IN THE ANIMAL ORGANISM. 243 



source is the conversion of living parts into lifeless, 

 amorphous compounds. 



Proceeding from this truth, which is independent 

 of all theory, animal life may be viewed as deter- 

 mined by the mutual action of opposed forces ; of 

 which one class must be considered as causes of in- 

 crease (of supply of matter), and the other as causes 

 of diminution (of waste of matter). 



The increase of mass is effected in living parts by 

 the vital force ; the manifestation of this power is 

 dependant on heat ; that is, on a certain tempera- 

 ture peculiar to each specific organism. 



The cause of waste of matter is the chemi- 

 cal action of oxygen; and its manifestation is de- 

 pendant on the abstraction of heat as well as on 

 the expenditure of the vital force for mechanical 

 purposes. 



The act of waste of matter is called the change of 

 matter ; it occurs in consequence of the absorption of 

 oxygen into the substance of living parts. This ab- 

 sorption of oxygen occurs only when the resistance 

 which the vital force of living parts opposes to the 

 chemical action of the oxygen is weaker than that che- 

 mical action ; and this weaker resistance is determined 

 by the abstraction of heat, or by the expenditure in 

 mechanical motions of the available force of living 

 parts. 



By the combination of the oxygen introduced in 

 the arterial blood with such constituents of the body 

 as offer no resistance to its action, the temperature 



R2 



