On October 21 had an attack of prostration to a more extreme degree than ever known before; she seemed, in fact, at the point of death from sheer exhaustion. And here again we are met by the important question—Was this due to oxygen? for experience recorded of its effects seems to warrant this apparent paradox, that although in many cases a stimulant, in some it is a depressant; that although it will increase the vital powers when only moderately depressed, it will tend to lower them when they are already very much lowered.[11] Or, again, was the prostration due to the bromide of potassium? Candidly, I do not think that it was due to these causes, partly because she had had no inhalation for two days before, and no medicine for three days, and partly because a depression similar, though less in degree, has followed menstruation on other occasions, and this had been more profuse than usual. For the time I gave her quinine and brandy and a little morphia, and on the 23d permitted her to resume inhalation, beginning at 12 to 60; she again gradually increased the dose to 30 pints in the day. For the bromide of potassium I substituted small doses of strychnia. The administration of the gas in varying doses was persevered with till November 4—a full month altogether—then I recommended her to discontinue it. The effect was certainly not marked; if there was any, it might be in relieving the sense of suffocation, which was not so bad during that month as it had been before and since; but on the whole the gas must be considered to have failed in this case. However, it will be remembered that many other remedies had failed also, and the further progress of the case has convinced me of the presence of serious organic disease; it is in fact two months since I have ceased to entertain or give any hope whatever of this lady’s recovery. CASE XII. was one of general debility with irritable heart. A gentleman of 35, who had lost several brothers by phthisis, and had been subject to unusual harass and exertion, began to lose appetite, to grow thin, and to suffer from lassitude, dyspnœa, and palpitation. When he came to me in May 1868, the symptoms had lasted for two or three months, but I could detect no physical signs of disease. For some weeks he took quinine, aconite, and cod oil, and applied belladonna; still he did not improve much.