270 VARIETIES IN THE, &c. 



and move by their own powers. In the corrup- 

 tion, the fermentation, or rather in the refolu- 

 tion of animal or vegetable fubftances, we find 

 real animals capable of propagating their fpecies, 

 though they were not themfelves produced in 

 this manner. Thefe varieties are, perhaps, more 

 extenfive than we imagine. Though it be right 

 to generalize our ideas, to aflemble the effeds of 

 Nature under one point of view, and to clafs her 

 productions ; yet numberlefs fhades, and even 

 degrees, in the great fcale of being, will always 

 efcape our obfervation. 



CHAP. 



