THE DIGESTIVE APPARATUS. 145 



The second glandular formation, the gastric mucous 

 glands, were long since discovered in the hog. In the dog, 

 cat, rabbit and Guinea-pig they occupy a large extent of the 

 pyloric region ; in man, on the contrary, but a small zone 

 here. They are, again, in part ramified, in part unramified 

 tubes. One may also recognize here in the excretory duct 

 (and it may acquire a very considerable length) the ordinary 

 cylindrical epithelium of the gastric mucous membrane (Fig. 

 122, a). The lower true portion of the gland shows, on the 

 contrary, lower cubical cells (b) richer in fine granules. They 

 become cloudy in acetic acid, and call to mind the " chief 

 cells " of the peptic-gastric glands. 



Small racemose glandules appear in the human pyloric re- 

 gion. Isolated lymphoid follicles form the lenticular glan- 

 dules, familiar to us from p. 112. 



At the border of the mucous membrane, towards the sub- 

 mucous tissue, there is a net- work of smooth muscular fibres, 

 the muscularis mucosae (p. 80). Thin strips pass up between 

 the gland tubes. 



The arrangement of the vessels in the gastric mucous mem- 

 brane (Fig. 126) is elegant and characteristic. Thin and slen- 

 der arterial branches, rising up through the submucous tissue,, 

 terminate in a long-meshed capillary net-work, circumvolut- 

 ing the gland tubes, and forming rings around the apertures 

 of the latter. The transition into venous roots takes place 

 on the surface only, and these rapidly unite into large de- 

 scending veins. The latter form a broad-meshed reticulum 

 of wider tubes beneath the mucous membrane. 



The lymphatic passages were recently discovered by an 

 eminent Swedish investigator, Loven. Large net-works, 

 situated in the submucous tissue, send upwards considerable 

 caecal canals, which pass between the glands and reach nearly 

 to the gastric surface. 



The gastric juice, an acid fluid, contains a peculiar fermen- 

 tative body, pepsine. The granules in the covering cells (and 

 possibly in the chief cells) are this substance, which has been 

 formed by the gland cells. The power of the secretion to 

 7 



