The effect of the inhalation of vomitus will depend on whether the material is entirely liquid or contains large fragments. In the latter case, the result will be suffocation or, if the obstruction be less complete, massive collapse of a portion of lung accompanied by mediastinal shift. If the vomitus be fluid, there results the asthma-like syndrome named after Mendelson, who first drew attention to it. The irritative effect of the fluid vomitus is due to its hydrochloric acid content, and the acute inflammatory response is due to this chemical irritant. Pathogenic organisms are not usually present in this material, so that resolution occurs in a relatively short time, although artificial respiration may be required to tide the patients over the acute attack. In those few cases where pneumonia has resulted, contamination of the vomit as a result of oral sepsis has been suggested. Attention is also drawn to the importance of laryngeal malfunction in connection with the pulmonary syndrome in the newborn.