200 FROM THE GREEKS TO DARWIN 



tive zoology, his views of community of origin, 

 laws of geographical distribution, extinction of 

 old species, and successive apparition of new 

 species. 



In order to be fair to Buffon's followers, we 

 must, however, test the breadth of his concep- 

 tion by his application of it to the actual succes- 

 sion of forms of life; and here we find in numer- 

 ous passages, as pointed out by Quatrefages, 

 that his conception was very limited and that he 

 lacked the courage of his convictions. 



First, after having maintained in his first pe- 

 riod the extreme special creation view, and in 

 his second period, especially between 1761 and 

 1766, the extreme transmutation view, he re- 

 turned finally to the moderate view, that species 

 were neither fixed nor mutable, but that specific 

 types could assume a great variety of forms. 



Second, in his theory of the causes of Evolu- 

 tion, considering temperature, climate, food, and 

 capillarity as the three causes of change, altera- 

 tion, and degeneration of animals, he did not 

 employ the terms heredity or transmission of ac- 

 quired characters, although it is evident that 

 these factors were implied. In other words, Qua- 

 trefages points out, Buffon did not follow his 

 theory into its details. 



Third, he also failed to reach the phyletic or 

 branching idea of Evolution. In this connection 



