The Nature and Origin of the Poison of Lotus Arabians. 225 



certain stages of its growth it is highly poisonous to horses, sheep, 

 and goats, the poisonous property being most marked in the young 

 plant up to the period of seeding. Owing to the trouble which this 

 plant has given to the military and civil authorities in Egypt, the 

 assistance of the Director of Kew was sought in order that the precise 

 nature of the poison might be ascertained, and, if possible, a remedy 

 found. The matter having been referred to the Scientific Department 

 of the Imperial Institute, Mr. E. A. Floyer, Director of Egyptian 

 Telegraphs, collected some of the material for investigation. 



It was found that when moistened with water and crushed, the 

 leaves of the plant evolved prussic acid in considerable quantity, the 

 amount being greatest in the plant just before and least just after the 

 flowering period. Further investigation has shown that the prussic 

 acid originates with a yellow crystalline glucoside (Co^HioNOio), which 

 it is proposed to name lotusin. Under the influence of an enzyme, 

 also contained in the plant, lotusin is rapidly hydrolysed, forming 

 prussic acid, sugar, and lotoflavin, a new yellow colouring matter. 



The hydrolysis may be effected by dilute acids, but is only very 

 slowly brought about by emulsin and not at all by diastase. The 

 peculiar enzyme, which it is proposed to call lotase, appears to be 

 distinct from the enzymes already known. Its activity is rapidly 

 abolished by contact with alcohol, and it has only a feeble action on 

 amygdalin. Old plants are found to contain lotase but no lotusin. 



The mgar has been proved to be identical with ordinary dextrose. 



Lotoflavin, the yellow colouring matter, has the composition expressed 

 by the formula CiaHioOc. It belongs to the class of phenylated 

 pheno-y-py rones, and is a dihydroxychrysin, isomericwith luteolin, the 

 yellow colouring matter of Reseda luteola, and with fisetin, the yellow 

 colouring matter of Rhus cotinus. 



The decomposition which ensues on bringing lotase in contact with 

 lotusin, as happens when the plant is crushed with water, is therefore 

 probably expressed by the following equation : 



Co,H 19 N0 10 + 2H 2 == C 15 H 10 Oo + HCN + CoH^Oo. 



Lotusin. Lotoflavin. Prussic acid. Dextrose. 



Hydrocyanic (prussic) acid occurs in small quantity in many plants, 

 and according to Treub and Greshof is often present in the free state. 

 The only glucoside at present definitely known which furnishes this 

 acid is the well-known amygdalin of bitter almonds, which under the 

 influence of the enzyme emulsin, also contained in the almond, breaks up 

 into dextrose, benzaldehyde, and prussic acid. 



Owing to the scientific interest which attaches to this new gluco- 

 side, its properties and those of its decomposition products have been 

 very fully studied, and the characteristics of the new enzyme have also 

 been investigated. 



