The occurrence of abscess of the brain as a complication of pleuropulmonary suppuration has long been recognized, though it is relatively infrequent. When the generally accepted mechanism for the formation of the abscess is considered, it is astonishing that it is not seen more often. The infiltrated and indurated pulmonary tissue, which fixes and holds open the veins running through it, invites the entrance of particulate matter to be carried to the left side of the heart and out into the general circulation. The blood-streaked sputum or the frank hemoptysis seen in suppurative bronchiectasis and abscess of the lung points to the intimate association of the blood vessels and the suppurative focus. The expulsive efforts of coughing or the suction action of inspiration can force or draw air or particulate matter into a vein thus held open. Whether these emboli more frequently traverse the carotid system and lodge in the