234 DIGESTION. 



The subject was placed on the right side in the recumbent posture, the valve was de- 

 pressed within the aperture, and a gum-elastic tube, of the size of a large quill, was 

 passed into the stomach to the extent of five or six inches. On turning him upon the left 

 side until the opening became dependent, the stimulation of the tube caused the secretion 

 to flow, sometimes in drops and sometimes in a small stream. The quantity of fluid or- 

 dinarily obtained was from four drachms to an ounce and a half. The usual time for 

 collecting the juice was early in the morning, before he had eaten. It was remarked 

 that under these circumstances there was never an accumulation of gastric juice in the 

 stomach, and its flow was only excited by the stimulus of the tube. It was also repeat- 

 edly observed that the introduction of alimentary principles, while the tube was in the 

 stomach, produced an almost instantaneous increase in the flow. 



Thanks to these opportunities for observing the action of the human stomach, followed 

 by the experiments of Blondlot and others on the inferior animals, now so common, 

 physiologists have become pretty well acquainted with the phenomena which attend the 

 secretion of the gastric juice. 



Secretion of the Gastric Juice. As the earlier observers were unacquainted with the 

 laws which regulate the production of secreted fluids as distinguished from those which 

 contain only excrementitious principles, their ideas concerning the secretion of the gastric 

 juice were necessarily indefinite. One of the most important facts developed by Beau- 

 mont was that the normal solvent fluid of the stomach is only produced in obedience to 

 the stimulus of food, during the natural process of digestion. Recent advances in physio- 

 logical chemistry have enabled experimenters to correct many errors in the observations 

 of Beaumont concerning the properties and action of the gastric juice, but his descrip- 

 tions of the phenomena which accompany its secretion have been repeatedly verified. 



During the intervals of digestion, the mucous membrane is comparatively pale, " and 

 is constantly covered with a very thin, transparent, viscid mucus, lining the whole inte- 

 rior of the organ." On the application of any irritation, or, better, on the introduction 

 of food, the membrane changes its appearance. It now becomes red and turgid with 

 blood ; small pellucid points begin to appear in various parts, which are, in reality, drops 

 of gastric juice ; and these gradually increase in size until the fluid trickles down the 

 sides in small streams. The membrane is now invariably of a strongly acid reaction, 

 while at other times it is either neutral or faintly alkaline. The thin, watery fluid thus 

 produced is the true gastric juice. Although the stomach may contain a clear fluid at 

 other times, this is generally abnormal, is but slightly acid, and does not possess the 

 marked solvent properties characteristic of the natural secretion. It has been shown by 

 Beaumont, and his observations have been repeatedly confirmed by experiments on the 

 inferior animals, that the gastric juice is secreted in greatest quantity and possesses the 

 most powerful solvent properties, when food has been introduced into the stomach by 

 the natural process of deglutition. Under these circumstances the stimulation of the 

 mucous membrane is general, and secretion takes place from the entire surface capable 

 of producing the fluid. When any foreign substance, as the gum-elastic tube used in 

 collecting the juice, is introduced, the stimulation is local, and the flow of fluid is com- 

 paratively slight. It has been also observed that the quantity immediately secreted on 

 the introduction of food, after a long fast, is always much greater than when food has 

 been taken after the ordinary interval. 



While natural food is undoubtedly the proper stimulus for the stomach, and while, in 

 normal digestion, the quantity of gastric juice is perfectly adapted to the work it has to 

 perform, it has been noted that savory and highly-seasoned articles generally produce a 

 more abundant secretion than those which are comparatively insipid. An abundant 

 secretion is likewise excited by some of the vegetable bitters. 



Impressions made on the nerves of gustation have a marked influence in exciting the 

 action of the mucous membrane of the stomach. Blondlot found that sugar, introduced 



