Ii6 PRACTICAL HISTOLOGY. 



e. The simple layer of epithelial squames that forms a basement 

 membrane under the columnar epithelium as described by Debove 

 (Archives de Physiologic, 1874, p. 19) may be shown without much 

 difficulty thus : Open the small intestine of a rabbit or cat just killed. 

 Isolate a small portion and wash the mucous membrane with distilled 

 water. Pour \ per cent silver nitrate solution over the interior, and 

 leave it till it becomes opalescent. Wash in distilled water. Then 

 pencil away the epithelium, and silver the subjacent tissue in the usual 

 way ( 328). If the villi are then snipped off and mounted in glycerine, 

 the silver lines of a squamous epithelial membrane, somewhat like that 

 of a serous membrane, may be seen. 



f. The same process as that just described also serves to show very 

 beautifully the superficial lacteals of the villi and their communications 

 with the spaces in the reticulum of adenoid tissue. 



192. Structure of Small Intestine, T. S. or V. S. 

 Small intestine of cat prepared as stated in 191 a. Mount 

 in Farrants' solution or in glycerine. (L.) The mucous 

 coat showing the villi, follicles of Lieberkiihn, and mus- 

 cularis mucosa. The submucous coat. The muscular 

 coat with its two layers of fibres. 



(H.) The columnar epithelium of the villi with their 

 striated border, and with a chalice cell here and there. 



The follicles of Lieberkuhn, lined throughout by colum- 

 nar epithelium, the nuclei of which are placed near to the 

 attached ends of the cells. In very thin sections the epi- 

 thelium may be found detached from the basement mem- 

 brane. (The membrane consists of simple epithelial 

 squames (Watney), but this can only be seen in silvered 

 specimens.) 



The muscularis mucosa forming here as in the stomach 

 two layers. Endeavour to trace bundles of fibres from it 

 up into the lateral part of the villus, where they run nearly 

 to its tip. 



The adenoid tissue ; the only connective tissue found 

 in the villi, and also largely found between the follicles of 

 Lieberkiihn. 



There is nothing remarkable about the submucous and 

 muscular coats. 



193. Lacteals. Examine (H.) villi silvered after removal 

 of the columnar epithelium ( ipi,/). The clear lines 

 parallel with the villus are the superficial lacteals which 



