342 COLLOIDS IN BIOLOGY AND MEDICINE 



in the tissues, and this would at first result in an impoverishment of 

 the blood in water and a proportional increase in molecular con- 

 centration. Gradually to the extent that the metabolic products 

 enter the blood, there would occur a water equilibrium so that 

 finally the molecular concentration of the blood would be increased, 

 but there would be no change in the content of water. If, however, 

 we do find an increase of the water, it must follow from this that the 

 osmotic relations offer no sufficient explanation of these phenomena, 

 and in order to understand them we are compelled to invoke the 

 condition of swelling in the cell and blood colloids. 



The Urine. 

 A. Normal Urine. 



Normally the urine contains no serum albumin; this does not 

 by any means mean that it is free from colloids. Even the fact that 

 urine gives a moderately permanent foam when it is shaken, shows 

 that it contains colloids. According to H. IscovEsco* 2 these colloids 

 have an electronegative charge. 



Exhaustive investigations on the total quantity of nondialyzable 

 substances in the urine have been undertaken in the laboratory of 



F. HOFMEISTER (KuMOJI SASAKI,* M. SAVARE,* W. EBBECKE*). 



In the normal urine these substances are: 



In men, 0.87-2. 356 gm average 1 . 44 gm. per day. 



In women, 0.24-0.70 gm average 0.44 gm. per day. 



Their quantity is strongly influenced by the diet, and increases 

 after the ingestion of albumin; it is especially high on a purely meat 

 diet. Of less importance is the work of TAMAKA,* who tried to 

 determine from the viscosity the quantity of hydrophile colloids. 

 Since this was done in undialyzed urine which contains very incon- 

 stant quantities of urinary salts, that influence the viscosity of 

 colloidal solutions in some unknown way, the method proposed 

 cannot be utilized. 



L. LICHTWITZ and F. J. ROSENBACH* showed that colloids could 

 be removed by three equally useful methods : by dialysis, by shaking 

 out in the foam made with benzine, and by alcohol precipitation. 

 The urine colloids exert a protective action upon colloidal gold 

 (gold figure 0.69 to 0.81 mg.); and in this regard they are between 

 gum arabic and gum tragacanth (table of R. ZSIGMONDY). Obvi- 

 ously they are hydrophile colloids whose activity is not diminished 

 by boiling, evaporation or freezing. By heating them their protec- 

 tive action is raised inasmuch as a finer distribution results, just as 

 occurs in the case of gelatin (L. LICHTWITZ * 2 ). 



