11 



poison, and that in the cases of feeding in which poisoning occurs it is 

 likely that there is some element which interferes with the inhibition 

 which would normally take place. The possibility of the formation of 

 hydrocyanic acid in the food before feeding is very likely in cases in 

 which the feeding stuff is manipulated or prepared before administra- 

 tion. In the case of green food, only the rupturing of the cells is suf- 

 ficient to produce the free poison, and in the case of the dry material, 

 which is generally more or less broken up, it is only necessary to intro- 

 duce moisture to produce the free poison. If inhibition can be due to 

 an alkaline medium, the normal conditions in the mouth during eating 

 and in the rumen of the animal would have a protective action and 

 would tend to prevent poisoning. Anything interfering with normal 

 mastication and the attendant mixing of saliva with the food would 

 evidently interfere with the inhibitory process and end with disastrous 

 results. Auld (loc. cit.) points out the protective effect of cellulose and 

 glucose, and that these carbohydrates have an inhibitory action on the 

 evolution of hydrocyanic acid has been observed by other investigators 

 with other plant materials. In fact, it has been recommended 5 that 

 glucose be used as an antidote in cases of< poisoning from this source. 

 As a matter of fact, it is probable that the administration of glucose 

 would have but little effect if done after the symptoms of acute poison- 

 ing have developed. However, if a suspicious food was to be fed, it 

 might be mixed with a glucose-containing material as a precautionary 

 measure. 



Another and equally important factor is that of the physical con- 

 dition of the animal when fed ; the state of its health and whether the 

 food in question is taken upon a partially filled or empty. stomach. It 

 would appear in the case of sorghum, for example, that cows turned 

 into sorghum would be fatally poisoned if nothing had been eaten for 

 a short time previously; but if they were first fed and then allowed 

 access to the same plants no poisoning would follow. 



The Season of the Year when Arrow-Grass Is Poisonous. 



Feedings were made with arrow-grass cut both in early summer and 

 during fall. It appeared equally poisonous at both seasons. There is 

 good reason for believing that the .plant is toxic during the entire 

 period of its growth. 



The Part of the Plant which Is Poisonous. 



The greater part of arrow-grass consists of the leaves, the flower 

 stalk making only a small portion of its total weight. The leaves have 

 been conclusively proven to be poisonous. We have not found out 

 whether the flower stalks are poisonous because they are more or less 

 tough and unpalatable and make up only a minor part of the total 

 weight of the plant. The roots are so firmly held down by their fibrous 

 growth that there is little or no chance of their being eaten. 



The following tables give the feeding tests which were made with 

 sheep and cattle in the fall of 1918 and the spring and summer of 1919 ; 

 all the animals were fed the fresh green leaves except a single sheep 

 weighing seventy pounds which was fed three-fourths of a pound of 

 the green fruits without results : 



"'Peters, A. F., Slade, H. B., and Avery, Samuel: Poisoning of Cattle by Common Sorghum 

 and Kafir Corn. Nebraska Station Bulletin No. 77. 



