SUMMARY OF STOMACH DIGESTION. 53 



the muscular coat, aided to a considerable extent by the respiratory 

 movements of the abdominal walls. The course of this ro- Motions of * the 

 tation commonly is, that after passing the cardiac orifice the food in the 

 food moves from right to left round the great extremity, and S1 

 then along the large curvature from left to right, returning along the small 

 curvature, and occupying from one to three minutes to perform this revo- 

 lution, the motion continuing for a few minutes at a time. 



While this is going forward digestion is rapidly taking place, and the 

 portions which have suffered complete action are oozing through the py- 

 loric valve into the intestine as a semi-fluid and apparently Formation of 

 homogeneous material called chyme. This process has fairly chvme - 

 set in in the course of an hour, and is usually finished in about four. 

 In consistency, color, and chemical reaction, the chyme varies with the 

 nature of the food, its chemical constitution, and its quantity ; but under 

 common circumstances it presents the acid reaction, for it is to be remem- 

 bered that the diurnal supply of hydrochloric acid to the stomach is about 

 the fifth of an ounce. Arrived in the intestine, the chyme is pushed for- 

 ward by the peristaltic movements, and soon after its appearance in the 

 duodenum is mixed with several important fluids the bile, which is fur- 

 nished by the liver, the secretion of the pancreas, and the enteric juice 

 which is exuding from Brunner's glands. 



The digestion of the albuminous part of the food commences in the 

 stomach, and in that cavity advances far toward completion. Summary of 

 The action is not merely for the purpose of bringing those dige^n1n 

 substances into a state of solution in water, but also of modi- the stomach, 

 fying them chemically. This change is so well marked that it has been 

 found expedient to indicate it by a designation, and hence we speak of 

 albumen peptone, fibrin* peptone, casein peptone. These peptones are, 

 for the most part, absorbed by the blood capillaries, though a portion of 

 them enters the circulation as a constituent of chyle. In the system, 

 whatever their origin may have been, they seem to revert to the state of 

 blood albumen. But, though the production of these peptones is accom- 

 plished to the extent that has been mentioned in the stomach by the gas- 

 tric juice, the action is continued and brought to its completion in the 

 small intestine by the aid of the intestinal juice. It does not appear that 

 the large intestine participates in this duty, since portions of coagulated 

 albumen, or of flesh introduced into it through fistulous openings, are 

 voided through the rectum. 



Such is the general description of the act of digestion. We have next 

 to enter on a physical examination of what it is that really Influence O f 

 takes place in the stomach. It was formerly supposed that the nerves on 



d,. i j , . .(. ,, digestion, 



igestion is entirely due to nervous agency, since, if the prieu- 



mogastric nerves be divided, the process is very much interfered with. 



