2 50 GLUCOSIDES 



glucoside which on hydrolysis yields coumarin,* the lactone 



of coumaric acid — 



yCH : CH 



^O CO 



a substance which occurs also in Anthoxanthum odoratum, the 

 grass which gives hay its characteristic smell, tonka bean 

 [Dipteryx odorata), and other plants. 



GEIN. 



Gein occurs in the roots of Geum urbanum ; on hydrolysis 

 by means of mineral acid or by the enzyme gease, it is broken 

 up into eugenol and vicianose f ; the occurrence of eugenol 

 in glucosidic combination accounts for the smell of cloves 

 emitted by the dried roots of this plant. 



MELILOTOSIN. 



This glucoside, obtained from Melilotus arvensis, forms 

 colourless and odourless crystals which melt at 240°. On 

 hydrolysis by mineral acid or emulsin, it yields glucose and 

 coumaric or o-hydroxycinnamic acid % — 



yCH : CH . COOH 



INDICAN. 



Indican,§ C7H6NC . O . CeHnOg, is the name given to a 

 glucoside which occurs not only in Indigo/era anil, I. arrecta, 



* Bourquelot and Herissey : " Compt. rend.," 1920, 170, 1545 ; 

 Herissey : id., 1925, 180, 1695 : 1926, 182, 865. 

 t Herissey and Cheymol : id., 1925, 180, 565. 

 + Charaux : " Bull. Soc. cliim. biol.," 1925. 7» 1056. 

 § The name indican is also applied to a compound of the formula 



C— O . SO3K 



/\ 

 C8H4 CH 



\/ 



NH 



This substance, which is more correctly described as indoxyl potassium 

 sulphate, occurs in small quantities in human urine and also in the urine 

 of herbivora. 



