FUNCTIONS OF THE STOMACH. 301 



by a delicate basement membrane, the capillaries are thus related 

 to the former precisely as we found them to be in the sweat- 

 glands. Indeed, if the intrinsic structures of the stomach are 

 compared with those of the organs reviewed, it soon becomes 

 evident that the mechanism to which the production of secre- 

 tions is due does not differ from them. 



We cannot, however, say the same in respect to the ex- 

 trinsic vessels and nerves, and to this feature of the process 

 we wish to call especial attention. As is well known, the 

 vascular supply of the stomach is made up of the gastric, 

 pyloric, and right gastro-epiploic branches of the hepatic artery 

 and the left gastro-epiploic and vasa brevia from the splenic. 

 The important feature referred to is this: The gastric, hepatic, 

 and splenic arteries arise from the coeliac axis, and, as shown 

 in the earlier chapters, the cceliac axis is the first great arterial 

 trunk to receive the blood from the lungs: i.e., before the activity 

 of the oxidizing substance in the downward blood-stream has 

 in any way been reduced. Another very suggestive feature is 

 that the cceliac axis is surrounded by the cceliac plexus, a portion 

 of the solar plexus of the sympathetic, and that extensions of the 

 coeliac plexus the gastric, hepatic, pyloric, gastro-duodenal, 

 and gastro-epiploic plexuses follow the arteries of the same 

 name to the walls of the stomach. We thus have, though in a 

 much more imposing form, one compatible with the impor- 

 tance of the function, the two structures required by the ex- 

 trinsic mechanism: arteries with muscular walls and what we 

 have termed "extrinsic constrictor" nerves since they are 

 sympathetic plexuses to decrease their lumen and thus in- 

 crease the rapidity of the blood-stream through the gastric 

 walls, during functional activity. 



Another feature requiring our attention is the formation 

 of the gastric secretion. In the blood-plasma we have sodium 

 and potassium chlorides; in the secretion of the stomach these 

 represent the most important and abundant salts, and consti- 

 tute the source of the hydrochloric acid in the gastric juice, 

 according to prevailing views. Has the oxidizing substance of 

 the plasma any influence upon the formation of this acid? The 

 marked affinity of chlorine for hydrogen seems able to fill the 

 want. It takes it up whether the gas be free or in vulnerable 



