ANACARDIACEiE. 185 



tus in his work on the plants of Canada, as a species of Ivy. It was known 

 to the Indians both as a poison and as a medicinal agent, and the effects of 

 emanations from it were mentioned by Kalm and other travellers in North 

 America, but it does not appear to have been introduced into medical practice 

 until about 1788, when Du Fresnoy, a French physician, made some trials 

 with it, in the treatment of obstinate cutaneous affections, which were suc- 

 cessful ; he also administered the extract in several cases of paralysis, four 

 of which he states were cured by it. Some years afterwards it was experi- 

 mented upon by Dr. Horsefield, who found that it possessed the properties of 

 an acro-narcotic, and when given in small doses, that it acted upon the sto- 

 mach as an immediate stimulant, causing heat and uneasiness, and afterwards 

 promoting perspiration and diuresis. It has subsequently been tried by a 

 great number of practitioners, both in Europe and this country, in a variety 

 of complaints, but with limited success. 



The poisonous effects of this plant on certain persons, and the exemption 

 of others from its influence, are universally known. Those, who by a pecu- 

 liar idiosyncrasy are obnoxious to its power, experience its ill effects merely 

 by approaching the plant, whilst in others it requires a direct application of 

 the juice to produce such a result, but fortunately the great majority of per- 

 sons are wholly unsusceptible, and may handle it with impunity ; were this 

 not the case a large proportion of our agricultural population would be per- 

 petually sufferers from it, as it is so commonly diffused as to render it almost 

 impossible to avoid it. The symptoms caused by it, are violent itching, red- 

 ness, and tumefaction of the affected parts, especially of the face, succeeded 

 by heat, pain, vesication and fever. In some cases the skin becomes covered 

 with a crust, and the swelling is so great as to obliterate the features. These 

 symptoms begin in a few hours after exposure to the poison, and are usually 

 at their height on the fourth or fifth day ; after which desquamation begins, 

 and the distress diminishes. In some instances the eruption is less general, 

 and is confined to the part exposed to actual contact with the poison ; in others, 

 again, the eruption continues a long time, one set of vesications succeeding 

 another, so as to protract the disease for an indefinite period. 



The juice of the Poison Vine, is yellowish and milky, but on exposure to 

 the air, becomes of a permanent black colour, and when applied to linen or 

 cotton, forms an indelible dye, not being subject to fade from age, washing, 

 or the application of the usual chemical agents. This quality of the juice is 

 probably attributable to a peculiar principle which exists in almost all vege- 

 tables which possess the power of poisoning, when applied to the surface or by 

 emanation ; as it is found in the Upas, the Manchineel, the Cashew apple, &c. 



Medical Properties, SfC. — It has been most successfully employed in para- 

 lysis, in which it appears to act somewhat like Nux vomica, but not with equal 

 power. It has also been used in chronic rheumatism, diseases of the skin, 

 and some affections of the eyes, but the success hitherto attendant on its em- 

 ployment, do not counterbalance the risk of producing its poisonous conse- 

 quences, and it is at present seldom or never resorted to by practitioners. It 

 is given in powder, in doses of half a grain, gradually increased until 

 some effect is produced ; it has also been advised in decoction, infusion and 

 extract, but as it appears that the active principle is very volatile, it is less 

 efficient in these forms than in substance. 



Many other species of Rhus possess the same properties, in a greater or less 

 degree, among which R. venenatum and R.pumilum, both natives of this coun- 

 try, are exceedingly active, and have a powerful influence on persons unsuscepti- 

 ble to the action of the R. toxicodendron. The first of these affords a bril- 

 liant black varnish, very analogous to that obtained in Japan from the R. ver- 



