376 



Messrs. W. E. Dunstan and T. A. Henry. 



With the exception of amygdalin, lotusin is the only glucoside 

 definitely known which furnishes prussic acid as a decomposition 

 product. 



Lotoflavin. 



Lotoflavin is a yellow crystalline colouring matter readily dissolved 

 by alcohol or by hot glacial acetic acid, and also by aqueous alkalis 

 forming bright yellow solutions. It is always present to some extent 

 in the plants, especially in old plants. Ultimate analysis leads to the 

 formula Ci 5 Hio0 6 . It is therefore isomeric with luteolin, the yellow 

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

 from young fustic, Rhus cotinus. Morin, from Morns tinctoria, appears to 

 be hydroxylotoflavin. 



Lotoflavin does not form compounds with mineral acids. It 

 furnishes a tetracetyl derivative and two isomeric mutually con- 

 vertible trimethyl ethers which are capable of forming one and the 

 same acetyl-trimethyl-lotoflavin. By the action of fused potash loto- 

 flavin is converted into phloroglucin and /3-resoreylic acid. 



Dextrose. 



The sugar resulting from hydrolysis has been found to correspond 

 in all properties with ordinary dextrose. 



Hydrocyanic acid. 



The amount of prussic acid given by plants at different stages of 

 growth has been ascertained. Mature plants bearing seed-pods have 

 furnished 0'345 per cent, of this acid, calculated on the air-dried 

 material which corresponds with 5*23 per cent, of lotusin. Younger 

 plants bearing flower buds gave 0*25 >per cent., whilst still smaller 

 quantities were furnished by very young plants and hardly any by quite 

 old plants from which the seeds had fallen. 



The formation of the poison, therefore, seems to reach its maximum 

 at about the seeding period, and after this period to diminish rapidly. 

 The Arabs are aware that the plant is safe to use as a fodder when the 

 seeds are quite ripe, but not before. We have found that it is the 

 lotusin which disappears during the ripening of the seeds. Old plants 

 contain some lotase and lotoflavin, but little or no lotusin. 



Lotase. 



In its general properties lotase resembles other hydrolytic enzymes, 

 from which, however, it differs in several important respects. It may 

 be compared with emulsin, the enzyme of bitter almonds. Emulsin, 

 however, only attacks lotusin very slowly, whilst lotase has but a feeble 



