In the second stage, again carried out a few days later, two dural flaps are turned down, each similar to the one described in unilateral exposure. This leaves a central portion of dura, that part which encloses the occipital sinus and to which the falx cerebelli is attached. By means of an aneurysm needle, threaded with catgut, passed through or around the falx, the occipital sinus is ligatured above and below, the ligatures being applied as high and as low as circumstances permit. The falx is then divided between the two ligatures and the two flaps thrown upwards and downwards respectively. The extra space so afforded not only allows of the exposure of both hemispheres, but also permits of the further dislocation of the one lobe towards the opposite side, thus facilitating the examination of the lateral aspect of the cerebellum and of the cerebello-pontine angle. This bilateral method is a serious operation. Hæmorrhage may be severe, and the attendant risks of respiratory failure are not inconsiderable. It should only be adopted (1) when a tumour is so situated or so extensive that more space is required than supplied by unilateral exposure, and (2) when bilateral cerebello-pontine tumours are suspected. =Palliative operations for cerebral and cerebellar tumours.= A primary palliative operation may be conducted over the region of the tumour itself, in the cerebellar region, or over the temporal lobe--one of the so-called ‘silent’ areas of the brain. It is obvious that the greatest degree of pressure relief will be obtained by craniectomy conducted over the region of the tumour itself. To this course, however, there are two great objections: (1) the exposed cortex most commonly includes the motor area, herniation of which will lead to disastrous effects on the extremities of the contra-lateral side--spasticity, paralysis, aphasia, &c.; and (2) the herniation of brain-matter including, or closely related to, an irremovable tumour tends to lead to œdema of the brain tissues and softening of and hæmorrhage into the growth, with subsequent rapid development of the outwardly protruded mass. With respect to cerebellar decompression operations, I must confess that I have formed a most unfavourable opinion. The subtentorial pressure can undoubtedly be relieved most effectually by such methods, but the immediate results are not infrequently disastrous, the patient dying within a few days as a result of the complete upset of medullary centres.