1. Homologous vaccine was injected into abdominal organs of rabbits after different intervals following sensitization by a single or by repeated intracutaneous injections of heat-killed pneumococci Type I or of formalin-killed hemolytic streptococci (Strain AB13).
2. Local inflammation with or without necrosis was observed in the liver and in the spleen of most of the rabbits. Injections into the kidney and into the anterior wall of the stomach usually caused hemorrhagic lesions at the site of injections, frequently accompanied by slight or moderate inflammation and seldom by necrosis.
3. No correlation was found between the skin and the organ reactions of the animals sensitized with killed streptococci or with killed pneumococci. There was also no correlation between skin or organ reactions and antibody titre of serum.
4. Allergic reactions occur in those organs, namely, liver and spleen, in which antibodies are demonstrable in a high titre, and they are usually absent in kidney and stomach wall in which the antibody titre is low or negative. It is probable that the reactions are caused by the union of antigen and its specific antibody in the tissue.