In every case of abscess of the brain a twofold responsibility is thrown on physicians. First, the condition must be recognized, if possible, when it exists; mistakes are brought home at necropsy and one learns to do better. Second, the right thing must be done at the right time; this is much more difficult; of blunders one is often unaware, and unwittingly they are laid to the will of God. In a valuable paper on this subject, Grant1stated: "Drainage of a brain abscess before encapsulation has occurred has been uniformly disastrous in our experience.... Only two patients died because operation was delayed too long." I should like to dwell briefly on this question of the optimal time for drainage of an abscess of the brain, which was called to my attention by Adson2and by Lillie,3and to raise the question whether the cell count of