DIGESTION 



179 



usually described as peristaltic in charae 



also serve to 



FIG. 75. SHADOW SKETCHES 

 OF THE OUTLINES OF THE 

 STOMACH OF A CAT IMMEDI- 

 ATELY AFTER A MEAL (n.o), 

 AND AT VARIOUS INTERVALS 

 AFTERWARD (AT 12.0, AT 2.0, 

 3.30, 4.30). (W. B. Camion.) 



the 



The movements of the human stomach as 

 described by Beaumont, as well as the movements 

 of the dog's stomach as stated by different ob- 

 servers are not in agreement in all respects, and 

 a i! e ' moreover > P en to question for the reason 

 that they were not observed under strictly physio- 

 logic conditions. The more recent investigations 

 of Cannon have thrown new light on this sub- 

 ject. By means of the Rontgen rays he has been 

 enabled to study the movements in the living 

 animal and under normal conditions. The 

 animal (the cat) was fed with bread and milk, 

 to which was added subnitrate of bismuth! 



Left 



Post 



FIG. 77. The cardiac portion is all that 

 part to the left, as the stomach lies in the 

 body, of WX. The cardia is at C. The 

 pylorus is at P, and the pyloric portion 

 is the part between P and WX. This 

 has two divisions: the antrum, between 

 P and YZ, and the pre-antral part, between 

 WX and YZ. The lesser curvature is on the 

 top of the outline between C and P, and the 

 greater curvature between the same points 

 along the lower border. (Amer. Jour, of 

 Physiology, Cannon.) 



This substance, being opaque, rendered the movements of the stomach walls 

 visible on the fluorescent screen. With paper placed over the screen it 

 was possible to sketch the change in shape that the stomach undergoes at 

 different periods of the digestive act. The results of these investigations 

 will be referred to in following paragraphs. 



As a result of many methods of investigation it has become apparent that 

 the activities of different portions of the stomach, whereby food is admitted 

 into it, retained there, triturated and mixed with the gastric juice and finally 

 discharged into the duodenum, are due (i) to causes resident in the stomach 

 walls and the stomach contents and (2) to nerve impulses descending from 

 the central nerve system through the vagi and splanchnic nerves. 



At the end of a digestive period the walls of the stomach contract and 

 almost obliterate its cavity. The sphincter cardiac and sphincter pylori 



