drawn; and this is the unconscious effect of the definite uniformity which they have been led to assume in nature. It may subsequently be organized into a law or general truth, and no doubt becomes a surer guide by that process. Then it goes to form the more precise instinct of the next generation. What we have said about this first kind of inference, which goes from phenomena to phenomena, is shortly this. It proceeds upon an assumption of uniformity in nature; and this assumption is not fixed and made once for all, but is a changing and growing thing, becoming more definite as we go on. If I were told to pick out some one character which especially colors this guiding conception of uniformity in our present stage of science, I should certainly reply, Atomism. The form of this with which we are most familiar is the molecular theory of bodies; which represents all bodies as made up of small elements of uniform character, each practically having relations only with the adjacent ones, and these relations the same all through--namely, some simple mechanical action upon each other's motions. But this is only a particular case. A palace, a cottage, the tunnel of the underground railway, and a factory chimney, are all built of bricks; the bricks are alike in all these cases, each brick is practically related only to the adjacent ones, and the relation is throughout the same, namely, two flat sides are stuck together with mortar. There is an atomism in the sciences of number, of quantity, of space; the theorems of geometry are groupings of individual points, each related only to the adjacent ones by certain definite laws. But what concerns us chiefly at present is the atomism of human physiology. Just as every solid is built up of molecules, so the nervous system is built up of nerve-threads and nerve-corpuscles. We owe to Mr. Lewes our very best thanks for the stress which he has laid on the doctrine that nerve-fiber is uniform in structure and function, and for the word neurility, which expresses its common properties. And similar gratitude is due to Dr. Hughlings Jackson for his long defense of the proposition that the element of nervous structure and function is a sensori-motor process. In structure, this is two fibers or bundles of fibers going to the same gray corpuscle; in function it is a message traveling up one fiber or bundle to the corpuscle, and then down the other fiber or bundle. Out of this, as a brick, the house of our life is built. All these simple elementary processes are alike, and each is practically related only to the adjacent ones; the relation being in all cases of the same kind, viz., the passage from a simple to a complex message, or vice versâ.