Secretion by the parotid gland of the sheep has been studied in acute preparations and by means of fistulae. The sheep is unusual in having a continuous flow of parotid saliva which increases in amount both with feeding and with cud chewing (Ellenberger & Hofmeister, 1887). As in the ox its parasympathetic nerve supply arrives via the buccal branch of the mandibular nerve as fine branches which go from the anterior border of the masseter muscle with the duct to the gland (Moussu, 1888(Moussu, , 1890, not via the auriculo-temporal nerve. Moussu demonstrated that after section of this nerve the gland continued to secrete and he attributed this continued secretion to a non-nervous mechanism postulated by Colin (1886). Eckhard (1893) who in 1867 (Eckhard, 1867), before Moussu's discovery, had convinced himself that there was no secretomotor nerve to the gland, held the view that it was due to the 'nature' of the gland.Eckhard (1893), after amplifying these observations and confirming Moussu's observation that stimulating the buccal branch of the mandibular nerve (henceforth referred to as Moussu's nerve) increased secretion, nevertheless stated that section of the nerve did not cause any reduction in the rapidity of secretion by the gland. This view has not been refuted, and is often quoted with the reservation that it requires confirmation (Langley, 1898, in Schafer's Physiology text-book; Babkin, 1944). It is associated with statements that salivary secretion in the ruminant is not stopped by atropine. However, the reduction by atropine of normal secretion to a lower rate is recognized by Babichev, Perstnov & Kulesco (1930) as indicating a biphasic secretomotor mechanism. In this paper we have endeavoured to establish with certainty the effect of the parasympathetic nerve on the gland.Another controversial matter is the effect of stimulation of the sympathetic fibre', to the parotid upon its secretory activity. Eckhard (1869) attacked the
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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