In an informal discussion1 of a paper at the Detroit session in 1916, I announced that I had been able to protect persons susceptible to attacks of ivy poison by the internal administration of minute but increasing doses of the tincture of Rhus toxicodendron. Later my assistant, Dr. Strickler, made an alcoholic extract of the plant, which after aqueous dilution was injected subcutaneously and was found to be effective in preventing attacks.
During the past few years I have been employing this method in my private practice, with uniform success. I have treated almost a score of susceptible persons, and all have remained free of dermatitis during the ivy season, whereas prior to undergoing this treatment they rarely escaped.
I may briefly mention the case of a 12-year-old girl who for several years had spent a couple of months in bed each year from severe and repeated attacks of