THE ACTION OF DIURETICS. 
343 
the blood are altogether unfit for the nutrition of the body, and 
ought to be completely ejected out of the system. Chemically, 
this secretion is especially depuratory , inasmuch as it is constantly 
taking matters out of the blood useless or hurtful, which are the 
products either of absorption or of the process of decomposition, the 
accompaniment of nutrition. In both these points of view the 
urinary apparatus ought to be considered as the veritable regulator 
of nutrition, since their office is to maintain in just equilibrium the 
divers organic and inorganic elements constituting the nutritive 
fluid, par excellence, the BLOOD. 
It is, in fact, through the urinary passages that are continually 
ejected, as useless or hurtful, the following principles: — 1. Water 
introduced by drink into the circulating fluid, at a time that it is 
not required to augment the proportion of serum in the blood, or to 
repair the losses occasioned in it by the divers secretions and 
excretions ; — *2dly, The innutritious heterogeneous principles 
which the divers absorptions, recrementitious or excrementitious, 
liquid or gaseous, may have accidentally introduced into the nu- 
tritive fluids; — 3dly, Matters belonging to other depuratory secre- 
tions, natural or accidental, whenever these may have become 
suppressed or have become diminished in their activity : — 4thly, 
Inorganic matters, the salts which in the process of decomposition 
have become separated from the body as no longer useful : — 5thly, 
Viruses, poisons, miasms, that might act as ferments in the nutri- 
tive fluids and produce grave disorders in the economy: — 6thly, 
and lastly, The azotic principles eliminated at every instant from 
the body as in excess of the azote introduced into the animal 
economy by the aliments for the wants of the nutritive function, 
or as the residue of the functional decomposition of the tissues. 
The experiments of modern chemists have shewn, in fact, in the 
most evident manner, that animals do not absorb azote from the 
atmosphere in the act of respiration ; that all the azote required 
for nutrition is furnished by the food ; and that, ultimately, the 
superfluous part of this principle is ejected almost entirely with 
the urine under the form of urea, urates, uric acids, hyppuric, &c., 
according to the animals. 
Of all the chemists, M. Dumas has described these processes 
with the greatest perspicuity. After having demonstrated that 
animal life is supported by veritable combustion ; that the carbon 
and hydrogen of the food, combusted within the organic passages 
by the inspired air, are ejected during respiration in the forms of 
carbonic acid and watery vapour; that the azote of the air is never 
assimilated in the act of respiration ; that that of the aliments, 
after having served for nutrition, is cast out in small quantity, 
accidentally, by the lungs, in the largest proportion by the urinary 
