LAMARCK'S THEORY OF DESCENT 317 



the giraffe, without standing on its hind legs, raises 

 its head and reaches six meters in height (almost 

 twenty feet). 



" Among the birds, the ostriches, deprived of the 

 power of flight, and raised on very long legs, prob- 

 ably owe their singular conformation to analogous 

 circumstances. 



" The result of habits is as remarkable in the car- 

 nivorous mammals as it is in the herbivorous, but it 

 presents effects of another kind. 



" Indeed, those of these mammals which are habit- 

 uated, as their race, both to climb as well as to 

 scratch or dig in the ground, or to tear open and kill 

 other animals for food, have been obliged to use 

 the digits of their feet ; moreover, this habit has 

 favored the separation of their digits, and has formed 

 the claws with which they are armed. 



" But among the carnivores there are some which 

 are obliged to run in order to overtake their prey ; 

 moreover, since these need and consequently have 

 the habit of daily tearing with their claws and bury- 

 ing them deeply in the body of another animal, to 

 seize and then to tear the flesh, and have been enabled 

 by their repeated efforts to procure for these claws a 

 size and curvature which would greatly interfere in 

 walking or running on stony soil, it has resulted in 

 this case that the animal has been obliged to make 

 other efforts to draw back these too salient and curved 

 claws which would impede it, and hence there has 

 resulted the gradual formation of those special sheaths 

 in which the cats, tigers, lions, etc., withdraw their 

 clav/s when not in action. 



" Thus the efforts in any direction whatever, main- 

 tained for a long time or made habitually by certain 

 parts of a living body to satisfy necessities called 

 out by nature or by circumstances, develop these 

 parts and make them acquire dimensions and a shape 

 which they never would have attained if these efforts ^ 



