78 



healthy urine, and by the additional constituents which maybe thrown 

 off in solution in the urine in disease. In this connection it is impor- 

 tant to obseive the following analysis of the horse's urine in health: 



Water 918,5 



Urea 13.4 



Uric acid and viratcs 0. 1 



Hippnric acid 26. 4 



Lactic acid and lactates 1.0 



Mucus and organic matter 22.0 



Sulphates (alkaline) 1.2 



Phosphates (lime and soda) 0. 2 



Chlorides (sodium) 1.0 



Carbonates (potash, magnesia, lime) 16.0 



1000. 



The carbonate of lime, which is present in large amount in the urine of 

 horses fed on green fodder, is practically insoluble, and therefore forms 

 in the passages after secretion, and its microscopic rounded crystals 

 give the urine of such horses a milky whiteness. It is this material 

 which constitutes the soft, white, pultaceous mass that sometimes fills 

 the bladder to repletion and requires to be washed out. In hay-fed 

 horses carbonates are still abundant, while in those mainly grain-fed 

 they aie replaced by hii)i)urates and phosphates — the products of the 

 wear of tissues — the carbonates being the result of oxidation of the 

 vegetable acids in the food. Carbonate of lime, therefore, is a very 

 common constituent of urinary calculi in herbivora, and in many cases 

 is the most abundant constituent. 



Oxalate of lime, like carbonate of lime, is derived from the burning 

 up of the carbonaceous matter of the food in the system, one important 

 factor being the less perfect oxidation of the carbon. Indeed, Fiirsten- 

 berg and Schmidt have demonstrated on man, horse, ox, and rabbit, 

 that under the full play of the breathing (oxidizing) forces oxalic, like 

 other organic acids, is resolved into carbonic acid. In keeping with 

 this is the observation of Lehmann that in all cases in which man suf- 

 fered from interference with ihe breathing, oxalate of lime appeared in 

 the urine. An excess of oxalate of lime in the urine may, however, 

 claim a different origin. Uric and hippuric acids are found in the urine 

 ofcarnivora and herbivora, respectively, as the result of the healthy 

 wear (disassimilatiou) of nitrogenous tissues. But if these products are 

 fully oxidized they are thrown out in the form of the more soluble urea 

 rather than as these acids. When uric a'cid out of the body is treated 

 with peroxide of lead it is resolved into urea, allantoine, and oxalic 

 acid, and Woehler and Frerrichs found that the administration of uric 

 acid not only increased the excretion of urea, but also of oxalic acid. 

 It may therefore be inferred that oxalic acid is not produced from the* 

 carbonaceous food alone, but also from the disintegration of the nitro- 

 genous tissues of the body. An important element of its production 

 is, however, the imperfect performance of the breathing functions, and 



