1. Potent Cl. chauvoei vaccine (anaculture) may be made in horse-flesh infusion broth plus 1.0 per cent. peptone, 0.85 per cent. salt and 2-5 per cent. of serum and/or the haemolysed red cells of the horse, ox and sheep (meat particles one-third by volume).
2. Tryptic digests of horse muscle media produce satisfactory vaccines.
3. Boiled, dense suspensions of Cl. chauvoei injected subcutaneously into sheep produce a high degree of protection to culture injected intramuscularly.
4. The medium and method finally decided on as a routine measure was: ox-liver infusion broth (liver particles one-third by volume) plus 1.0 per cent. peptone, 0.85 per cent. salt and 1 per cent. glucose added after sterilization, pH 7.8, 36 hours’ incubation, and 0.5 per cent. formolization for three days at 37°C.