EARLY VIEWS. 45 



He ends by arguing that the adaptations of animals 

 confined to certain areas cannot be related to the 

 peculiarities of climate or country, because other 

 animals introduced by man are often so much more 

 successful than the aborigines. As to the causes of 

 extinction, " all that at present can be said with cer- 

 tainty is that, as with the individual, so with the 

 species, the hour of life has run its course, and is 

 spent." 



/At this time he had the conception — as we see in 

 the succeeding extracts from his Diary — of species 

 being so constituted that they must give rise to other 

 species ; or, if not, that they must die out, just as an 

 individual dies unrepresented if it has no offspring; 

 that change — and evidently change in some fixed 

 direction — or extinction, is inevitable in the history 

 of a species after a certain period of time. With this 

 view, which presented much resemblance to that of 

 the author of the " Vestiges," and which seemed upper- 

 most in his mind at this time, there are traces of others. 

 Thus in one extract the ''wish of parents " was thought 

 of as a very doubtful explanation of adaptation, while 

 in another we meet a tolerably clear indication of 

 natural selection, a variety which is not well adapted 

 being doomed to extinction, while a favourable one 

 is perpetuated, the death of a species being regarded 

 as "a consequence ... of non-adaptation of cir- 

 cumstances." 



It seems certain that for fifteen months after 

 July, 1837, he was keenly considering the various 



