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PART I. THE INFLUENCE OF NERVES AND DRUGS ON SECRETION.IT is generally agreed that direct mechanical and chemical stimulation of the intestinal mucosa causes a secretion of succus entericus. There is also some evidence that hormonal influence is involved, but the role of the vagus and sympathetic nerves is not clear.In the following paper experiments will be described dealing with the influence of extrinsic nerves and hormones on the production of succus entericus. Savitch and his co-workers [1917, and cited by Babkin, 1928] have reported experiments on the influence on intestinal secretion of stimulation of the vagus nerves in the neck of decapitated cats. The animals were placed in a saline bath at 370 C. and the small intestine was milked downward with the fingers at regular intervals. Under these conditions the unstimulated control animals began to produce fluid after 4-5 hours. After stimulating the vagus nerve in the neck the secretion appeared after the long latent period of 1-1! hours, and, though stated to be dependent on the continuation of stimulation, the experimental records reproduced by Babkin do not indicate very clearly that this was so. These would appear to be the only experiments reporting positive effects from vagal stimulation.In the following experiments decerebrate or decapitate cats have been used exclusively, for, as will be seen later, anesthetics have a profoundly depressing action on intestinal secretory phenomena. The animals were starved for 24 hours before operation. Under ether anaesthesia, with artificial respiration, the chest was opened along the eighth right costal interspace, and the eighth rib divided near the 73 Wright, Jennings, Florey, and Lium vertebrae. The vagus nerves were dissected below the lung roots where they lie beside the cesophagus. They were tied, cut and the peripheral ends drawn on to protected platinum electrodes. Fine enamelled wires from these electrodes were passed through the chest wall, the lungs were fully inflated and the chest closed. Through a midline abdominal incision, the accessory pancreatic duct, the main pancreatic duct and the common bile duct were tied. When the duodenum only was under investigation the pylorus was closed either by a glass ball or by a ligature embracing the mucosa applied through a small longitudinal incision in the muscle just proximal to the pyloric sphincter. Cannule were tied into the stomach and into the duodenum 6 centimetres from the pylorus. When the jejunum or ileum was being investigated as well as the duodenum, a glass obturator in the form of a cone was passed into the duodenum and secured to its wall 6 centimetres from the pylorus, thus isolating the duodenum from the rest of the small intestine without interrupting the continuity of the intestinal wall. The cone was placed in position by attaching it to a thread which passed through the eye in the tip of a probe; the end of the probe was inserted through a hole in the stomach wall and guided through the pylorus and down the intestine for 6 centimetres. ...

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