292 Mr. W. R Dunstan and Dr. T. A. Henry. [June 10, 



cultivated plant furnishes prussic acid, and, as is proved in the present 

 communication, the seeds of the wild Mauritius plant contain con- 

 siderable quantities of the cyanogenetic glucoside phaseolunatin, which, 

 however, is not found in the seeds of the same plant after systematic 

 cultivation. 



Rangoon Beans. 



Whilst the investigation of the glucoside of Phaseolus lunatus was in 

 progress, there were received at the Imperial Institute several specimens 

 of beans imported into this country from Burma for the manufacture 

 of a feeding stuff for cattle under the names of "Rangoon," "Burma," 

 or "Paigya" beans. These beans varied in colour from light to 

 dark brown with purple patches, and closely resembled the seeds of 

 Phaseolus lunatus both in appearance and size, and are, no doubt, 

 derived from this plant. On examination in the manner previously 

 described, Rangoon beans yielded small quantities of hydrocyanic 

 acid, amounting usually to not more than 0'004 per cent. The 

 isolation of the small quantity of glucoside represented by such a 

 proportion of hydrocyanic acid was not possible, but evidence of the 

 existence of the glucoside phaseolunatin was obtained by extracting 

 several pounds of the beans and hydrolysing the extract with dilute 

 hydrochloric acid, when a distillate containing both hydrocyanic acid 

 and acetone was obtained, the latter being identified by its conversion 

 into dibenzylidene acetone. 



General Considerations. 



The present investigation had for its principal object the determina- 

 tion of the question as to whether the production of prussic acid in 

 the seeds of Phaseolus lunatus originated with a glucoside, and if so to 

 isolate this constituent and ascertain its chemical composition, 

 Phaseolunatin proves to be a cyanogenetic glucoside with an aliphatic 

 nucleus, and in this respect differs from the glucosides of this class 

 already known, viz., amygdalin, lotusin and dhurrin, which contain 

 aromatic (benzenoid) nuclei. 



The occurrence in Plwseolus lunatus^ apparently throughout its life 

 history, of a cyanogenetic glucoside, together with the enzyme 

 appropriate for its hydrolysis, seems to strengthen the view expressed 

 by us in a previous paper, that these glucosides must play some definite 

 part in the metabolism of plants. 



Treub, as the result of his investigations of the production and 

 distribution of hydrocyanic acid in Pangium edule, suggested that the 

 immediate precursor (probably a cyanogenetic glucoside) of the acid 

 in this plant is a formative material utilised in the synthesis of proteid. 

 In this connection it is of interest to note the ease with which cyanogen 





