OF THE VITAL POWERS. 19 



35. Nor has there been less variety in the notions and 

 definitions to which it has given rise; though in this 

 one point all have agreed, — that its nature and causes 

 are most obscure. 



36. As to the question so long agitated by physiolo- 

 gists, — whether the diversity of the phenomena exhibited 

 in the similar parts of the living solid is to be attri- 

 buted to modifications only, or to distinct species, of 

 the vital energy, we think it best to establish distinct 

 orders of the vital powers, according to the variety of 

 phenomena by which they are manifested. 



37. These phenomena are threefold. — Organic for- 

 mation and increase ; motion in the parts when formed ; 

 sensation from the motion of certain similar parts. 



38. The first requisite involved in the name and notion 

 of an organised body, is a determinate foim designed 

 for certain ends. That species, therefore, of the vital 

 powers is most general, which produces the genital and 

 nutritive fluids and prepares them for organic nature. 

 This species we have denominated the nisus formativus, 

 since it is the source of all generation, nutrition, and 

 reproduction, in each organised kingdom. 



39. Those vital powers which are manifested by 

 motion,(37) properly so called, in parts already formed, 

 may be divided into common and proper. The common 

 are those belonging to similar parts which are widely 

 distributed: v.c. contractility to the mucous structure ; 

 irritability to the muscular fibre. The proper are those 

 possessed only by individual organs whose motions 

 are peculiar and characteristic. 



40. Contractility is as generally distributed as the 

 mucous structure, which it may be said to animate ; and 

 therefore would perhaps not improperly be called the 



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