Darwinism 



theory to our system of classification demands 

 attention. 



The systematic naturalists who had long 

 , studied the classification of living and extinct 



,' animals generally accepted the theory readily be- 

 cause it gave a clear and satisfactory answer to 



I the questions which their work had raised in.- 

 their minds. The classification of the animal 

 kingdom had been plotted so as to bring to- 

 gether like forms and to separate unlike. The 

 great groups, like classes and orders, had been 

 based on deep-seated characters, which changed 

 slowly. The minor subdivisions, genera and spe- 

 cies, were characterized by more superficial traits 

 which might easily be modified. It was soon 

 found that all animals could not be arranged 

 naturally in one line or series, but that the clas- 

 sification must take the form of a tree with many 

 branches.^ It had long been recognized that the 

 oldest members of each great division were 

 generalized — that is, they combined characters 

 which In later forms were found only in sepa- 

 rate classes or orders. The oldest amphibia 



1 See Appendix, Charts; cf. Cope, E. D., "Primary 

 Factors of Evolution," Chapter II. 



13 



