1. Rabbits infected with bovine tubercle bacilli develop hyper-sensitiveness to an intracutaneous injection of tuberculin. This sensitiveness appears from the 2nd to the 6th week after infection and increases rapidly thereafter. Tests, as a rule, show fluctuation in the intensity of the sensitization. Sensitization is followed by an interval of several weeks preceding death during which the animals fail to react.
2. Rabbits infected with bovine tubercle bacilli form antibodies that fix complement in the presence of tubercle bacilli. The antibodies appear after 2 weeks, increase during 6 to 10 weeks, and persist until the animals die.
3. In the later period of infection the skin fails to react to tuberculin at a time when the serum contains complement fixing antibodies.