Let us now see how the brain writes when it guides the pen itself. I have already collected a few volumes of these autographs, from which I here give a single line as an example, written by Bertino’s brain in the night of September 27, 1877. He was lying on a sofa. I had applied the apparatus which traces the movements of the brain to his forehead, and watched the pen writing on the cylinder while I waited for him to fall asleep. At first the pen traced large undulations, a certain sign of great restlessness in the blood-vessels of the brain; the pulse-lines were considerably modified from time to time in form and height, and this, although profound silence reigned. I might have asked him what he was thinking of, but I did not do it, as I wished urgently to see him fall asleep. At last the undulations began to decrease, becoming lower and less frequent, sometimes separated from each other by long periods of repose, like a lake gradually growing calm, but upon which from time to time a little wave ripples, troubling the smooth surface. At length Bertino fell asleep. Consciousness was extinguished, the troublous thoughts of life had ceased, only the last sentinels of the nervous system were still vigilant. At the slightest noise a wave of blood disturbed the surface of the brain. If the hospital clock struck the hour, or someone walked along the terrace, if I moved my chair, or wound up my watch, or if a patient coughed in the next room--everything, the slightest sound was accompanied by a marked alteration in the circulation of the brain, all immediately traced by the pen which the brain guided on the paper of my registering apparatus. [Illustration: FIG. 1.--PULSE OF THE HUMAN BRAIN DURING SLEEP] After an hour and a half, when I saw that Bertino was breathing quite calmly, with the rhythm and in the characteristic manner of a sleeper, I rose with great caution, approached the pillow on which he had laid his head, and at that point in the curve where is the sign of the arrow, ↓, I called him gently by name, 'Bertino.’ He did not move or answer. If we examine the curve in fig. 1, we find that even before the sign, ↓, four pulsations are somewhat higher than the preceding ones. This first increase in the volume of the brain is due to the very slight noise which I involuntarily made with the chair on rising to approach Bertino.