During the last few years, much has been written on drainage of the biliary tract by means of lavage of the duodenum with magnesium sulphate solution. It is my purpose to report here the results of experiments undertaken to determine the effect, if any, of magnesium sulphate on the secretion of bile. METHOD OF EXPERIMENTATION Dogs were used in all experiments, and ether anesthesia and rigid sterile technic were employed. Permanent biliary fistulas were made according to the method worked out in this laboratory.1In certain experiments the gallbladder was removed; in others it was not. The fistulas were made in two stage operations. If the gallbladder was to be removed, it was done during the first stage, which consists of transplanting the duodenum just beneath the skin and fascia. About two weeks later, when the wound had healed, the second stage operation was performed. At this time, only