12 THE NEW PHYSIOLOGY. 



carbon dioxide and disappearance of oxygen in respira- 

 tion, an immense step forward was taken. This step 

 was in two distinct respects a very great one. In the 

 first place, it revealed an element of identity between 

 organic and inorganic phenomena, since heat-produc- 

 tion in an animal was shown to be accompanied by 

 chemical changes quantitatively identical with those 

 accompanying heat-production by oxidation outside the 

 body. In the second place, and from the distinctively 

 physiological point of view, it revealed a fundamental 

 relation between heat-production, respiratory exchange, 

 and the consumption of food. 



As regards the first of these points I should like to 

 say definitely that I, for one, firmly believe that could 

 we only understand them fully we could bring organic 

 and inorganic phenomena under the same general 

 conceptions. Lavoisier's discovery, like that of Mayer 

 in relation to the sources of muscular energy, was a 

 great advance in this direction. But this is a very 

 different thing from an advance in the direction of 

 rendering life intelligible in terms of physico-chemical 

 conceptions as we commonly understand them. La- 

 voisier's discoveries did nothing in the direction of 

 reducing to physico-chemical terms the apparent teleo- 

 logical or, as I should prefer to say, " physiological " 

 element in the phenomena of Animal heat. 



It is to the second point that I wish to direct special 

 attention at present. Lavoisier's discovery rapidly 

 brought the phenomena of animal heat into direct 

 relation, not only with respiration but with nutrition, 

 circulation of blood, excretion, and other processes ; 

 and it was gradually discovered that the maintenance 



