1. The size of the dose of the infecting material exerts an appreciable effect upon the duration of the incubation period in experimental syphilis of the rabbit. Other things being equal, the larger the dose the shorter is the incubation period.
2. The size of the inoculum was not found to exercise any marked effect upon the course of the disease as a whole.
3. In individual rabbits inoculated with minimal amounts of virus the disease may run a malignant course.