10 



In the plants known as cyanogenetic plants, substances have been 

 found in which hydrocyanic acid is in combination with other com- 

 pounds. As an example of such compounds may be cited amygdalin, a 

 compound, which will yield hydrocyanic acid and benzaldehyde, found 

 in the bitter almond. Compounds of this sort may be made to give up 

 their hydrocyanic acid by the action of suitable reagents, such as by the 

 action of acids upon amygdalin. Another method of breaking off the 

 hydrocyanic acid is by the action of certain ferments. Almost invari- 

 ably the cyanogenetic substance is found to be accompanied in the plant 

 by a ferment most suitable for that substance. When the cells of the 

 plant are broken the ferment has opportunity to act upon the hydro- 

 cyanic acid-holding compound and the acid is liberated. 



The poisonous properties of the cyanogenetic plants may be reason- 

 ably thought to be due to hydrocyanic acid liberated as described above. 

 That other poisons are present may be possible and has been suggested, 

 but laboratory examination has failed to disclose the presence of 

 notable amounts of other poisonous substances such as alkaloids or 

 saponins. 



In the sample submitted, which had lost 79.2% of moisture in drying, 

 there was found 0.264% hydrocyanic acid. Calculated to the original 

 green weight of the plant, this is equivalent to 0.0549% hydrocyanic 

 acid in the original plant. That there is a possibility that a part of the 

 hydrocyanic acid originally present in .the green plant was lost in 

 drying, has been shown to be the case in the drying of sorghums. This 

 would make the above figure lower than it should be for the green 

 plant. Dowell 3 showed that in the drying of sorghum approximately 

 three-fourths of the acid is set free. 



Laboratory evidence in this case shows that we have been dealing 

 with a cyanogenetic substance, the nature of which will form the sub- 

 ject of a more technical paper from this Station in the future. 



Poisonous plants of this type sometimes appear to have an erratic 

 action both in feeding experiments and also when animals are grazing 

 at will. Apparently the grazing of sheep and cattle upon such plants 

 has not been accompanied with fatal results in every case. The areas 

 from which the samples used in these experiments were obtained have 

 been and are used for the grazing of sheep with the only results that 

 at times lambs succumb. Cattle have been fed safely upon sorghums 

 which unquestionably contained hydrocyanic acid and which at other 

 times and under different conditions of feeding caused fatal results. 

 The leaves of the choke-cherry contain hydrocyanic-producing sub- 

 stances, but poisoning does not necessarily accompany natural feeding, 

 although fatal results have been reported. Linseed cake has been the 

 subject of many experiments, 4 and has been found to contain lethal 

 doses of hydrocyanic acid in the amounts fed, but still was successfully 

 used in feeding and fattening. 



In explaining such a state of affairs it is necessary to consider all of 

 the possible factors which contribute to the action of these compounds. 

 Auld 4 has pointed out that under digestive conditions cyanogenesis is 

 likely to be inhibited. He shows that the presence of acids, alkalies, 

 salts, cellulose and glucose all tend to prevent the liberation of the 



3 Dowell, C. T. : Cyanoprenesis in Androposron Sorjfhum, J. Agr. Res. (1919) 16, 17, 175-81. 

 <Auld, S. J. M. : CynnoRenesis under Dij?estive Conditions. Jour. Agr. Sci. (1913) 51 

 408-33. 



