NUTRITION. 211 



years past been engaged in analyzing ingesta and 

 egesta, in drawing up schedules of nutrition, in order 

 to determine the course of decomposition and re- 

 constitution of the living material. 



If I were asked what, in my opinion, is the most 

 general result of all this labour, I would reply that it 

 has affirmed and corroborated the important distinc- 

 tion which must be drawn between living substance, 

 properly so called, and reserve-stuff. The latter, the 

 reserve-stuff of albuminoids, carbohydrates, and fats, 

 are so intimately intermingled with the living sub- 

 stance that they are in most cases very difficult to 

 distinguish from it. 



Organic Destruction. — A second point, which is 

 placed equally beyond doubt, is that the vital func- 

 tional activity is accompanied by a destruction of the 

 immediate principles of the organism, in the direction 

 of their simplification. This functional destruction 

 cannot be doubted in the case of differentiated organs 

 in which the functional activity is evident, inter- 

 mittent, and in some measure distinct from the other 

 vital phenomena which take place in them. For 

 example, in the case of contracting muscles the 

 respiratory carbonic acid and urinary carbon are the 

 irrefutable proofs of this destruction : weak in repose, 

 abundant during activity, and in proportion to it. 

 There can be no doubt on this point. The truth 

 laid down by Claude Bernard under the name of 

 the law of functional destruction has been doubly 

 consecrated by experiment and theory. According 

 to the energetic theory, in fact, mechanical and 

 thermal energies manifested in the vital functional 

 activity can only have their source in the chemical 

 energy set free by the destruction of the immediate 



