NTTKOGENIZED PRINCIPLES. 373 



Various combinations of bases with organic acids taken 

 as food, as the acetates, tartrates, etc., found in fruits, 

 undergo decomposition in the body, and are transformed 

 into carbonates. In this form they behave precisely like the 

 other inorganic salts. 1 



Principles consumed by the Organism. 



All of the assimilable organic matter taken as food is con- 

 sumed in the organism ; and none is ever discharged from the 

 body, in health, in the form under which it was introduced. 

 The principles thus consumed in nutrition have been di- 

 vided into nitrogenized and non-nitrogenized ; and, although 

 they both disappear in the organism, they possess certain 

 marked differences in their properties, and probably, also, in 

 their relations to nutrition. 



Nitrogenized Principles. The nitrogenized principles, 

 having for their basis, carbon, hydrogen, nitrogen, and oxy- 

 gen, undergo, in the process of digestion and absorption, 

 remarkable changes ; but these are more marked with rela- 

 tion to their properties than their ultimate chemical com- 

 position. They are all converted into the nitrogenized 

 elements of the blood, which, in their turn, are transformed 

 into the characteristic nitrogenized principles of the different 

 tissues, and are appropriated by these tissues, to supply the 

 place of worn-out matter. With the intimate nature of this 

 series of transformations, we are entirely unacquainted ; but 

 we know that the deposition of new nitrogenized matter in 

 the tissues, constituting one of the most important of the 



1 It is a fact well established that the ingestion of certain salts of vegetable 

 origin produces alkaline carbonates of the same bases, which are discharged in 

 the excretions. The replacement of the vegetable acid in this way by carbonic 

 acid, which is weaker, is supposed by Milne-Edwards to be due to the action of 

 the oxygen in the process of respiration. This explanation is not very satis- 

 factory, but the fact of the production of the alkaline carbonates from the 

 vegetable acid salts cannot be doubted ( MILNE-EDTTARDS, Lemons sur la physio- 

 logic, Paris, 1862, tome vii., p. 531). 



