RISE AND PROGRESS OF ZOOLOGY. Ixxiil 



were long obliged to adhere to those systems 

 of pure nomenclature, established like the 

 Linnaean on some isolated organ, often chosen 

 in an arbitrary manner. 



Zoology offers greater facility for the forma- 

 tion of a natural method than botany. The 

 resemblances between animals are more striking, 

 and their causes more easy to ascertain. The 

 distinctive characters of the leading divisions, 

 were ascertained even by Aristotle, as we have 

 seen, with sufficient justice and precision ; and 

 as these divisions were introduced into almost 

 every subsequent zoological system, they ren- 

 dered the other incongruities of detail less strik- 

 ing. Thus, the necessity of a natural method 

 being less felt, the search after such a method 

 was neglected. From this, it happened that 

 the classes of vertebrated animals, though 

 distinguished naturally enough, were yet sub- 

 divided in a fantastic manner, and still greater 

 confusion prevailed among the invertebrated 

 tribes. 



The first leading distinction between our 

 author and Linnaeus, is in the grand division 

 of the animal world. These the Baron makes 

 to rest on the nervous and sensorial, not on the 

 circulatory and respiratory systems. From a 

 profound study of the physiology of the na- 



