272 COLLOIDS IN BIOLOGY AND MEDICINE 



always contain albuminous elements and they usually show a scaly 

 and radial structure. These formations have been studied with 

 especial care by H. SCHADE* as well as by L. LicHTwrrz.* 1 



In the following pages, we shall consider the origin of urinary and 

 biliary calculi from the standpoint of these studies. 



Urinary Calculi. H. SCHADE mixed ox plasma, which had been 

 made uncoagulable by the addition of potassium oxalate, with an 

 emulsion of calcium phosphate and calcium carbonate. When he 

 coagulated the mass by the addition of CaCl2, a hard cake formed, 

 which, when preserved in salt solution at 40, shrank, and after eight 

 weeks had approximately the hardness of a fresh urinary calculus. 

 Fibrin was absolutely necessary, yet from 0.07 to 0.1 per cent in 

 plasma diluted ten times sufficed to produce a coagulation, and the 

 phenomenon was the same if neutral urine was used for dilution 

 instead of physiological salt solution. 



By changing the composition of the sediment (mineral ingredients) 

 it is not difficult to produce stratified structures resembling urinary 

 calculi. This similarity is not a mere superficial one. Renal calculi 

 have been repeatedly found which were still soft and plastic like the 

 initial stages of these artificial stones. Whether the organic layered 

 framework of natural urinary calculi (see Plate II, Fig. 51) consists 

 of fibrin is still an open question, though there is much in favor 

 of this view. According to H. SCHADE the formation of urinary 

 calculi is somewhat as follows: coagulum and urates sediment 

 simultaneously or in close succession, shrink and harden. By the 

 repetition of such processes layers form, the stone grows, and after 

 a while becomes stony hard, because the crystalloid ingredients grow 

 into large crystal aggregates and take on a radial structure. The 

 lesson for therapeutists is, that not only must the formation of 

 crystalloid sediments be prevented, but also the passage of fibrin or 

 similar colloids into the urine. Alone, urinary sediments form a 

 crumbling mass. Calculus formation is possible only by means of 

 colloidal " mortar." 



Gallstones (biliary calculi): Gallstones differ very widely in their 

 chemical composition. We recognize those which merely consist of 

 cholesterin and others which contain only calcium bilirubin; between 

 these extreme forms occur all sorts, consisting of mixtures of these 

 two chief constituents with albuminous material. 



Without going into the individual reasons, it may be said that, 

 according to H. SCHADE, cholesterin appears to be dissolved in the 

 bile as a hydrophile, and calcium bilirubin as a hydrophobe colloid. 

 It must also be noted that, besides the cholates, the bile contains 

 salts of the fatty acids, lecithin and mucinous substances which 



