Dog's-Mercury, or Mercu-rialis perer,nLs, L. an indigenous plant, growing under hedges and in woods, in many parts of Britain. Its perennial root creeps in the ground ; the stalks are single, and without branches, rising ten or twelve inches high, with rough leaves : these have their male flowers, growing in spikes upon plants different from those which produce seeds.

This vegetable is of a soporific and poisonous nature, both to man and brute. There are instances of persons who, by mistake, have eaten this plant like spinach, instead of Chenopodium, or English mercury, in consequence of which they never awaked from their mortal sleep. In the Isle of Skye, an infusion of it is sometimes taken to bring on a salivation.

Ray, relates the case of a man, his wife, and three children, who experienced highly deleterious effects from eating this herb fried with bacon. Notwithstanding its hurtful properties, sheep and goats feed on it, but cows and horses refuse it.

When the dog's-mercury has accidentally been eaten among culinary plants, the most effectual method of procuring relief, is a brisk emetic speedily administered ; and after having evacuated the contents-of the stomach, vinegar, lemon-juice, or other vegetable acids ought to be taken in copious draughts. But, when the poison has been discovered only after the lapse of several hours, small doses of camphor may be given, till medical assistance can be procured.—• See also Antidotes : vol.i.p. 75.

Lastly, the roots of the dog's-mercury afford, according to Bech-stein, a blue and crimson colour, both in dyeing and painting.