1908.] 



Phaseolus Lunatus Beans. 



729 



98 per cent, of true linseed. The amount of prussic acid 

 yielded by the two samples was estimated and found to be as 

 follows : — 



These quantities it will be seen are about 50 per cent, greater 

 than those obtained from any of the samples of Burma beans 

 examined. Although cases of the poisoning of cattle by the 

 .green stems of linseed have been recorded in India, there are, 

 so far as is known, no cases of poisoning of cattle by linseed 

 cake on record in this country. 



There is, however, one important difference between the 

 <f availability " of prussic acid in the beans of Phaseolus lunatus 

 and in the linseed cake of commerce. The former when ground 

 and placed in water develop prussic acid immediately, but no 

 prussic acid is formed when ground linseed cake is placed in 

 water. This difference appears to be due to the fact that 

 linseed cake is now made by hot expression of the oil, and the 

 heat applied in this process is sufficient to destroy the activity 

 of the ferment, to the effect of which on the glucoside contained 

 in the linseed, the liberation of prussic acid is due. There is, 

 however, always the possibility that the prussic acid-yielding 

 glucoside may be decomposed by ferments present in other 

 feeding stuffs used along with the linseed cake, even if it is not 

 acted on by intestinal ferments after ingestion. 



In connection with this subject it may be of interest to 

 mention what is known regarding the use of cassava in tropical 

 countries. Two varieties of this plant, the bitter and the 

 sweet, are known, and it was long supposed that only the roots 

 of the bitter sort yielded prussic acid and were toxic. Recent 

 investigations have, however, shown that at least in the 

 West Indies both the sweet and bitter varieties yield 

 similar amounts of prussic acid. Oar investigations have 

 shown that the origin of prussic acid in cassava is the same 

 as in the beans of Phaseolus lunatus and linseed, viz. : — the 

 interaction of phaseolunatin and a ferment. (Proc. Roy. Soc, 

 1906, B. LXXVII, 152). In preparing meal from cassava 

 roots these are usually rasped into a coarse powder and the 



Prussic Acid. 



Sample No. I 

 No. 2 



Per cent. 

 0-035 

 0*041 



