The reference here is primarily to the continuance rather than the invariability of species. But the latter seems also to be implied; and certainly Buffon does not improve the opportunity to introduce a hint of the doctrine of mutability—as he could hardly have failed to do if he had at this time held that doctrine and had been desirous of propagating it. It must be remembered that these passages also were written before Buffon's opinions had been censured by the Sorbonne.
No account of Buffon's position in the history of biology can be other than misleading which fails to note the decisive significance, for nearly all of his positions from the second volume onward, of the peculiarly Buffonian criterion of identity and diversity of species. Unless this criterion (and the implied distinction between species and varieties, which latter term covers many Linnæan species) be borne in mind, most of the pages in the "Histoire Naturelle" which have an evolutionistic sound are likely to misinterpreted. This is what has happened in a number of the studies of Buffon's relation to evolutionism. The error is especially conspicuously in Samuel Butler's "Evolution Old and New." Butler has devoted nearly one hundred pages to a review of Buffon's utterances on the subject; yet he nowhere lets his reader know that Buffon was the propounder of a new definition of species, which set up a radical distinction between species and varieties, and implied that a species was a definite, objective, "natural" entity. The oversight is not due to any neglect of Buffon's to emphasize and reiterate his definition. He recurs to it frequently in later volumes. His sense of its importance was such that the question of hybridism and the limits of fertility in cross breeding was one of the very few subjects which he can be said to have studied experimentally on his own account. He writes, for example, in 1755:
We do not know whether or not the zebra can breed with the horse or ass; whether the large-tailed Barbary sheep would be fertile if crossed with our own; whether the chamois is not a wild goat; . . . whether the differences between apes are really specific or whether the apes are not like dogs, one species with many different breeds. . . . Our ignorance concerning these questions is almost inevitable, as the experiments which would settle them require more time, care and money than can be spared from the fortune of an ordinary man. I have spent many years in experiments of this kind, and will give my results when I come to speak of mules. But I may as well say at once that I have thrown but little light on the subject and have been for the most part unsuccessful.[2]
(To be concluded)
