Abstract
Phagocytosis of formol-killed Escherichia coli was promoted by previous contact with filter paper or with p-hydroxybenzoic acid. The latter, an active principle in filter paper, was effective in concns. of 1 to 0.001 mg./ml. Fixed tissue inhibited phagocytosis. The activity of the several surfaces reported by Wood et al. to promote phagocytosis may be ascribed to the wet filter paper in their expts. These observations open to question the phenomenon of "surface" phagocytosis.

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