sensory excitement is diffused; the qualitative excitement of the P-system serves the mobile quantity of the psychic apparatus as a regulator for its discharge. We may claim the same function for the overlying sensory organ of the Cons. system. By assuming new qualities, it furnishes a new contribution toward the guidance and suitable distribution of the mobile occupation quantities.

By means of the perceptions of pleasure and pain, it influences the course of the occupations within the psychic apparatus, which normally operates unconsciously and through the displacement of quantities. It is probable that the principle of pain first regulates the displacements of occupation automatically, but it is quite possible that the consciousness of these qualities adds a second and more subtle regulation which may even oppose the