556 THE POPULAR SCIENCE MONTHLY 



writers — dealing somewhat less than fairly with their readers — have 

 failed to mention that his rejection of the evolutionary hypothesis was 

 not put forth by him as resting exclusively upon these religious con- 

 siderations. If the words just quoted stood alone, it would, indeed, be 

 scarcely possible to take them seriously. But they do not stand alone; 

 they are directly followed by arguments of quite another order against 

 the possibility of the descent of one real species from another ; and the 

 essence of the most emphasized of these arguments lies in the Buffonian 

 conception of the nature of species, already expounded in the second 

 volume. In other words, the fact of the sterility of hybrids, and certain 

 other purely factual considerations, were urged by Buffon as conclusive 

 objections against the theory of descent. 



Specifically, his arguments against evolution are three: (1) Within 

 recorded history no new true species (in his own sense of the term) 

 have been known to appear. (2) There is one entirely definite and 

 constant line of demarcation between species : it is that indicated by the 

 infertility of hybrids. 



This is the most fixed point that we possess in natural history. No other 

 resemblances or differences among living beings are so constant or so real or so 

 certain. These, therefore, will constitute the only lines of division to be found 

 in this work. 



But why, it may be asked, should the sterility of hybrids be a proof 

 of the wholly separate descent of the two species engendering such 

 hybrids ? This question Buffon does not neglect to answer. An " im- 

 mense and perhaps an infinite number of combinations " would need to 

 be assumed before one could conceive that " two animals, male and fe- 

 male, had not only so far departed from their original type as to be- 

 long no longer to the same species — that is to say, to be no longer able 

 to reproduce by mating with those animals which they formerly re- 

 sembled — but had also both diverged to exactly the same degree, and 

 to just that degree necessary to make it possible for them to produce 

 only by mating with one another." The logic of this is to me, I con- 

 fess, a trifle obscure; but it is evident that Buffon conceived that the 

 evolution from a given species of a new species infertile with the first 

 could come about only through a highly improbable conjunction of cir- 

 cumstances. (3) Buffon's third reason for maintaining the fixity of 

 species is the argument from the " missing links." 



If one species had been produced by another, if, for example, the ass species 

 came from the horse, the result could have been brought about only slowly and 

 by gradations. There would therefore be between the horse and the ass a large 

 number of intermediate animals. Why, then, do we not to-day see the repre- 

 sentatives, the descendants, of these intermediate species? Why is it that only 

 the two extremes remain? 



Taking these three arguments into account, then, Buffon arrives 

 at this conclusion : 



Though it can not be demonstrated that the production of a species by 



