THE DIGESTIVE APPARATUS IN MAMMALIA. 



epithelium throughout their extent ; the peptic glands (Figs. 263, 204) are lined 

 with cylinder-epithelium at their origin (Fig. 263, a), but the secretory tubes 

 contain round peptic cells. (Each caeca, when highly magnified, is found to 

 consist of a delicate basement membrane (Fig. 265, a) inflected over a series 

 of nearly globular cells (b), which occupy almost the 

 whole cavity of the tube, and contain a finely granular 

 matter ; the narrow passage left vacant in the centre 

 is, however, still surrounded by a layer of epithelial cells 

 (c), the small size of which is in striking contrast to the 

 large dimensions of the gland-cells.) 



The muscular layer (of the mucous membrane) is 

 immediately beneath the glandular structure, and con- 

 tains two planes of intersecting fibres. Lastly, the con- 

 nective tissue layer of the corium is thick and loose, 

 sustains the vessels (and nerves), and unites the mucous 

 to the muscular tunic of the stomach. 



4. Vessels and nerves. — The stomach receives its 

 blood by the two branches of the gastric artery, the 

 sple7iic and its terminal branch — the left epiploic artery, 

 and by the pyloric and right epiploic arteries. The 

 principal arterial ramifications extend between the mucous 

 and muscular layers, where they furnish two capillary 

 reticulations to the glandular layer — a deep network that 

 sun-ounds the secretory tubes, and a superficial placed 

 between the alveoli. The blood is carried from the organ 

 to the vena portae by the satellite venous branches. The 

 MUCOUS GASTRIC GLAND WITH lymphatics form a subserous and two deep networks at 



CYLINDER EPITHELIUM. ,, i /■ .1 i j i i 3 ■ .^ n-, 



, , , . the base of the glandular layer and m the fibrous mem- 



^' ' * appendage.' ' ^ ^^^^ brane. They enter small glands situated along the 

 curvatures, and from these to Pecquet's reservoir. The 

 nerves are derived from the pneumo-gastrics and solar plexus, and in accompanying 

 the vessels show microscopic ganglia in their course ; their mode of termination is 

 not known. 



Fig. 266. 



APPEARANCE OF THE PROPER GASTRIC MEMBRANE OF THE STOMACH IN AN INJECTED 

 PREPARATION (HUMAN). 



A, From the convex surface of the folds, or rugcB ; B, from the neighbourhood of the pylorus, where 

 the orifices of the gastric follicles occupy the interspaces of the deepest portions of the vascular 

 network. 



Functions. — In the stomach is begun those transformations by which 

 alimentary matters are rendered capable of being assimilated. There the food 



