_Brain Abscess._--This is most frequently associated with chronic suppuration of the middle ear and mastoid, and labyrinthine disease. As stated before, we must consider two principal types, namely, those outside the dura and those within. They may exist at the same time, or the intradural abscess may frequently follow, especially in acute exacerbations, the extradural abscess. The paramount symptom is the great pain in the head, most frequently localized at or in close proximity to the abscess. I have, however, found several instances where the patient located the pain in the anterior portion of the head, and operation or post-mortem examination disclosed it in the posterior cerebral fossa. This pain is not at all unlike that in brain tumor, and there are exacerbations in the headaches sometimes at night, other times in the mornings, and in one of my cases the patient would have about ten attacks of severe head-pains within twenty-four hours, and in the intervals be fairly comfortable. The next group of symptoms of importance are the focal lesions, which will correspond to the anatomicophysiologic locations and actions. These focal symptoms will vary in degree in that they be either irritative or destructive. So, for instance, a small abscess pressing over the motor area will cause clonic contraction and a still larger abscess, especially if it be intradural, will produce paralysis of that portion of the body governed by that particular area. Again, if it be located in the cerebellar region it will cause a train of symptoms of imbalance and loss of interpretation of direction, which must be carefully differentiated from the irritation of the labyrinth. In this department there has been much work done by Barany, Ruttin, Neumann, and other Viennese, and many others to make it possible to make a differential diagnosis; and there is a great deal more to be done. One of the most important recent contributions in this regard is the “pointing test” of Barany in connection with cerebellar lesions; and careful study and experimenting at every opportunity is very much recommended, in order to familiarize one’s self with this test. This in connection with the various labyrinth tests makes the differential diagnosis much more easy. One must remember that both labyrinthian irritation in connection with suppuration of the ear and cerebellar irritation from brain abscess may exist at the same time.