LAMARCK'S THEORY OF DESCENT 



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wants which they have created have given for a long 

 period, as also to others of its race, the habit of 

 browsing on grass, only walks on the ground, and is 

 obliged to rest there on its four feet the greater part 

 of its life, moving about very little, or only to a mod- 

 erate extent. The considerable time which this sort 

 of creature is obliged to spend each day to fill itself 

 with the only kind of food which it requires, leads it 

 to move about very little, so that it uses its legs only 

 to stand on the ground, to walk, or run, and they 

 never serve to seize hold of or to climb trees. 



" From this habit of daily consuming great amounts 

 of food which distend the organs which receive it, and 

 of only moving about to a limited extent, it has re- 

 sulted that the bodies of these animals are thick, 

 clumsy, and massive, and have acquired a very great 

 volume, as we see in elephants, rhinoceroses, oxen, 

 buffaloes, horses, etc. 



" The habit of standing upright on their four feet 

 during the greater part of the day to browse has 

 given origin to a thick hoof which envelops the ex- 

 tremity of the digits of their feet ; and as their toes 

 are not trained to make any movement, and because 

 they have served no other use than as supports, as 

 also the rest of the leg, the most of them are short, 

 are reduced in size, and even have ended by totally 

 disappearing. Thus in the pachyderms, some have 

 five toes enveloped in horn, and consequently their 

 foot is divided into five parts ; others have only four, 

 and still others only three. But in the ruminants, 

 which seem to be the most ancient of mammals, 

 which are Hmited only to standing on the ground, 

 there are only two digits on each foot, and only a 

 single one is to be found in the solipedes (the horse, 

 the ass). 



" Moreover, among these herbivorous animals, and 

 especially among the ruminants, it has been found 

 that from the circumstances of the desert countries 



