RHUS — SUMAC. 121 



ma}' be iDreserved in proper solvents for a great length of time. The 

 author himself has experienced poisonous effects fi'om a tincture of li. 

 venenata prejDared thirt}' years before, which was apj)lied by way of experi- 

 ment. Peculiar as the principle is, it tinds its parallel in the well-known 

 fact that only certain persons are susceptible to its influence. This sus- 

 ceptibility may exist in all the members of a family, or in one or two only, 

 the others enjoying complete immunit}-. And again, there are great differ- 

 ences in the degree of the susceptibility of different individuals. One may 

 be violently poisoned by the emanations from a growing j^lant, while an- 

 other may require actual contact to produce even slight manifestations. 

 The poisonous principle is present in all parts of these plants, but is most 

 concentrated in the milky juice. The other constituents are vmimportant 

 and inert, being only the ordinary vegetable jDrinciples. 



Preparations. — None are official. The fresh leaves of E. Toxicodendron 

 were admitted into the Pharm'acoi^oeia with the idea that the prescriber 

 would order a tinctute made from them according to the formula provided 

 for tinctures of fresh herbs. The other species are susceptible to similar 

 treatment. There can be no doubt that an alcoholic tincture kept tightly 

 corked is the best means for preserving the drug in activity. 



Medical Froixrties and Uses. — Here we are altogether in the dark. 

 Cases are reported of persons suffering from various cutaneous eruptions 

 having been permanently cured by accidental rhus-j)oisoning. Cases are 

 now and then reported also of paralytics having been restored by strokes 

 of lightning, yet paralytics, as a rule, would prefer not to undergo such 

 heroic treatment. Granting that it may be possible to cure certain skin 

 diseases by this substitutive action, the first thing to decide in a given case 

 would be the susceptibility of the patient to the remedy, and the second, 

 how to limit its action within reasonable bounds. In endeavoring to settle 

 the first by experiment, great risk would be run of going beyond the sec- 

 ond altogether ; for as no man has yet discovered anything like an infallible 

 remedy for rhus-poisoning, though palliatives are numerous, no one is 

 likely to be able to prescribe limits for it when used as a remedy. Certain 

 it is that rhus will never be very popular as an external application with 

 patients who, like the writer, have experienced its poisonous effects. Re- 

 garding its use as an internal remedy, still less need be said. Nearly all 

 the testimony to its value when used in this manner comes from sources 

 discredited in scientific medicine. It is claimed, of course, that it exerts 

 specific effects in certain cases, even when administered in infinitesimal 

 doses ; but when we consider that personal susceptibility is the first requi- 

 site for any effect whatever, we may well doubt the specific effect of even 

 minute doses upon humanity, or disease, at large. Finally, admitting the 

 potency of rhus as a cause of disease, we have yet to learn its power and 

 mode of use as a remedy. 



