While doing some work with the lysate therapy of warts, we discovered two cases in which there was a prolonged period of incubation between the experimental inoculation of the wart lysate and the development of the wart. Warts of the common variety had been curetted from many patients and had been sent to Dr. T. D. Beckwith, professor of bacteriology at the University of California. He had prepared a lysate by grinding warts in a physiologic solution of sodium chloride and filtering the mixture through a Berkefeld N filter. We attempted to discover the thermal death point of the wart virus by heating portions to 50, 55, 60 and 65 C. in a water bath for one-half hour. Six human volunteers were given an intradermal injection of each of these heated fractions and also an injection of the Berkefeld filtrate. The sites of inoculation were observed for six months.