DIGESTION. 



177 



of protein and carbohydrate varies the rate of discharge of each separately. 

 Thus under these circumstances the carbohydrates are not discharged so 

 rapidly nor are the proteins detained so long as usual; a combination of fat 

 with either protein or carbohydrate delays the time of discharge of both. 

 From these facts it may be inferred that the time any given food remains in 

 the stomach will depend on its chemic composition or the relative amounts 

 of its contained protein, fat, and carbohydrate principles. 



Movements of the Stomach. During the period of gastric digestion 

 the muscle walls of the stomach become the seat of a series of movements, 



peristaltic in character, which not only incorpo- 

 rate the gastric juice with the food, but also serve 

 to eject the liquefied portions of the food into 

 the small intestine. 



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 

 are, moreover, open 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- 

 , Q , / J ect - By means of the Rontgen rays he has been 



Right. 



Left 



FIG. 77. 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. Cannon.} 



Post 



FIG. 78. 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 FZ, 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.} 



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. 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. Some of these changes are represented in Fig. 77. The anatomic 

 features of the cat stomach of interest in this connection are represented 

 in Fig. 78. 



12 



