1. Pulmonary consolidation may be produced in normal mice by the inhalation of Friedländer's bacillus or Streptococcus hæmolylicus.
2. The initial lesion is in both instances interstitial in character and the spread is by way of the interstitial tissue, though the ultimate consolidation may come to resemble in the gross a lobar pneumonia.
3. The lesions grossly and microscopically may be distinguished from the lobar consolidation associated with pneumococcus infection of the lung.
4. Friedländer's bacillus and Streptococcus hæmolyticus give rise to pneumonia in mice previously normal, whereas the pneumococcus produces pulmonary lesions only under special circumstances, as when the animals are alcoholized after partial immunization.