SIR ASTLEY COOPER1in 1836 reported the results of a series of experiments in which he ligated the principal cervical arteries and nerves in various combinations and sequences. He concluded that death following pressure on the neck was due to cerebral anemia rather than to a direct nervous mechanism. During the ensuing hundred years a large number of investigators studied the effects of generalized cerebral anemia of various degrees and of various durations.2The pathological picture of such cerebral anemia has been worked out in detail, and the susceptibility of various types of neurons of the brain, spinal cord and sympathetic nervous system to total and near total anemia has been well established.3 The study of focal cerebral anemia was initiated by Flourens'4description, in 1847, of the effects of experimentally produced emboli in the cerebral vascular system. Subsequent studies of this type have elucidated further