224 THE PHENOMENA OF MOTION 



held in equilibrium by the vital force, which is free 

 and available in the living tissue, or is annihilated 

 by a chemical agency opposed to that of oxygen, 

 the manifestation of which must be considered as 

 dependant on the vital force. 



In chemical language, to annihilate the chemical 

 action of oxygen, means, to present to it substances, 

 or parts of organs, which are capable of combining 

 with it. 



The action of oxygen (affinity) is either neutra- 

 lized by means of the elements of organized parts, 

 which combine with it (after the free vital force has 

 been conducted away), or else the organ presents to 

 it the products of other organs, or certain matters 

 formed from the elements of the food, by the vital 

 activity of certain systems of apparatus. 



It is only the muscular system which, in this 

 sense, produces in itself a resistance to the che- 

 mical action of oxygen, and neutralizes it com- 

 pletely. 



The substance of cellular tissue, of membranes, 

 and of the skin, the minutest particles of which are 

 not in immediate contact with arterial blood (with 

 oxygen), are not destined to undergo this change of 

 matter. Whatever changes they may undergo in 

 the vital process, affect, in all cases, only their 

 surface. 



The gelatinous tissues, mucous membranes, ten- 

 dons, &c., are not designed to produce mechanical 

 force ; they contain in their substance no con- 



