348 MANUAL OF POISONOUS PLANTS 



matic conditions and different conditions of growth may produce varying 

 amounts of prussic acid. I was told in Texas that the sorghum most poisonous 

 to live stock is the second growth. 



In regard to the chemistry of the subject. Dr. S. Avery says: 



In 1886 Berthelot and Andre ascribed the cause to excessive amounts of potassium 

 nitrate (salt peter). Williams of the U. S. Department of Agriculture also suggests 

 saltpeter as a cause of the trouble. Hiltner has shown that the amount of nitrate in 

 Nebraska fields was too small to produce fatal results. This writer suggests that the 

 plant under certain conditions develops a highly poisonous chemical compound. Slade 

 in the Annual Report of the Station for the present year (1902) put forward the 

 theory that such a compound might be produced by the action of an enzyme upon a 

 glucoside found in the plant through a process of abnormal growth. On June 27th of the 

 present year the Chemical News of London contained an article on Cyanogenesis in 

 Plants by Dunstan and Henry. This article, which finally confirms Slade's prediction, 

 was not known to Mr. Slade or to the writer till October 10th. In brief, the English 

 Chemists isolated from Egyptian Sorghum vulgare a glucoside capable of liberating prussic 

 acid. In the meantime Mr. Slade had detected Prussic acid in fatal sorghum grown in 

 western Nebraska, determined the per cent, and secured strong evidence in favor of the 

 glucoside theory. 



During the first two weeks in September, the writer discovered that Prussic acid 

 could be obtained from leaves of healthy sorghum in the fields about the Station. 

 As the past season was abnormally wet, nearly all of the fields had made a vigorous growth. 

 By distilling water from a sufficient quantity of leaves, determinable amounts of Prussic 

 acid were evolved in all cases, though the amount was well below the danger line. 

 Of the common Nebraska forage plants, sorghum and Kaffir corn alone yield Prussic 

 acid 



The substance dhurrin C^H^.NO. occurs according to Dunstan and Henry 

 in young plants of A. Sorghum. A glucoside resembling that found in almonds 

 also occurs ; it differs however but is capable of being converted into hydro 

 cyanic acid, HCN. The investigations made at this station show that the 

 prussic acid is not present as such, but that it is liberated from a glucoside. 

 (1) by an enzyme in the plant as in the case of sorghum poisoning, and (2) 

 by the action of boiling water on the plant. Glucosides of this sort are in 

 themselves harmless and are dangerous only when they liberate prussic acid. 

 The experiments mentioned above also showed that even dried plants may con- 

 tain a very large amount of combined prussic acid. We should expect that 



( 



such a fodder would be as fatal to stock after curing as when standing in the | 

 field. Experience, however, seems to prove the contrary. Enzymes rapidly 

 become inactive when dried in the presence of protein substances, according to ) 

 Dr. A. F. Woods, Chief of Division of Plant Pathology. 



Antidotes. Prussic acid has a tendency to unite with certain carbo- 

 hydrates, forming additional products. These compounds are much less poison- 

 ous than the free acid. Both glucose and milk sugar unite with Prussic acid 

 to some extent even in dilute solutions. Aside from this action these carbo- 

 hydrates retard the action of the enzyme in liberating Prussic acid. These 

 facts suggest that, in case the animal is not in such a conditon as to render 

 medical treatment out of the question, the following may be affective : 



A strong solution of glucose, which nearly ever)' farmer has at hand in the 

 form of "corn syrup" or molasses, may be administered. 



Large quantities of milk have in a number of instances been administered 

 apparently with good effect. 



In all cases the animal should have as much fresh air as possible. 



