380 BUFPON 



prising. Only such low things as spiders, insects, frogs, 

 and toads thrive best in America. He assures us, with- 

 out offering any proof, that all animals which have been 

 introduced by man, or have migrated into America, 

 have diminished in size. Then comes the pourquoi, for 

 Buffon seems to have forgotten his own maxim (p. 386). 

 He attributes to the humidity and low temperature of 

 America the poor development of its quadrupeds and 

 the rank growth of its reptiles and insects. The humidity 

 and low temperature he explains by the shape of the 

 American continent, the direction of its mountain- 

 chains, the longer duration of its submergence, the 

 greater antiquity of its high land, and the more recent 

 formation of its plains. It is true that the largest living 

 mammals of America are small when compared with the 

 largest of the Old World, but Buffon's explanation is 

 demolished by the gigantic extinct animals of America 

 (elephants, Uintatherium, Megatherium, Diplodocus), as 

 Darwin ^ remarked. 



BUFFON'S OEGANIC MOLECULES 

 Everybody knows that a tree produces a great number 

 of parts (buds and seeds), each of which is able to pro- 

 duce a new tree. Buffon carries the analysis still further 

 (in his imagination), and arrives at what he calls the 

 "organic molecules" as the smallest living units of a 

 tree or any other organism. He had some ground for 

 believing in the material existence of such organic mole- 

 cules, though he does not profess to have . seen them 

 with his own eyes. While the first three volumes of 

 the Histoire Naturelle were in hand he had been reading 

 Leeuwenhoek, and had there found such things as the 



^Naturalist's Voyage, chap. viii. 



