236 FROM THE GREEKS TO DARWIN 



stant organization, as well as a form determined and 

 invariable in its parts, which forces each species to 

 live in the places and climates where it is found, and 

 there to preserve the habits which we know belong 

 to it. 



My personal conclusion: nature, in producing 

 successively all the species of animals, and commenc- 

 ing by the most imperfect or the most simple to con- 

 clude its labor in the most perfect, has gradually 

 completed their organization; and of these animals, 

 while spreading generally in all the habitable regions 

 of the globe, each species has received, under the in- 

 fluence of environment which it has encountered, the 

 habits which we recognize and the modifications in its 

 parts which observation reveals in it. 



The first conclusion (Special Creation), he 

 goes on to say, is one which has been held by 

 nearly every one up to the present time. It at- 

 tributes to each animal a constancy of structure, 

 and parts which have never varied and will never 

 vary. To disprove the second conclusion (grada- 

 tion), he continues, it is necessary to prove that 

 each point upon the surface of the globe never 

 varies in its nature, climate, exposure, elevation, 

 and so forth. 



The belief in the uniformity of past and pres- 

 ent changes was the next great factor in the de- 

 velopment of Lamarck's theory. It arose from 

 his contemplation of the data of geology in con- 

 nection with those of biology, as was afterward 



