1. When a guinea pig with well developed peritoneal tuberculosis is injected intraperitoneally with about 20 cc. of a heavy suspension of a virulent tubercle bacillus (Culture H37) death occurs within 24 hours or the animal becomes extremely toxic. Such a peritoneal tuberculosis develops in about 1 month after 1 cc. of. a very heavy suspension of Culture H37 has been introduced into the abdominal cavity. If the viscid fluid which is contained within the peritoneal cavity is mixed with saline solution and passed through a Berkefeld filter a bacillus-free filtrate is obtained which induces in normal guinea pigs a certain degree of cutaneous hypersensitiveness to tuberculin.
2. The abdominal organs and the parietal peritoneum, to which masses of leucocytes and tubercle bacilli are adherent, when crushed and extracted with saline solution yield a filtrate which likewise induces a cutaneous hypersensitiveness.
3. The cutaneous hypersensitiveness does not appear before the 7th or 8th day after the filtrate injection and is therefore considered to be the result of an active sensitization of the animal.