100 THE PYLORIC GLANDS AND JUICE. [BOOK II. 



Methods of The gastric juice is distilled, and if butyric and 

 separating bu- acetic acids are present they will pass in the distillate 

 tyric and other w here they may be detected by their physical characters 

 volatile acids. Qr ^ p re p ar i n g from them barium or lime salts, and 

 determining the proportion of barium or calcium which they contain. 

 The determination of the ' coefficient de partage ' of the distillate 

 affords moreover an easy and good method of identification. 



SECT. 9. SEATS OF FORMATION OF THE Mucus, PEPSIN, AND HYDRO- 

 CHLORIC ACID IN THE STOMACH. THE ANTECEDENTS OF THESE 

 BODIES. 



SECRETION OF Mucus. 



During fasting, the mucous membrane of the stomach is always 

 covered by a thin layer of mucus, which is doubtless being continu- 

 ously secreted, though, as was stated previously, the quantity formed 

 in the normal state of the stomach is less than would be surmised 

 from an examination of the stomach of dogs with gastric fistulae, in 

 which the cannula keeps up a constant condition of irritation. 

 When gastric digestion is proceeding, the secretion of mucus occurs 

 even more actively than before. The gastric mucus is produced by 

 the cylindrical epithelium cells, which covers the whole internal sur- 

 face of the stomach, and of which the protoplasm undergoes a trans- 

 formation into mucin 1 . 



THE PYLORIC GLANDS AND THE PYLORIC JUICE. 



It has already been remarked that the gastric glands are divisible 

 into two classes ; of which the one, the so-called mucous glands of the 

 older authors, occur in some animals alone at the pyloric end of the 

 stomach, the other so-called peptic glands being situated at the car- 

 diac end of the organ. 



As is implied by the name mucous glands,' it was until lately 

 held that the pyloric glands are mucus-secreting glands, and that 

 the elements of the gastric juice were elaborated in the so-called 

 peptic glands. 



Since the time of Eberle it has been known that any part of the 

 mucous membrane of the stomach will, if digested with dilute acids, 

 furnish an active digestive fluid, yet it was soon recognized (Was- 

 mann) that the digestive fluid prepared with the mucous membrane 

 of the cardiac end of the stomach is much more active than that 

 prepared with the pyloric end. 



When v. Wittich's method of extracting pepsin from the gastric 

 mucous membrane by means of glycerin was adopted it was found 



1 Heidenhain, Hermann's Handbuch, Vol. v. Part i. Chap. iii. p. 122. 



