Among the most noteworthy features of ethylene-oxygen anesthesia, as noted in the clinical report of Luckhardt and Lewis,1are the facts that recovery from the anesthetic is unusually prompt and that the subsequent postoperative condition is distinctly better than after ether. Less than half as many patients suffer from postanesthetic nausea and vomiting after ethylene-oxygen as in a comparable series after ether. These considerations led Dr. A. B. Hertzman and me to try to ascertain whether any differences might be noted between the effect of ethylene-oxygen anesthesia on the acid-base balance of blood and the now well recognized acidotic effect of ether. This action of ether may be a considerable factor in contributing to the postanesthetic complications following etherization. FACTORS INFLUENCING BLOOD REACTION IN ANESTHESIA Apart from the doubtful possibility that anesthetic agents may themselves exert a direct action on the acid and basic elements of bloods, variations in