Chap. V.] GENERAL HISTOLOGY. 79 



(4.) submucosa of connective tissue ; (5.) muscular layer of the 

 mucosa ; (6.) mucosa. In the mucosa of the mammalian stomach 

 great numbers of glandular tubes (the peptic glands) are seen. 

 In each gland (28, iii.) there is a single layer of secreting cells 

 continuous with the epithelial lining of the stomach. 



In the intestine of the mammal or the bird there are a vast 

 number of minute processes (villi) projecting inwards, and giving 

 a velvety appearance. Fig. 28, iv. shows one of these villi, in 

 which the blood-vessels are injected, while 28, v. shows the end 

 of a villus. It is covered with columnar epithelium cells, many 

 of which are converted into goblet or mucous cells, larger and clearer. 

 Beneath this the tissue is lymphatic in structure, and is apt to 

 be crowded with leucocytes. The central blind tube in Fig. 28, 

 v. is the chyle-vessel or terminal rootlet of the lacteal system of 

 lymphatics. The layers of the intestine are essentially similar 

 to those of the stomach. 



12. The larger Alimentary Glands. In favourable sections 

 of a salivary gland the alveoli (29 i. from the sublingual gland 



FIG 29. SALIVARY GLAND, LIVER, AND KIDNEY. 



Alveolus of sublingual gland of rabbit, ii. Duct of same. iii. Liver of rabbit 

 stained, with bile canaliculi injected, iv. Liver (cat) with blood-vessels injected. 

 v. Kidney of rabbit injected to show glomeruli. All from sections. 



of a rabbit) or true secreting terminations of the ducts may be 

 made out. Their cavities are nearly or quite obliterated. In 

 the ducts, on the other hand, the cavity or lumen is generally 

 obvious, and the cells more columnar (29, ii.). 



A section of the pancreas shows a somewhat similar structure. 



