vm GASTRIC GLANDS 131 



p. 70). The epithelium consists of a single layer of cells 

 only (B, ep), all columnar, and with their long axes at 

 right angles to the elevations into which, as we have 

 seen (p. 71), the mucous membrane is thrown. Amongst 

 the ordinary epithelial cells numerous mucus-secreting 

 goblet-cells will be recognised. The submucosa, like 

 the derm, contains blood-vessels, lymphatics, and 

 nerves. 



The muscular layer (A, m) is also divisible into two : 

 an outer layer of longitudinal fibres (B, /. m), running 

 parallel with the long axis of the tube, and an inner, 

 much thicker layer of circular fibres (c. m) which encircle 

 it, and consequently lie at right angles to the longi- 

 tudinal fibres. Thus in a transverse section, such as 

 Fig. 39, the fibres of the circular layer are cut longi- 

 tudinally, those of the longitudinal layer transversely, 

 while the opposite would be the case in a longitudinal 

 section. 



The peritoneum (pr) which, as we have seen (p. 27), 

 forms an outer covering to the intestine, is formed of a 

 thin inner layer of connective-tissue and an outer of 

 squamous epithelium. 



The Stomach. Transverse sections of the stomach 

 (Fig. 40) show it to differ from the intestine not only in 

 the much greater thickness of all its layers, but also in 

 the fact that the epithelium, instead of simply forming 

 an even layer over the ridges of mucous membrane, is 

 sunk into the mucous membrane in the form of simple or 

 branched tubes, the gastric glands (g. gl). These differ 

 from the cutaneous glands in being not flask-shaped 

 but test-tube-shaped, each being a long, narrow tube, 

 with an extremely small cavity (B and C, c) . They are 

 lined by a single layer of gland-cells, and open by minute 

 apertures (m) on the surface of the mucous membrane. 



The cells of the gastric glands have the power of 



K 2 



