FROM the earliest ages, the functions of the brain have been a fascinating study to cultivated minds, and the greatest intellects of all ages have occupied themselves in attempting to solve its difficult and complicated problems. With the ancients this was a favourite pursuit, and engrossed the thoughts and talents of their most illustrious philosophers. Owing to the absence of exact methods of scientific observation and experiment, the conclusions on this subject were for many centuries of a purely speculative character, and the errors and fallacies thus deduced have been handed down and accepted till comparatively recent times. Modern investigations have, however, thrown a flood of light on the question, and although much still remains in the dark, the former obscurity has of late years been brightly illumined by the lamp of science. The accumulated clinical experience of ages had left knowledge on the cerebral functions in a state of confusion and uncertainty, and owing to the obvious difficulties and complications associated with disease, the results, however significant, were at best imperfect. That the brain should be subjected to direct physiological experiment was, until modern times, never attempted. During the last generation only has the practicability of this been demonstrated, and numerous observers have, by direct operations on the brain substance of animals, arrived at new conclusions as to its functions, and greatly revolutionised our ancient conceptions on the subject. Evidence has also been given against the noli me tangere theory, and abundant proof has been adduced of the fact that the brain may be handled, irritated, or partially destroyed without necessary danger to life. One of the latest developments of this method of investigation has been the discovery of those centres in the cortex which preside over voluntary motion, which have been, more especially by Prof. Ferrier, differentiated and localised with great precision. This important knowledge has been arrived at by an extended series of experiments conducted on living animals, in which, by observing the several effects of stimulating or destroying limited areas of their brains, the different functions of these special localities have been determined. A topography of the cerebrum has thus been constructed, in which the various faculties have been mapped out, but these, unlike the illogical visions of the phrenologists, have stood the test of sceptical criticism and rigid experimental inquiry. Researches of a purely scientific nature, carried out only with the object of elucidating truth and advancing knowledge, without immediate prospects of material gain, have in this instance led to most important and useful practical advantage. Armed with the knowledge acquired on animals in the laboratory, the physician has been enabled to utilise at the bedside the conclusions thus arrived at for the service of human beings. Clinical experience combined with morbid anatomy had already enabled the medical man to suspect the presence of disease in the brain, but as to its precise locality he was formerly in doubt. Now, however, guided by the recent revelations of physiology, he is enabled to predict the posi- tion in a large number of cases with great certainty and precision. Evidence of this is afforded by the proceeding adopted in a case of disease, notice of which has lately appeared in the medical papers. It appears that a man presented a series of symptoms which enabled Dr. Hughes Bennett to diagnose a tumour of the brain, that it involved its cortical substance, that it was probably of limited size, and that it was situated at a certain definite spot. The skull was trephined over the suspected region; there a tumour was found and removed. On recovering from the immediate effects of the operation the patien was and continued for three weeks in a satisfactory condition. He was perfectly intelligent, his functions, except for certain defects of motion caused by the disease, were normally performed, and there was an absence of all the distressing symptoms from which he had formerly suffered and from which he must necessarily soon have succumbed. Unfortunately, at the end of this time a complication, incident to all serious surgical operations supervened, from which the patient ultimately died. The unhappy termination of this particular case does not in any way detract from the importance of the principles which it involves. It still remains a signal triumph of diagnostic accuracy, a precision mainly attained by exact experimental research. It is, moreover, further proof that by utilising this improved knowledge the surgeon may not only remove disease from the brain, but that he may do so without necessary shock or risk to the nervous system, and that the procedure, under modern antiseptic precautions, need not be attended with greater danger than may follow any other severe surgical injury. This interesting and instructive case will doubtless inaugurate a new era in medical practice, for although this particular individual has succumbed to measures adopted to avert his otherwise certain death, the experience thereby gained is sufficient to encourage further efforts in a similar direction which may prove beneficial to others. In the Marshall Hall oration of last year Prof. Ferrier remarked, “There are already signs that we are within measurable distance of the successful treatment by surgery of some of the most distressing and otherwise hopeless forms of intercranial disease, which will vie with the splendid achievements of abdominal surgery.” He further added, reflecting on the success which had attended brain operations on animals, “I cannot but believe that similar results are capable of being achieved on man himself.” That distinguished physiologist cannot but feel gratified that his prophetic words have been partially realised.