BY DR. KLEIN. 137 



which covers the surface, consisting of slender cylindrical 

 elements. 



When these structures are compared as seen in fed animals 

 and in animals in inanition, it is found that in the former the 

 staining extends both to the ovoid cells and to the columnar 

 cells. A difference of the same kind may be shown in similar 

 sections stained with anilin. An extremely dilute aqueous 

 solution is used. The sections must be placed in a watch- 

 glass containing the liquid, which is allowed to stand twenty- 

 four hours in a closed vessel, the air of which is kept saturated 

 with moisture. The preparations can then be at once inclosed 

 in glycerin. The only difference between the results of the 

 two methods is, that the cylindrical cells are here slightly 

 tinged even in inanition. The convoluted and modi-branched 

 tubes which occur in the region of the pylorus contain only 

 cylindrical cells, which correspond to those of the same form 

 in the proper peptic glands. Between these last and the 

 branched glands, intermediate forms are met with, which 

 differ from each other in the number of ovoid cells (Beleyzel- 

 len) which they contain, the number diminishing according 

 to the distance from the pylorus. 



The processes of the muscularis mucosa?, which stretch 

 towards the surface through the mucosa between the glands, 

 can be better seen in chromic acid preparations. 



Small Intestine. The characters of the epithelium of the 

 small intestine in the fresh state have been already described. 

 They may be further advantageously studied in sections of 

 hardened organs, which will also serve for the demonstration 

 of the following structures the dense reticulum of the sub- 

 stance of the villi, with the round cells in its interspaces ; the 

 anatomical relations of the single or double central lymphatic 

 vessel which each villus contains ; the slender bundles of 

 longitudinal unstriped muscular fibres which run out around 

 the lymphatics towards the apex of each villus ; the reticular 

 tissue of the mucosa, identical in its characters with that of 

 the villi, in which the tubes of Liebcrkuhn arc sunk ; the mus- 

 cularis mucosse. with the distinct layers of which in many 

 parts it is seen to consist and the bundles of fibres which ex- 

 tend from it, either towards the villi or between the glands ; 

 and, lastly, the submucosa and muscularis externa. The in- 

 testine should be treated as follows: The intestine of a cat. 

 dog, rabbit, rat, or hedgehog just killed is opened, small por- 

 tions are at once placed in water colored with bichromate of 

 potash, and washed. They are then transferred to a one-tenth 

 or one-eighth per cent, solution of chromic acid, and live or 

 six days later to dilute alcohol, in which they are steeped for 

 some days. Thereupon small portions are embedded in gum, 

 and colored and mounted as directed in Chapter VI. 



