IN THE ANIMAL ORGANISM. 225 



of oxygen are in equilibrium together, that the tem- 

 perature of the body can remain unchanged. If the 

 loss of heat by cooling go beyond a certain point, the 

 vital phenomena diminish in the same ratio ; for the 

 temperature falls, and the temperature must be consid- 

 ered as a uniform condition of their manifestation. 



Now experience teaches, that when the temperature 

 of the body sinks, the power of the limbs to produce 

 mechanical effects (or the force necessary to the vol- 

 untary motions) is also diminished. The condition of 

 sleep ensues, and at last even the involuntary motions 

 (those of the heart and intestines, for example) cease, 

 and apparent death or syncope supervenes. 



It is obvious that the cause of the generation of force, 

 namely, the change of matter, is diminished, because, 

 with the abstraction of heat, as in the plant by abstrac- 

 tion of light, the intensity of the vital force diminishes. 

 It is obvious, that the momentum of force in a living 

 part depends on its proper temperature ; exactly as the 

 effect of a falling body stands in a fixed relation to cer- 

 tain other conditions ; for example, to the velocity at- 

 tained in falling. 



When the temperature sinks, the vital energy dimin- 

 ishes ; when it again rises, the momentum of force in 

 the living parts appears once more in all its original in- 

 tensity. 



The production of force for mechanical purposes, 

 and the temperature of the body must, consequently, 



