344 COLLOIDS IN BIOLOGY AND MEDICINE 



Clinicians have paid more attention to the serum albumin and 

 globulin than to the other colloidal constituents. All the usual 

 methods of detecting them depend upon the fact that albumin is 

 made irreversible by boiling or by the addition of a substance with 

 which it combines (sublimate, picric acid, potassium ferrocyanid, 

 etc.), and by a second process (addition of nitric acid or other electro- 

 lyte) it is flocked out. If the urine is to be examined further, es- 

 pecially for sugar, every trace of albumin must be removed first. It 

 is frequently impossible to remove the final traces of albumin by 

 coagulation and flocculation. In these cases an adsorptive sub- 

 stance must be employed; the urine is shaken with animal charcoal or 

 diatomaceous earth or a precipitate is formed in the urine (lead acetate 

 is added, filtered and the lead removed with sodium phosphate). 



The other nondialyzable constituents also show quantitative 

 changes, especially in pathological urine. They are much increased 

 in lobar pneumonia (422 to 488 gm. per day) and to an enormous 

 extent in eclampsia (as high as 13.84 gm. per liter). 



The determination of the surface tension of the urine which points 

 to certain constituents may in the future become of great impor- 

 tance for diagnostic purposes. Though the surface tension of normal 

 urine is about 10 per cent less than that of water and is not much 

 changed by either albumin or sugar, the salts of the bile acids (sodium 

 taurocholate and sodium glycocholate) produce a very definite 

 lowering (as much as 40 per cent below that of water). W. D. DON- 

 NAN and F. G. DONNAN * found that the degree of icterus ran parallel 

 with changes in the surface tension of the urine. 



Fibrin, nucleoalbumins, blood and blood pigments, as well as all 

 the other organized constituents coming from the organism, are the 

 result of local disease of the kidneys or urinary passages, and at this 

 point they cannot be discussed at greater length. More thorough 

 studies of albumosuria and peptonuria from a colloid-chemical stand- 

 point are much needed. 



Casts occupy an entirely distinct place. To a certain extent, 

 these are actually casts of the uriniferous tubules; they are spiral 

 or cylindrical structures which occur in inflammation of the kidneys 

 (nephritis), whose form and properties are of diagnostic importance 

 (hyaline, fine and coarsely granular, etc.). Casts, according to 

 M. H. FISCHER, ** are epithelial cells of the kidney dissolved away 

 as the result of the formation of acid. By changing the concentra- 

 tion of acid, he was able to change hyaline casts into granular casts 

 and the reverse. 



Urinary calculi have been exhaustively studied by H. SCHADE* 

 (see p. 272). 



