We turn now to Bergson’s fertile comparison of the physiological analysis of the organism with the action of a cinematograph. If we take a series of photographic snapshots of, _e.g._, a trotting horse and then superpose these pictures upon each other, we produce all the semblance of the co-ordinated motions of the limbs of the animal. Yet all that is contained in the simulated motion is immobility. From a succession of static conditions we appear to produce a flux. Yet if we could contract our duration of, _e.g._, a week, into that corresponding to five minutes--if we could speed up our perceptual activity--should we not see the cinematographic pictures as they really are--a series of immovable postures and nothing more: truly an illusion? If, again, we reverse the direction of motion of the film, we integrate our snapshots into something which is absolutely different from the reality which they at first represented; and by such devices the illusions and paradoxical effects of the picture-house farces are made possible. Well, then, in the physiological analysis of the activity of the organism do we not do something very analogous to this? The complexity of even the simplest function of the animal is such that we can only attend to one or two aspects of it at once, arbitrarily neglecting all the rest. We find that the hydrostatic pressure of blood, and lymph, and secretion, the osmotic pressure, the diffusibility, vaso-motor actions, and other things must be investigated when considering the question of how the submaxillary gland secretes saliva. One, or as many as possible, of these reactions are investigated at one time, and then the results are pieced together--integrated--in order to reproduce the full activity of the whole indivisible process. But in doing this do we not introduce something new--a _direction_ or order of happening--into the elements of the dissociated activity of the organism? Each elemental process must occur at just the right time. What right have we to say that the activity of the organism is _made up_ of physico-chemical elements? Just as much as we have in saying that a curve is made up of infinitesimal straight lines. Let us adopt Bergson’s illustration, with a non-essential modification. [Illustration: FIG. 10.]