42 SCIENCE PROGRESS 



by animals, the acid being formed in the usual way by the decom- 

 position of a cyanogenetic glucoside by an enzyme, both these 

 substances being simultaneously present in the plants. 



Investigations have been somewhat actively prosecuted along 

 these various lines during the last few years, and results of 

 some general interest have been obtained, the most important 

 points of which are dealt with in the succeeding paragraphs 

 of this article. 



Cyanogenetic Glucosides 



Amygdalin. — This, the best-known member of the group of 

 •cyanogenetic glucosides, was isolated from bitter almond seeds 

 by Robiquet and Boutron-Charlard l in 1830, and was subse- 

 quently investigated by Liebig and Wohler, 2 who first explained 

 its real nature. 



It can be decomposed by enzymes in two stages, which may 

 be represented by the following equations : 



(1) CooH.A.N + H 2 = C 6 H,A + C 14 H 17 6 N 



Amygdalin. Dextro-glucose. Mandelic nitrile glucoside. 



(2) C 14 H 17 6 N + H 2 = C 6 H,,0 6 + HCN + C 6 H 5 . CHO 



Mandelic nitrile glucoside. Dextro-glucose. Prussic acid. Bensaldehyde. 



Y 



Oil of bitter almonds. 



The first stage is brought about by the action of the enzyme 

 maltase of yeast, 3 and the second by the action of the enzyme 

 £rnulsin, which occurs in both sweet and bitter almonds ; but 

 it should also be stated that emulsin has the property of 

 decomposing amygdalin directly into glucose, prussic acid, and 

 benzaldehyde without the apparent intervention of mandelic 

 nitrile glucoside, and it is to the interaction of these two 

 .substances in ground bitter almond seeds that the production 

 of " natural oil of bitter almonds " is due. 4 



It is generally believed that sweet almond seeds contain the 

 enzyme emulsin but not the glucoside amygdalin, although 

 Fliickiger and Hanbury 5 state that moist sweet almond seeds 

 invariably yield traces of prussic acid when comminuted. 

 Jorissen 6 has also observed that the embryo of the sweet 



1 Ann. chim. fihys. 1830 [ii.], 44, 352. 



2 Ann. Chem. Pharm. 1837, 22, 11. 



3 Fischer, Ber. der Deutsch. Chem. Ges. 1894, 27, 2989 ; 1895, 28, 1809. 



4 Liebig and Wohler, loc. cit. 



5 Pharmacograpkia, London, 1879, 247. 



6 Ann. Agron. 1885, 10, 468. 



