BUFFON AND THE PROBLEM OF SPECIES 5 6 3 



among species in their endowment for the struggle for survival. This 

 is perhaps one reason why it did not occur to him to think of that 

 struggle as causing a process of natural selection, or to see in it a factor 

 in the formation of so-called species. 



4. It must be evident to the reader from all that precedes that Buf- 

 fon's mind, throughout nearly the whole of his life, was played upon 

 by two opposing forces. Quite apart from any illegitimate and external 

 influences, such as fear of the ecclesiastics — of which too much has been 

 made — his thought was affected by two conflicting sets of considerations 

 of a factual and logical sort. He saw certain definite reasons for re- 

 garding species as the fundamental constants of organic nature; what 

 those reasons were has been sufficiently indicated. But he also saw that 

 there was some force in the argument from the homologies ; and — what 

 in his case was still more important — he was committed to the program 

 of explaining the diversities of organisms, so far as might be, by the 

 hypothesis of modification in the course of descent; he was deeply 

 impressed by the fact of variability; and he held to a theory of heredity 

 (namely, of the heritability of acquired characters) which acted as a 

 sort of powerful undertow towards a generalized evolutionism. Add to 

 this that he was little careful of consistency and extremely careful of 

 rhetorical effect — and it is not surprising that he occasionally forgot one 

 side of his doctrine in emphasizing the other. There is one and, so far 

 as I can discover, only one passage in which he seems categorically to 

 contradict his ordinary teaching of the impossibility of the descent of 

 really distinct species, sterile inter se, from common ancestors. This 

 occurs at the end of the chapter on " Animals Common to Both Conti- 

 nents " (Vol. IX., 1761). 



It is not impossible that, without any deviation from the ordinary course of 

 nature, all the animals of the New World may be at bottom the same as those 

 of the Old — having originated from the latter in some former age. One might 

 say that, having subsequently become separated by vast oceans and impassable 

 lands, they have gradually been affected by a climate which has itself been so 

 modified as to become a new one through the operation of the same causes which 

 dissociated the individuals of the two continents from one another. Thus in the 

 course of time the animals of America have grown smaller and departed from 

 their original characters. This, however, should not prevent our regarding them 

 to-day as different species. Whether the difference be caused by time, climate 

 and soil, or be as old as the creation, it is none the less real. Nature, I maintain, 

 is in a state of continual flux and movement. It is enough for man if he can 

 grasp her as she now is, and cast but a glance or two upon the past and future, 

 to endeavor to perceive what she may once have been and what she may yet 

 become. 



Here Buffon seems either to have forgotten or to have deliberately 

 discarded his own usual criterion of diversity of species. He does not 

 propose to inquire whether the American species are capable of having 

 fertile progeny when mated with their respective congeners in the old 

 world, but predicates difference of species solely on the ground of dis- 

 similarity of form; and to the distinct species so determined he at- 



