1. A method is described for producing pulmonary congestion, together with what may be termed a differential spirometer method for studying lung ventilation.
2. The method utilized permits an approximately accurate prediction of degrees of pulmonary edema in the living animal, and suggests avenues of approach for the very difficult problems of pulmonary capillary pressure.
3. It is shown that intravascular blood can encroach markedly upon the pulmonary air space. Although the methods used in these animal experiments do not resemble vital capacity measurements in man, their result is so definite that their applicability to clinical conditions may be considered.
4. The similarity between the experiments described and certain conditions of cardiac decompensation, of which mitral stenosis is the best example, is pointed out.