438 THE UEINE. 



0.7 gram per diem, being increased three or four times this 

 amount if fruits enter largely into the diet. 



Creatinin. This substance exists in human urine under a mixed 

 diet to the extent of about 1 gram in the twenty-four hours. Its 

 principal source is the creatin contained in the meat ingested, as 

 is represented by the following equation : 



C 4 H 9 N 3 2 - H 2 =C 4 H 7 N 3 



Creatin. Water. Creatinin. 



It is possible that some of the creatinin in the urine may come 

 from the creatin of the muscular tissue of the body, although 

 this is not established. 



Proteids. In the urine is a minute quantity of a nucleoproteid 

 from the cells lining the urinary passages. This may be present 

 in sufficient quantity to react to Heller's test, which consists in 

 allowing urine to flow down the side of a test-tube in which is 

 strong nitric acid. The urine floats on the acid, and where the 

 two join a white ring of coagulated proteid forms. In cystitis, 

 an inflammation of the mucous membrane lining the bladder, the 

 quantity of the nucleoproteid may be increased, and this is precip- 

 itated when acetic acid is added to the urine. The nucleo- 

 proteid of the urine is also increased in leukemia. 



Albuminuria. Under some circumstances serum-albumin and 

 serum-globulin are found in the urine, constituting albuminuria. 

 These doubtless always exist in minute quantities in health, but 

 may come from the cells of the passages along which the urine 

 travels, and not from the blood as it flows through the glomeruli, 

 as they undoubtedly do in true albuminuria, which is a patho- 

 logic condition. 



Peptonuria and Albumosuria. These conditions are character- 

 ized by the presence in the urine of peptones and albumoses, 

 respectively. We have already seen that the products of digestion, 

 peptones, are changed in their passage through the gastric and 

 intestinal walls by the cells into, probably, serum-albumin and 

 serum-globulin ; certainly, they do not enter the blood as peptones. 

 If either wall is much diseased, as in cancer of the stomach, 

 the peptones and albumoses or proteoses may not be changed, 

 but may enter the blood in these forms and appear in the urine, 

 being eliminated by the kidneys. It is probably in the form of 

 albumoses or proteoses rather than peptones that this elimination 

 takes place. This condition of peptonuria may occur in connec- 

 tion with abscesses or collections of pus, the pus-cells having 

 broken down, and peptone being one of the products which is 

 taken up by the blood and carried to the kidneys, where it is 

 eliminated. 



