44 SCIENCE PROGRESS 



paragraphs, was isolated by Dunstan and Henry : from the 

 common sorghum, or " great millet " {Sorghum vulgare), a plant 

 widely cultivated in tropical and sub-tropical countries for the 

 sake of its edible grain, which forms a staple food-stuff of the 

 great majority of the natives of India, Egypt, and other countries. 

 The glucoside is secreted in the young green parts of the plant, 

 and the amount present increases up to the time that the plant 

 is about 12 inches high, after which it diminishes, the mature 

 plant and the seed being quite free from it. 



Dhurrin is decomposed by hot dilute hydrochloric acid or 

 by emulsin (which also occurs in the plant) in accordance with 

 the following equation : 



C 14 H 17 7 N + H.,0 = C 6 H 12 O a + HCN + C fi H 4 (OH). CHO 



Dhurrin. Dextro-glucose. Prussic acid. Para-hydroxybeiizaldehyde. 



This reaction indicates that the relation of dhurrin to mandelic 

 nitrile glucoside (or sambunigrin) is that of a para-hydroxy 

 derivative. Young sorghum plants have long been known to 

 be occasionally poisonous to cattle, and much speculation has 

 at different times been indulged in as to the nature and origin 

 of this poison, some authorities asserting that it was a secondary 

 effect only exhibited by diseased sorghum, and others that what 

 was called "sorghum poisoning" was really "hoven" (a form 

 of indigestion), produced by immoderate consumption of the 

 young green plant. There can be no doubt now, however, 

 that the toxicity of young sorghum is due to the generation 

 of prussic acid by the interaction of "dhurrin" and emulsin in 

 the plant. 



The glucoside has as yet only been isolated from sorghum 

 grown in Egypt; butSlade 2 and Brunnich 3 have shown inde- 

 pendently that green sorghum grown in the United States and 

 in Queensland yields prussic acid, and there can be little doubt 

 therefore that Sorghum vulgare always contains the glucoside at 

 least in the earlier stages of growth. 



Dhurrin is the only cyanogenetic glucoside so far isolated 

 from a grass ; but several members of the same natural order 

 have been shown to yield prussic acid, notably "Guinea 

 grass " iPanicum maximum), " Para grass " (P. muticum)? and 

 ordinary maize {Zca mays), in which, as in sorghum, the amount 

 of prussic acid obtainable increases up to a certain stage, and 



1 Phil. Trans. 1902, A. 199, 399. 3 / Chan. Soc. 1903, 83, 788. 



*/. Amer. Chem. Soc. 1903, 25, 55. " Ibid. 



