1 68 FROM LAMARCK TO ST. HILAIRE. 



of the Philosophic Zoologique he summarizes his 

 own doctrine as follows: 



" But great changes in environment bring about changes in the 

 habits of animals. Changes in their wants necessarily bring about 

 parallel changes in their habits. If new wants become constant 

 or very lasting, they form new habits, the new habits involve the 

 use of new parts, or a different use of old parts, which results 

 finally in the production of new organs and the modification of 

 old ones." 



Again, he says : 



" Circumstances influence the forms of animals. But I must 

 not be taken literally, for environment can effect no direct changes 

 whatever upon the organization of animals." 



He illustrates his theory in advancing proofs 

 that it is not the organ which gives origin to the 

 habit, but the habit which gives origin to the 

 organ, and points out examples of the effects of use 

 and disuse. He refers all rudimentary structures 

 to disuse, such as the embryonic teeth of the whale- 

 bone whales, which had recently been discovered 

 by St. Hilaire, the eyes of the mole, and of the 

 Proteus, the blind salamander of the Austrian caves. 

 He is inconsistent with his own theory when he 

 says that the organ of hearing has been developed 

 everywhere by the direct action of vibrations of 

 sound. Again, he explains the development of the 

 webbed feet of birds, by their being attracted to 

 swampy ground by hunger, making efforts to swim, 

 spreading the toes, the skin being thus stretched 

 between them. 



