Studies of the Viruses of Vaccinia and Variola.

In this laboratory study under the auspices of the Medical Research Council, the nasal mucosa of the rabbit was found highly susceptible to the virus of vaccinia. Immunity was produced by heated as well as by living virus. No difference was detected between the virus of the mild type (alastrim) and of the severe type of smallpox, except that virus from a confluent case of smallpox was decidedly more virulent than that of alastrim when the two were tested on the skin of the same monkey. Positive results with variola virus of both types were obtained in complement fixation and agglutination tests with antivaccinia serum.