The subject of aphasia is one which has offered some of the most interesting problems presented to the physician for solution, and, although many remain unsolved, yet the study of aphasia has been more fertile of great discoveries as to the function than that, perhaps, of any other brain symptom or group of symptoms. The researches of Broca, indeed, were the beginning of localisation, and, as far as the cerebral cortex is concerned, formed the starting-point of any scientific knowledge which has since been attained.