348 DARW1NIANA. 



siderable number of the lower forms of vegetable and 

 animal life, and of a few of the higher plants from 

 the Tertiary period to the present, tells even more di- 

 rectly for the limitless existence of species. The dis- 

 appearance is quite compatible with the latter view ; 

 while the persistence of any species is hardly explicable 

 upon any other. So that, even under the common be- 

 lief of the entire stability and essential inflexibility of 

 species, extinction is more likely to have been acciden- 

 tal than predetermined, and the doctrine of inherent 

 limitation is unsupported by positive evidence. 



On the other hand, it is an implication of the Dar- 

 winian doctrine that species are essentially unlimited 

 in existence. When they die out — as sooner or later 

 any species may — the verdict must be accidental death, 

 under stress of adverse circumstances, not exhaustion 

 of vitality ; and, commonly, when the species seems to 

 die out, it will rather have suffered change. For the 

 stock of vitality which enables it to vary and survive 

 in changed forms under changed circumstances must 

 be deemed sufficient for a continued unchanged exist- 

 ence under unaltered conditions. And, indeed, the 

 advancement from simpler to more complex, which 

 upon the theory must have attended the diversification, 

 would warrant or require the supposition of increase 

 instead of diminution of power from age to age. 



The only case we call to mind which, under the 

 Darwinian view, might be interpreted as a dying out 

 from inherent causes, is that of a species which refuses 

 to vary, and thus lacks the capacity of adaptation to 

 altering conditions. Under altering conditions, this 

 lack would be fatal. But this would be the fatality 



