262 LAMARCK, HIS LIFE AND WORK 



tions, seeing that with the aid of much time, of 

 changes in local circumstances, in climates, and con- 

 sequently in the habits of animals, the progression in 

 the complication of their organization and in the 

 diversity of their parts has gradually operated (a dA 

 s'op&er) in a way that all the animals now known 

 have been successively formed such as we now see 

 them, it becomes possible to find the solution of 

 / the following question : 



" What is a species among living beings ? 



f" All those who have much to do with the study 

 of natural history know that naturalists at the pres- 

 ent day are extremely embarrassed in defining what 

 they mean by the word species. 



" In truth, observation for a long time has shown 

 us, and shows us still in a great number of .cases, col- 

 " lections of individuals which resemble each other so 

 much in their organization and by the ensemble of 

 their parts that we do not hesitate to regard these 

 collections of similar individuals as constituting so 

 many species. 



" From this consideration we call species every col- 

 lection of individuals which are alike or almost so, 

 and we remark that the regeneration of these individ- 

 uals conserves the species and propagates it in con- 

 tinuing successively to reproduce similar individuals. 



" Formerly it was supposed that each species was 

 immutable, as old as nature, and that she had caused 

 its special creation by the Supreme Author of all 

 which exists. 



" But we can impose on him laws in the execution 

 of his will, and determine the mode which he has 

 been pleased to follow in this respect, so it is only in 

 this way that he permits us to recognize it by the 

 aid of observation. Has not his infinite power created 

 an order of things which successively gives existence 

 to all that we see as well as to all that which exists 

 and which we do not know ? 



