VIII. 



THE SUPPOSED TRANSMISSION OF 

 MUTILATIONS. 



WE know well the manner in which Lamarck imagined that the 

 gradual transformation of species occurred, when he first made 

 the attempt to penetrate into the mechanism of the process of 

 evolution, and to ascertain the causes by which it is produced. In 

 his opinion, a change in the structure of any part of an organism 

 was chiefly brought about when the species in question met with 

 new conditions of life and was thus forced to assume new habits. 

 Such habits caused an increased or diminished activity, and there- 

 fore a stronger or weaker development, of certain parts, and the 

 modified parts were then transmitted to the offspring. Inasmuch 

 as the offspring continued to live under the same changed conditions, 

 and kept up the altered manner of using the part in question, the 

 inherited changes would be increased in the same direction during 

 the course of their life, and would be further increased in each 

 successive generation, until the greatest possible change had been 

 effected. 



In this way Lamarck was able to give an apparently satisfactory 

 explanation of at any rate those changes which consist in the mere 

 enlargement or diminution of a part ; such, for instance, as the 

 great length of neck in the swan and other swimming birds, which 

 he believed to have been produced by the habit of stretching after 

 food at the bottom of the water ; or the webbed feet of the same 

 animals, supposed to be produced by the habit of striking the water 

 with outspread toes, etc. In this way he was also able to explain 

 the disappearance of a part after it had ceased to be of use ; as, for 



