222 HIPPUEIC ACID, LACTATES, PROTEIN BODIES. 



ing a difficulty to its absorption. In the case of some animals it occurs 

 Production of naturally in the excrement. When, in man, it is found in the 

 dSturbe^re^ 1 urme * ts occurrence may be often traced to a disturbance 

 piration. of the respiratory function, or to abnormal metamorphosis 

 occurring in the blood. Under such circumstances it presents itself in 

 convalescence from typhus. That it can arise from such metamorphosis 

 is proved by the circumstance that it is found in the urine after the in- 

 jection of urates into the veins. When the kidneys act vicariously for 

 the lungs, there thus appears to be a tendency to the removal of carbon 

 under the form of oxalic instead of carbonic acid. 



Hippuric acid may arise in the organism from the metamorphosis of 

 Occurrence of benzoic and cinnamic acids, the administration of these sub- 

 hippuric acid, stances being followed by its excretion in the urine. If any 

 thing was necessary to prove that the seat of its origin is the blood, its 

 discovery therein, in the case of the ox, by Verdeil and Dollfass would 

 be sufficient. Its general occurrence in the urine of graminivorous ani- 

 mals, and its absence in that of the carnivora, indicate that its normal 

 production is connected with the nature of the food. However, among 

 some of the lower animals it is still excreted while they are in a state of 

 starvation, and it has been recognized in the urine of diabetic patients 

 under a strict animal diet. 



After the injection of alkaline lactates into the jugular, the urine be- 

 Disappearance comes alkaline in the course of a quarter of an hour. If 

 tates^from the tnev nave ^ een taken into the stomach, in about double that 

 blood. time. The passage of other salts is sometimes even more 



rapid ; thus the ferrocyanide of potassium has been detected in the urine 

 in less than two minutes. 



The excess of protein bodies absorbed from the digestive canal, and 

 Excess of ro- unnece ssary for the repair of the system, is removed as urea 

 tein bodies re- and uric acid ; and, in like manner, the sulphur and phos- 

 phorus introduced by those bodies are, after oxidation, dis- 

 charged as sulphates and phosphates. Under the use of a strictly ani- 

 mal diet, the urine resembles that of carnivorous animals in color, acid 

 reaction, and freedom from lactic and hippuric acids. 

 Disappearance ^e Phosphate of lime often almost totally disappears 

 of phosphate of during pregnancy, and fractures unite at that period with 

 difficulty. -. 



Many circumstances regulate the length of time that extraneous sub- 

 Period that ex- stances will remain in the system ; thus it sometimes occurs 

 traneous sub- that, after the administration of alkaline salts of organic acids, 

 main in the the alkalinity of the urine will disappear in the course of 

 system. j^f a ^ av? w hji e on O ther occEsions it will continue for sev- 



eral days. The period also varies very much with different individuals. 



