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We found that influenza virus had the capacity to replicate in the peritoneal macrophages of normal mice, as revealed by the development of hemadsorption and the appearance intracellularly of S and V antigens. Cell-mediated resistance was studied in mice infected with influenza virus or a bacterial sytem of induction-elicitation. In the homologous system, mice were injected intraperitoneally or exposed by aerosol to a sublethal dose of an egg-adapted swine strain of influenza virus. In the heterologous system, they were infected repeatedly with Staphylococcus aureus and elicited by subcutaneous or aerosol administration of staphylococcal antigens. The peritoneal macrophages from mice specifically or nonspecifically immunized were significantly more resistant than those from normal mice. Also longer survival to in vivo challenge by the mouse-adapted virus, as compared with normal mice, was indicated in bacterially stimulated mice.

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Before undertaking a more direct study of the physical-chemical factors involved in the penetration of bacteria through the epithelia of the animal body, and as an essential guide in such an investigation, it has seemed desirable to study mechanisms capable of transporting bacteria in and through simpler systems. Certain critical relations of bacterial dimensions and motility to pore size of filters) effects of electric charge and electroendosmotic streaming, 2,3 and bacterial chemotropisms 4 have already been considered. The following notes describe a kinetic mechanism dependent primarily upon interfacial surface tension forces in the boundary between two wholly or partly immiscible fluids. The question whether or not such a mechanism plays a part in actual processes of infection will have to wait upon further study. TECHNIQUE.The preparations studied are two-phase liquid films with bacteria suspended, usually in the aqueous phase. Films and bacteria are made visible with a darkground illuminator. A small drop of one liquid, usually distilled water, sea water, or Ringer-Tyrode solution, is placed upon a clean slide on the microscope stage. Bacteria, scraped with a platinum loop from an agar slant, are suspended in this