THE SECRETION OF THE GASTRIC JUICE. 293 



4. For a consideration of the milk-ferment, reference may be made 

 to page 300. 



5. The large amount of mucus adherent to the surface of the mucosa 

 is a secretion of the mucous goblet-cells. 



6. Inorganic matters are present in percentages for human beings 

 (and for dogs, in parenthesis) as follows: Water, 994.40 (973.06); hydro- 

 chloric acid, 0.20 (2.84); calcium chlorid, 0.06 (0.96); sodium chlorid, 

 1.46^(2.82); potassium chlorid, 0.55 (1.09); ammonium chlorid (0.5); 

 calcium, magnesium, and iron phosphates, 0.125 (2.7). Organic matters, 

 principally pepsin, are present to the amount of 0.32 per cent. (1.71). 



Of foreign substances, the following appear in the gastric juice after 

 introduction into the body: potassium sulphocyanid, iron lactate, 

 potassium ferrocyanid, sugar, etc. Ammonium carbonate is found in 

 the presence of uremia. 



THE SECRETION OF THE GASTRIC JUICE. 



During the course of digestion characteristic changes take place in 

 the chief cells, and in the parietal cells of the fundus glands and in the 

 cells of the pyloric glands. 



The chief cells contain granules that are consumed during the process 

 of secretion. The granules contain the pepsin-forming substance, which 

 is transformed into pepsin. The size of the chief cells diminishes also 

 during secretion. At rest these cells take from the lymph, material for 

 the production of the granules. The parietal cells, during the period 

 of secretion, appear first to be swollen, then to become smaller. All 

 of the cells, further, are darker, and the nucleus of the cells of the 

 pyloric glands moves toward the center. The secretory ducts become 

 more distended. 



In some animals the chief cells, during secretion, bear a fringe of 

 short, hair-like processes (Tornier's "brush-fringe"!), directed toward 

 the lumen of the gland. 



The pepsin is formed in the chief cells. If these are swollen, they 

 produce much pepsin; if shrunken, they produce but little. The pyloric 

 glands also secrete pepsin, though in much less amount. During the 

 first stage of hunger the pepsin accumulates; while during the period 

 of digestive activity it is eliminated, as it is also when hunger is pro- 

 tracted. 



Klemensiewicz removed the pyloric portion of the stomach of a dog with two 

 incisions; sutured the duodenum to the stomach, and allowed the pyloric portion, 

 still in communication with its blood-vessels, to heal in the abdominal wound, 

 after closure of its lower extremity by sutures. The secretion of this portion of 

 the stomach was viscid and alkaline, containing 2 per cent, of solid matters, 

 including pepsin. 



The glands themselves contain no pepsin, but only a zymogen, 

 namely, the pepsinogenic substance or propepsin, which occurs in 

 the granules of the chief cells. The zymogen, of itself, exerts no influ- 

 ence upon proteids. If, however, it be treated with hydrochloric 

 acid or sodium chlorid, it is transformed into pepsin. In addition to 

 pepsin, the pepsinogenic substance may be extracted from the mucous 

 membrane of the stomach by means of water free from acid. The 

 milk-ferment also originates in the chief cells. 



The hydrochloric acid is formed by the parietal cells. It is found 



