THE GASTRIC JUICE AND STOMACH DIGESTION. 153 



while others are compound or branched. Another distinction between 

 the follicles is that some of them are lined throughout with cylindrical 

 epithelium cells, not very different from those on the free surface of the 

 mucous membrane, while others contain also larger cells of a rounded 

 form, which give to the follicles a peculiar aspect. Both simple and 

 branched follicles may be found, presenting both these two kinds of epi- 

 thelium ; but as a general rule, the simple tubular follicles are distin- 

 guished by their lining of cylindrical epithelium, while the compound or 

 branched follicles more especially contain the larger cells of glandular 

 epithelium. 



In the pyloric portion of the stomach, the follicles with cylindrical 

 epithelium preponderate, or in some instances are present exclusively. 

 In the dog, according to the observations of Ebstein, and in man, ac- 

 cording to Kb'lliker, the mucous membrane in the immediate proximity 

 of the pylorus, for a zone of considerable width, contains follicles of this 

 kind only. They present the same essential characters in man and in 

 different species of animals. They are nearly straight or slightly tor- 

 tuous tubules, y 1 ^ of a millimetre in diameter, lined with cylindrical 

 epithelium cells, and terminating in blind extremities at the under sur- 

 face of the mucous membrane (Fig. 41). In their lower half they are 



Fig. 41. 



Fig. 42. 



Mucous MEMBRANE OF PIG'S STO- 

 MACH, from Pyloric portion; vertical sec- 

 tion; showing tubular follicles, and, at o, a 

 closed follicle. Moderately magnified. 



TUBULAR FOLLICLES, from Pyloric 

 portion of Pig's Stomach, showing their 

 coecal extremities and epithelial lining. At 

 a, the torn end of a follicle, showing its 

 cavity. More highly magnified. 



often slightly branched, one or more lateral diverticula passing off from 

 the principal tubule, and forming a little mass or lobule of glandular 

 tubes. At their upper extremities they open on the free surface of the 

 mucous membrane, in the interspaces between the projecting folds or 

 villi. The cylindrical epithelium cells, which cover the general surface 

 of the gastric mucous membrane, extend downward into the cavity of 

 11 



