594 THE CHEMISTRY OF THE URINE. 
Salkowski, in 1889, 1 was among the first to give prominence to this 
view, but the experiments upon which he then based his opinion were not 
wholly calculated to decide as to what is the effect, if any, of the ingestion 
of ordinary proteids. They were in the main those of Hirschfeld, 2 but 
the experiments of this investigator were directed to a broader question 
than that of uric acid excretion, and the diet for the purposes of his 
research was made entirely abnormal, so that definite conclusions on the 
point we are discussing cannot be fairly drawn from them. In the experi- 
ments of Horbaczewski and Camerer, 3 undertaken with the object of ascer- 
taining the effect of glycerin, carbohydrates, and fat, respectively, on uric 
acid excretion, there were certain " normal periods," in which a standard 
mixed diet was taken alone. The fact that the diet was carefully maintained 
at a uniform level makes these very careful experiments more or less unavailable 
for our purpose. Nevertheless, during one of these control periods, which 
lasted for many days, the urea excreted fluctuated somewhat widely, pre- 
sumably from varying degrees of proteid absorption. Of this period the 
author says : " The uric acid eliminated went hand in hand with the nitrogen 
excretion. In general, the more the total nitrogen present the more the uric 
acid found." 
There are but few experiments recorded which bear properly on our 
problem, fundamental though it be ; that is to say, experiments where the 
uric acid and urea (or total nitrogen) have been estimated from day to day 
by reliable processes ; while the quantity, but not the quality, of the proteids 
ingested has been made to vary widely. Schiiltze 4 found the uric acid rise 
with increase of flesh diet. Hester and Smith 5 found it raised when the 
ingestion of proteids was increased, though it was somewhat less affected than 
the urea. I myself have repeatedly observed a rise to follow an increase in 
the diet where the composition of this has been carefully maintained constant. 
But these observations are open to one criticism. "Whatever the effect of 
globulins or albumins, there appears to be no doubt that ingestion of 
nucleo-proteids increases the excretion of uric acid ; calves' thymus, with its 
abundant nuclein, has been largely used to test this point. Umber 6 and 
Weintraud " have found that with thymus the excretion of uric acid may 
amount to double that of the same individual upon ordinary proteid (muscle) 
diet of equal nitrogenous value. 
Is, then, the smaller increase found when ordinary proteid diet is taken, 
merely due to any nuclein present and not to the absorption of the ordinary 
proteids 1 AVe shall be able to add the last word to this discussion 
immediately. 
If the effect of an isolated meal of ordinary mixed diet be studied, it 
is found that an increase in the excretion of uric acid occurs very rapidly 
after the food is taken. According to Mares 8 the maximum hourly excretion 
occurs at the fifth hour after the meal ; four hours before the urea reaches 
its maximum. This observer held, therefore, that it was not derived directly 
from the ingested proteid, but from cellular activity during digestion. 
Horbaczewski confirmed this result, and believed that it was due to a digestive 
leucocytosis {vide article, " Metabolism "), with its consequent liberation of 
nucleins in the body. But Camerer 9 has recently found that this rise of 
1 Virchow's Archie, 1889, Bd. cxvii. S. 572 ; comments on a paper by Spilker. 
* Ibid., Bd. cxiv. S. 301. 
3 Sitzungsb. d. k. Akad. d. Wissensch,, Wien, 1886, Bd. xcviii. Abth. 3, S. 301. 
4 Arch./, d. ges. Physiol., Bonn, 1SS9, Bd. xv. S. 427. 
5 Neio York Med. Journ., 1892, p. 3S. 
6 Ztschr.f. klin. Med., Berlin, 1896, Bd. xxix. S. 174. 
7 Berl. klin. U'chnschr., 1895, S. 407. 
8 Centralbl.f. d. med. Wissensch., Berlin, 1888, S. 2. 
9 Ztschr. f. Biol., Munchen, 1896, Bd. xxxiii. S. 136; also Weintraud, Chem. Centr.- 
Bl.. Leipzig, 1895, Bd. ii. S. 234. 
