The patient became insensible, without any excitement or struggling, in the course of three or four minutes, and the operation was commenced. A little more chloroform was administered two or three times during the operation, in order to keep up the insensibility. After a few minutes had elapsed, I observed that the face and lips of the patient became pale. At this time he had not inhaled any chloroform for about two minutes. Immediately afterwards, however, his face became red, and he made straining efforts with the muscles of respiration, as if he were beginning to feel the operation. To prevent his becoming altogether sensible, therefore, I commenced to give him a little more chloroform, with the valve of the inhaler about one-third open, as on the former occasions. He had only taken two or three inspirations, however, when the breathing ceased. He appeared to be merely holding his breath, as sometimes happens during the exhibition of chloroform, and I expected that he would begin to breathe again in about a quarter of a minute. In the meantime, I endeavoured to feel the pulse in the temporal artery, but did not perceive any. Instead of the breathing recommencing at the time I expected, the countenance became suddenly pale, and a little afterwards rather livid. I applied my ear over the region of the heart, but could not hear any sound. After a few seconds, however, the patient took a rather deep inspiration, and immediately after this I was pretty sure that I heard the heart beating very feebly and rather frequently, but only for a few seconds, after which no sound could be heard. There were one or two more very feeble inspirations at intervals of about a quarter of a minute, after which there were no further signs of life. As soon as the patient had entirely ceased to breathe, artificial respiration was performed, but no sign of returning animation appeared. At the examination of the body fifty-two hours after death, the heart was found to be larger than natural, and there was a good deal of fat on its surface. Its right cavities contained air or gas, probably resulting from the partial decomposition of the blood. The right ventricle was dilated, and its walls were very thin. At one place, near the apex, they were extremely thin. The left ventricle was also dilated, but its walls were of the proper thickness. They were, however, like those of the other ventricle, very soft and friable. There was a calcareous incrustation on one of the aortic valves. There was scarcely any blood in the heart, but its lining membrane was stained in places, showing that blood had been present after death. Mr. Pollock and the late Mr. W. F. Barlow examined the structure of the heart under the microscope, and the latter gentleman furnished me with the following account of the examination:—