POISONOUS PLANTS 195 



iodine coloration than wheat, or other cereal, or potato 

 starches. Eoughly, about seven to ten times as much 

 iodine is required (Tabourin). A meal of corn-cockle flour 

 (like that of lolium) gives a full orange-yellow solution when 

 10 grammes are warmed with 30 to 40 c.c. of 70 per cent, 

 alcohol, with 5 per cent, of dilute hydrochloric acid (Yogi's 

 test). Under the same conditions various other flours give 

 to the acid alcohol the following tints : fine wheat and rye, 

 colourless ; coarse wheat and rye, pale yellow ; barley and 

 oats, straw yellow ; pea meal, full yellow ; vetch and bean 

 meal, purple-red ; ergot, blood - red ; meals containing 

 rhinanthia, green. Ehinanthin is a glucoside contained in 

 certain of the Scro'phulariacea — e.g., Melampyrum, Rhinan- 

 ilius, etc. {g.v.). 



HYPERICACE.S;. 



Botanical Chapacters. — The only member of this family 

 reputed to be dangerous is Hypericum perforatum, or St. 

 John's- wort, which is abundant in woods, thickets, and 

 hedges, and found in Europe and America. It reaches 

 about 1 to 1^ feet, and bears a yellow flower. As cases of 

 poisoning by it are rare, a detailed description is un- 

 necessary. 



Active Principle, — The active principle of the St. John's- 

 wort has not been accurately studied. It appears to contain 

 a resin and a volatile oil. The resin is probably allied to 

 the drastic gamboge, obtained from species of the related 

 order, Guttiferce. 



Eifects. — The plant is not taken by animals save when 

 mixed with such forage as lucerne. Cornevin relates that 

 a mare under the influence of the plant became semi-coma- 

 tose, the head drooping between the outstretched forelegs. 

 The pulse was full and slow, respiration deep and slow, and 

 the appetite lost. The pupils were dilated, conjunctivae 

 injected, and the unpigmented skin of the nose coloured 

 wine red, as in purpura. In about twelve hours the con- 

 dition passed off. 



