1. Chick embryos infected by the chorio-allantoic route with a bacteria-free strain of vaccinia virus develop a general dissemination of the virus throughout the entire organism with the exception of the central nervous system.
2. Quantitative estimation of the distribution of the virus in the various organs of the infected chick by cutaneous inoculation on the rabbit skin offers no evidence for a heightened affinity of the virus for special tissues.
3. Histological study of the lesions in the various organs demonstrates the focal character of the lesions which apparently originate as perivascular infiltrations around the smaller blood vessels. No lesions could be demonstrated in the central nervous system proper.
4. In the earlier stages of the disease Guarnieri bodies are clearly demonstrable in the cells of the epidermis and the squamous epithelium of the buccal mucosa. Inclusion bodies closely resembling Guarnieri bodies are demonstrated in all the lesions occurring in the various other organs.
5. It was not possible to demonstrate conclusively the presence of Paschen bodies in the lesions of the internal organs by the Morosow method usually used for the demonstration of these bodies in the membranal lesion.