THE MOVEMENTS OF THE STOMACH. 281 



Evacuation of the stomach occurs only when the intestine is free from con- 

 tents. The following experiment will serve to determine when the ingesta enter 

 the intestine. In the presence of an alkaline reaction in the intestine, salol is 

 decomposed into carbolic acid and salicylic acid; the latter can be recognized in 

 the urine from the violet color produced upon adding ferric chlorid. In healthy 

 persons this reaction begins in from half an hour to an hour and disappears after 

 twenty-four hours; while in the presence of motor insufficiency of the stomach 

 it is delayed from three to twenty-four hours. Liquids are rapidly propelled from 

 the stomach into the intestine. 



The thick, muscular walls of the stomach in many grain-eating birds aid in 

 triturating the ingesta. The energy of muscular action necessary for this purpose 

 has often been measured by earlier investigators, who found that glass balls were 

 broken, and lead pipes that could be flattened only by a pressure of 40 kilograms 

 were compressed, in the stomach of the turkey. The masticating stomach of many 

 insects also is capable of similar activity. 



Mechanical stimulation causes contraction of the muscular layers directly 

 affected ; as does also application of potassium-salts, segmentary contraction of the 

 circular muscles often taking place at the same time. Sodium-salts, on the con- 

 trary, usually cause semicircular contractions or contractions progressing toward 

 the cardiac orifice. At the pyloric antrum the stimulations as a rule spread more 

 rapidly. Electrical stimulation of the internal surface of the stomach causes no 

 movement. The contraction induced by stimulation of the intestinal mucous mem- 

 brane is always less than that due to stimulation of the external surface of the in- 

 testine. In human beings both endogastric and percutaneous electrical stimulation 

 are without demonstrable effect on the evacuation and the secretion.of the stomach. 



Nervous Activity. Openchowski and his pupils make the following statements 

 with respect to the influence of the nerves upon the movements of the stomach: 

 The cardia contains automatic ganglion-cells, which are connected with the pneu- 

 mogastric and the sympathetic nerves. A center for the contraction of the cardiac 

 orifice is situated in the posterior quadrigeminal bodies, whence the paths pass 

 downward, mainly through the pneumogastric, and in lesser degree through the 

 splanchnic nerves. The center for opening the cardia lies in the corpus striatum, 

 and in connection therewith one in the cruciate sulcus of the central cortex, in 

 the dog; the pneumogastric nerves constitute the conducting paths. Dilatation 

 centers are situated also in the upper portion of the spinal cord, whence the path 

 passes through the sympathetic nerve (aortic plexus, lesser splanchnic nerve). 

 Reflex opening of the cardiac orifice can be induced by irritation of the sensory 

 splanchnic nerves, and of the sciatic also. 



The body of the stomach contains also automatic ganglia, connected with the 

 pneumogastric and the sympathetic nerves. A center for contraction is situated 

 in the corpora quadrigemina, whence paths pass through the pneumogastric nerves 

 and the spinal cord, and from the latter into the sympathetic. The upper cord 

 contains inhibitory centers; the paths pass through the sympathetic and the 

 splanchnic nerves. 



The pylorus contains automatic ganglia. It exhibits a certain, varying degree 

 of tone during closure: the splanchnic nerve may more fully open the pylorus, 

 while the pneumogastric tends to close it. The center for opening the cardiac 

 orifice inhibits the movement of the pylorus ; the path passes through the spinal 

 cord and the splanchnic nerves. Inhibitory pyloric centers are situated in the 

 corpora quadrigemina and the olivary bodies; the path passes through the spinal 

 cord. The cortical center for opening the cardia causes simultaneous contraction 

 of the pylorus; the path passes through the pneumogastric nerves. Centers for 

 the contraction of the pylorus are situated in the corpora quadrigemina; the path 

 passes through the pneumogastric nerves, a few fibers through the spinal cord and 

 the sympathetic nerve. 



Stimulation of the peritoneum and also of the skin causes reflex 

 of the pylorus and of the small intestine. Stimulation of the central 

 of one pneumogastric, the other being intact, gives rise to immobility of the pylorus, 

 contraction of the stomach and dilatation of the cardiac orifice, 

 temperature to 25 C. causes movements in the excised empty stomach. 



Vomiting takes place in consequence of contraction of the walls of the s 

 the pyloric sphincter being at the same time closed. It occurs most readily 

 when the stomach is distended. Dogs usually distend the stomach greatly b 

 vomiting, bv swallowing air. There is no doubt that in infants vomitl 

 due principally to contractions of the walls of the stomach, though will 



