From these studies we conclude that the water-soluble protein from the tubercle bacillus, when not denatured, is toxic to normal rabbits, inducing fever and hemorrhage when introduced intravenously, but is not lethal except in massive doses. By the intraperitoneal route it is less toxic, but calls forth a local response of leucocytes and phagocytes without any striking proliferation of new connective tissue. A damage to endothelium is indicated by hemorrhage, chiefly in the bone marrow. Tuberculous guinea pigs succumb rapidly to protein 304 when given intraperitoneally.
The polysaccharide is non-toxic when introduced intravenously in the normal animal; introduced intraperitoneally, on the other hand, it is irritative and each succeeding dose continues to elicit a fresh emigration of leucocytes from the vessels. These leucocytes appear to be damaged, for they are actively engulfed by clasmatocytes. Guinea pigs with extensive tuberculosis may die soon after subcutaneous or intraperitoneal injections of the polysaccharide.
Aspergillina fungus may produce a pseudo-tuberculous lesion, resembling, both macroscopically and microscopically, the cellular reaction of tuberculosis. The absence of positive skin tests with Old Tuberculin when such lesions are present, as furthermore when tubercular tissue has been produced by chemical stimulation with the tuberculo-phosphatide, emphasizes the necessity for considering tubercle formation as a mechanism apart from allergy in the disease tuberculosis.