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Herbage Studies. II. — Variation in Lotus corniculatus and 

 Trifolium repens (Cyanophoric Plants). 



By H. E. Armstrong, F.R.S., E. Frankland Armstrong, and 

 Edward Horton. 



(Received January 1, — Read January 23, 1913.) 



Lotus corniculatus. 



In Part I of these studies, it is shown that Lotus corniculatus is a plant in 

 which a glucoside containing cyanogen is frequently present together with 

 the corresponding enzyme. During 1911 we were able to make observa- 

 tions practically over the whole of Europe, owing to the assistance we received 

 from Dr. Eyre, which led us to the conclusion that the glucoside and enzyme 

 were normal constituents of the plant in almost all districts, though 

 occasionally, in close proximity to plants which were cyanophoric, others 

 were met with in which little if any cyanide could be detected. In 

 Scotland, in South Ayrshire, the plant was uniformly acyanophoric, except 

 on the coast ; nor could cyanide be detected in plants collected in Norway. 



Lotus major, which is a sufficiently distinct variety to have been recognised 

 by botanists as a separate species, was uniformly free from cyanide and also 

 apparently from enzyme ; but no regular distinction could be made between 

 the various other forms which botanists look upon as merely varieties of the 

 plant. Lotus major, it should be added, always affects damp situations and 

 is a rank grower ; it can be distinguished by the manner in which the 

 large number of flowers in the umbel spread out from a common centre 

 instead of at intervals from the flower stalk ; the calyx teeth also tend to 

 spread outwards, whereas in other forms they are almost uniformly strongly 

 incurved. We have found the double form of L. corniculatus (var. pleno) to 

 be strongly cyanophoric. 



During 1912, we have again examined specimens of L. cornicxdatus from many localities 

 in England and Wales and, as a rule, have found them to be strongly cyanophoric* Out 



* During 1912, in testing for cyanide, the Guignard picrate paper used was always 

 prepared as required and we have substituted toluene for chloroform in order to avoid 

 the possibility of any trace of acid being introduced. In the morning, before going into 

 the field, strips of paper were impregnated with the alkaline picrate solution and the 

 moist strips were at once placed in the tubes which were to be used in testing the plants. 

 The tubes were then incubated in the pocket, in order to ascertain whether any 

 hydrogen cyanide was retained in the cork. Recently prepared undried paper is usually 

 more sensitive than paper which has been dried and then moistened just before it is to 

 be used ; the once dried paper rarely has the bright yellow appearance of freshly stained 

 paper. 



