Perhaps the most interesting part of the whole body is that little band of the cortex running upwards from behind the temple to the crown of the head, in which (_cf._ Diagrams 64, 65 and 66) the motor areas of the limbs, and the perception of those sensations which we have grouped together and called ‘touch,’ are situated. The minute structure of this region is roughly shown in section in Diagram 67, as it has been made out with the microscope; but only a few of the nerve cells are shown, the connective tissue of feltwork in which they are suspended, and the bloodvessels by which they are nourished, being left out. All the structures represented are of course very, very small; the large black patches which represent cells would really be invisible, and the whole field of the diagram only a mere speck, to the naked eye. [Illustration: DIAGRAM 64.—POSITION OF THE BRAIN IN THE HEAD.] A represents the nerve by which impulses are brought in. It runs straight up to the surface of the cortex, and there its branches end, interlaced with those of a many-branched distributing cell (B). The two cells (C and D) shaped like pyramids, which send up branched processes from their apexes, receive an impulse from the distributing cell, and transmit it along the fibre which runs downwards from the middle of their base. Where the fibre from the smaller one goes to we are not sure—probably to another part of the brain to insure harmonious working—but the large pyramidal cell sends its fibre right away through the lower parts of the brain, passing the cell-stations they contain, on into the spinal cord, till it reaches the centre there, which immediately works some particular limb. [Illustration: DIAGRAM 65.—MAP OF THE CEREBRAL HEMISPHERE, SHOWING THE AREAS IN WHICH VARIOUS FUNCTIONS ARE LOCALIZED.] Supposing we anæsthetized somebody, throwing him into deep unconsciousness, and then opened his skull, laying bare the brain as is done in Diagram 64, only not quite in such a wholesale manner. If we then stimulated the part of the brain we are now considering at different places with electric needles, using a weak induction current, we should see him moving different members according to the different regions touched—now an arm, now a leg, now the whole head. If we were to place the electrodes in the centre for the hand, and then gradually increase the strength of the current, the activity of the hand centre would throw other centres into activity. The arm would move next, raising the hand towards the face. Then the eyes would turn, and the whole head to meet the hand. Lastly the mouth would open. The movements are those of putting something into the mouth—the ruling passion strong in unconsciousness. [Illustration: DIAGRAM 66.—MAP OF THE CEREBRAL HEMISPHERE, SHOWING THE AREAS IN WHICH VARIOUS FUNCTIONS ARE LOCALIZED.]