316 Prof. Dunstan and Drs. Henry and Auld. [Feb. 27, 



respects with that first isolated by us from the practically wild Phaseolus 

 lunatus of Mauritius.* We have found no difficulty in confirming our 

 previous observation that this glucoside yields acetone on hydrolysis, and is, 

 in fact, a dextrose ether of acetonecyanohydrin. 



We have shown recently^ that the linamarin first isolated by Jorissen and 

 Hairs from flax (linseed) is identical with phaseolunatin, and that the latter 

 also occurs in the cassava of tropical countries. This identification of 

 linamarin with phaseolunatin makes it possible to discuss the divergent 

 views, which have been held by various investigators regarding the nature of 

 the enzyme, which occurs in association with phaseolunatin in flax and in 

 the beans of Phaseolus lunatus. 



Jorissen, in his first paperj dealing with the production of prussic acid by 

 flax, stated that the seed contained a substance on which emulsin acted in the 

 same way as on amygdalin. In a later paper, Jorissen and Hairs§ recorded 

 the isolation of linamarin (phaseolunatin) from flax and stated that it was 

 decomposed by the enzyme associated with it in flax seed, but not by the 

 emulsin of almonds. Subsequently linamarin was re-examined by Jouck,|| 

 who stated that it was decomposed by emulsin. In the third paper of the 

 present series,1T dealing with the isolation of phaseolunatin, the identity of 

 which with linamarin had not then been established, it was stated that this 

 glucoside was decomposed by emulsin, and that as the range of activity of 

 the enzyme, occurring with phaseolunatin in the beans of Phaseolus lunatus, 

 appeared to be identical with that of the emulsin of almonds, it might be 

 assumed provisionally that these beans contained emulsin. 



This statement was based on the result of a single experiment, in which 

 prussic acid was undoubtedly liberated when a commercial emulsin 

 preparation was added to an aqueous solution of the glucoside. This 

 experiment has, however, been repeated frequently, using several different 

 commercial emulsin preparations as well as emulsin prepared by ourselves 

 from sweet almonds, and in no case have we been able to observe again the 

 formation of prussic acid within a reasonable time, though in every case 

 prussic acid was liberated on the further addition of the mixture of enzymes 

 prepared from the beans of Phaseolus lunatus or from flax or cassava. 



* M. Kohn-Abrest's results are dealt with more fully in a recent paper (Dunstan and 

 Henry, ' Annales de Chimie et de Physique/ January, 1907). 



t Dunstan, Henry, and Auld, ' Eoy. Soc. Proc.,' 1906, vol. 78, p. 145. 



J Jorissen, ' Bull. Acad. Eoy. Belg.,' 1884 (iii), vol. 6, p. 718. 



§ Jorissen and Hairs, 'Bull. Acad. Eoy. Belg.' (iii), vol. 21, p. 529. 



|| Jouck, ' Beitrage zur Kenntnis der Blausaure abspaltenden Glycoside,' Strassburg, 

 1902. 



1" Dunstan and Henry, ' Eoy. Soc. Proc., 5 1903, vol. 72, p. 285. 



