EXPERIMENTAL STUDIES ON THE INNERVATION OF THE MUCOUS MEMBRANE OF THE GUT BY

THE nerve supply of the gut has been the subject of intensive histological investigation ever since Remak (1840, 1852) observed the presence of microscopic ganglion cells with processes in the wall of the pharynx and of the stomach. Meissner (1857), Billroth (1858) and Auerbach (1862, 1864) made detailed examinations of the submucous, mucous and muscle layers respectively in the gut and discovered nerve plexuses which were similar in many respects to neural elements elsewhere in the autonomic nervo.us system. Each of the plexuses in the submucous and muscle layers of the gut wall was shown to contain aggregations of nerve cells in ganglia linked by bundles of fine nerve fibres, some of which were con-tinuous with similar bundles of fibres in the mesentery of the gut. With the advent of specific methods for demonstrating neural struc-tures, the connexions between the various plexuses of the gut wall were defined more clearly. Drasch (1881), using gold chloride after formic acid fixation, drew attention to the tiered arrangement of the submucous plexus, illustrating it as consisting of outer, middle and inner divisions which are linked together and connected externally with the myenteric plexus and internally with the mucosal plexus. Dogiel (1895, 1896, 1899) classified the neurons of the gut wall, in specimens stained with methylene blue, according to the length of their processes. He believed that the neurons which give rise to short processes (designated type I cells) were motor to the musculature of the gut, whereas the neurons with long processes (type II cells) were sensory in nature. Dogiel's concept that motor and sensory functions are mediated by morphologically distinct neurons has received little support. According to most investigators the enteric neurons are either motor or associative 1Nuffield Dominions Demonstrator. On study leave from the University o