Gas has one advantage, in that it in no way interferes with the pain activities; and Lynch and Davis have shown that with a proper admixture of oxygen, it may be given with comparative safety for the two or three hours which may mark a normal second stage. To administer it a competent machine for mixing the gas is necessary. It should not be given to patients who have bad hearts, high blood pressure, or toxæmia. Neither is it a satisfactory anæsthetic when the head delivers, for the mother being less relaxed and more rigid, the legs and muscle action are harder to control and unnecessary perineal lacerations are liable to occur. The patient is instructed to take several deep breaths just as the uterine contraction comes on and the gas bags supply about 75 per cent nitrous oxide and 25 per cent oxygen. As the pain passes off the oxygen is increased and the nitrous oxide diminished until the mind is again clear. To save the perineum and better to control the patient, when the head is about to pass the vulva, it is wiser to abandon the gas for chloroform or ether. Obstetrical operations, such as forceps and version, require ether or chloroform, and not gas. The dangers vary with the anæsthetic chosen, as well as the amount and the method of administration. Ether affects the respiration, chloroform attacks the heart. Ether must not be given near an open flame. Chloroform is not explosive but is decomposed by fire into an irritating gas. Chloroform must be diluted with 90 per cent of air, hence the mask must be open, or the napkin held free from the face, so that plenty of air can enter. Ether and chloroform, when given “_a la reine_;” i. e., a few drops on the mask at the beginning of each pain and increased up to the acme, is relatively free from danger. They have the additional advantage that the sleep may be instantly deepened if operation is required. Chloroform, it is now believed, predisposes mildly to post partum hæmorrhage. Davis has shown that neither ether, gas, nor chloroform affects the child injuriously if the administration is intermittent and not too greatly prolonged. To summarize: Morphine and scopolamine combined is a first stage analgesic, which has too much value to be neglected. Gas, if an apparatus is to be had, may work well for the greater part of the second stage, while for operations, or for the period of expulsion, during which the head passes the perineum, chloroform and ether give bests results. Moreover, chloroform “_a la reine_” may be given safely and efficiently by a competent nurse and in many instances _must_ be given by the nurse, if at all. When the perineum bulges, or the head becomes visible at the vulva, the nurse should anoint the lips, cheeks and tip of the nose with cold cream or olive oil, to avoid burning the skin, and lay two or three thicknesses of handkerchief or gauze over the nose (an inhaler is best). An abundance of room must be left underneath and at the sides of the mask for air to enter.