1888

American George Nuttral confirmed Metchnikoff’s finding of phygocytosis in anthrax-infected frogs, but found that under frog skin, anthrax bacilli were destroyed in great numbers. This led to belief in blood’s bactericidal capacity, which in turn led to finding that opsonins participate in the complex killing process. This led other critics of Metchnikoff to the view that phygocytosis occurred only after bacteria had been fatally wounded, as a post facto scavenger process. This initiated the humoral theory or mechanism of immunity, which was advanced by the 1890 studies of Behring and Kitasato which showed that cell-free serum neutralized the toxins of tetanus and diphtheria and could be transferred to another animal. “Metchnikoff presented the cellularist localist position, arguing for a sovereign activity of a certain cellular group; his humoralist opponents presented a holist position, defending the sovereignty of the organism over its constituents” (Tauber & Chernyak, 149-150, 154-159; quote at 159; Silverstein, 47).