1912.] 



Studies on Enzyme Action. 



373 



were able, during the past season, which was so exceptionally favourable 

 to ripening, to place this conclusion beyond doubt. Eipe seeds were always 

 found to be free from cyanide but we have invariably detected it in unripe 

 seeds. Flax being a plant which continues, during a considerable period, to 

 flower and produce seed, the seeds never ripen all at once, so that when the 

 crop is harvested the plants always carry a mixture of ripe and unripe seed : 

 it is therefore easy to understand the presence of cyanide in the com- 

 mercial cake. 



The tendency has been to regard the potential presence of hydrogen 

 cyanide in linseed cake as harmful but taking the very special and peculiar 

 properties of the cyanide into account, it may well be that it is of positive 

 condimental value and that the peculiar value of linseed cake as a cattle 

 food is at least in part due to the liberation of minute proportions of such a 

 substance.* 



Hydrogen cyanide was detected by Jorissen in only two of the Linaceae, 

 L. usitatissimum and L. perenne. During 1910, owing to the kindness of 

 Dr. Hugo Miiller, we were able to test several of the yellow flowered 

 species, in addition. Last year, we procured seed from various European 

 Botanic gardens and from seedsmen of as many varieties of Linaceae as 

 possible and grew these ourselves. A considerable proportion of the seeds 

 we obtained bore fancy names and proved to be varieties either of 

 L. usitatissimum or of L. angustifolium or L. perenne. We were able to 

 satisfy ourselves that all the species resembling either ordinary flax 

 (L. usitatissimum) or L. perenne in general habit of growth, carrying white, 

 blue or red (L. grandijiorum) flowers, were more or less richly cyanophoric ; 

 we uniformly failed, however, in obtaining hydrogen cyanide from the 

 yellow-flowered species (L. arboreum, L. flavum, etc.). The amount of 

 cyanophoric glucoside present in different species is different and is subject 

 to variation throughout the period of growth. In the case of L. usitatissimum, 

 the maximum proportion is reached at a very early stage but even when 

 mature and full of seed this species still contains cyanide. In the case 

 of L. perenne, the mature foliage may contain no cyanide, although it is 

 easily detected in the young shoots. Linum grandijiorum appears to contain 

 the major proportion of cyanide at the flowering period.f 



* Compare ' Koy. Soc. Proc.,' 1912, B, vol. 84, p. 471. 



t Note added June 24, 1912. — The observations have now been extended to other 

 species of blue-flowering Linaceae, and evidence has been obtained that besides L. perenne 

 several others, namely L. narbonense, L. hologynum, and L. suffruticosum, also lose the 

 cyanophoric glucoside at quite an early stage of their development. 



Up to the present the following yellow-flowering species have been examined : — 

 L. arboreum, L. campanulatum, L. flavum, L. flavum luteum, L. salsoloides, L. maritimum, 



