68 PRACTICAL HISTOLOGY. 



duodenum with logwood, and mount it in dammar. Stain sections of the intestine with and 

 without a Peyer's patch with logwood ; mount one in dammar, and another in Farrant's 

 solution. Place sections of the small intestine in a quarter per cent, solution of osmic acid 

 for twenty-four hours, and mount a very thin section in Farrant's solution. 



Vertical Section of the Stomach and Duodenum. Make a vertical section through the pyloric 

 valve, so as to include a part of the stomach and the upper part of the duodenum. Stain a 

 section in logwood, and mount it in dammar. 



EXAMINATION (L). Observe the gastric mucous membrane with its mucous glands, and 

 trace a gradual transition from these into the compound tubular and more branched glands 

 of the duodenum Brunner's glands, which present exactly the same structure as the mucous 

 glands of the stomach, with this difference, that their duct is larger, and each duct has a 

 greater number of long branched tubes attached to it. The alveoli lie in the submucous 

 layer outside the muscularis mucosai, and from these the duct lined by columnar cells pierces 

 the muscularis mucosa;, and ascends between the crypts of Lieberkiihn to open on the surface. 

 A few villi are seen on the duodenal mucous membrane. At the line of junction of the 

 mucous membrane of the stomach and duodenum the muscularis mucosae is absent. 



SMALL INTESTINE. 



Transverse Section. (Logwood and dammar.) EXAMINATION (L). Mucous coat. - 

 Observe the conical pointed villi ; some of them may be contracted and show the epithelial 

 covering thrown into folds. Each villus consists of a central core covered with columnar 

 epithelial cells, with their nuclei placed near the attached end of each cell. Beneath the villi 

 the mass of the mucous membrane is made up of Lieberkiihn 's follicles, consisting of simple 

 tubular glands lined by epithelium. Note the adenoid tissue between the bases of the 

 glands, and outside this the muscularis mucosce. The submucous coat consists of connective 

 tissue containing blood-vessels and nerves. Muscular coat. Note the thick inner circular 

 layer, which- will appear different according as the section has been made across or parallel to 

 the long axis of the gut ; if the latter, note that the muscular fibres are arranged in blocks 

 separated and surrounded by connective tissue ; outside this the narrower longitudinal layer, 

 and outside all the serous coat. This specimen does best for a general study of the relation of 

 parts. Select a villus and examine it with (H). Notice the long fusiform nuclei in that part 

 of the core of the villus, next the central lacteal vessel. They are the nuclei of non-striped 

 muscular fibres, which pass from the muscularis mucosae into the villi. (Indicate t lie general 

 arrangement in one-half of \. XIV., Fig. i.) 



Examine now a similar preparation stained with logwood, but mounted in Farrant's solu- 

 tion. Observe the same relation of parts as described above. Fix a villus in the field, and 

 observe (H) the epithelial investment, consisting of columnar nucleated cells with a clear hem 

 containing vertical stria; (compare p. IO, on epithelium). Observe goblet-cells scattered between 

 the epithelial cells and study them. (Indicate the covering and structure of a villus in PL 

 XIV., Fig. 2). Search for these cells seen en face. In the substance of the villus observe the 

 adenoid tissue of which it consists, with nuclei in its meshes, and perhaps a lacteal vessel in 

 its centre. 



Lieberkiihri s Glands. Study one. Observe its test-tube shape, and the low nucleated 

 columnar epithelium lining it. At their bases and outside them observe adenoid tissue. 

 Study the two layers of the muscularis mucosas. 



