SO INTRODUCTION. 



is concerned, mere fasciculi, or bundles, of its rami- 

 fications. The muscular fibre is a peculiar species 

 of filaments, of which, in the living subject, the dis- 

 tinctive property is contraction, arising either from 

 the contact of some external body, or the action of 

 the will communicated through the medium of the 

 nerves. 



The muscles are merely bundles of fleshy fibres. 

 Every membrane and every vessel to which the ope- 

 ration of compression is essential, is provided with 

 fibres of this description ; and others are also always 

 closely attached to the medullary filament, of the 

 nerves. Those of the former description which minister 

 to the merely vegetative functions of the animal sys- 

 tem, contract without the consciousness of the mind, 

 while the latter are the immediate organs of volun- 

 tary motion, when excited thereto by the nerves: 

 though, therefore, volition is a chief exciting power, 

 through the agency of the nerves, to set the muscu- 

 lar fibres in action, it is neither the general nor the 

 sole power of this description. 



The basis of the fleshy or muscular fibre is a 

 peculiar substance, by chemists denominated fibrin. 

 It appears naturally calculated to assume this filmy 

 character, being soluble neither in boiling-water 

 nor in alcohol. 



The nutrative fluid, or the blood, as it is found in the 

 circulating vessels, may be resolved for the most 

 part into the general elements of the animal body, 

 i. e., into carbon, hydrogen, oxygen, and azote. Be- 

 sides these it contains fibrin and gelatine, in a state 



