Poison Ivy

■Tust what it is that induces poiscra ivy to play lts uijurious prauks on sonits people at scme times aud uot at others is Still a profotind mystery. One thing is certain- the uumber of people susceptible to the poisouiug infiuence must be estremely few, from the tact that in the viciuity of Philadelphia the higbways aud byways are overruu with the plant to au euoruious exteut. it is frequeutly impossible for people to go by without brushing against it, and ïf it is the vapor or souie exudatiou frum the plant which causes the trouble thousan'cis of peráOüs must be uudr the iufluence to every oue who suffers from it. The writer of this paragraph knows of a tract of land on whioh the plaut grows profusely and ou which many séores of lafoorers are employed. These laborera are frequently set to weediug and puliing out the plant by the naked hand, and. so far as the writer knows, uúue of these men was ever poisoned by it. The oattle eat it greedily whenever they get an opportunity. It seems to have uo iniurions inüueuce on them.-