206 MAN AN ADAPTIVE MECHANISM 



From all this evidence we conclude that the brain, 

 the thyroid, the adrenals, the liver and the muscles 

 are mutually dependent upon each other for the con- 

 version of latent into kinetic energy. Each is a vital 

 organ ; each equally vital. While it may be said that 

 excision of the brain causes death in less time than 

 excision of the liver or the adrenals, this statement must 

 be modified by our definition of death. After the 

 entire brain of an animal has been removed by decapi- 

 tation, its body may live on for eleven hours or more, 

 if the circulation be maintained by an over-transfusion 

 of blood. An animal may live for weeks or months 

 after excision of the cerebral hemispheres and the cere- 

 bellum, while an over-transfused animal may live 

 many hours or even days after destruction of the 

 medulla. It is possible, therefore, that, in this sense, 

 the brain actually is a less vital organ than either the 

 adrenals or the liver. 



Summing up our evidence in regard to the principal 

 factors in energy transformation, therefore, we have 

 the fact that if communication between the brain and 

 the muscles, the brain and the adrenals, the brain 

 and the thyroid or the brain and the liver be severed, 

 the power f the body to transform latent into kinetic 

 energy for heat or motion is diminished. The body 

 without the brain, the thyroid, the adrenals or the 

 muscles can make little or no response to environment ; 

 little or no febrile response to infection. After excision 

 of the brain there is an immediate fall to a low degree 

 of energy transformation in the body, accompanied 

 by no histologic changes in other organs or tissues, 

 showing that without the brain there is no activation. 



