SECRETION OF GASTRIC JUICE. 437 



his views is effected by the epithelium covering the mucous membrane. 

 The pyloric glands also seem to contain zymogens. Alkali chlorides, 

 alkali phosphates, and calcium phosphates are found in the mucous coat- 

 ing of the stomach. 



LIEBERMANN J obtained an acid-reacting residue on digesting the mucosa 

 of the stomach with pepsin-hydrochloric acid, which strangely enough contained 

 no nuclein, but only a protein containing lecithin, called lecithalbumin. To 

 this lecithalbumin he^ ascribes a great importance in the secretion of hydrochloric 

 acid. 



The Gastric Juice. The observations of HELM and BEAUMONT on 

 persons with gastric fistula led to the suggestion that gastric fistulas 

 be made on animals, and this operation was first performed by BASSOW 2 

 in 1842 on a dog. VERNEUIL performed the same on a man 1876 with 

 successful results. PAWLOW 3 has recently improved the surgery of 

 gastric fistula and has added much to the study of gastric secretion. 



As most investigations upon gastric digestion, and also upon digestion 

 as a whole, are based on observations upon dogs, and then upon man, 

 and for this reason, when not otherwise stated, in this chapter on the 

 study of digestion we give the conditions in dogs and man. 



The secretion of gastric juice is not continuous, at least in man and in 

 the mammals experimented upon. It only occurs under psychic influence, 

 and also by stimulation of the mucous membrane of the stomach or the 

 intestine. The most exhaustive researches on the secretion of gastric 

 juice (in dogs) have been made by PAWLOW and his pupils. 



In order to obtain gastric juice free from saliva and food residues they arranged 

 besides a gastric fistula also an cesophageal fistula from which the swallowed food 

 could be withdrawn with the saliva without entering the stomach, and in this manner 

 an apparent or sham feeding was possible. In this way it was possible to study 

 the influence of psychical moments on one side and the direct action of food on 

 the mucous membrane on the other. After a method suggested by HEIDENHAIN 

 and later improved by PAWLOW and CHIGIN, they have succeeded in preparing 

 a blind sac by partial dissection of the fundus part of the stomach, and the secre- 

 tion processes could be studied in this sac while the digestion in the other parts 

 of the stomach was going on. In this way they were able to study the action of 

 different foods on the secretion. 



The most essential results of the investigations of PAWLOW ^and his 

 pupils are as follows: Mechanical stimulation of the mucosa does not 

 produce any secretion. Mechanical irritation of. the mucous membrane 



1 Pfliiger's Arch., 50. 



2 Helm, Zwei Krankengeschichten, Wien, 1803, cited from Hermann's. Handbuch, 

 5, part II, 39; Beaumont, "The Physiology of Digestion," 1833; Bassow, Bull, de 

 la soc. desnatur. de Moscou, 16, cited from Maly in Hermann's Handbuch, 5, 38; Ver- 

 neuil, see Ch. Richet, " Du sue gastrique chez 1'homme," etc. (Paris, 1878), 158. 



3 Pawlow, Die Arbeit der Verdauungsdriisen (Wiesbaden, 1898), where the works 

 of his pupils are also mentioned. See also Er^ebnisse der Physiologic, 1, Abt. 1. 



