Much evidence has accumulated indicating that the rhythmic contractile activity of the duodenum and small intestine is primarily intrinsic in nature. It has also been suggested that this intrinsic muscular activity is under the supplementary influence of a "pace maker," probably located in the duodenum near the entrance of the common bile duct. Milton et al1,2 demonstrated the presence of a slow, rhythmic, electrical wave which starts in the first part of the duodenum and passes aborally as a coordinated stimulus to the muscular wall of the distal small bowel. Brass et al confirmed this observation and, by means of radially placed electrodes, showed that the electrical impulses travel down the intestine in a sheathlike manner.3 Later, they added additional data which indicate that the electrical activity is conducted by the smooth muscle fibers themselves, and that the pylorus serves as a type of insulating barrier across which