The Harveian Oration. 33 siology than that by Marshall Hall when he established the conditions of a reflex nervous aetion. This unit appears to be the key of the most complex nervous phenomena, if it be not, indeed, an expression of the law which determines the form of the whole. From it physiologists have obtained a elue whereby to track the labyrinths of instinet. and habit; for, assuming, as we must, that the mechanical arrangements in the nervous system, at periphery and centre, are, in their way, as artificial as the optical arrangements of the eye, or the acoustic arrangements in the ear, we can recognise how the instinctive. and volitional acts are performed indepen- dently of the conseious determination of the individual.
Physiologists have long pointed out that the basis of our volitional acts is instinetive. That the most instructed anatomist has no advantage over the ignorant in direeting his voluntary movements, caeli being guided by the objective intention, and both equally in- tellectually uneoncerned in the steps whereby
