Tw'o' methods for preparing crystal-violet vaccine for the prevention of hog eholera are reported. The first, in which the vaceine ismade of blood, is the teehnique developed by Penha artd d'Apice while tbe second, based upon viscera, is the Penha method. In order to obtain vaccine with high antigenie properties it was neeessary to inoculate healthy nogs with a strain of virus that produeed symptoms of the disease and a high temperature on the 3rd or 4th day after inoculation. The blood vaccine was always sterile whereas that made from the viscera was contaminated in about 70 % of the cases.
The vaccine obtained from either method when used at a dosage rate of 5 cc. in hogs up to 40 kilos in weight and 10 cc. in heavier animals produced an immuníty by the 21st day sufficient to protect the hogs against an inoculation of 2 cc. of virus. The total duration of the immunity was not determined but observations indicate that protection against natural infection was afforded for at least 8 months. The vaccinated animals did not transmit the disease to unvaccinated hogs with which they were in contact and the vaccine did not affect the health of the animals even though some were in a weakened condition.