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 <ftie 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 w r ith 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 7 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? We 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 Archiv, 1889, Bd. cxvii. S. 572 ; comments on a paper by Spilker. 



2 Ibid., Bd. cxiv. S. 301. 



8 Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1886, Bd. xcviii. Abth. 3, S. 301. 



4 Arch.f. d. ges. PhysioL, Bonn, 1889, Bd. xv. S. 427. 



5 New York Med. Journ., 1892, p. 38. 



6 Ztschr.f. klin. Med., Berlin, 1896, Bd. xxix. S. 174. 



7 Berl. klin. Wchnschr., 1895, S. 407. 



8 CentralU.f. d. med. Wissensch., Berlin, 1888, S. 2. 



9 Ztschr. f. BioL, Miinchen, 1896, Bd. xxxiii. S. 136; also Weintraud, Chem. Centr.- 

 1., Leipzig, 1895, Bd. ii. S. 234. 



