[_Mancinella_, I. 188. Hyppomane. With the milky juice of this tree the Indians poison their arrows; the dew-drops, which fall from it, are so caustic as to blister the skin, and produce dangerous ulcers; whence many have found their death by sleeping under its shade. Variety of noxious plants abound in all countries; in our own the deadly nightshade, henbane, hounds-tongue, and many others, are seen in almost every high road untouched by animals. Some have asked, what is the use of such abundance of poisons? The nauseous or pungent juices of some vegetables, like the thorns of others, are given them for their defence from the depredations of animals; hence the thorny plants are in general wholesome and agreeable food to graminivorous animals. See note on Ilex. The flowers or petals of plants are perhaps in general more acrid than their leaves; hence they are much seldomer eaten by insects. This seems to have been the use of the essential oil in the vegetable economy, as observed above in the notes on Dictamnus and on Ilex. The fragrance of plants is thus a part of their defence. These pungent or nauseous juices of vegetables have supplied the science of medicine with its principal materials, such as purge, vomit, intoxicate, &c.] [_Urtica_. I. 191. Nettle. The sting has a bag at its base, and a perforation near its point, exactly like the stings of wasps and the teeth of adders; Hook, Microgr. p. 142. Is the fluid contained in this bag, and pressed through the perforation into the wound, made by the point, a caustic essential oil, or a concentrated vegetable acid? The vegetable poisons, like the animal ones, produce more sudden and dangerous effects, when instilled into a wound, than when taken into the stomach; whence the families of Marfi and Psilli, in antient Rome, sucked the poison without injury out of wounds made by vipers, and were supposed to be indued with supernatural powers for this purpose. By the experiments related by Beccaria, it appears that four or five times the quantity, taken by the mouth, had about equal effects with that infused into a wound. The male flowers of the nettle are separate from the female, and the anthers are seen in fair weather to burst with force, and to discharge a dust, which hovers about the plant like a cloud.] And fell LOBELIA'S suffocating breath Loads the dank pinion of the gale with death.-- 195 With fear and hate they blast the affrighted groves, Yet own with tender care their _kindred Loves!_-- So, where PALMIRA 'mid her wasted plains, Her shatter'd aqueducts, and prostrate sanes,