vii KATABOLIC CONSTITUENTS OF URINE 395 



another compound, which he terms ornithine, and which, with 

 benzoic acid, forms oriiithuric acid. 



In his Text-book Hoppe-Seyler cites a whole series of com- 

 pounds similar to hippuric acid, in which the benzoic acid is 

 replaced by other aromatic bodies, e.g. salicylic, toluic, anisic, 

 cumin ic, and other acids, which with glycocoll give rise to sali- 

 cyluric, toluylisuric, anisuric, cuminuric acid, etc. According to 

 Salkowski, phenaceturic acid is found in the urine of the horse, 

 and perhaps in small traces in that of man also. It arises from 

 the combination of glycocoll with phenylacetic acid. 



Among the aromatic substances of normal urine, the ethereal or 

 conjugated sulphates are more important from the physiological 

 standpoint. Stiideler in 1861, while distilling the urine of ox and 

 man, discovered the presence of phenol or carbolic acid. Buliginski, 

 and at a later date Hoppe-Seyler, found that the phenol of the 

 urine present is not in the free state, but bound up with an acid 

 from which it separates on distillation. Baumann (1876) first 

 discovered that phenol forms an ethereal compound with the 

 radical of sulphuric acid (HSO 3 ), and that in the urine several 

 potassium salts of ethereal sulphates were present, the principal 

 being those containing phenol, cresol, catechol or pyrocatechin, 

 indoxyl, and scatoxyl. The latter are formed from indole and 

 scatole by oxidation, and .they form with sulphuric acid indoxyl- 

 and scatoxyl-sulphuric acid. 



In the urine of herbivora the group of ethereal sulphates is 

 more abundant than in that of the carnivora or man, but it is 

 present in small quantities in the urine of all animals. 



The ethereal sulphates present in the urine of herbivora are 

 undoubtedly formed from the aromatic substances contained in the 

 vegetable food : they are formed in the intestine from the aromatic 

 compounds by putrefactive processes ; after absorption they enter 

 the circulation, combine with the sulphuric acid radicle, and are 

 eliminated (in the form of potassium salts) as conjugated 

 sulphates. 



In dogs and man the aromatic substances introduced with the 

 food are small in quantity ; they are excreted as ethereal sulphates 

 and give a measure of the putrefactive processes carried on in the 

 intestine. When intestinal putrefaction was arrested in dogs by 

 strong doses of calomel or iodoform, Baurnann and Morax observed 

 a total disappearance of ethereal sulphates from the urine. In 

 man it is difficult to obtain this result, since too strong a dose of 

 the disinfectant would be required, but it is possible to reduce the 

 amount of ethereal sulphates considerably by other means. 



Rovighi's experiments (1891) are interesting from the clinical 

 point of view. He found the elimination of ethereal sulphates to 

 be relatively higher in the daytime than at night; ingestion of 

 fluids increases excretion of aromatic bodies as compared with 



