198 Inheritance of Acquired Characters 



species can not only force this species to emigrate, or at 

 least to widen its range of habitation, thus placing 

 itself in contact with different telluric conditions and 

 with different fauna and flora, but also it can itself 

 induce directly very considerable modifications of the 

 environment. 



Thus, to take an already famous example, it is pos- 

 sible that the long neck and forelegs of the giraffe are 

 to be ascribed to the overcrowding of the territory 

 inhabited by its ancestors. For if we suppose that these 

 ancestors at a definite time and in a definite region had 

 become altogether too numerous in proportion to the 

 trees present whose leaves served them for nourishment, 

 then all the leaves up to a certain height would naturally 

 have been eaten first, and there would finally remain only 

 those leaves situated very high, so that in order to reach 

 them the animal was forced to stretch out its neck with 

 a greater effort than formerly and to stand upon its 

 hind legs, falling later on the fore legs after plucking 

 off the leaf. And these efforts so very different from the 

 ordinary would have produced quite new morphological 

 adaptations. But it is not at all necessary to suppose 

 that all the individuals of this former species of giraffe 

 were forced indiscriminately to this transformation. For 

 many, perhaps becoming accustomed to another diet, could 

 remain unaltered or undergo transformations of little 

 importance. 



In other cases, on the contrary, that part of the 

 species which was driven through overcrowding of the 

 territory to change its diet would be compelled to undergo 

 the most considerable transformations. This would be 

 the case, for example, when the overcrowding of a given 

 tract of meadow land by a species feeding exclusively 



