Strain 13 was described as a virus-induced tumor in 1935. Its study was dropped for lack of support, but it was preserved by desiccation after freezing. Twenty years later the desiccated virus was reactivated by injection into day-old-chicks. Attempts to produce resistance by introduction of the virus into the vent, by vent drop and vent brush methods, and into the bursa of Fabricius, failed. Methods for extraction of the virus were studied followed by injection of different dilutions of the virus into the wing-web, with analysis of the data by dose responses, time frequencies, and tumor incidences, resulting in a method of bio-assay. Three weeks old chicks were found more susceptible than younger or older chicks, and female chicks showed a higher number of tumors than males. The virus was found sensitive to ether and chloroform. The virus remained stabile at pH 6.0 through pH 9.0. Contact of the virus with the enzymes, trypsin, lipase, and hyaluronidase, showed no effect on its ability to produce tumors when injected into chickens. Young guinea fowl developed tumors when injected with the virus.
