496 MATER1A \ITJE OF 



plied with living blood, the vis insita and the vis 

 nervosa can have no existence ; nor can they be 

 supported by the blood, unless the latter be vita- 

 lized by respiration. It is therefore evident that 

 these fundamental properties of life are derived 

 from the atmosphere, and not inherent in any 

 part of animal bodies, whether solid or fluid. 



With the most distinguished philosophers of 

 ancient and modern times, it was maintained by 

 John Hunter, that all the phenomena of animal 

 life are governed by an independent principle, 

 which he termed the materia vitte, and some- 

 times the architect or organ builder. But so far 

 was he influenced by the neuro physiology of 

 Hoffman and Cullen, that in his Treatise on the 

 Blood, he confounds it with the hypothetical 

 nervous fluid, and even with the medullary sub- 

 stance. He says, " I consider that something 

 similar to the materials of the brain is diffused 

 through the body, and even contained in the 

 blood, between which and the brain a commu- 

 nication is kept up by nerves : I have therefore 

 adopted terms explanatory of this theory, calling 

 the brain the materia vita> coascervata ; the nerves 

 cordce inter-nuncio; and that which is diffused 

 through all parts of the body, the materia mtce 

 diffusa." (P. 89.) But, again : he observes that 

 breathing seems to communicate life to the 

 blood, which imparts it to all the other organs ; 

 that as the brain and nerves are composed of 



