THE KINETIC SYSTEM 187 



tologic changes produced by these activating agents, 

 not only in the brain-cells, but also in the adrenals and 

 the liver, while at the same time the body temperature 

 is reduced. We postulate, therefore, that the brain- 

 cells participate as actively in the production of heat 

 as in the production of motion. That is, the brain 

 drives the body in response to the activation of infec- 

 tion or of foreign proteins within the body, exactly as 

 it drives the body in response to an external stimulus 

 which induces the reactions of running or of fighting. 

 The end effect in one case is the production of chemi- 

 cal action and of heat ; in the other the production of 

 motion. 



If the production of heat, like the production of 

 motion, results from impulses sent from the brain to 

 the muscles, any break in the connection between the 

 brain and the muscles would hinder the production of 

 heat as well as of motion. We know that when nerve 

 connection between the brain and the muscles is nulli- 

 fied by curare, which paralyzes the muscles, or severed 

 by high transection of the spinal cord, the animal is not 

 only deprived of motion, but its heat-producing power 

 is at once on a par with that of cold-blooded animals. 1 

 That is, with the external application of cold the tem- 

 perature falls ; with the application of heat the tempera- 

 ture rises. When the activity of either the brain or the 

 muscles is depressed or eliminated, therefore, the animal 

 becomes incapable of converting potential into kinetic 

 energy for the production of either heat or motion. 



The postulate that the brain cells contribute to the 

 production of heat as well as of motion by sending 



1 Starling. 



