568 
On the Probable Hxistence of Emulsin in Yeast. 
By THomas ANDERSON HEnRy, D.Sc. (Lond.), Principal Assistant in the 
Scientific and Technical Department of the Imperial Institute, and 
S. J. M. AuLp, Ph.D. (Wiirzburg), Assistant in the Scientific and 
Technical Department of the Imperial Institute. 
(Commi nicated by Professor Wyndham Dunstan, F.R.S. Received July 22, 
1905.) 
The observations of Treub,* Greshofft Jouck,{ and other investigators 
have established the fact that hydrocyanic acid is furnished by a compara- 
tively large number of plants belonging to a wide range of natural orders. 
Dunstan and Henry have applied to this process the name “ cyanogenesis,’ 
and have shown that in many plants the production of hydrocyanic acid is 
due to the interaction of a cyanogenetic glucoside with a specific enzyme. 
Thus in Lotus arabicus, the hydrocyanic acid is produced by the decomposition 
of the glucoside lotusin by the enzyme lotase,§ in Sorghum vulgare by the 
action of emulsin on the glucoside dhurrin,|| and in the seeds of Phaseolus 
lunatus as the result of the decomposition of phaseolunatin by the enzyme 
emulsin.{/ The same authors have indicated that similar actions probably 
take place in cassava (Manihot utilissima), Lotus australis and Chaalletia 
cymosa, all of which have been found to yield hydrocyanic acid when crushed 
in presence of water.** | 
The isolation of these cyanogenetic glucosides is often a matter of 
considerable difficulty, because, as a rule, they are only soluble in water and 
aqueous alcohol, and it is therefore a troublesome operation to separate them 
from the associated sugar (usually dextrose) and pectous matter which are 
also, in general, only soluble in the same solvents. In a few cases it has been 
found possible to remove dextrose from such mixtures by the action of 
phenylhydrazine, but this process usually leads to the loss of a portion of the 
glucoside, owing to partial condensation with the reagent.t+ Some cyano- 
genetic glucosides are also slightly soluble in ethyl acetate, and this solvent 
* ¢ Annales du Jardin Botanique de Buitenzorg,’ vol. 9, p. 259. 
+ ‘Berichte,’ 1890, vol. 23, p. 3548. 
{ ‘Inaug. Dissertat.,’ Strassburg, 1902. 
§ ‘Phil. Trans., B, 1901, vol. 194, p. 518. 
|| Ibid., A, 1902, p. 399. 
J ‘ Roy. Soc. Proc.,’ 1903, vol. 72, p. 285. 
** ¢Phil. Trans.,’ A, 1902, vol. 199, p. 399, and ‘Bulletin of the Imperial Institute,’ 
1903, vol. 1, pp. 12 and 112. 
++ Dunstan and Henry, ‘ Phil. Trans.,’ A, 1902, vol. 199, p. 402. 
a 
