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Stimulation of the vagus nerves in decerebrate or decapitate cats causes a secretion from the duodenum which comes principally from the Brunner's gland area. 2. No clear evidence has been obtained that vagal stimulation causes secretion from the jejunum or ileum. 3. Cutting the greater splanchnic nerves in the thorax causes secretion from the duodenum, but not from the lower levels of the small intestine. 4. Cutting all the preganglionic sympathetic fibres causes secretion from all the small intestine. 5. The ganglia of the solar plexus exert an inhibitory influence on secretion after section of the preganglionic fibres. 6. The subcutaneous administration of eserine causes secretion from all the small intestine. 7. The concomitant administration of eserine and acetylcholine may cause extreme damage to the intestinal mucosa. 8. Stimulation of the Nervi Erigentes has no influence on the secretion of the small intestine. 9. Histamine has no influence on the secretion of the small intestine. 10. Certain anæsthetics abolish or considerably reduce secretory activity produced by the above methods. 11. Atropine also abolishes it. 12. Confirmation has been obtained of the presence of a secretory hormone acting on the first part of the duodenum in cats. A similar hormone has been shown to be present in pigs. In dogs, innervated fistulæ cease to secrete after 24 hours' starvation and recommence soon after feeding. 13. Duodenal secretion obtained experimentally contains amylase and enterokinase. It does not contain protease or peptidase. It sometimes contains traces of invertase and lipase, but their digestive power is insignificant. 14. The duodenal secretions of five different species of animal and of both denervated and innervated fistulæ have the same digestive properties. 15. In a few experiments no differences were found between the digestive properties of secretion from the duodenum and from other levels of the small intestine. 16. Juices from the same level of the small intestine secreted in response to different stimuli show differences in digestive properties which are due to cells and not to differences in the secreted fluid. Dr. E. Chain has kindly advised on the conduct of the enzyme investigations. We are glad to acknowledge the technical help of J. Kent and A. Sale. We are indebted to the Government Grants Committee of the Royal Society and to the Nuffield Trust for grants towards expenses. One of us (R. D. W.) was also in receipt of a personal grant from the Nuffield Trust.
Wright et al. (Mon,) studied this question.