^J Graminese 83 



kiUed by giving it 2 kilogrammes (4-4 lb.) of Darnel. Comevin concluded 

 that the amounts of Darnel necessary to kill certain animals would be 

 as follows: — 



Horse 0-7 lb. per 100 lb. Hve weight. 



Ruminants .. .. 1-5 to 1-8 lb. per 100 lb. Uve weight. 

 Poultry .. .. 1-5 to 1-8 lb. 



^°g i-8ib. „ ,; 



He found pigs very little affected. As regards man 30 grammes 

 (1 oz.) of the flour appear to be about the most that can be taken without 

 showing dangerous symptoms. 



The presence of Darnel flour in flour of the cereal grains may be 

 determined by an examination of the starch granules, which are given by 

 Comevin as only 5 to 8/* in diameter (compared with 25 to 45 /x for 

 rye), simple in general, but sometimes in groups of 2 to even 5, poly- 

 hedral or partly rounded, with a nucleus or fusiform nucleal cavity, 

 and readily coloured blue with iodine ; they resemble those of maize but 

 are only about one-eighth the size. 



Toxic Principle. The grains only are harmful, and contain the 

 narcotic alkaloid Temuline (C^HijNaO), which Hofmeister showed to 

 be a strong nerve poison, and which is said to occur to the extent of 

 0-06 per cent, in the seeds. Other authorities impute the toxic property 

 to Loliine, while Smith states that the toxic principle is Picrotoxin. In 

 relation to the grain fungal hyphse have usually been found, though not 

 invariably, 20 to 30 per cent, of the plants sometimes being free from 

 it. The fungus (Endoconidium temulentum) is propagated vegetatively 

 by means of mycelium. It appears to live symbiotically in the maturing 

 grain, and perhaps to a sUght extent renders possible the assimilation 

 of nitrogen from the atmosphere ; but Freeman observed that though 

 generally stimulating to the Darnel, it is occasionally injurious to it. 

 Esser sums it up by saying that according to most authorities who have 

 investigated Darnel the fungus alone contains the toxic substance — 

 the Temuline — and hence the grains in which the fungus does not 

 occur should be harmless. The fungus is found in Darnel grain in all 

 countries — Chile, Brazil, S. Africa, Persia, Spain, France, Sweden, 

 Germany, etc. So far as can be ascertained there have been no feeding 

 experiments to determine the difference in toxic character between 

 fungus-infested and fxmgus-free grains. The dangerous properties are 

 said to be most pronounced in wet seasons. 



Symptoms. In France Darnel is called Iwaie, because, when brewed 

 with barley, it acts as a narcotic intoxicant. 



6—2 



