1901.] 



Gyanogenesis in Plants. 



153 



large arterial trunk in its continuity does not find, on clearing the 

 vessel of its sheath with the point of his knife, that he is dealing with 

 a body that swells at every pulse, but with one of unvarying dimen- 

 sions." Experimenting on the metacarpal artery (horse) with the 

 circulation going on, he found that transverse measurements with 

 suitable callipers showed no change as long as the limb was kept in 

 any one position. 



" Oyanogenesis in Plants. Part II. — The Great Millet, Sorghum 

 vulgare"* By Wyndham E. Dunstan, M.A., F.E S., Director 

 of the Scientific Department of the Imperial Institute, and 

 T. A. Henky, D.Sc. Lond. Eeceived April 24, — Eead May 

 15,1902. 



(Abstract.) 



The authors have investigated the nature of the poison contained in 

 the young plants of Sorghum vulgare, the Great Millet or Guinea Corn 

 (the Judr of India or Dhurra shirshabi of Egypt). This plant is cultivated 

 in tropical countries for the sake of the seed, which is important 

 as a food grain. The young plants have proved fatal to animals, 

 especially in Egypt, where the attention of the authors was directed to 

 the subject by Mr. E. A. Floyer, of Cairo, who has kindly provided 

 the material required for the investigation. 



The authors show that the young plant, but not the seeds or old 

 plants, when crushed with water furnishes prussic acid (about 0*2 per 

 cent, of the dried plant). The acid is not present in the free state, nor 

 is it produced by acting on the plant with boiling water or with 

 alcohol. The production of the poison is due to the action of a hydro- 

 lytic enzyme, apparently identical with the emulsin of bitter almonds 

 on a cyanogenetic glucoside which has been named " dhurrin," from the 

 Arabic name for the plant, " dhurra." This glucoside has been proved 

 to be derived from parahydroxymandelic nitrile by the association of 

 the residue of one molecule of dextrose. Its formula is therefore 

 Ci 4 H ir 7 N, 



-OC 6 H u 5 



HO 



* The authors' previous paper, entitled "The Nature and Origin of the Poison of 

 Lotus arabicus" ('Proceedings,' vol. 67, 1900, p. 224; vol. 68, 1901, p. 374 ; and 

 ' Phil. Trans.,' B, vol. 194, 1901, p. 515), is to be regarded as Part I of this series. 



