148 



Drs. Dunstan, Henry, and Auld. 



[Apr. 11, 



distillate. Detailed accounts of the methods of carrying out the estimation 

 of the amounts of cyanogenetic glucoside contained in plants are given in the 

 preceding papers of this series.* 



The results obtained by the estimation of the amounts of hydrocyanic acid 

 yielded under these conditions by young flax plants were as follows : — 



Height of flax 

 plants in inches. 



Grown at — 



Hydrocyanic 

 acid found. 



Q-lucoside 

 calculated. 







per cent. 



per cent. 



Seed 





0-008 



0-07 



1— 1-5 





0-15 



1-4 



2— 3 



>> >; 



0-17 



1 -5 



3— 4 



)j >> 



0-15 



1 -4 



4- 5 





0-13 



1-2 



5— 6 



0-10 



0-9 



6- 7 





0-10 



0-9 



8—10 





0-08 



0-7 



12—15 





0-07 



0-6 



15—18 





0-03 



0-3 



18 





0-009 



0-08 



18 





None 



None 



These results are of special interest since, apart from indicating the stages 

 in the growth of the plant at which the isolation of the glucoside could be 

 most hopefully undertaken, they show that the course of cyanogenesis in the 

 flax plant is different from that in Lotus arabicus and in Sorghum vulgare. 

 In each of these two plants it has been shown in the first two papers of this 

 seriesf that the amount of the characteristic glucoside present steadily 

 increases until the plants approach maturity, then decreases, and that none is 

 present in the seed. In flax, on the other hand, the seed contains a small 

 amount of the glucoside which increases on germination, reaches a maximum 

 at a very early stage in the growth of the plant (when it is from 2 to 3 inches 

 high) and then diminishes steadily and finally disappears altogether. These 

 results on the whole confirm those of Jorissen, who also observed that a very 

 large increase of the glucoside occurred with the germination of the seed, 

 though the amounts recorded by him are smaller than those now found. 

 These differences are probably due to the fact that Jorissen estimated the 

 amount of glucoside present by determining the amount of hydrocyanic acid 

 formed, by merely moistening a known weight of ground seed. Under these 

 conditions it is improbable that the whole of the glucoside undergoes hydro- 

 lysis, and for this reason Jorissen's results are probably too low. 



* Dunstan and Henry, ' Phil. Trans.,' B, 1901, vol. 194, p. 515 ; A, 1902, vol. 199, 

 p. 399 ; and ' Koy. Soc. Proc.,' 1903, vol. 72, p. 285. 

 t Loc. cit. 



