22 VETEEINARY TOXICOLOGY 



search after the event discloses such a cause open to all 

 observers. The same remarks apply to paint, which is 

 eagerly eaten by cattle, and generally contains lead, though 

 green copper arsenite is often used. Paint tins are left in 

 fields. Paint splashes are not removed. Eefuse is fre- 

 quently thrown over the fence. A case of lead poisoning 

 occurred recently due to old tarpaulin, crusted with oil 

 paint, stripped from a roof and thrown into a field. 



Bullet splashes have caused lead poisoning, and the 

 impregnation of herbage with lead and other metals on 

 account of smelting and similar operations sometimes leads 

 to chronic poisoning. 



Water is less often the vehicle. In spite of the consider- 

 able solubility of lead and zinc in rain water, it is not likely 

 that a very large quantity of poison would be taken in this 

 way, so that acute poisoning from this cause is rare. On 

 the other hand, chronic poisoning may happen. 



Another prolific source of trouble is the inveterate habit 

 of dosing the animals common to so many attendants and 

 even owners, who might be presumed to possess more 

 judgment. Wholesale administration of condition powders 

 and salts always does more harm than good, and often 

 destroys life. 



Vegetable poisons are more likely to be eaten by animals 

 in the spring and early summer, when the tender green 

 food is especially tempting after the winter fodder, or in 

 a dry season, when herbage is scarce (c/. the acorn 

 poisoning of 1911). Fortunately many poisonous plants 

 contain less poison in the young than in the mature state, 

 but this rule is not general. For instance, certain cyanide- 

 producing plants are more poisonous in the earlier than 

 the later stages of growth. 



Poisonous plants in general display great variation of the 

 proportion of poison. Two conditions of significance both 

 tend to modify the poison content. They are latitude and 

 cultivation. 



In higher latitudes plants of the same species are often 

 less poisonous than in lower and warmer situations ; for 



