534 MANUAL OF HISTOLOGY. 



proportional to that of urea, which likewise originates in the splitting up 

 .of some of the albuminates. 



Among the urinary salts we also find sulphates of the alkalies, amount- 

 ing in the day to 2 '09 4 grammes (Vogel). These are augmented by 

 animal food, and diminished, on the other hand, by vegetable &\Q\>(Lehmann}. 

 From the fact that, as a rule, no sulphates are introduced into the body 

 with the food, those which appear in the urine must be looked upon as 

 developed in the decomposition of histogenic substances having sulphur 

 as an ingredient. This latter element is also cast out of the economy as 

 a component of taurin, as well as of those particles of horny tissue con- 

 stantly being shed from the surfaces of the body. 



The secretion of the kidney possesses likewise traces of iron and 

 silicates, and small quantities of ammonia; further, nitrogen and 

 carbonic acid gas, both free and in combination, together with a trace of 

 oxygen. 



Among the abnormal and occasional constituents of urine, we have 

 (without taking into account casual matters) albumen in many diseases 

 and disturbances of the circulation. Then again, haemoglobin, as, for 

 instance, after poisoning with phosphorus or injection of biliary acids into 

 the blood, causing destruction of the red corpuscles of the same. Grape 

 sugar is found in diabetes, and inosite likewise, as also in Briglifs 

 disease. Lactic acid, too, is frequently to be found in normal urine 

 and after acid fermentation. Besides these fatty matters, butyric, 

 succinic, benzoic, and biliary acids ( 27), present themselves here ; also 

 the pigmentary matters of the bile ( 37), cystin (partly in solution and 

 partly in crystalline concretions), leucin, and tyrosin (in various diseases). 

 Allantoin, likewise ( 29), a product of the artificial decomposition of uric 

 acid, which occurs also in the liquor amnii of ruminants and urine of 

 sucking calves, was met with by Frerichs and Staedeler in the urine of 

 dogs suffering from obstructions to respiration. It was found also by 

 Meissner in abundance after fleshy food or injection into the circulation of 

 kreatin. Cats fed in the same way excrete it also. 



According to an old and, we believe, correct view, urine, when exposed for 

 several days to the air, undergoes a process of acid fermentation, by which, 

 as has just been observed, lactic and acetic acids are produced, increasing 

 its acid reaction, and during which crystals of free uric acid, coloured by 

 the pigments of the urine, are deposited. This view, however, is stated 

 by some later observers to be incorrect. According to them, the acid 

 reaction of the urine becomes less marked the longer it stands, the acid 

 phosphate of sodium is converted into a neutral combination, and acid 

 urates and free uric acid are produced. The latter are then thrown down 



(J 25). 



Later on, another, an alkaline fermentation, is frequently observed, in 

 which urea is split into carbonic acid and ammonia ( 28). Coincident 

 with this, the urine becomes somewhat decolorised, extremely foetid and 

 turbid, and deposits a whitish sediment, while a light pellicle forms upon 

 its surface. The former consists of crystals of ammoniaco-magnesian 

 phosphate ( 42), and of urate of ammonium ( 25). This process of 

 alkaline fermentation may take place, on the other hand, almost immediately 

 after the urine has been voided, or even during its sojourn in the bladder. 



275. 

 We now come to the question, how far the secretion of urine is to bo 



