372 



Prof. H. E. Armstrong and Dr. J. V. Eyre. [Apr. 3, 



The conclusion that both glucosides can be hydrolysed by one enzyme 

 (linase) rests, however, at present, on the observations made with the enzyme 

 or enzymes extracted from the Phaseolus bean ; hence the importance of 

 ascertaining the effect produced by enzymes obtained from other sources. 

 Whatever their range of activity, as the activity of both enzymes is much 

 diminished by the presence of glucose, it is to be supposed that both are so 

 constructed that each can fit the glucose section of its " co-glucoside " while 

 in correspondence also with the radicle with which the glucose residue is in 

 association ; so that if it be proved eventually that only the enzyme corre- 

 sponding to the simpler compound is compatible with both glucosides, it 

 will follow that the smaller key can be passed into both locks but that the 

 larger will not fit into that to which the smaller key properly belongs. The 

 problem whether linase can exercise such a dual activity, therefore, is one of 

 very great interest. 



Hydrogen Cyanide from Linacece. 



Of late years, much uneasiness has been felt in agricultural circles owing 

 to statements that have been made that hydrogen cyanide may be present 

 even to a dangerous extent in linseed cake. There is no doubt that usually, 

 if not always, it can be detected in the commercial article. In view of the 

 constant presence of linamarin in the green plant and the unripe seed, this 

 is not surprising. During the past two years we have studied the seed 

 systematically from this point of view. 



It is easy to detect hydrogen cyanide even in a single flax seed by means 

 of Guignard's picrate test. For this purpose, a convenient length — 2 or 

 3 inches — of narrow quill tubing is sealed at one end and rounded in the 

 flame at the other ; a similar piece of narrower tube, which will just slide into 

 the wider tube, is also prepared ; and an air-tight joint between the two 

 tubes is provided by means of a short length of narrow rubber tubing. 

 After the'seed to be tested has been pricked in several places with a pin, it 

 is placed at the bottom of the larger tube together with a drop of water and 

 a minute drop of chloroform. A diamond-shaped piece of moist picrate 

 paper, a few square millimetres in area, having been fixed in the open end of 

 the narrower tube, this tube is adjusted within the wider tube so that the 

 picrate paper is just above the seed. The tube is then maintained at about 

 35° in an incubator or simply kept in the waistcoat breast pocket. If 

 cyanide be present, the yellow paper darkens and becomes orange or orange- 

 red within 24 — 48 hours. 



We had fairly satisfied ourselves during 1910 that the presence or absence 

 of the cyanide was dependent on the degree of maturity of the seed ; we 



