302 LAMARCK, HIS LIFE AND WORK 



ments to recognize that in each one of these places 

 the order of things that he discovers there has not 

 always been the same, and to perceive that it will 

 change more. 



" The races of animals which live in each of these 

 places should, then, retain their customary habits 

 there also for a long time ; hence to us seems an ap- 

 parent constancy of races which we call species — con- 

 stancy which has originated among us the idea that 

 these races are as ancient as nature. 



" But in the different points of the earth's surface 

 which can be inhabited, nature and the situation of 

 the places and climates constitute there, for the ani- 

 mals as for the plants, different circumstances of all 

 sorts of degrees. The animals which inhabit these 

 different places should then differ from each other, 

 not only on account of the state of nature of the 

 organization in each race, but, besides, by reason of 

 the habits that the individuals of each race there are 

 forced to have ; so, in proportion as he traverses the 

 larger parts of the earth's surface the observing 

 naturalist sees circumstances changing in a manner 

 somewhat noticeable ; he constantly sees that the 

 species change proportionately in their characters. 



" Now, the true order of things necessary to con- 

 sider in all this consists in recognizing : 



" I. That every slight change maintained under 

 the circumstances where occur each race of animals, 

 brings about in them a real change in their wants. 



" 2. That every change in the wants of animals 

 necessitates in them other movements {actions) to 

 satisfy the new needs, and consequently other habits. 



" 3. That every new want necessitating new actions 

 to satisfy it, demands of the animal which feels it both 

 the more frequent use of such of its parts of which 

 before it made less use, which develops and consider- 

 ably enlarges them, and the use of new parts which 

 necessity has caused to insensibly develop in it by 



