28 NERVES AND MUSCLES 



into the conditions necessary to keep it in the normal 

 state, is not more difficult than in the case of a clock. 



V. The want of a just conception of force and 

 effect, and of the connexion of natural phenomena, has 

 led chemists to attribute a part of the heat generated in 

 the animal body to the action of the nervous system. 

 If this view exclude chemical action, or changes in the 

 arrangement of the elementary particles, as a condition 

 of nervous agency, it means nothing else than to derive 

 the presence of motion, the manifestation of a force, 

 from nothing. But no force, no power can come of 

 nothing. 



No one will seriously deny the share which the ner- 

 vous apparatus has in the respiratory process ; for no 

 change of condition can occur in the body without the 

 nerves ; they are essential to all vital motions. Under 

 their influence, the viscera produce those compounds, 

 which, while they protect the organism from the action 

 of the oxygen of the atmosphere, give rise to animal 

 heat ; and when the nerves cease to perform their func- 

 tions, the whole process of the action of oxygen must 

 assume another form. When the pons Varolii is cut 

 through in the dog, or when a stunning blow is inflicted 

 on the back of the head, the animal continues to respire 

 for some time, often more rapidly than in the normal 

 state ; the frequency of the pulse at first rather increases 

 than diminishes, yet the animal cools as rapidly as if 

 sudden death had occurred. Exactly similar observa- 

 tions have been made on the cutting of the spinal cord, 



