204 LAMARCK, HIS LIFE AND WORK 



grounded than those of Erasmus Darwin, who was a 

 close observer as well as a profound thinker. 



In his chapter on the D^gindration des Animaux, or, 

 as it is translated, " modification of animals," Buffon 

 insists that the three causes are climate, food, and 

 domestication. The examples he gives are the sheep, 

 which having originated, as he thought, from the 

 mufiflon, shows marked changes. The' ox varies 

 under the influence of food ; reared where the 

 pasturage is rich it is twice the size of those living in 

 a dry country. The races of the torrid zones bear a 

 hump on their shoulders ; " the zebu, the buffalo, is, 

 in short, only a variety, only a race of our domestic 

 ox." He attributed the camel's hump to domesticity. 

 He refers the changes of color in the northern hare 

 to the simple change of seasons. 



He is most explicit in referring to the agency of 

 climate, and also to time and to the uniformity of 

 nature's processes in causing variation. Writing in 

 1756 he says: 



^^ " If we consider each species in the different climates 

 which it inhabits we shall find perceptible varieties as 

 regards size and form ; they all derive an impress to 

 a greater or less extent from the climate in which 

 they live. These changes are only made slowly and 

 imperceptibly. Nature's great workman is time. He 

 marches ever with an even pace and does nothing by 

 leaps and bounds, but by degrees, gradations, and 

 succession he does all things ; and the changes which 

 he works — at first imperceptible — become little by 

 little perceptible, and show themselves eventually in 

 results about which there can be no mistake. Never- 

 theless, animals in a free, wild state are perhaps less 

 subject than any other living beings, man not ex- 



