there is no border-space, where the one merges into the other, but a sharply dividing line. The truth, therefore, appears to be, that reflex action, instinct, and reason are not derived the one from any other, but that each one is distinct from and has arisen independently of the others—is not a more or less complex form of the others. Concerning the latter two faculties, I think we have no choice but to believe that, when, by the action of Natural Selection during the phytogeny, a nervous system was evolved, then, in consequence of the high compounding of reflex action, another and totally distinct faculty, instinct, was evolved, and was superimposed on reflex action, the evolution of it' being rendered possible by the developed state of the nervous system. But this faculty was an entirely new thing, as was also reason, which was subsequently evolved, its evolution being rendered possible by a still greater development of the nervous system. To illustrate the subject, however faultily, we may compare the evolution of the nervous system with these three faculties to the evolution of the fore limbs of mammals with three faculties which may be possessed by them. Reflex action may be compared to locomotion, to which the limbs were primarily devoted; instinctive action to the power of delivering blows with the fore limbs as in bears, a thing totally distinct from locomotion, yet only possible to the fore limbs in consequence of the evolution of the organs of locomotion; rational action to the power of carrying objects, as in man—a thing distinct both from locomotion and the delivering of blows, yet only possible because of still further evolution in the organs which subserve locomotion and the delivering; of blows.
