22 PHILOSOPHY OF ZOOLOGY. 



and it is capable of being divided or multiplied by the process 

 of generation. In the various kinds of organized bodies, it ex- 

 hibits its different qualities, according to the structure of the 

 fabric which it animates ; hence we must conclude, either 

 that the same principle is modified by the substances which 

 it pervades, or that there are many different kinds. If we 

 adopt the practice of the chemist, when examining the ele- 

 mentary bodies, and their combinations, and consider those 

 substances distinct in kind, whose affinities and appearances 

 are different, we must conclude, that there are different 

 kinds of vital principles, distinguished by different affinities 

 for the various kinds of inorganic matter, and forming, 

 with these, combinations, whose peculiar characters are ob- 

 vious and precise. In all organized bodies, we witness an 

 origin, progress and termination ; but, in each species, 

 these circumstances exhibit some peculiarity which is not 

 observable in any other species. We are, therefore, led to 

 conclude, that there are as many different kinds of vital 

 principles, as there are species in nature. Hence all the 

 knowledge which we possess regarding the structure and 

 functions of different kinds of organized beings, is, in fact, 

 a knowledge of the attributes of the different vital princi- 

 ples from which these have originated ; an4 our systemati- 

 cal arrangements, an attempt towards their classification. 

 Even the vulgar, talk of the life of plants as distinct in 

 principle from that of animals, although they seldom carry 

 their views on this subject so far as to admit of any inferior 

 division. 



II. Conditions necessary for the Existence of tht Vital 

 Principle. It is, doubtless, a curious subject of inquiry, 

 to ascertain those conditions which are necessary to the 

 display of this principle of life, or the circumstances under 

 which it is generated or excited to action. Our knowledge 

 ,of organized bodies, however, is stilt too imperfect to en- 



