The subject of the tissue lesions in anaphylaxis, and especially in chronic anaphylaxis, has attracted the attention of but few investigators. The phenomenon of Arthus (1) is well known. He found that the repeated subcutaneous injection of small amounts of horse serum into rabbits at intervals of five to seven days eventually produced infiltration, edema, sterile abscesses, and gangrene of the part, even though the injections were given in different locations. This effect was noted without the definite production of anaphylactic shock. Gay and Southard (2) studied the lesions of acute anaphylaxis. They reported finding three types of lesions. The first was hemorrhage, and in many cases this was plainly due to lesions of capillary endothelium. The second was fatty changes, principally in capillary endothelium, but also noted in voluntary muscle, heart muscle, nerve fibres, and in some epithelial structures.