0?r TllE CHEMICAL ASPECTS OF CYANOGENESIS IIS PLAJ^TS. \i7 



thouyh Simon,' Michelsohn,* Lehmauii,^ and Jouck ^ had previously 

 obtained the glucoside in an impure state. In this impure form it was 

 known as ' laurocerasin,' or ' amorphous amygdalin.' The production of 

 prussic acid when laurel leaves are crushed and moistened with water was 

 lirst recorded by Schrader,^ and subsequently by Winkler, wlio also 

 noticed the presence of benzaldehyde in the distillate.'' Prulaurasin is 

 isomeric with raandelic nitrile glucoside and with sambunigrin, and, like 

 both these substances, is hydrolysed by emulsin or by hot, dilute hydro- 

 chloric acid, yielding one molecule each of prussic acid, benzaldehyde, and 

 dextrose. The principal properties of these three isomerides are shown in 

 the following table : — 



If it may be assumed that they are diflerent — and the evidence oil 

 this point is not as conclusive as is desirable, having regard to the diffi- 

 culty of isolating these glucosides in a pure state from plants- the 

 differences Ijetwetii thciii probably lie in the nature of the sugar i-esidue, 

 and it is desirable that the sugars produced from them on liydrolysis 

 should be carefully examined. 



Glucosides yielding both prussic acid and benzaldehyde are also known 

 to occur in the barks, seeds, and leaves of a large number of rosaceous 

 plants. Lists pf these and references to the literature dealing with them 

 are given by GreshofFin ' Monographia de plantis venenatis et sopientibus 

 quae ad pisces capiendos adhiberi solent,' ii.,' and by .Jouck in ' Beitragc 

 zur Kenntnis der Blausiiui-e abspaltenden Glycoside,' Strasburg i. E , 

 1902. Crystalline glucosides have not been isolated from any of these 

 plants, though in several cases an ' amorphous amygdalin ' has been 

 obtained. 



Dhurrin, 



This glucoside was isolated by Dunstan and Henry ^ from the leaves 

 and stems of the ' great millet ' (Sorrjlium vulgare) grown in Egypt. This 

 plant is much cultivated in tropical countries for the sake of its edible 

 graiji, which forms one of the staple foods of the natives of India (Jiair), 

 Egypt {dlinrra), West and East^Vfrica (*;iffto/H«), t^outh Africa ('Guinea' 

 or * KaHir ' corn), the West Indies, the United >States, and elsewhere. 

 With the gradual introduction of European methods of agriculture into 

 tropical countries it has become customary to take advantage of the 

 rapidity and ease witji which crops of 'great millet' can be obtained to 



' Ann. Chem. Pharm, 18.S0. 



•■• Neucs Jiepertormm, 1874, 23. 449. 



* Vber das Ami/ifdali7t, 1S70. 



* Inaug. Diss. Strashvrg, 1002. 

 ■■' Tfommndnrfg Journal, 180.S. " Hep. Pharm., 18H9. 



♦ Published in Mededeclingen uit 's lands plantentuin, Batavia, 1900. 

 « Phil. Trans., 1902, A, 199, 399. 



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