II 



EXTERNAL DIGESTIVE SECRETIONS 



119 



of gastric juice, and still more its acidity, is much diminished 

 when fat is present. 



Among the many proofs of the presence of a lipolytic ferment 

 in the gastric mucosa, those adduced by Laqueur (1904) are of 

 special importance, because he makes use of Pawlow's miniature 

 stomach, in which there can be no question of any possible reflux 

 of pancreatic juice. 



Laqueur points out one essential difference between the 

 gastric and the pancreatic lipolytic enzymes, viz. that the former is 

 not aided by bile, which multiplies the activity of the pancreatic 

 juice twenty or more, times. With this reservation, the lipolytic 



' 



-^ 



Fic. 30. Cross-section of cardiac glands from human stomach during fasting. (Bohm and v. 

 Davidoff.) 4 i". c, central cell ; I, lumen of gland ; p, parietal cell ; t, connective tissue between 

 glands. 



enzyme of gastric juice behaves like the lipolytic enzyme of succus 

 entericus. 



XIV. Heidenhain and Ebstein, in their alcohol - hardened 

 preparations of gastric niucosa, studied the cytological changes 

 that occur in the secretory cells in hunger and in the digestive 

 process. These changes are quite similar to those suffered by 

 the cells of the serous salivary glands and the pancreas. In the 

 fasting state, and during the intervals of digestion, the chief cells 

 of the fundus glands enlarge and look clear ; while the parietal 

 cells are small, and triangular in section. During the first hours 

 of digestion, the former continue large, but become clouded ; the 

 latter, on the contrary, increase in size and grow round, bulging 

 forward to the outer surface of the tube. From the sixth to the 

 ninth hour of digestion, the chief cells are reduced and grow more 

 turbid, while the lining cells remain large or become still more 

 swollen. At the fifteenth hour the cells begin gradually to resume 

 the appearance and characters which they exhibited during hunger. 



