104 HEALTH AND DISEASE 



he has made an exhaustive enquiry into the origin and quality of the 

 food which has been supplied, and the particular animals which have 

 suffered in consequence. 



Some plants have distinctly poisonous qualities, e.g. the yew, horse- 

 chestnuts, the Colchicum autumnale, acorns, and potatoes in the raw state 

 (see " Poisoning "). 



It is a curious circumstance that some of these poisonous plants may 

 be eaten for a considerable time with perfect impunity. The yew, for 

 example, only manifests its poisonous quality on certain occasions, and 

 the same thing is true of potatoes, the poison of which seems to lie chiefly 

 in the skin, and horses which have consumed large quantities of them 

 uncooked have died rapidly with symptoms of poisoning. Potatoes, or 

 potato skins, however, appear to be perfectly harmless when boiled. 

 Some foods become injurious in consequence of defective modes of pre- 

 paration; for example, hay which has been highly dried or burnt in the 

 making. Foxy oats, so called on account of the red colour which they 

 assume as the result of having been exposed to moisture and subsequently 

 dried in kilns, assume a decidedly poisonous character, acting chiefly on 

 the kidneys. Numerous cases of the poisoning of cattle have been traced 

 to the consumption of large quantities of frozen turnips. 



Of the rapidly poisonous action of the yew under certain circum- 

 stances there is no doubt. Many instances have occurred where yew 

 clippings have been thrown over a fence, and a considerable number of 

 animals which had partaken of it have been found dead, or seen to be 

 in a dying state, with the symptoms of narcotic poisoning. Yet horses 

 have been known to graze for years in pastures the hedges of which 

 were mainly composed of yew, and nothing has happened; when sud- 

 denly the introduction of one or two strange animals has been followed 

 by the death of them from eating a small quantity of yew. 



Perhaps in the majority of cases the animals which remain unaffected 

 in the pastures do not eat the yew at all, and it is certainly the case that 

 in experiments which have been made, some of them lately, the greatest 

 difficulty has been met with in persuading the horses to eat the yew 

 which was supplied to them, and it was always necessary to keep them 

 without other food for a considerable time. In some experiments which 

 were performed a few years ago a sheep, after being kept without food 

 for two or three days, ate, in the course of tw T enty-four hours, 14 oz. of 

 the dried leaves of the yew, and two days later it ate 6 oz., yet no effect 

 was observed. A yearling heifer ate in twenty-four hours 2 Ib. 6 oz. 

 of half-dried leaves and twigs without effect. Three calves, about seven 

 months old, consumed in two hours 3 Ib. 6 oz. of half-dried leaves and 



