I THE DARWINIAN HYPOTHESIS 19 



offspring, which will of course tend to reproduce 

 the peculiarities of their parents. Their offspring 

 will, by a parity of reasoning, tend to predominate 

 over their contemporaries, and there being (sup- 

 pose) no room for more than one species such as 

 A, the weaker variety will eventually be destroyed 

 by the new destructive influence which is thrown 

 into the scale, and the stronger will take its place. 

 Surrounding conditions remaining unchanged, the 

 new variety (which we may call B) supposed, for 

 argument's sake, to be the best adapted for these 

 conditions which can be got out of the original 

 stock will remain unchanged, all accidental devia- 

 tions from the type becoming at once extinguished, 

 as less fit for their post than B itself. The tend- 

 ency of B to persist will grow with its persistence 

 through successive generations, and it will acquire 

 all the characters of a new species. 



But, on the other hand, if the conditions of life 

 change in any degree, however slight, B may no 

 longer be that form which is best adapted to with- 

 stand their destructive, and profit by their sus- 

 taining, influence ; in which case i it should give 

 rise to a more competent variety (C), this will take 

 its place and become a new species ; and thus, by 

 natural selection, the species B and C will be suc- 

 cessively derived from A. 



That this most ingenious hypothesis enables us 

 to give a reason for many apparent anomalies in 

 the distribution of living beings in time and space, 



