PROGRESS in the knowledge of infectious hepatitis has been slow owing to the fact that the disease has not been transmitted to an experimental host. Colbert1 has recorded the negative data obtained in many hosts by different workers. In 1950 Henle and co-workers 2 reported the propagation of the agent in tissue culture and embryonated hen's eggs. Although no lesions in these hosts were recognized, inoculation of volunteers with passage materials thought to contain hepatitis virus produced a mild disease, described as hepatitis without jaundice.3 Other investigators * have been unable to confirm this. In addition Henle, Drake, Henle, and Stokes 4 have described a skin test for infectious hepatitis, using as antigen amniotic fluid prepared from chick embryos thought to be infected with the virus of hepatitis (IH) and irradiated by ultraviolet light. This was seen to give allergic reactions in a high percentage of persons who had