Trt 



FIG. 178. CUVIER. 



CHAPTER XV. 



NATURAL HISTORY OF THE EIGHTEENTH CENTURY. 



EACH of the sciences which we here group together by the title 

 of "Natural History Sciences" covers a vast field of knowledge, 

 and comprehends extensive subdivisions, any one of which would re- 

 quire for its complete and successful cultivation a great part of any 

 ordinary lifetime. The phenomena which are the objects of these 

 sciences are more numerous, more varied, and especially more com- 

 plex than those which engage the attention of the astronomer, the 

 physicist, or the chemist. The philosophic naturalist has not only to 

 take into account the operations of all the physical and chemical forces 

 under infinitely varied conditions and in endless combinations ; but 

 in the study of vital phenomena he has besides to deal with new and 



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