INFECTIONS OF THE DIGESTIVE TRACT 147 



aldehyde reaction of the urine, but it is possible that 

 other substances are also concerned. 



The relation of the hydrobilirubin reaction to the 

 urobilinogen reaction of the faeces with Ehrlich's 

 aldehyde is a point of interest on which one cannot 

 at present express an opinion. There are instances in 

 which the faeces, after distillation of all the indol pres- 

 ent (as shown by the aldehyde reaction, which is very 

 delicate), still give a reaction in the cold with a di- 

 me thylamidobenzaldehyde solution. This reaction is 

 believed to depend on the presence of urobilinogen. It 

 has been fairly well marked in some of our anaemia 

 cases, but there is as yet no evidence that the reaction 

 bears any definite relation to the hydrobilirubin 

 reaction, although the two substances urobilinogen and 

 urobilin (hydrobilirubin ?) are closely related chemically. 



The Dimethylamidobenzaldehyde Reaction of the Urine. 

 It is well known that on the addition of acid 

 solution of dimethylamidobenzaldehyde to certain 

 urines a red color is obtained, sometimes in the cold, 

 more often only on the addition of heat. The explana- 

 tion of the reaction has been the occasion of considerable 

 discussion. Ehrlich * was inclined to attribute it to 

 glycosamin; Neubauer 2 and Bauer 3 referred it to 



1 "Ueber die Dimethylamidobenzaldehydreaction," Med. 

 Woche, p. 151, 1901. 



2 " Ueber die neue Ehrlich'sche Reaction mit Dimethylamido- 

 benzaldehyd," Sitzungsber. d. Gesellsch. /. Morphol. u. Physiol., ii, 

 p. 32, 1903. 



3 "Die Ehrlich'sche Aldehydreaktion im Harn und Stuhl," 

 Zentralbl. f. inn. Med., xxvi, p. 833, 1905. 



