POISONING BY PLANTS. GENERAL PRINCIPLES 15 



beings are most susceptible to the deadly night shade, Atropa Belladonna. 

 The cat and dog are less susceptible. The horse is much less so, and the 

 pig, goat, sheep and rabbit are little susceptible to poisoning, even on 

 eating the root, the most poisonous part. 



12. Individual Susceptibility. There is a difference in the individual 

 susceptibility to poisons. The best illustration of this is the case of 

 poison ivy producing the characteristic inflammation on fair persons with 

 blue eyes (blondes), and the immunity of persons with dark, swarthy 

 complexions (brunettes). This individual difference varies with the health 

 of the animal, or man. The healthy individual having greater immunity 

 than the one in a depleted condition. Animals familiar with certain 

 ranges escape poisoning, while those not so familiar may be poisoned. 



13. Physical State of Animal. The physical state of the animal, 

 whether hungry, or well-fed, whether kept in confinement, or allowed the 

 freedom of the open fields influences the number of cases of poisoning. 

 When animals are hungry; or are turned out into the open fields after con- 

 finement, they are more likely to eat of poisonous plants than otherwise. 

 This has been shown recently in the case of laurel poisoning of heifers at 

 Narberth, Pennsylvania. 



14. Animals with Depraved Appetite. The animal may acquire a 

 depraved appetite where it leaves off feeding on the nutritious pasture 

 plants and takes to eating the deleterious ones. This happens with the 

 ioco weeds; when the depraved appetite of the animals leads them to eat 

 only the plants which have induced the loco disease. 



15. Unpalatable Poisonous Plants. Poisonous plants are frequently 

 unpalatable and so are not usually eaten, but in dry spells, when other 

 forage is scarce, they may be eaten with poisonous results. 



16. Secondary Fermentations in Fodders. Perfectly wholesome fod- 

 ders may become poisonous owing to secondary fermentations within them, 

 as occurs sometimes in maize silage. 



17. Poisonous Plants as Impurities. A perfectly harmless feed may 

 become poisonous owing to the admixture of a poisonous plant, or plant 

 part with it, as oats with corn cockle and barley with darnel. In Europe 

 dry meadow-saffron may be included in hay. 



18. Removal of Animals to New Locality. Farm stock reared in a 

 locality where certain poisonous plants abound are much less likely to be 

 poisoned by these plants than animals brought from a region where they 

 do not occur. 



