PRACTICAL HISTOLOGY. 



mercuric chloride are stained with aniline-blue and then with safranin. In 

 balsam preparations the parietal cells are pale blue, the inner cells red. 



12. Isolated Cells of Gastric Glands. Macerate fragments of the gastric 

 mucous membrane of a newt in 5 per cent, ammonium chromate (24-48 hours). 

 Stain in picro-carmine, and tease in glycerine. Numerous isolated cells from 

 the ducts and secretory parts of the glands are obtained. 



LESSON XXV, 

 THE SMALL AND THE LARGE INTESTINE. 



SMALL INTESTINE. 



IT has four coats mucous, submucous, muscular, and serous. 



Study specially the mucous coak In man, in certain parts, there 

 are permanent folds of the mucous membrane valvulse con- 

 niventes and everywhere the surface is beset with small conical 

 elevations villi. At the bases of the villi is a layer of simple 

 tubular glands Lieberkiihn's glands embedded in an adenoid 

 tissue matrix. Underneath this is the muscularis mucosse, usually 

 consisting of three thin layers of smooth muscle. 



A villus (.5-3 mm. long) consists of a central core, enclosing a 

 lacteal, and covered by a single layer of columnar epithelium with 

 goblet-cells (Lesson V.). The body of a villus consists of a tissue 

 like adenoid tissue with leucocytes and other cells. The central 

 lacteal is really a lymphatic, and begins by a closed extremity. 

 Several strands of smooth muscle pass from the muscularis mucossB 

 into the villus, and reach its upper extremity. It is very vascular, 

 and the blood-vessels are distributed immediately under the epi- 

 thelium. 



The mucous membrane also contains solitary follicles, and in 

 some situations Peyer's patches, the latter are most abundant in 

 he ileum. 



Methods. Make transverse sections of the small intestine of a 

 cat or dog hardened in a mixture of potassic bichromate and 

 chromic acid ; Klein's fluid ; i per cent, chromic acid ; Kleinen- 

 berg's fluid ; or mercuric chloride. 



(i.) Stain a section in hsematoxylin and mount it in balsam, or 

 stain another in picro-carmine and mount it in Farrant's solution. 



(ii.) All the parts and their relations are best preserved by 

 staining in bulk in borax-carmine and cutting in paraffin, or embed 

 in paraffin, cut, fix on a slide, and then stain. 



