Elementary Bodies of Vaccinia from Infected Chorio-allantoic Membranes of Developing Chick Embryos

By a method of differential centrifugation and tryptic digestion suspensions of elementary bodies have been prepared from chorioallantoic membranes of chick embryos infected with vaccine virus. The infective titer of the final suspension of elementary bodies was usually the same as that of the original tissue emulsion. Elementary bodies from infected chick membranes were agglutinated as well by antivaccinal serum obtained from different mammalian species as were bodies prepared from inoculated rabbit skin. Seitz filtrates of infected chick material contained soluble precipitable substances of vaccinia; these filtrates and filtrates from infected rabbit skin, respectively, reacted equally well with rabbit serum which contained either L or S antibodies.