DIGESTION 349 



are present. But, as we have said, in the glands of the fundus 

 there are besides large ovoid cells scattered at intervals like 

 beads between the basement membrane and the lining or chief 

 cells. The cells of the pyloric glands have a general resemblance 

 to the chief cells of the fundus glands, but they are not quite the 

 same. For example, the granules are less distinct in the 

 pyloric glands. In the human stomach it is only quite near 

 the pylorus that the parietal cells disappear altogether. The 

 parietal cells also contain granules, but they are smaller and less 

 numerous than those of the chief cells, so that the deeper por- 

 tions of the fundus glands are much darker in appearance than 

 the more superficial portions, since the oxyntic cells are more 

 numerous in the neighbourhood of the ducts (Bensley). 



The histological changes connected with gastric secretion do not 

 differ essentially from those described in the pancreas and the 

 parotid, but there is much greater difficulty in making observa- 

 tions on the living, or at least but slightly altered, cells. For 

 the mammal the best method is to use animals with a permanent 

 gastric fistula, and to remove from time to time small portions 

 of the mucous membrane for examination in the fresh condition. 

 During digestion the granules disappear from the outer part of 

 the chief cells of the fundus glands, leaving a clear zone, the 

 lumen being bordered by a granular layer. Or, more rarely, 

 there may be a uniform decrease in the number of granules 

 throughout the cell. The total volume of the cell is less than in 

 the fasting condition. The ovoid cells, which are small in the 

 fasting animal, swell up, so as to bulge out the membrana propria. 

 They reach their maximum size (in the dog) very late in digestion 

 (the thirteenth to the fifteenth hour). No such definite changes 

 in their contents as those observed in the other cells have been 

 made out. The granules in the ovoid cells during and after 

 activity seem to be as large and as numerous as in the resting 

 cell, or even larger. After sham feeding in dogs the histological 

 changes in the gastric glands are very slight, even when con- 

 siderable amounts of gastric juice have been secreted (Noll and 

 Sokoloff). 



The chief cells of the oxyntic; and the.'similar if not identical 

 cells of the pyloric glands, are believed to manufacture the pepsin- 

 forming substance. The ovoid cells of the former are supposed 

 to secrete the hydrochloric acid. The evidence on which this 

 belief is based is as follows : , , 



The glands of the antrum pylori in the dog, in which in most 

 situations no ovoid cells;are to.be seen, secrete pepsin, but no acid. 

 The pyloric end of the stomach or a portion of it has been isolated, 

 the continuity of the alimentary canal restored by sutures, and 

 the secretion of the pyloric pocket collected. It was found to be 



