4 INTRODUCTION. 



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- 



S 



FlQ. 1. Internal structure of a Chameleon in its natural position, to show the 

 lungs, p, and the long air-sacs, f. 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 

 will inevitably fall into many gross errors in his attempts to 



