766 



PHYSIOLOGY OF DIGESTION AND SECRETION. 



cases in whom the esophagus has been occluded by an accident of 

 one kind or another, usually as a result of drinking strong lye. In 

 these cases a fistulous opening is established through the abdominal 

 wall into the stomach. Through this opening the individual can 

 be fed successfully, and, when desired, specimens of gastric juice 

 can be obtained. The study of these exceptional cases has added 

 greatly to our knowledge of the functions of the stomach. Gastric 

 juice may be obtained from human beings also in cases of vomiting 

 or by means of the stomach-tube, but in such cases it is necessarily 

 more or less diluted or mixed with food and cannot be used for exact 

 analyses, although specimens of gastric juice obtained by these 

 methods are employed in the diagnosis and treatment of gastric 

 troubles. 



From the standpoint of experimental investigation a very im- 

 portant addition to our methods was made by Heidenhain. This 

 observer showed that a portion of the stomach — the fundic end, for 

 instance, or the pyloric end — ^might be cut away from the rest of the 



organ and be given an 

 artificial opening to the 

 exterior. By this means 

 the secretion of an isolated 

 fundic or pyloric sac may 

 be obtained and examined 

 as to its quantity and prop- 

 erties. The method was 

 subsequently improved by 

 Pawlow, whose important 

 contributions are referred 

 to below. Fig, 294 gives 

 an idea of the operation as 

 made by Pawlow to isolate 

 a fundic sac with its blood 

 and nerve supply unin- 

 jured. 



The normal gastric se- 

 cretion is a thin, colorless 

 or nearly colorless liquid 

 with a strong acid reaction and a characteristic odor. Its spe- 

 cific gravity varies, but it is never great, the average being about 

 1.002 to 1.003. Upon analysis the gastric juice is found to contain 

 some protein, some mucin, and inorganic salts, but the essential 

 constituents are an acid (HCl) and two or possibly three enzymes, 

 pepsin, rennin, and lipase. According to Rosemann,* the secretion 

 in dogs has a specific gravity of 1002 to 1004 and contains 0.4277 

 per cent, of dry material, of which 0.1325 per cent, is ash. Analysis 

 * Rosemann, "Archiv f. d. ges. Physiologic," 118, 467, 1907. 



Fig. 294 — ^To show Pawlow's operation for 

 making an isolated fundic sac from the stomach: 

 V, Cavity of the stomach; s, the fundic sac, shut off 

 from the stomach and opening at the abdominal 

 wall, a, a; b indicates the line of sutures. — (Paw- 

 low.) 



