24 COMPARATIVE ANATOMY HKl'ORK (T'YIKR 



The idea of a gradation of beings appears also in Bullmi 

 (1707-1788), but here it takes more definitely its true 

 character as a functional gradation. 1 "Since everything in 

 Nature shades into everything else," he says, " it is possible 

 to establish a scale for judging of the degrees of the intrinsic 

 qualities of every animal." 



He is quite well aware that the groups of Invertebrates 

 are different in structural plan from the Vertebrates "The 

 animal kingdom includes various animated beings, whose 

 organisation is very different from our own and from that 

 of the animals whose body is similarly constructed to ours." 



He limits himself to a consideration of the Vertebrates, 

 deeming that the economy of an oyster ought not to form 

 part of his subject matter ! He has a clear perception of the 

 unity of plan which reigns throughout the vertebrate series. 1 

 What is new in Buffon is his interpretation of the unity of 

 plan. For the first time we find clearly expressed the 

 thought that unity of plan is to be explained by com- 

 munity of origin. 



Buffon's utterances on this point are, as is well known, 

 somewhat vacillating. The famous passage, however, which 

 occurs in his account of the Ass shows pretty clearly that 

 Buffon saw no theoretical objection to the descent of all the 

 varied species of animals from one single form. Once admit, 

 he argues, that within the bounds of a single family one 

 species may originate from the type species by "degenera- 

 tion," then one might reasonably suppose that from a 

 single being Nature could in time produce all the other 

 organised beings. Elsewhere, <\<, r ., in the discourse DC /<i 

 Degeneration dcs Aninuinx^ Buffon expresses himself with 

 iin ire caution. He finds that it is possible to reduce the two 

 hundred species of quadrupeds which he has described to 



1 Histoire nafurelle, i., p. 13 ; ii , p. y ; iv., p. 101 ; and xiv., pp. 

 28-y, I74y and later. 



' No translation can render the beauty of the original "Coinnie 

 tout se fait et que tout est par nuance dans la Nature . . ." (iv., p. 101). 



:; Hist, nat., iv., p. 5. 



1 Sec particularly his comparison of the skeleton of the horse with 

 that of man. Hist. Nat., iv., p. 381, also p. 13. 



Loc. '/., p. 382. 



Tome xiv., pp. 31 1 -374. 



