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 pro- 

 cess 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 therefore 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 satis- 

 factory 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 instance, the 

 degeneration of the eyes of animals inhabiting caves or the 

 sunless depths of lakes or the sea. 



Ff 



