The introduction of antibiotics has practically eliminated infection of the paranasal sinuses as source of intracranial infeetions. Thoracic surgery has nearly eradieated a for merly fairly frequent source of abseess of the brain, namely infections of the lung, such as lung abscess, bronchiectasia and lung gangrene. Gunshot wounds of the head are of course a very important course of brain abseess and meningitis, but in civilian practice fortunately rare. Complieated fractures of the vault and fractures of the base of the skull are at present the most important source of intraeranial...