The cause and treatment of mucous colitis are among the outstanding problems of medicine today. This disorder, in common with esophageal spasm, involves hypertonus of smooth muscle of a portion of the alimentary tract and therefore both conditions will be reported in the present introductory study of their physiology. In parts of this article alimentary spasm in general will be considered. The innervation of the alimentary tract in mammals and in man is not yet a closed question. In conflict with theories of "vagotonia" and "sympatheticotonia," certain recent studies emphasize that under varying conditions the vagi, as well as the splanchnics, have both motor and inhibitory effects on the lower part of the esophagus, cardia, stomach and small intestine.1The striated muscle of the esophagus probably receives only motor fibers from the vagus.2The colon is supplied from the mesenteric plexuses, the pelvic plexus and the pelvic nerve,3but it