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 Dégénération 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 
mufflon, 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: 
‘“‘ Tf 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- 
