46 ] our nal of Agriculture. [11 Jan., 1909. 



effects. The perfumes or acridity of such plants act as a deterrent, except 

 when the taste is depraved and the animal ravenous from starvation. Field 

 experience in the in\estigation of outbreaks of contagious disease tends to 

 discredit the alleged frequencv of plant poisoning. At all events, when 

 dealing with disease outbreaks it is but rarely that the " plant poison " 

 theory to account for the mortality is not trotted out. Recently there has 

 been a slight di\'ersion from the previously universal plant-poison hypothesis 

 in the direction of " impaction " or " starvation from soil -exhaustion " 

 as accounting for many fatalities amongst stock apparently otherwise 

 unexplainable. The average stock owner is loth to believe that he has got 

 contagious or infectious disease amongst his flocks or herds and he prefers 

 to encourage the feeling of security against the continued losses which he 

 knows will accompany a disease outbreak. It is a further solace to him 

 that mortalities from plant poisoning do not involve visits of inspectors or 

 the imposition of isolation, quarantine or other annoying and, as he thinks, 

 unnecessary restrictions. 



Nfany deaths of cattle and sheep occur from a kind of pseudo-poisoning 

 which is really onlv acute indigestion, resulting from a too free indulgence 

 in indigestible foods which therefore often get the credit of being poisonous. 

 If, when these animals are ravenous for food, they are injudiciously 

 allowed access to highly succulent herbage such as lucerne, trefoil, rape, 

 young thistles, clover, larkspur. Cape weed, dandelion, marsh mallow, 

 milk weed (Euphorbium Drumniondii) and several other plants which have 

 rapid growth, the animals oftentimes gorge their stomachs beyond the power 

 of ordinary digestion. Chemical changes in the food as it lies in the 

 stomach, give rise to the formation of gases which cannot get exit. A 

 condition of "hoven " or flatulence is set up and many beasts die — suffo- 

 cated, not poisoned. Stock should only be allowed to feed sparingly on 

 such food until they become accustomed to it. 



Classification of Poisorjs. 



Poisons are classified as Mineral, Vegetable and Animal 

 Poi'=ONS, according to the kingdom thev are deri\ed from. 



They are also classified according to their action into two main divi- 

 sions : — 



(a) Irritant Poisor\s which have an inflammatory or destructive action 

 on the tissues with which they come in contact, and give rise to svmptoms 

 of pain, colic, fever and inflammation. Of these, arsenic in the 

 mineral kingdom, euphorbium in the vegetable kingdom, and cantharides 

 (Spanish fly) in the animal kingdom are typical examples. 



(b) Narcotic Poisons which exert a depressing influence on the ner- 

 vous svstem and produce stupor, unconsciousness, staggering, paralvsis, 

 and convulsions. Narcotic poisons principallv belong to the vegetable 

 kingdom, the most marked exception lo this being perhaps the venom of 

 snakes. 



Antidotes. 



Antidotes are agents which mitigate, arrest or counteract the action 

 of poisons, and according to the manner in which the antagonizing of the 

 poison is effected they are classified as mechanical, chemical and physiolo- 

 gical antidotes. 



