



METHODS OF OBTAINING THE GASTRIC JUICE. 295 



stomach excite, in a centripetal direction, the medulla oblongata which 

 contains the center for this reflex. The centrifugal path to the mucous 

 membrane traverses the pneumogastric nerves, after the division of 

 which the reflex is abolished. The mucous membrane subsequently 

 furnishes a moderate amount of a feebly active, paralytic secretion. 

 During sleep in the stage of digestion, the amount of acid increases. 



Heidenhain found in experiments upon dogs in which, in the same way as 

 the pylorus, he isolated the fundus for the formation of a blind sac that mechan- 

 ical irritation induced only local secretion. If, however, absorption of digested 

 substances took place at the point of irritation, the secretion spread out over a 

 larger surface. 



Small quantities of alcohol, introduced into the stomach, increase the secretion 

 Of the gastric juice, while large amounts abolish it and enfeeble the movements 

 ot the stomach. Fat inhibits the secretion of the gastric juice. Artificial digestion 

 is somewhat disturbed by alcohol up to 2 per cent., and in greater degree by 10 

 per cent, alcohol; 20 per cent, alcohol retards, while still larger amounts abolish 

 it. Beer and wine retard digestion, and undiluted they prevent artificial diges- 

 tion. The administration of large amounts of sodium chlorid diminishes the secre- 

 tion of hydrochloric acid, while the ingestion of much sugar only delays it After 

 two days of fasting the secretion of hydrochloric acid ceases (in the dog). Gastric 

 ulcers cause reflex increase in the production of hydrochloric acid; jaundice, 

 nervous gastric affections and anemias, a reflex diminution. 



The gastric juice, which passes into the duodenum after digestion 

 is completed, is neutralized by the alkalis of the intestinal and of the 

 pancreatic juices. The pepsin is absorbed as such, and can be found in 

 small amounts in the urine and in the muscle-juice. 



If the gastric juice is removed completely through a gastric fistula, 

 the alkalies in the intestines become so abundant that the urine is ren- 

 dered alkaline. 



The acid gastric juice in the new-born is quite intensely active. It most 

 readily digests casein, and next in order fibrin and other proteids. In consequence 

 of excessive acidity of the gastric juice, large masses of casein, difficult of digestion, 

 form in the stomach of infants, and are especially tough after the ingestion of 

 cow's milk. 



The following drugs are excreted by the gastric juice after introduction into 

 the body-juices: Morphin, veratrin, caffein, quinin, antipyrin, chloroform, chloral 

 hydrate, methyl-alcohol, ethyl-alcohol and acetone. 



Comparative. According to Klug, the parietal cells of grain-eating birds pre- 

 pare also pepsin, in addition to hydrochloric acid. The gastric glands of the frog, 

 which possess only parietal cells, likewise secrete pepsin; the pyloric glands of the 

 dog, which contain only chief cells, nevertheless secrete acid. Accordingly both 

 kinds of cells secrete hydrochloric acid. 



METHODS OF OBTAINING THE GASTRIC JUICE. 



THE PREPARATION OF ARTIFICIAL DIGESTIVE FLUIDS; DEMONSTRA- 

 TION AND PROPERTIES OF PEPSIN. 



To obtain the gastric juice Spallanzani had fasting dogs swallow bits of sponge 

 enclosed in perforated leaden capsules, and withdrew them after they had become 

 saturated with the gastric juice. In order to prevent admixture with the secre- 

 tions of the mouth, the sponge is best introduced through an opening made in 

 the esophagus ligated above. 



Beaumont (1825-1833), an American physician, was the first to obtain gastric 

 juice from a human being, in the case of the Canadian hunter, Alexis St. Martin, 

 whose stomach had been opened by a bullet-wound, with the formation of a per- 

 manent gastric fistula. Various substances were introduced directly into the 

 stomach through the opening, and examined from time to time as to their digestion. 



Guided by this, Bassow, in 1842, was the first to establish an artificial gastric 

 fistula in a dog. The wall of the stomach is opened below the xiphoid process, 

 and the margins of the gastric opening are united by suture to the margins of 



