ALIMENTARY EXERGETICS. IIQ 



legist and medical man who attempted it had failed, 

 and this for various reasons. 



The general cause of this failure was that most de- 

 finitions, popular or technical, interposed the condition 

 that the food must be introduced into the digestive 

 apparatus. "It is," said they, * a substance which 

 when introduced into the digestive tube undergoes, 

 etc., etc" But plants draw food from the soil, and 

 they possess no digestive apparatus; many animals 

 have no intestinal tube; and in the case of certain 

 rotifera, the females possess a digestive apparatus, 

 while the males have none. Nevertheless all animals 

 feed. 



On the other hand, there are other substances than 

 those which use the digestive tract for the purpose of 

 entering the organism, and which are eminently useful 

 or necessary to the maintenance of life. In par- 

 ticular we may mention oxygen. 



The distinctive feature of food is its utility when 

 conveniently introduced or employed to the living 

 being. Claude Bernard's definition is this: A sub- 

 stance taken in the external medium " necessary for the 

 maintenance of the phenomena of the healthy organism 

 and for the reparation of the losses it constantly 

 suffers." " A substance which supplies an element 

 necessary for the constitution of the organism, or 

 which diminishes its disintegration? (stored-up food); 

 this is the definition of C Voit, the German physio- 

 logist. M. Dnclaux says, in his turn, but in far too 

 general terms, that it is a substance which contributes 

 to assure the sound functional activity of any of the 

 organs of the living being. None of these ways of 

 describing food gives a complete idea. 



Food, tlu Source of Energy and Matter. The inter- 



9 



