406 PHYSIOLOGY CHAP. 



conclude that the ferments of the urine are derived from the 

 intracellular ferments which have been demonstrated within 

 every organ, and which give rise to the so-called autolytic cleavage 

 products (Salkowski. See Vol. I. p. 34). 



Matthes attempted to solve the question of the origin of the 

 enzymes of the urine by experiment (1903-4). On analysing the 

 urine of dogs from which he had previously removed the whole of 

 the stomach, or pancreas, he saw that in the first case no pepsin 

 could be detected in the urine; while after removal of the pancreas 

 ferments were still present, which were able to split up protein in 

 alkaline solution. This led him to conclude that the proteolytic 

 enzyme of the urine which acts in an acid medium, is reabsorbed 

 pepsin, and not an autolytic ferment. On the other hand, even 

 when the possibility of trypsin reabsorption is excluded, proteolytic 

 cleavage can take place in an alkaline medium ; this is evidently 

 due to ferments eliminated with the urine, which must be autoch- 

 thonous in the different tissues of the body. 



X. The inorganic constituents of urine are chlorides, carbonates, 

 sulphates, and phosphates, the bases of which are represented by 

 soda, potash, ammonia, lime, and magnesia. Small quantities of 

 fluorine, silicic acid, and iron are also found in urine. The total 

 quantity of salts in the urine fluctuates from 9 to 25 grms. per diem. 



The salt most abundantly present in the urine is sodium 

 chloride, with which are associated small amounts of potassium 

 chloride and traces of calcium and magnesium chloride. 6-8 grms. 

 chlorine can be found in the urine in one day, which correspond to 

 10-13 grms. sodium chloride. The whole of the salt used as a 

 condiment reappears in the urine partly on the same, partly on 

 the next day (Dehn). A small proportion of it is decomposed by 

 the glands of the fundus of the stomach in the formation of hydro- 

 chloric acid, and is then regenerated in the intestine by the sodium 

 carbonate of the succus entericus. (See Chapter IV. p. 222.) 



The sodium chloride of the urine increases after an abundant 

 meal, and diminishes in the night hours. It increases after copious 

 draughts of water. It diminishes temporarily after an abundant 

 secretion of gastric juice. It increases after inhalation of chloro- 

 form, and not after taking chloral (v. Mering), although both these 

 are compounds of chlorine. Injection of potassium salts increases 

 the elimination of sodium chloride (Bunge). 



It must not be thought that the whole of the sodium chloride 

 remains in a free state dissolved in the plasma, serving merely as 

 a vehicle for the metabolic exchanges of the tissues. Part of it is 

 chemically combined with the organic molecules of the bioplasm, 

 and enters, as it were, into the chain of its metabolic processes is 

 in short, a true mineral aliment. In proof of this it is only 

 necessary to consider how the total chlorine content of the urine 

 varies during and after fasting. We ourselves, in the case of 



