INDICANE 191 



INDICANE. 



Indicane,* C^H^NC • O 'CeHijOj, is the name given to a 

 glucoside which occurs not only in Indigofera anil, I. arrecta, 

 I. tinctoria, and /. sumatrana, but also in other plants, such as 

 Isatis tinctoria, Polygonum tinctorimn, species of Phajus and 

 other orchids, e.g. Calanthe and Strobilanthes. In the plant, 

 indicane is well distributed in the aerial organs. Thus in Indi- 

 gofera, it is found in all the tissues of the leaf except the 

 tracheae of the xylem, it is also abundant in the apex of the 

 stem in all tissues except the wood vessels and the laticiferous 

 system. The flowers also have a small quantity, but the root 

 is characterized by its absence. f 



At one time it was considered that the chloroplasts played 

 an important direct part in the formation of indicane, but Leake 

 can find no evidence of this. 



Identification. 



1. The tissue may be boiled in a 2 per cent solution of 

 ammonia. The addition of chloroform to the filtered extract 

 may be made to separate the indigo ; the chloroform will rise 

 to the top of the solution, carrying with it the indigo. 



2. Tissues containing indicane on exposure to the vapour 

 of alcohol for twenty-four hours will turn blue ; the reaction 

 will be better marked if the chlorophyll be subsequently dis- 

 solved out with absolute alcohol. 



3. The tissue, in bulk or in section, may be boiled in 

 strong hydrochloric acid and ferric chloride added. The in- 

 digo will separate out, 



4. The tissue is cut up into pieces and quickly immersed 

 in the following mixture : — 



* The name indicane is also applied to a compound of the formula 



C— O . SO3K 



/\ 

 CfiH, 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. 

 t Leake : " Ann. Bot.," 1905, 19, 297. 



