Observations on Experimental Typhoid Infection of the Gall Bladder in the Rabbit

1. Besredka's living sensitized vaccine, given intravenously, does not produce a typhoid lesion of the gall bladder in the rabbit. 2. The first transplant of this vaccine is capable of producing this lesion. Hence this vaccine is not entirely safe to handle. 3. Regular infections of the gall bladder have not been produced by carrying a known pathogenic strain on rabbit blood agar, by successive passage through animals, or by the use of freshly isolated strains. 4. No evidence could be demonstrated in the rabbit of the immunity produced in man by vaccination with a whole killed vaccine. 5. Vaccine treatment did not cure the gall bladder lesion. 6. With the present methods of producing infections in the chimpanzee and the rabbit, neither of these animals is suitable for deciding the problems of the immunization of man by vaccines. These problems must be settled, as some of them already have been settled, by actual experience with large numbers of men kept under close observation.