4 IKTKODUCTION, 



morphological and physiological characters — or Inheritance. 

 Secondly, the plasticity of the organism, which enables it, by 

 modifications of its original characters, to accommodate itself to 

 the altered conditions of existence in its successive stages of life — 

 or Ada[>tation. 



Hence it directly follows that the problem of the morpho- 



Fio. l.-Intemal strnoture of a Chameleon in its natural position to show the 

 lungs, p, and the long aii'-sacs, s, proceeding from them. 



legist is to learn to distinguish such characters as have been 

 perhaps recently developed by Adaptation, from such as have 

 been transmitted by Inheritance through a long series of genera- 

 tions ; for if he should be incapable of making this distinction he 

 wiU inevitably fall into many gross errors in his attempts to 



