The amount of vomiting which after this stage may be regarded as normal is difficult to determine. The author took notes of some 300 cases on this point. The details of his results are not suitable for a text book, but, broadly speaking, it would appear that after an operation of ordinary duration and severity, the vomiting returns on the average some five or six times, and usually ceases on the evening of the operation day. A limited number continue to vomit at intervals until the early hours of the following morning. With nitrous oxide and oxygen the vomiting is far less than the above, though even with this anæsthetic quite severe emesis may occur. With closed-ether, the trouble is very violent for a short time, large quantities of mucous being ejected: it is probable that after the first two hours, it is no more marked than after open methods. The use of morphia and atropine before operation most certainly reduces the violence and duration of this sequela. Prolonged more than twenty-four hours, the condition must be regarded as definitely abnormal. PREVENTION AND TREATMENT. The adoption of open-ether preceded by morphia and atropine and due skill and thought on the part of the anæsthetist, combined with proper preparation of the patient, are the only means of prevention at our command. The raised position of the head and shoulders during the recovery stage undoubtedly tends to reduce the nuisance. It is a vexed question whether to give or to withhold fluids after operation--and this matter is of course in the hands of the surgeon, not the anæsthetist. In certain cases, the author believes that it is worth while trying the effect of a cup of fresh tea with very little sugar or milk. Even if rejected in a few moments, the astringent effect of the infusion seems to soothe the gastric mucous membrane, and give relief. Post-operative Acidosis. (Synonym--Delayed Chloroform Poisoning). In a limited number of cases, post-operative emesis assumes a grave type, and definitely threatens life. Such cases began to be studied in the early part of this century, and though our knowledge of the condition is still incomplete, the student should be acquainted with the present views held upon the subject.