Vol. XII. No. 28G. 



THE AGRICULTL'KAL NEWS- 



m 



THE PRODUCTION OF HYDROCYANIC 



ACID IN PLANTS AND SEEDS 



Keference has been made from time to time in this 

 journal to the poisoning ol cattle thiough eating sorghum or 

 Guinea corn, one of the last instances being in the issue of 

 January 20, 1012, where a description was given of a case 

 in Queensland, in which cattle feeding on young sorghum grow- 

 ing on a rich soil were poisoned, whilst others feeding on sorg- 

 hum, all of the same age, growing in adjacent areas on a much 

 less fertile soil, remained healthy. Tlii- circmstance led to an 

 investigation in which sorghum was grown in a very sandy 

 soil, both unmanured and manured with nitrate of soda; the 

 re.sults showed that the manured plants always contained the 

 greatest amount of hydrocyanic acid, and that sorghum 

 grown in very rich nitrogenous soils cannot be safely used for 

 feeding stock until the plants are about to set seed. L'Ai/ri- 

 cuUurf Pratique dcs Fai/x Chai'ds, for August 1912, after 

 referring to observations as to the poisonous nature of young 

 sorghum in India and Algeria, gives detailed consideration to 

 Ihe case in (^'ueensland, and draws attention to the rather 

 useful suggestion that young sorghum might be safely fed to 

 stock if it is first mixed with dry forage 



Further evidence, if it is needed, of the danger of young 

 sorghum as a cattle food, is to be found in the A;/ricultuval 

 Gazette of JVeir South Walef, for September 2, 1912. Here, in 

 dealing with a specific instance of poisoning, it is stated that 

 the affected animals were saved, in all cases wherr the remedy 

 was applied before convulsions had set in, by ilrenching them 

 with a mixture consisting of; aromatic spirits of ammonia 1 

 lo 2 oz., nitrous ether 1 to 2 oz., water 1 piiit. This was 

 a treatment in emergency, 'and proved as .satisfactory as 

 circumstances permitted.' The article proceeds to quote the 

 recognized antidotes for hydrocyanic (prussic) acid poisoning 

 in cattle; they are: subcutaneous injection of ,r\, grain of 

 atropine: subcutaneous injection of ether (.5 to 10 o c); 

 a mixture of ferrous and ferric salts w ith magnesia, given as 

 a drench. 



The effect of manures on the amount of hydrocyanic 

 acid in plants or the parts of plants receives additional 

 interest from the work that has been done in connexion with 

 the formation of this and other poisonous substances in seeds. 

 Articles appear in the Atnicidtural JWws, Vol. XI, pp. 63 

 and 104, dealing with investigations carried out at the 

 Lome Agricultural Experiment Station with species of 

 Phaseolus such as the haricot bean {P. '•(t/yacj.s) and 

 P. iiiidti1i<yriis. In the experiments, the amount of non- 

 protein nitrogen, as a measure of the toxic principle in the 

 seeds of these plants, was compared in seeds from unmanured 

 plants with that in seeds from plants receiving such manures 

 as nitrate of soda and superphosphate The quantities of non- 

 protein nitrogen present were always least when manure was 

 used; so that if these are taken as a measure of the hydro- 

 cyanic acid present, manuring appears to decrease the 

 amount of this substance in seeds— a result that is the 

 reverse of the case of the formation of that body in sorghum 

 stems. The matter goes further for, as is explained in the 

 A'jticultuval Ned'!!, Vol. XI, p. 104, this fact of the decrease 

 of non protein nitrogen in seeds, through manuring, affords 

 an explanation as to why medicinal plants in cultivation 

 with the aid of nitrates are less rich in alkaloids than the 

 vild plants. 



In considering these results, it i> only fair to state that 

 recent work on the occurrence of hydiocyanic acid in plants 

 dtscribfd shortly' in the Journal of tli<- Chemical Sucieti/, 

 November 1912, p ii, 1085, indica'.es that the method u.sed 

 for determining the proportion of the acid present often gives 

 result.s that arc far too high, because of it* formation during 



the process of ordinary ways of analysis. It is of some- 

 interest, too, that an abstract on the same page indicatea- 

 th^t the amount of the acid in sorghum may be lessened by 

 inoculating it with various aromatic substances. 



To return to the gi-uoral matter, this may l>e given, 

 additional interest by considering the fact that many 

 seeds, when germinating, produce hydrocyanic acid, and 

 that the amount of this may be changed by altering 

 the conditions surrounding the developing embryo. An 

 abstract of papers in Nature for February 22, 1912, 

 pays attention to work which has shown that such seed& 

 form an increased quantity of this acid when exposed 

 to light or to an atmosphere of carbon dioxide; whilst 

 the amount is decreased in darkness or the ab.sence of 

 carbon dioxide, unless a carbohydrate such as dextrose is 

 present, when actually a considerable increase takes place. 

 The last fact has led to the suggestion that the sugar 

 (dextrose) acts with inorganic nitrogen, probably present afr 

 ammonia, to form hydrocyanic acid directly or indirectly. 

 The abstract gives attention, further, to a more recent 

 investigation, in which the formation of hydrocyanic acid by 

 .sprouting seeds of linseed (Limtmu s(7«/t.ss/»iw»i) and sorghum 

 was largely increased by adding 1 per cent, of ammonium 

 chloride to the water supplied for germination. Hydrocyanic 

 aoid is not present at the commencement of the germination ot 

 sorghum; it is found after some growth has been made, and 

 as soon as chlorophyll begins to appear. Ammonia is present 

 in sorghum seedlings before hydrocyanic acid is detected, 

 and there is an increase in the amount of the latter substance 

 as the quantity of ammonia in the plant increases. 



As may be inferred from part of what has been said 

 above, hydrocyanic acid (or at least the cyanogenetic glucoside 

 which produces it) is present in linseed; this accounts for the 

 well-known fact that cattle are sometimes, though very rareljv 

 poisoned by eating linseed meal — a circumstance to which, 

 attention has been given in this journal. The poisoning- 

 generally takes place, however, in a very irregular way, one 

 or more animals being atiected whilst the others remain ia 

 a normal state of health. Some light is thrown upon the 

 varying action in the difl'erent animals in a paper presented 

 recently to the Durham University Philosophical Society, 

 which is abstracted in the Experiment Station Record issued 

 September 30, 1912. The investigation consisted in subjecting- 

 linseed meal to temperatures apiiroaching those of animal life 

 and collecting and examining the volatile products, when it 

 was found that the amount of hydrocyanic acid among them. 

 was dependent on the quantities present of cyanogenetic gluco- 

 side (glucoside producing hydrocyanic acid) and of enzymes, 

 the temperature and degree of acidity of the liquid contain- 

 ing the meal, and on the presence or absence of certairt. 

 other substances. These facts led to the conclusioii- 

 that in normal health the acidity of the stomach of an. 

 animal is too high for the production of the poisonous acid, 

 but that it may be produced under abnormal circumstances 

 such as when the meal is fed to an animal suffering front 

 indigestion of such a peculiar character that the food is not 

 made acid. If this supposition is correct, it forms some- 

 explanation of the very rare, but puzzling, cases of the 

 poisoning of cattle by linseed meal. 



Finally reference must be made to a description of 

 work in the Journal of the Board of Ayrictdtiin- for 

 November 1912, which was designed to ascertain if the- 

 activity of the enzymes upon the cyanogenetic glucoside in 

 linseed is greater when it has passed through the hot press 

 process than it was before. The results, stated shortly, 

 show that the hot press process does not either in«re»se ot 

 decrease such activity. 



