ABSTRACT
We note an orderly sequence of actions in the movement of animals, even in cases where every observer admits that the coordination is merely reflex. We see one act succeed another without confusion. Yet, tracing this sequence to its external causes, we recognize that the usual thing in nature is not for one exciting stimulus to begin immediately after another ceases, but for an array of environmental agents acting concurrently on the animal at any moment to exhibit correlative change in regard to it, so that one or the other group of them becomes—generally by increase in intensity—temporarily prepotent. Thus here dominates now this group, now that group in turn. It may happen that one stimulus overlaps another in regard to time. Thus each reflex breaks in upon a condition of relative equilibrium, which latter is itself reflex. In the simultaneous correlation of reflexes some combine harmoniously, being reactions that mutually reinforce.
