SUMMARY OF'PHILOSOPHIE ZOOLOGIQUE! 2? I 



various phenomena of animal organization, in the mani- 

 fold diversity of its developments, is to be found in the 

 fact that Nature conserves in offspring all that their 

 life and environments has developed in parents." 

 Heredity "the hidden bond of common descent" 

 tempered with the modifications induced by changed 

 habits which changed habits are due to new condi- 

 tions and surroundings this with Lamarck, as with 

 Buffon and Dr. Darwin, is the explanation of the 

 diversity of forms which we observe in nature. He 

 now goes on to support this briefly, in accordance 

 with his design but with sufficient detail to prevent 

 all possibility of mistake about his meaning. 



" In the same climate differences in situation, and a 

 greater or less degree of exposure, affect simply, in the 

 first instance, the individuals exposed to them ; but in 

 the course of time, these repeated differences of sur- 

 roundings in individuals which reproduce themselves 

 continually under similar circumstances, induce differ- 

 ences which become part of their very nature ; so that 

 after many successive generations, these individuals, 

 which were originally, we will say, of any given species, 

 become transformed into a different one." ' 



" Let us suppose that a grass growing in a low-lying 

 meadow gets carried by some accident to the brow of a 

 neighbouring hill, where the soil is still damp enough 

 for the plant to be able to exist. Let it live here for 

 many generations, till it has become thoroughly accus- 

 tomed to its position, and let it then gradually find its 

 way to the dry and almost arid soil of a mountain side ; 



* ' Phil. Zool.,' torn. i. pp. 79, 80. 



