136 LIFE AND DEATH. 



alimentary substances to have been elaborated and 

 incorporated in the living cells. It is supposed that 

 an appreciable time is required for this complete 

 assimilation. The products of alimentary digestion 

 are therefore in all probability still in the blood, and 

 in the interstitial liquids in communication with it. 

 The increase of oxygen consumed would show that a 

 considerable portion of these nutritive substances 

 absorbed and passed into the blood would be oxy- 

 dized and then and there destroyed. But this 

 interpretation, however probable it may be, does not 

 really fit in with the facts in such a way that we may 

 consider it as proved. Certain experiments by Zuntz 

 and Mering are opposed to the idea that combustion 

 in the blood is easy. These physiologists injected 

 certain oxydizable substances into the vessels without 

 being able to detect any instantaneous oxidation. 

 It is only fair to add that against these fruitless 

 attempts other more fortunate experiments may be 

 quoted. 



Category of Purely Thermogenic Foods, zvith Ac- 

 celerated Evolution. Alcohol. Acids of Fruits. — 

 The accelerated evolution of foods — an evolution 

 which takes place in the blood, that is to say outside 

 the really living elements — remains, therefore, very 

 uncertain as far as ordinary food is concerned. It 

 has been thought that it was a little less uncertain 

 as far as the special category of alcohol, acids of 

 fruits, and glycerine is concerned. 



Some authors consider these bodies as pure 

 thermogens. When alcohol is ingested in moder- 

 ate doses, they say that about a tenth of the 

 quantity absorbed becomes fixed in the living tissues; 

 the rest is " circulating alcohol." It is oxidized 



