Hartley — On a Violet Colouring-Matter, Sfc. 73 



in the red less refrangible than A 6600, and the transmission at nearly all 

 thicknesses of the rays from X 6600 to A 6439. 



There was brought to my notice recently a paper by Miss Wheldale 

 on the production of Anthooyanin, in which she states hypothetical reactions 

 for its production by oxidases acting on colourless ohromogens present in 

 plant-tissues in combination with glucosides. 



The conditions under which colour was produced by BaciUm violaceus 

 are not apparently at variance with the conditions presumably required 

 by the hypothetical reactions. 



H. E. and E. F. Armstrong,' in a paper on " The Origin of Osmotic 

 Effects — III," describe Guignard's reaction for the detection of cyanophoric 

 glucosides by means of sodium pierate paper in proximity to macerated tissue, 

 which is incubated at 37°0. in au atmosphere of chloroform vapour. This 

 test gave a positive result with my cultures. 



As I have been unable to find sufiioient record of either the chemical 

 reactions or the absorption-spectra of Anthocyanin, I cannot say whether 

 it is a substance resembling the violet colouring-matter of B. violaceus ; but 

 the latter appears to be formed in a similar manner, and I propose for 

 purposes of comparison to investigate Anthocyanin as the subject of a furtlier 

 paper. 



I hope with further opportunity to make a more complete investigation 

 of the nature and biological significance of these bacterial colouring- 

 matters. 



Finally, I wish to offer my sincerest thanks to the Department of 

 Agriculture and Technical Instruction for Ireland, for granting me a 

 Research Scholarship at the Royal College of Science ; and I also wish to 

 thank Professor Morgan and Mr. Houston, for giving me every facility 

 for my work in the Chemical and Bacteriological Laboratories. 



' Proceedings Eoy. Soc, vol. l.wxii, series B. No. 559, p. 558. 



