New Observations on Pneumococcal Transformations in vivo.

Summary 1. Succesful pneumococcal transformation in vivo has been achieved by injecting the transforming preparation subcutaneously and the live avirulent culture intraperitoneally. 2. The transforming activity of a vaccine preparation lasted in vivo at least 24 hours. 3. Transforming preparations active in vivo have been prepared from a lysate of a culture of strain A-66 (Type III). This preparation was inactivated by mild protein denaturation. 4. The genetic marker of streptomycin resistance was transferred between pneumococcal strains in vivo.