It is well to study that brain more carefully and try to relate it with the germ-cells of the protoplasmic streams from which it arose. We have to consider how it is that the brain of a son comes to resemble the brains of his parents, when the carrier of his parents' lives to him was only that fertilized germ-cell, a jelly with a nucleus, to all appearances no more. Here we must confine our study to one problem, that of memory, partly because we have no space for more, but chiefly because memory is an 'Open Sesame' to many wonders. We may if we please link it with heredity, with that passing on of characters and habits from parents to child through the comparative, but only comparative and very misleading, simplicity of the germ-cell. 'The man who could penetrate into a brain,' it is said, 'and watch what happens there would very likely see it full of sketched-out movements, there is no evidence that he would see anything else. He would have no more knowledge of what was going on in the corresponding consciousness than we should have of a play were we watching the comings and goings of the actors on the stage without hearing a word of it. If the play were no more than a pantomime the movements of the players would tell us nearly everything about it; if it were a comedy of life and manners they would give us next to nothing.' It has been said, too—and the simile is illuminating—that the brain is like a sort of central telephone exchange, permitting, delaying, or arresting communication. It is an instrument of analysis, of hesitation and of choice; but its office is said to be limited to the transmission and division of movement, movement started by things outside the body and movement started from within the body. The body is the conductor of these movements to and fro between objects acting upon it and objects upon which it acts. Only in the form of motor contrivances do brain and body, we are told, store up the action of the past. This is a point of great importance in regard to both our own lives and our inheritance from our forerunners. We may distinguish two kinds of memory; one graven as it were in the living stuff of our body; another enshrined and active in the fluent personal history we ourselves most really are. Let us see what the evolutionist philosopher has to tell us about this. Let us illustrate our subject after his fashion.