DR. EDWARD SCHUNCK ON INDIGO-BLUE. 233 



as it ascends, causes a dark discoloration ; and the part 

 discoloured, after immersion in boiling alcohol to remove 

 the chlorophyll, appears blue. 



Indigofera tinctoria. 



It would be a matter of some interest to ascertain in 

 what state the colouring-matter exists in this the most 

 important of all the plants yielding indigo. From what I 

 have said, however, it will be apparent that, in order to 

 arrive at a certain conclusion, it would be necessary to 

 work with fresh leaves ; for if they contain a glucoside re- 

 sembling indican, this would^ in a very short time, undergo 

 complete decomposition. I obtained some seeds of Indi- 

 gofera tinctoria from Messrs. Vilmorin, Andrieux & Co., 

 and treated them in accordance with the directions they 

 kindly gave me. The seeds germinated and the young 

 plants lived for some time in a hothouse ; but, unfortunately, 

 they attained no great size, and soon decayed and died, so 

 that I was unable to obtain a quantity of leaves sufficient 

 for examination. 



Mr. P. Michea, an intelligent indigo-planter, with whom 

 I have been in correspondance, gives me, however, some 

 interesting information relating to this part of the subject. 

 Mr. Michea writes to me as follows : — " It was my finding 

 in the Indigoferce of India (in the wild plant which grows 

 at many places in the three Presidencies as well as in the 

 cultivated species of Bengal, the North West, and Madras) 

 a glucoside substance perfectly similar to the indican of 

 the Isatis tinctoria in all its properties, which made me 

 declare that the colouring-matter of the Indian Indigqferee 

 was due to indican." 



The experiments just described lead to the onclusion 

 that in all the indigo-yielding plants hitherto examined, 

 the colouring-matter is derived from a glucoside which 



