422 MATER IA MEDIC A AND THERAPEUTICS. 



by the mouth is neutralised in the stomach before it reaches 

 the duodenum. For the same reason we cannot administer 

 pancreatic juice by the mouth as we can give pepsin, for its 

 ferment is destroyed at once in the stomach. Malt extract 

 contains an amount of active diastase, which, however, is also 

 destroyed in the stomach, unless the extract be given at the 

 very end of gastric digestion, when the acid is exhausted. 

 We possess, however, equally physiological and less artificial 

 means for stimulating the duodenal secretions. First, by in- 

 fluencing gastric digestion we can transmit the chyme into 

 the duodenum with greater acidity, an indirect duodenal stimu- 

 lant measure. Secondly, acids, such as Diluted Nitric, Nitro- 

 hydrochloric, or Phosphoric Acid, given after meals, will be 

 conveyed in the chyme to the mouths of the ducts, and act as 

 direct duodenal stimulants ; and it is possible that these may 

 have a further influence in the same direction by being absorbed 

 from the stomach and reaching the liver and pancreas through 

 the blood. Ether is believed by some to stimulate the pancreas, 

 and probably assists in emulsifying oils. On the other hand, 

 an alkali given before meals will stimulate duodenal digestion 

 by improving gastric digestion ; whilst an alkali given after 

 meals would interfere with duodenal digestion by diminishing 

 the natural and necessary acidity of the chyme. 



We possess a considerable number of substances which 

 increase the flow of bile, which are designated cholagogues. 

 Cholagogues are either direct, when they act upon the liver 

 itself; or indirect, when they stimulate the liver by sweeping 

 the intestinal bile out of the body. These facts may be accepted 

 temporarily in connection with the digestive function of the 

 bile ; they will be fully discussed along with the purgative 

 function of the bile in the sixth chapter. Mercurials not only 

 clear the duodenum of chyme and bile, and furnish it with a 

 supply freshly secreted, but also stimulate the duodenal glands, 

 and thus have a remarkably stim rlant influence on digestion. 



HI. PATHOLOGICAL RELATIONS. 



Duodenal dyspepsia is not uncommon, and may be either 

 secondary or primary. The secondary form is the necessary con- 

 sequence of gastric indigestion. The acid decomposing mass 

 which passes the pylorus in acute gastric dyspepsia completely 

 neutralises the alkaline secretions of the duodenum ; the re- 

 maining proteids, fats, starches, and sugars, undergo further 

 decomposition, instead of the proper chemical transformation; 

 absorption is arrested; the peristaltic movements are unna- 

 turally increased; and the contents are hurried through the 

 bowel, and violently expelled the whole constituting the 



