IN NATURAL HISTORY. 13 



Many modifications of Cuvier's great divisions 

 have been attempted ; but though some improve- 

 ments have been made in the details of his 

 classification, all departures from its great funda- 

 mental principle are errors, and do but lead us 

 away from the recognition of the true affini- 

 ties among animals. Some naturalists, for in- 

 stance, have divided off a part of the Radiates 

 and Articulates, insisting upon some special fea- 

 tures of structure, and mistaking these for the 

 more important and general characteristics of 

 their respective plans. Subsequent investiga- 

 tions have shown these would-be improvements 

 to be retrograde movements, only proving more 

 clearly that Cuvier detected in his four plans 

 all the great structural ideas on which the vast 

 variety of animals is founded. This result is 

 of greater importance than may at first appear. 

 Upon it depends the question, whether all such 

 classifications represent merely individual im- 

 pressions and opinions of men, or whether there 

 is really something in Nature that presses upon 

 us certain divisions among animals, certain affin- 

 ities, certain limitations, founded upon essen- 

 tial principles of organization. Are our systems 

 the inventions of naturalists, or only their read- 

 ing of the Book of Nature ? and can that book 

 have more than one reading ? If these clas- 

 sifications are not mere inventions, if they are 



