=Deadly Nightshade= (_Atropa Belladonna_ L.). This plant has long been known to be exceedingly poisonous, all parts containing a toxic principle. Both man and domestic animals may be poisoned, though the latter are very unlikely to touch the plant. As regards man, children are most likely to be affected, owing to the attractive character of the large bright black berries. Domestic animals appear to be rarely poisoned and are less affected than man, and in any case the susceptibility of various species—and even individuals of the same species—is very variable. Human beings are most susceptible, followed by the cat and dog; 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 (Cornevin). Gohier and others have given over 2 lb. of the green plant to horses without ill effects, and this repeated on three days did not cause marked pathological troubles. Hertwig considered large ruminants to be more sensible than horses to the action of Belladonna. It appears to be agreed that small ruminants are very slightly susceptible to this plant. Birds are considered almost insensitive, while rabbits may be fed for weeks on the leaves without poisoning, as also sheep, goats, and pigs. Horses and cattle are more sensitive but nevertheless resistant. The poison is no doubt quickly removed by the kidneys, since ordinary injection of Belladonna causes the usual symptoms. It is stated that the flesh of rabbits and birds which have eaten the plant and have been slaughtered apparently healthy is poisonous to man. One berry can induce symptoms of human poisoning, and a child died after eating only three berries. Mortality in human cases of poisoning by Belladonna is given by Kanngiesser as 10 per cent. _Toxic Principle._ Deadly Nightshade is the source of drugs widely used in medicine, and its properties as regards man have been extensively studied. The principal substance present is the alkaloid _Hyoscyamine_ (C_{17}H_{23}O_{3}N), readily converted into _Atropine_ (C_{17}H_{23}O_{3}N); _Scopolamine_ or _Hyoscine_ (C_{17}H_{21}O_{4}N), and in smaller quantity _Apoatropine_, and _Belladonine_ are also present. All parts of the plant contain the toxic alkaloids, but in unequal degree. The total quantity of the alkaloids is largest in the roots (0·4 to 1 per cent.), which in the fresh state contain no Atropine, but only Hyoscyamine; the leaves and fruits contain less of the alkaloids, and cultivated plants have been found to be poorer (0·26 per cent.) than wild (0·4 per cent). The root has been found to be five times as toxic as the berries. Drying does not destroy the poisonous properties.