554 TEE POPULAR SCIENCE MONTHLY 



BUFFON AND THE PROBLEM OF SPECIES 



By Professor ARTHUR O. LOVEJOY 



THE JOHNS HOPKINS UNIVERSITY 

 II 



WE have thus far noted three generally disregarded but funda- 

 mental facts concerning Buffon's opinions about the nature of 

 species. The first fact is that in his preliminary discourse in the first 

 volume of the " Histoire Naturelle," in which he sought to apply the 

 Leibnitian principle of continuity to natural history, Buffon's empha- 

 sis upon the continuity of the gradations between species probably had 

 no evolutionary implications. The second fact is that the principal 

 doctrine of this discourse is to the effect that only individuals exist in 

 nature, while species exist only by grace of the human imagination, 

 which, aided by human ignorance, sees sharp lines of cleavage among 

 organisms where no such lines are. The third fact is that this doctrine 

 was already tacitly but decisively abandoned in Buffon's second vol- 

 ume, where he represents species as real and well-marked natural enti- 

 ties, their limits being determined by the test of the sterility of the 

 products of cross-breeding. There are, indeed, many later passages 

 where the old phraseology incongruously recurs; but it recurs in con- 

 texts in which the reality of species is expressly insisted upon. 



2. When the fourth volume of the " Histoire Naturelle " — the first 

 dealing specifically with the lower animals — appeared in 1753, four 

 years after the first three, Buffon's departure from the notions set 

 forth in the preliminary discourse became still more evident. He had 

 by this time, in the first place, been greatly impressed by the homolo- 

 gies in the structure of the vertebrates ; he had come to see some signifi- 

 cance in those facts of comparative anatomy which his own treatise— 

 though more through the contributions of Daubenton than through his 

 own — was for the first time setting in a clear light. The existence 

 throughout at least all the immensely diverse vertebrate forms of an 

 underlying unity of type, Buffon was, I suppose, the first to bring 

 forcibly to the attention of naturalists and philosophers, as a fact call- 

 ing for serious consideration and explanation. 



If we choose the body of some animal or even that of man himself to serve 

 as a model with which to compare the bodies of other organized beings, we shall 

 find that . . . there exists a certain primitive and general design, which we can 

 trace for a long way. . . . Even in the parts which contribute most to give variety 

 to the external form of animals, there is a prodigious degree of resemblance, 

 which irresistibly brings to our mind the idea of an original pattern after which 

 all animals seem to have been conceived. What, for example, can at first seem 

 more unlike man than the horse? Yet when we compare man and horse point by 



