This “nice distinction” amounts to something very like an evasion of the real difficulty, unless we assume Dr. Humphry to mean only what Dr. Buchanan states, that during the weakness of infancy and childhood the two hands are used indiscriminately; and the preferential use of one side rather than the other does not manifest itself until the muscular system has acquired active development. All the processes by which dexterity in the manipulation and use of tools is manifested, are acquired, whether the right or the left hand be the one employed. Men are not born, like ants, bees, spiders, martins, and beavers, with carpentering, weaving, modelling, and architectural instincts, requiring no apprenticeship or culture; though the aptitude in mastering such arts is greater in some than in others. If the tendency in their practice to use the right hand is natural, that is to say, innate or congenital, then there need be no nice distinctions in affirming it. But on any clearly defined physiological deductions of right-handedness from the disposition of the organs of motion or circulation, or any other uniform relation of the internal organs and the great arteries of the upper limbs, left-handedness becomes mysterious, if not inexplicable, unless on the assumption of a corresponding reversal of organic structure; for Dr. Humphry’s assertion that “in all persons the left hand may be trained to as great expertness and strength as the right,” is contradicted by the experience of left-handed persons in their efforts to apply the same training to the right hand.