4 IKTItODUCTION. 



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 Adaptation. 



Hence it directly follows that the problem of the morpho- 



FlG. 1. — Internal structure of a Chameleon In Its natural position, to show the 

 lungs, jp, and the long air-saLs, i, proceeding from thera. 



logist 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 

 will inevitably fall into many gross errors in his attempts to 



