AMYGDALIN, DHURRIN, ETC. 179 



If crystals of amygdalin be dissolved in water and then 

 subjected to the action of maltase the hydrolysis will not 

 proceed further than is represented in the first of the two 

 above equations ; emulsin, on the other hand, can hydrolyse 

 the mandelonitrile glucoside as indicated in the second 

 equation, and, of course, it can bring about the whole series 

 of changes. 



The formation of mandelonitrile glucoside in this process 

 is of some interest since it is isomeric with the glucoside 

 sambunigrin which occurs in the fruit of the elder, Sambucus 

 nigra. 



The crude oil of bitter almonds contains hydrocyanic acid 

 which may be removed by distillation with lime and ferrous 

 chloride which converts the prussic acid into Prussian blue. 

 Pure benzaldehyde is a colourless or pale yellow liquid, soluble 

 in alcohol, but practically insoluble in water. Its specific 

 gravity is 1*05, and its boiling point 180° C. On exposure 

 to air it becomes converted into benzoic acid, 



DHURRIN. 



This is a glucose closely allied to amygdalin, and occurs 

 in the seedlings of Sorghum vulgare, but not in the older 

 plants ; it has the empirical formula Q^Hj^NO^ and yields, 

 on hydrolysis, glucose, hydrocyanic acid and parahydroxy- 

 benzaldehyde : — 



C14HJ7NO7 + H2O = CeHiaOg + HCN + CeH40HCH0 



Similar glucosides occur in the seedlings of Panicmn and 

 Zea. 



PHASEOLUNATIN. 



Phaseolunatin, Ci^Hi^OgN, occurs in the seeds of wild 

 plants of Phaseolus lunatus, it is present only in very small 

 quantities, or is entirely absent from the seeds of the culti- 

 vated plants. It is also present in Linum and many rubber- 

 yielding plants, such as Hevea braziliensis and species of 

 Maniliot. Associated with it in its natural surroundings is 

 the enzyme phaseolunatase which is able to hydrolyse it to 

 acetone, glucose, and prussic acid.* 



* Dunstan, Henry and Auld : " Proc. Roy. Soc, Lond.," B., 1906, 78, 145, 152. 

 12 * 



