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A double-blind study was carried out to determine the effect of dosage in the treatment of ragweed hay fever with injections of aqueous ragweed pollen extract. Two concentrations of extract were used, one 20-fold smaller than the other. The volumes administered were such that the dose at the higher concentration was close to the maximum that it is practical to administer. During the ragweed season, the group of patients receiving the higher concentration fared significantly better than the group receiving the lower concentration. It is concluded that large dosages of pollen extract are more effective than small dosages in the treatment of hay fever. The findings indicate that the very low dosages recommended by some would have little influence on the course of pollenosis.

To the Editor.— This concerns a double-blind study of the neutralizing dose as used in the provocative testing technique. The technique of testing for abnormal reactivity or allergy by deliberate trial of suspected allergens is often the only practical way to identify offenders. In the last eight or nine years, an attempt has been made to systematize this study by using injections of various dilutions of antigens to provoke a mild systemic response after which it is claimed that often another dose of antigen can be found which relieves the induced symptoms within minutes (Rinkle or Lee provocative testing method). This "relieving dose" is administered repeatedly for therapy when continued exposure to the antigen is anticipated as in coseasonal treatment for pollenosis or to offset intolerance to common food offenders. This study did not investigate the possible long-term benefit of such therapy, but was concerned with whether immediate effectiveness of