1. Thirty‐six patients in whom barium‐enema examination had suggested the possibility of carcinoma in a segment of diverticular disease were examined by colonoscopy. 2. Colonoscopy is particularly difficult in such patients and it failed to examine the diseased segment in 17 cases. 3. Colonoscopy gave a firm diagnosis of carcinoma in 4 cases, excluded it in 5, and was helpful in another 9. There was 1 false negative.

SUMMARY1. 5-HT was released into the lumen of the intact isolated rat stomach and into the bath fluid surrounding a preparation of the body and antrum stretched mechanically.2. Release of 5-HT increased when the pressure inside the intact stomach was raised or when the body/antrum preparation was stretched.3. This increased release was not prevented by hexamethonium, atropine, hyoscine or procaine, and was probably due to distortion of cells containing 5-HT.4. During periods of peristalsis induced by transmural stimulation the pharmacological activity of the fluid in the stomach was usually increased owing to a greater release of 5-HT and also to the release of an unidentified substance.5. In reserpine-treated rats, 5-HT was released into the stomach but transmural stimulation did not produce true peristalsis and only rhythmic contractions occurred.6. Peristalsis was seldom reduced by methysergide, and it is concluded that 5-HT is not essential for gastric peristalsis in the rat.

SUMMARY1. A rat stomach-duodenum preparation in which pressures in the body and the antrum and flow through the pylorus could be recorded simultaneously has been used to study the effects of pressure and pharmacologically active substances on the peristalsis induced by transmural stimulation.2. Vagal and transmural stimulation produced vigorous peristalsis and episodic flow. Simultaneous stimulation of the peri-arterial nerves abolished peristalsis and relaxed the pylorus.3. After repeated stimulation the preparation lost tone and peristalsis failed. Peristalsis and tone could then be improved by lowering intragastric pressure. Vigorous peristalsis could be restored in an inactive preparation by eserine and more transiently by 5-HT.4. Drugs which increased smooth muscle tone improved peristalsis and, under the conditions used, they reduced flow. Eserine was more active in this respect than acetylcholine or 5-HT.5. Adrenaline and hyoscine abolished peristalsis and caused the stomach and the pylorus to relax.6. The results suggest that the peristaltic activity of the antrum is more important than the tone of the pylorus itself in controlling gastric emptying.

EDITORIAL SYNOPSIS The function of the pylorus and the pyloric antrum in the control of gastric emptying has been studied in an isolated rat stomach-duodenum preparation. Pressures in the body and pyloric antrum and flow through the duodenum were recorded using electronic transducers. Vigorous peristalsis and episodic flow were induced by electrical stimulation. The pylorus is normally open until it is transiently closed by an advancing peristaltic wave. High pressures could develop in the antrum when it was separated from the body by another peristaltic wave. Exclusion of the pylorus had very little effect on the pressures developed in body and antrum. The clinical implications of these findings are discussed.In recent years detailed studies of pressures in the body, antrum and duodenum have been made to investigate the mechanics of gastric emptying. Continuous measurement of the changing flow from the stomach to the duodenum is essential for correlating intragastric pressures with the emptying of gastric contents but this is extremely difficult in patients and conscious animals. By using a preparation in vitro, however, pressure in different parts of the stomach and the flow produced can be studied simultaneously. Experiments in vitro have the additional advantage that the mechanical and pharmacological control can be studied uncomplicated by extrinsic factors. Much of our recent knowledge of the physiology of peristalsis has in fact been obtained from such studies (Bulbring, 1957-58; Bulbring and Crema, 1958).Recent investigations, such as those of Atkinson, Edwards, Honour and Rowlands (1957) and Edwards (1961), show that the pylorus does not act as an independent sphincter controlling the exit of gastric contents, and the results reported here provide further evidence that the pylorus functions as an integral part of the antrum. METHODThepreparation and the method ofpressure recording have been described in detail in a previous paper (Armitage and Dean, 1962). The stomach and duodenum were suspended in oxygenated Krebs' solution as shown in Figure 1. Any desired pressure could be applied to the stomach by varying the height of a Marriotte bottle 'Some of the results reported here were communicated to the Surgical Research Society meeting at Manchester, May, 1962. connected to the body cannula at X. Pressure in the body of the stomach was recorded by an electronic transducer (T1) attached by an air-filled tube to the second limb of the body cannula at Y. Pressure in the antrum was recorded by a transducer (T2) attached by a saline-filled tube to the antral cannula at Z. Blockage of the cannula was prevented by the slow injection of saline through a three-way tap. Fluid passing from the stomach into the duodenum dropped on to a thin rubber dam tied over a small funnel attached to a third transducer (T3).