The object of this paper is to present, first, the results of research on fixed virus, i.e., the action of disinfectants, the effect of heat, passage through Berkefeld filters, infectivity, exposure to peritoneal fluid in vivo, and dialysis; second, the determination of the M.L.D. of the virus and the results of immunity tests on sets of animals which had been vaccinated by the various methods of antirabic treatment, i.e., H6gyes, Pasteur, and a new method, devised in this laboratory, which will be designated the method of dialysis. Throughout the experimental work, unless otherwise stated, a standard suspension (I-Ioo) of fresh rabic brain in physiological salt solution was employed. The preparation of this standard homogeneous suspension is given in detail under the consideration of the M.L.D.