If the attention of physiologists devoted to cerebral investigations is specially turned to the present aspect of research, cases of well-marked left-handed patients, or what is manifestly of even greater significance, of exceptionally dexterous right-handed patients, in hospitals, asylums, and gaols, will from time to time present themselves. It has indeed been affirmed that left-handedness prevails among the “light-fingered” experts who find frequent lodging in our gaols. The statement rests on no basis of statistical evidence; but I can readily imagine that a left-handed pickpocket turning his exceptional dexterity to account, might find at times the same advantage that Ehud, the son of Gera the Benjamite, derived from using the hand ordinarily recognised as passive or inert. As to the more daring burglar, his sinister dexterity fills peaceful householders with trepidation as soon as the rumour transpires of his presence in their midst. In reality, however, the fancied prevalence of left-handedness among savages, criminals, and idiots, is a mere reflex of the long prevalent misconception that the preferential use of the left hand is solely due to acquired habit, incurable awkwardness, and incapacity. This is an idea that has often checked the development of exceptional dexterity and a full command of both hands. Meanwhile it is only in so far as the hand may prove to be an index of the brain that observation is possible on the living subject. If the transposition of the viscera, and the exceptional pressure of the heart on the right, instead of the left side, were the source or the unvarying concomitant of left-handedness this could be tested with ease on the living subject. But the brain is beyond our reach; though pathological phenomena, along with the results of vivisection in the study of lower animal life, have thrown a flood of light on its functions; as well as on the localisation of specific cerebrations in their relation to sense, to language, and to general perceptions as elements of mental action.