IN THE ANIMAL ORGANISM 223 



of vital force consumed as mechanical force, an 

 equivalent of chemical force is manifested ; that is, 

 an equivalent of oxygen enters into combination 

 with the substance of the organ which has lost the 

 vital force ; and a corresponding proportion of the 

 substance of the organ is separated from the living 

 tissue in the shape of an oxidised compound. 



All those parts of the body which nature has 

 destined to effect the change of matter, that is, to 

 the production of mechanical force, are penetrated 

 in all directions by a multitude of the most minute 

 tubes or vessels, in which a current of oxygen con- 

 tinually circulates, in the form of arterial blood. 

 To the above-mentioned separation of part of the 

 elements of these parts, in other words, to the dis- 

 turbance of their equilibrium, this oxygen is abso- 

 lutely essential. 



As long as the vital force of these parts is not 

 conducted away and applied to other purposes, the 

 oxygen of the arterial blood has not the slightest 

 effect on the substance of the organized parts ; and 

 in all cases, only so much oxygen is taken up as 

 corresponds to the conducting power, and, conse- 

 quently, to the mechanical effects produced. 



The oxygen of the atmosphere is the proper, ac- 

 tive, external cause of the waste of matter in the 

 animal body ; it acts like a force which disturbs 

 and tends to destroy the manifestation of the vital 

 force at every moment. But its effect as a che- 

 mical agent, the disturbance proceeding from it, is 



