In previous work on the virus of vaccinia, done in conjunction with Drs. Lambert and Israeli,1 it was found that, in combination with tissue cultures, there was a definite multiplication of the virus with active transfers to the third generation and a resistance of the virus to thirty-four days' incubation at 37 C. We found that living tissue was necessary to the growth of the virus in this method and that the cornea of the rabbit or guinea-pig was more favorable than the heart, liver, or kidney. In the corneal preparations, the epithelium showed an active lateral spreading throughout the clot, forming sheets or groups of cells in the plasma. The cells early showed an accumulation of fat in their cytoplasm, but frequently retained their form for several weeks, even when not transferred to fresh plasma. In these preparations, altho the corneal cells were living and the virus of vaccinia was multiplying, we were unable to find any specific vaccine bodies; only smaller, undifferentiated forms have been seen. These undifferentiated forms have been found in the controls in incu-