PRUSSIC ACID IN THE LEGUMINOS^ 233 



much higher in the young- leaves and that it disappears as 

 the leaf ages and withers. 



Very younjT leaves ... ... ... ... 0232 per cent. 



Leaves on the point of falling... ... ... o'oog ,, 



There is, however, one exception to this rule, and it 

 occurs among the Leguminos^e. The species in cjuestion is 

 hidigofera galegoides, and it gives the following results : — 



Very young leaves 

 Young leaves 

 Adult ,, 

 Yellow ,, 

 Fallen ,, 



o'ii4 per cent. 

 0115 



0-I45 

 0-104 



o-io8 ,, 



One phenomenon observed by M. Treub is that the leaves 

 of Phascolus lunatus yield prussic acid when distilled direct, 

 that is, without previous maceration. 



Percentage of Prussic Acid in Fresh Leaves. 



M. Treub draws the following conclusions from these 

 experiments : *' Undoubtedlv a portion of the prussic acid 

 set free in direct distillations is due to a dissolution of 

 glucosides. Xo matter how rapid be the means adopted for 

 raising the temperature of the leaves to that of the boiling 

 point of water there still remains sufficient time for the 

 enzymes to bring about a certain reduction of the cyanhydric 

 glucosides. On this point a comparison of the mixture, after 

 direct distillation by means of boiling water, with that 

 obtained from a boiling sea-water solution, can leave no 

 doubt." 



Percentage of Prussic Acid in Fresh Leaves. 



X} •!• . Boiling salt water 



DOiline water ? .- 



° solution 



Phaseolus liinaliis ... ... ... o-o'o ... 0026 



„ ,, ... ... ... 0052 ... 0-029 



The differences which exist between direct distillations 

 and those after maceration allow us to suppose that the 



