410 PHYSIOLOGY CHAP. 



the urine, with the exception of ammonium carbonate, which 

 is converted into urea by the liver (supra). Schmiedeberg's 

 theory of the origin of the ammonia of the urine seems to us the 

 most acceptable. He holds that the small amount of ammonium 

 salts in the urine represent the residue of the large quantity of 

 ammonium carbonate (and, as we should add, of ammonium 

 carbamate also) which are formed along the course of the aliment- 

 ary canal, and which have escaped conversion into urea by the 

 liver. 



The content of ammonium salts in the urine increases under 

 all conditions which produce increase of the acids absorbed from 

 without, or formed within the body (acid intoxication). The same 

 factors which tend to form oxalic acid and lactic acid in the dog 

 simultaneously increase the ammonia of the urine (Eeale and Boeri). 

 The same occurs in acute poisoning by phosphorus (Miinzer). The 

 ammonia content rises in the urine in high and persistent fevers, 

 as almost invariably in diabetes (Hallervorden, Coranda, Schmiede- 

 berg), probably because in these cases there is increased develop- 

 ment of acids in the body. 



XL It is evident from this review of the most important 

 constituents of normal urine, that the physiological office of the 

 kidneys is to eliminate from the body the chief part of the waste 

 products developed by the katabolic processes of the tissues, 

 whether these metabolites are derived from the substances intro- 

 duced in the food, or from those which constitute the materials 

 proper of the bioplasm. This elimination is a real purging of the 

 organism, indispensable to the normal exercise of its functions. 

 Should the greater part of the urinary katabolites, either from 

 abnormal conditions, or from profound degeneration of the kidneys, 

 be retained in the blood and accumulate in the tissues, grave 

 phenomena of auto-intoxication arise which shortly cause the 

 death of the animal. 



According to Prevost and Dumas (1822), animals do not 

 survive the loss of the kidneys for more than 42 hours ; according 

 to Cl. Bernard (1847-59), dogs can survive 50-75 hours. After 

 10-12 hours they vomit the food previously ingested, and 

 subsequently become depressed, weak, and refuse food, their 

 respiratory "movements become dyspnoeic, and they utter cries. 

 These phenomena grow more pronounced, with a tendency to 

 coma, and at a given moment, without any perceptible external 

 cause, the animal is seized with epileptic convulsions, which get 

 worse and worse, till it dies. On experimenting with a dog that 

 had previously been operated on by gastric fistula, Bernard 

 observed that the secretion of gastric juice, a few hours after 

 nephrectomy, increased considerably in quantity and became 

 continuous even during abstinence ; that it contained ammonium 

 salts, and preserved its acidity and digestive powers ; lastly, that this 



