Inheritance of Acquired Characters 223 



This view is prominently associated with the name of 

 Lamarck, who held, however, a different view in- regard 

 to the origin of some of the other structures of the organism. 

 Moreover, Erasmus Darwin, even before Lamarck, had sug- 

 gested the principle of the inheritance of acquired characters. 

 As has just been said, Lamarck held that the inheritance of 

 acquired characters was only one of the ways in which ani- 

 mals have become changed, and he clearly stated that in the 

 case of all plants and of some of the lower animals the change 

 (evolution) which he supposed them to undergo was due to 

 the general influence of the environment. Since plants and 

 the lower animals (as he supposed) have no central nervous 

 system, or at least no such well-defined nervous system as 

 have the higher animals, Lamarck thought that they could 

 not have evolved in the same way as have the higher animals. 

 We now know that, so far as the lower animals, at least, are 

 concerned, there was no need for such a distinction, since 

 many of their responses are like those of the higher animals. 

 This distinction that Lamarck made is responsible, no doubt, 

 for a misconception that was long held in regard to a part of 

 his views. It is often stated that he supposed the desire 

 of the animal for a particular part has led to the develop- 

 ment of that part ; while in reality he only maintained the 

 desire to use a particular organ to fulfil some want led to 

 its better development through exercise, and the result was 

 inherited. Lamarck also supposed that the decrease in use 

 of a part which leads to its decrease in size accounts for the 

 degeneration of organs. 



Lamarck first advanced his theory in 1801, when he cited 

 the following examples in its favor. A bird, driven through 

 want to the water to find its food, will separate its toes when 

 they strike the water. The skin uniting the bases of the toes 

 will be stretched in consequence, and in this way the broad 

 membrane between the toes of ducks and geese has been 

 acquired. The toes of a bird that is in the habit of perching 



