OF VITAL MOTION. 41 



that the accompanying force, which is its exponent, 

 is ordinary and mechanical in its characters. The 

 essence of this function consists in the formation of 

 water and carbonic acid by the union of the oxygen 

 of the atmosphere with certain hydrogen and carbon 

 constituents of the organism ; and, as the volume of 

 the products is less than that of the constituent 

 elements, it follows that the extrication of a certain 

 amount of heat must attend their formation; and 

 hence there can be no doubt that the force operating 

 upon the vessels may be ordinary force. And that 

 such is its nature may be ascertained, if the subject 

 be fully analyzed. 



What, it may be asked, is the true and essential 

 character of the function of respiration? On a first 

 glance at the physical and chemical nature of the act, 

 without any reference to ulterior consequences, it 

 would not seem to differ widely from the ordinary 

 processes of combustion and decay. The atmosphere 

 acts in the same way in each case, and the products 

 which mark the action are similar; and except a mere 

 question of degree, the only difference would appear 

 to be, that in the one case the dissolution of the bodily 

 fabrics is slow and gradual, and masked by the depo- 

 sition of new matter in the function of nutrition, while 

 in the other the disorganization is more rapid, and 

 altogether undisguised by the counteracting function. 



The parallelism of the acts of decay and respiration 



