CHAP. II.] FUNCTION OF THE BORDER CELLS. 107 



represent hours ; the relative amounts of pepsin are represented by the 

 ordinates. These curves exhibit in a startling manner the remarkable 

 want of coincidence in the richness in pepsin of the mucous mem- 

 brane of the fundus and pylorus. In the experiments which fur- 

 nished the data for these curves, the mucous membrane of the pylorus, 

 and of the fundus, respectively, were extracted first with glycerin 

 and afterwards with hydrochloric acid. The curves indicate that the 

 relationship between the amount of pepsin in the pyloric mucous 

 membrane and that of the fundus is a very varying one. 



THE SEAT OF THE FORMATION OF THE ACID OF THE 

 GASTRIC JUICE. 



Those facts have already been adduced which are considered to 

 prove that the pepsin of the gastric juice is formed in or by the central 

 cells of the glands of the fundus of the stomach and by the pyloric 

 glands, and that the border cells of the former glands form the 

 acid. Some of the most important evidence which appears to shew 

 that these border cells are the active acid-forming structures has 

 already been referred to, particularly that from that part of the stomach 

 of which the glands are free from border cells (pyloric region) can be 

 obtained a juice rich in mucus and containing pepsin, but alkaline. 



Evidence in the same direction is afforded by a study of the 

 oesophagus and stomach of the frog. In this animal the principal 

 seat of the production of pepsin is in the oesophagus," where glands 

 are found of which the secreting cells are somewhat like the chief 

 cells of the gastric glands ; but the total amount of pepsin in the 

 stomach is not much less than in the oesophagus. These glands secrete 

 an alkaline fluid. On the other hand, the glands of the stomach 

 consist apart from mucous cells of cells somewhat like border cells, 

 and here an acid juice is formed 1 . 



The view was formerly held that the border cells were not acid-producing 

 but pepsin-forming cells, and it formerly received the support of Nussbaum 2 

 and of Edinger 3 , but on grounds which warranted no such conclusion. 

 Nussbaum in 1881 however adopted the opinion that the chief cells are 

 the principal sources of pepsin. The first of these writers observed that 



1 H. v. Swiecicki, ' Untersuchungen iiber die Bildung und Ausscheidung des Pepsins 

 bei den Batrachiern.' Pniiger's Archiv, Vol. xm. (1876), p. 444. Langley and Sewall, 

 ' On the Changes in Pepsin-forming Glands during Secretion. ' Journal of Physiology, 

 Vol. ii. (187980), p. 281. Langley, Phil. Trans. 1881. 



2 Nussbaum, 'Die Fermentbildung in den Drusen.' Habilitationsschrift. Bonn, 

 1876 (not seen). 



3 Edinger, ' Zur Kenntniss der Driisenzellen des Magens besonders beim Menschen. 

 Archiv f. mikroscop. Anat., Vol. xvn. p. 194 212. 



