis ; and natural selection 

 cannot, other things remaining the same, restore the rate of 

 Genesis while the higher Individuation is maintained. Con 

 versely, survival of the fittest, acting on a species that has, 

 by spontaneous variation or otherwise, become more prolific, 

 cannot again raise its lowered Individuation, so long as every- 

 thing else continues constant. 



364. Here, however, a qualification must be made. It 

 was parenthetically remarked in 327 that the inverse varia 

 tion between Individuation and Genesis is not exact ; and it 

 was hinted that a slight modification of statement would be 

 requisite at a more advanced stage of the argument. We 

 have now reached the proper place for specifying this 

 modification. 



