Certain lianas, common enough in the South American forests, belong to the family of _Sapindaceæ_, which, like the orders Loganiceæ and Euphorbiaceæ, owe their reputation chiefly to the medicinal or poisonous substances extracted from them. Among the Sapindaceæ I shall mention only the genus _Paullinia_, which includes several species endowed with narcotic properties. These properties appear especially developed in the _Paullinia pinnata_. Its bark, leaves, and fruit contain an abundant acrid principle with which the Indians of Brazil prepare a slow but certain poison. The Indians of Guiana extract from the _Paullinia cururu_ another substance with which they envenom their arrows, and which was long supposed to be the veritable _Wourali_. But Sir Richard Schomburgk has shown that the latter formidable poison is really extracted, as I have already recorded, from the _Strychnos toxifera_, a shrub of the family _Loganiaceæ_, which flourishes in Guiana and Brazil. To the same family and the same countries belong the _Ignatia amara_, whose seeds are known by the name of "St. Ignatius' Beans." These beans contain two alkaloids, _Strychnine_ and _Brucine_, which we also extract from the _Nux vomica_, and which must be classed among the most violent poisons known to the toxicologist. While speaking of the poisonous plants of South America, a few words in reference to the Manchineal (_Hippomane Mancenilla_) will not be inappropriate. This tree thrives best, it is said, on the sea-shore. It bears a profusion of very pretty fruit, resembling in colour and form the Red Apple (the Spanish _Manzanilla_), and exhaling an agreeable, lemon-like odour. They are, therefore, scarcely less beguiling than Dead Sea fruits; but they are also very poisonous, yet less deadly than the milky juice which flows from the slightest incision made in the tree's thick and grayish bark. This juice, received into the stomach, or introduced into the blood through a wound, slays the victim with awful quickness. If it do but touch the skin, it excites a violent irritation, and raises swellings or boils of the worst description. The very vapour which it emits causes a painful itching in the eyes, the lips, and the nostrils. It was formerly asserted that to sleep under the shade of a Manchineal tree was certain death; but the naturalist Jacquin, in the interests of science, courageously made the experiment, and proved the falsity of the story. The Manchineal is not unfrequently confounded with other poisonous Euphorbiaceæ, as the _Sapium aucuparium_ and the _Excoecaria agallochia_, which flourish in very nearly the same regions. The _Excoecaria_, it is said, is not less dangerous than the Manchineal. It owes its name (_ex_, and _coecus_, "blind") to the circumstance (or the fable) that some European sailors, while felling wood in the forest, having accidentally struck with their axe a tree of this species, were blinded by the milky juice which sprang into their eyes.