SALIVARY AND GASTRIC DIGESTION 197 



rather large share of well-cooked starch is turned to 

 dextrins and sugar in the stomach. There is no doubt 

 that the fullest measure of salivary digestion is to be 

 desired since it lessens the work which remains to be 

 done in the intestine and it makes the proteins more 

 accessible to the action of the gastric juice. We must 

 now pass to a discussion of the formation and characters 

 of this secretion. 



Gastric Juice. This is a clear, free-flowing liquid 

 which is furnished at and after each meal by the simple 

 glands in the lining of the stomach. The major part, 

 secreted in the fundus, is strongly acid; the smaller 

 contribution of the antrum is neutral or alkaline. The 

 appearance of the drops of the. gastric juice upon the 

 mucous membrane of the stomach is described as like 

 that of profuse perspiration on the skin. The acid is 

 hydrochloric; it must have come from the chlorids of 

 the blood. It amounts to as much as 0.2 per cent, in 

 the human subject and may be somewhat more. 



The activity of the gastric glands depends much upon 

 the higher centers. The flow seems to begin in advance 

 of the actual arrival of food in the stomach and to be 

 proportional to the pleasure afforded by the meal. 

 Anger and anxiety, the same psychic disturbances which 

 may abolish the movements of the stomach, may also 

 prevent the production of the gastric juice. We are 

 not likely to overestimate the advantages of attractive 

 food and congenial society about the table. 



Skillful experiments upon dogs have shown that it is 

 only necessary for the animals to taste and chew food 

 to have a lively secretion of juice. The morsels swal- 

 lowed may be diverted to come out through an opening 

 in the neck and thus never reach the stomach, yet the 

 gastric glands are active as long as the dogs are enter- 

 tained. Human beings who have had artificial openings 

 made into the stomach on account of permanent ob- 

 struction of the esophagus still find it beneficial to take 

 samples of their food into the mouth and to dwell upon 



