events too numerous and heterogeneous to be provided against by an unvarying machinery.
The entire passage from reflex action in its lowest manifestations, to reason in its highest manifestations, is therefore a process of increasing adaption to environments increasing in complexity. Low in the animal scale a few heterogeneous structures and reflexes provide against the few heterogeneous events that occur in the simple environment. Higher in scale the greater heterogeneity of the events to be provided against is met by the evolution, through Natural Selection, of a greater number of heterogeneous structures and reflexes. Higher still, when the environment becomes yet more complex, reflex action is supplemented by instinct, which, though undeviating in its promptings, is associated with consciousness and controlled to some extent by volition, whereby the element of choice is introduced, and the adaptability of the organism to its environment vastly increased. Highest of all, increasing still more the adaptability, when the events in the environment to be provided against have become so heterogeneous and multitudinous that by no evolution of new physical structures, accompanied by new reflexes and instincts, can they be provided against, there occurs that physical variability, in adaption to circumstances, to which I have so persistently called attention, and that accompanying mental variability on which I as strongly insist, and which we call reason.
Now there is no vestige of proof that instincts are increased by stimulation, i.e. that they are not only called into activity by stimulation, but are sharpened by it. Indeed, if our definitions are correct, such a supposition involves a contradiction in terms, since whatever is mentally acquired pertains to reason, not to instinct. Again, it is obvious that reason is not transmissible, since in each generation it must be acquired
