268 THE URINE. 



X C(CH 3 ). 



C 6 H 4 < 3C.COOH. 



\NH-- 



The substance is usually present in exceedingly small amounts, 

 however, and has not been isolated in substance. 



In addition to the aromatic bodies which have thus far been con- 

 sidered, traces of the aromatic oxy-acids may also appear in the 

 urine in combination with sulphuric acid, but the amount is exceed- 

 ingly small and may well be ignored. 



The Conjugate Glucuronates. 



Glucuronic acid as such does not occur in the urine. The sub- 

 stance can combine with various aromatic bodies, however, and may 

 in this manner escape further oxidation. Normally it is found only 

 in traces (approximately 0.004 per cent.), in combination with 

 indoxyl, skatoxyl, and especially with phenol, while the greater por- 

 tion of these bodies is eliminated in the form of conjugate sulphates, 

 as already described. Larger , amounts of conjugate glucuronates 

 are found in the urine after the administration of chloral, camphor, 

 naphthol, terpene, borneol, menthol, toluol, euxanthin, morphin, 

 antipyrin, and numerous alcohols and ketones. The resulting com- 

 pounds are closely related to the glucosides. So far as the hydrox- 

 ylated compounds are concerned, these are apparently capable of 

 uniting with glucuronic acid (or sulphuric acid) to form conjugate 

 glucuronates (or sulphates) without previous oxidation, while this is 

 not the case with compounds of the same composition, in which, 

 however, the oxygen is present in ketone form. At the same time 

 it is an open question whether the union of such alcohols with the 

 acids occurs directly, or, as is possibly the case with glucuronic acid, 

 with antecedents of the same, and that the resulting compounds are 

 subsequently oxidized to glucuronates during their passage through 

 the organism. 



In part at least the synthesis of the conjugate glucuronates occurs 

 in the liver, and in some cases their appearance is manifestly the 

 expression of a poison-destruction on the part of the organism. This 

 explanation does not hold good in all cases, however. Following 

 the ingestion of glucose in large amounts or in diabetes the appear- 

 ance of glucuronates is evidence primarily of deficient oxidation. 

 We may here imagine that the oxidation of glucose to glucuronic 

 acid (see below) pursues a normal course, but that its further de- 

 struction is impeded. The larger amount of the circulating glucuro- 

 nic acid then combines with phenol, indoxyl, and skatoxyl, which 

 would otherwise have united with sulphuric acid, and as a result we 

 find a diminished excretion of conjugate sulphates. Any glucuronic 

 acid remaining is probably oxidized to oxalic acid. This explains 

 satisfactorily the oxaluria which is frequently observed in diabetes 

 and which follows the ingestion of large amounts of glucose. Ac- 



