EPIDERMIS. 



59 



slightly rounded on one side and excavated on the other, 

 or where a cell is so thrust in between others as to assume 

 a clubbed or jagged form. 

 But in these cases also the 

 one cell always corresponds 

 with the other in form, and 

 it is not any peculiarity in 

 the cell which gives rise to 

 its shape, but the way in 

 which it lies, its relations 

 to the neighbouring cells, 

 and its having to adapt 

 itself to the arrangement of the parts next to it. In 

 the direction of the least resistance the cells acquire 

 points, jaggs and projections of the most manifold descrip- 

 tion. As they did not well admit of classification, Henle 

 gave them the name, which has since been adopted, of 

 transitional epithelium, to express their gradual transi- 

 tion into distinct scaly and cylindrical epithelium. Some- 

 times, however, this is not the case, and another name 

 for them might just as well have been adopted. 



On account of the importance of the subject, I will 

 just add a few words with regard to the cuticle (epider- 

 mis). In this it fortunately happens that, what is not 

 the case in many mucous membranes, many layers of 

 cells lie one above the other, and that the young layers 

 (the rete Malpighii [mucosum]) can easily and con- 

 veniently be separated from the older ones (the epider- 

 mis proper). 



Fig. 15. Transitional epithelium from the urinary bladder, a. A large cell, with 

 excavations along its border, into which more delicate club- and spindle-shaped 

 cells fit. 6. The same ; the larger cell with two nuclei, c. A larger, irregularly 

 angular cell, with four nuclei, d. A similar cell, with two nuclei and nine depres- 

 sions, as seen from above, corresponding to the excavations of the border. (Comp. 

 ' Archiv. fur path. Anat. und Phys.,' vol hi, plate i., fig. 8.) 



