BY DR. KLEIN. 0!) 



Epithelium of Villi of Intestine. In the rabbit we 

 proceed as follows: The animal is killed, the small ink-slim-, 

 immediately opened, and from the borders (which then curl 

 outwards) we remove a small portion with curved scissors as 

 in the previous case. This is to be covered with the mucous 

 surface upwards. The villi seen exhibit, on their surfaces, a 

 regular mosaic of epithelium ; at their borders, where the epi- 

 thelium is iu profile, it is seen to consist of tegular cylindrical 

 cells. If the observation of the mosaic is continued for some 

 time, granular spherical bodies come into view ; at first singly, 

 but afterwards in numbers, which are raised above the general 

 surface of the cells, as may be learnt by using the fine adjust- 

 ment. These spherical bodies have escaped from the cylindri- 

 cal cells. We shall see that it is by this means that the goblet 

 cells already mentioned are produced. The epithelial cells on 

 the borders of the villi display distinctly the broad, finely- 

 striated border, which spreads over their ends like a cuticle. 

 Equally instructive specimens may be obtained from the intes- 

 tine of the cat, dog, guincapig, rat or hedgehog. The epithe- 

 lium of the villi may be as successfully studied, while still 

 attached, in a preparation, mounted in serum, or half per cent, 

 solution of common salt. For more prolonged examination, 

 especially if we wish to stud}'- isolated cells, we put a piece of 

 intestine, cut from the rabbit, dog, or cat, into a sherry-yellow 

 solution of bichromate of potash, allow it to remain there for 

 one or more days, and make our preparation in the manner al- 

 ready described with regard to the trachea. In such speci- 

 mens we find not only numerous isolated cells, but also com- 

 plete villi, and parts of the same, on which the epithelium, 

 when its surface is viewed, resembles, as in the fresh prepara- 

 tion, a pavement of granular cells, each of which contains a 

 relatively large, sharps-bordered, and apparently round nu- 

 cleus. The lines of interstitial substance are sharp and dark. 

 ""ATfhe edges of each villus the epithelial cells are cylindrical, 

 with finely-striated border. Each cell consists of granular 

 protoplasm, and contains a sharply-defined nucleus, in which a 

 distinct nucleolus is to be seen. 



If we examine attentively the surface of a villus, or of a por- 

 tion of villus (especially in a preparation from the intestine of 

 the dog or cat, which luis been allowed to remain in a solution 

 of bichromate of potash), we shall find, between the mosaic of 

 granular cells, roundish structures, cither single or in small 

 groups, and with a diameter greater than that of the cells of the 

 mosaic ; these are quite clear in the centre, have a doubly-con- 

 toured membrane, and give the impression of vesicular bodies. 

 If we search on the borders of the villi for a structure in profile 

 corresponding to this surface appearance, we find between the 

 cylindrical cells, which are full of protoplasm, bodies of a lell- 



