THE PRINCIPLE OF VITAL AFFINITY. 325 
living body were useful, as this theory supposes, only by yielding to the simply 
chemical action of oxygen, and so giving off caloric, we do not see how these 
changes in diabetes should interfere with that office, or how they should involve 
so great derangement of the system, and particularly so much gradual wasting of 
all the textures. But if the starch taken into the system is liable to transforma- 
tions resulting from vital affinities, and in which albumen is generated, then we 
can understand, that a disease in which starch seems to lose all tendency to vital 
action, and is rapidly thrown off, should be attended with this emaciation and 
debility. 
4. When we attend to the phenomena of Lithiasis, 7. ¢., the morbid forma- 
tion of uric acid, and the effects of different kinds of diet upon it, we meet with 
facts hardly to be reconciled to the idea of the albuminous ingesta being all des- 
tined for nutrition, and the non-azotised for combination with oxygen and excre- 
tion. It is well known, that Liesic pointed out that this diseased state depends 
on imperfect oxidation of the albuminous matter in the blood, which is destined 
to excretion (causing a formation of uric acid, when a fuller oxidation would pro- 
duce urea and carbonic acid); and that he supposed all the albuminous matter 
which unites with oxygen in the blood, to be the product of absorption from the 
textures, the recently introduced albumen being, according to his theory, destined 
for nutrition only. Hence he argued, that a vegetable diet, increasing the quan- 
tity of non-azotised ingredients of the blood, with which the oxygen most readily 
unites, would leave less oxygen for the azotised or albuminous constituents, and 
ageravate the disease. But experience has shewn, particularly since the obser- 
vations of MAGENDIE were published, that the disease is more generally mitigated 
by a vegetable diet, under which, as it would appear, the whole quantity of azo- 
tised matter in the blood and in the urine is diminished, and the oxygen taken in 
is sufficient for its full oxidation. And the experiments of several authors have 
shewn, that the quantity of azotised matter thrown off by the kidneys increases 
greatly (may be nearly doubled) within a few hours after highly azotised food 
is taken. From which facts it would appear, that the azotised matter thrown off 
by the kidneys, is derived not merely from absorption of the textures, but like- 
wise directly from the ingesta; and if so, the distinction of the azotised ingesta, 
destined only for nutrition, and the non-azotised, destined only for excretion, is 
not observed by nature; and it becomes extremely probable, that, as part of the 
albuminous ingesta are excreted, so a portion of fresh albuminous matter is formed 
in the blood, and applied, in the first instance, to the nutrition of textures. 
IV. It is at all events certain, that Gelatin is formed in the living body, and 
its composition, as stated by LirBic, Cy; Nis Hs, Ox 
or by Muuprr, Cuz Nis Hoo Ors 
compared with that of albumen, Cin Nis His Ow 
VOL. XVI. PART III. 4N 
