The patient recovered strength after energetic treatment, and was able to walk about the garden after a few weeks. It was then that we began to study her brain. I shall not describe the various instruments we constructed, but only remark that we lost much precious time with different attempts, and when we were at last ready, the most favourable time was already past, the wound was covered with a thick scab, which dulled the pulse of the brain. Nevertheless, we made some rather important observations, the results obtained being the most complete up till that time in the physiology of cerebral circulation. In order to give an instance of the delicacy of the apparatus, and to prove the accuracy of our investigations, I mention the following circumstance. One day we were assembled in the laboratory of Professor Giacomini, intent on studying the brain of the patient, who was sitting in her arm-chair, and seemed absent-minded. There were a few spectators in the room, who were told to remain quietly behind the patient’s back. In solemn silence we observed the curve marked by the cerebral pulse on the registering apparatus. Suddenly, without any external cause, the pulsations rose higher, and the brain increased in size. This striking me as strange, I asked the woman how she felt; the answer was, well. Seeing, however, that the circulation in the brain was very much altered, I examined the instrument carefully, to see whether it was all in order. Then I asked the patient to tell me most minutely what she had been thinking about two minutes before. She said that, as she had been looking absent-mindedly into a bookcase standing opposite to her, she had caught sight of a skull between the books, adding that it had frightened her by reminding her of her malady. This poor woman was called Margherita; she was rather timid, but willingly allowed herself to be examined and studied, full of confidence in us, who vied with each other in showing her polite attentions. Her children often visited her, but she was ashamed to go back to her native place with her terribly disfigured face, preferring to remain away from her family and perform the duties of nurse to the other invalids in the hospital. After many years I felt a wish to see her again. As I pressed her hand to encourage her, she told me that she had at last given up the wish to die. III Chance furthered the continuation of these observations, new opportunities for this study soon offering themselves in Turin and elsewhere. In the lunatic asylum I found a boy a portion of whose skull was wanting. In the year 1877 I came across a man in the hospital of San Giovanni, who had an opening in his forehead which seemed made on purpose for examination; and finally, last year, I was able to repeat and conclude my investigations on a perfectly healthy man who had also a hole in his skull. As yet I have had no opportunity of publishing the observations and experiments made on this man.