EPITHELIUM OF THE MUCOUS MEMBRANE. 485 



The illustrations given by Henle* and Kolliker,f and especially 

 those of the former, correspond to this description ; Kolliker only 

 giving a couple of very wide tubes, in which the triangular 

 form is of course a less marked feature. The appearances are 

 differently represented by Hennig, J in whose drawing the cells 

 float freely in the lumen of the gland. 



In longitudinal sections, on the other hand, the cells every- 

 where present the form of a parallelogram, with their long 

 diameter vertical to the membrane. Lott maintains this in 

 opposition to several authors, who state that the epithelium 

 is of the tesselated or pavement variety. (See, in regard to the 

 Dog, Ercolani; in regard to the Rabbit, Reichert|J and Ercolani; 

 in regard to the Mouse, Ercolani ; and in regard to the human 

 subject, Gerlach,1f Scanzoni,** and Schroder. ff Lott found the 

 above-mentioned character to be everywhere present, though 

 not with equal distinctness in all animals. 



The cells only undergo modifications of form at the points 

 where the gland tubes make sharp curves. In longitudinal 

 sections they here become pointed towards one side, so that 

 on the convex side of the tube their pointed extremities are 

 directed inwards, and on the concave side outwards. 



By means of corresponding changes of the focal distance we 

 may also obtain a clear image of the cell boundaries on the 

 external and internal surfaces of the tubes, and thus com- 

 plete our conception of the form of these cells. On their ex- 

 ternal surfaces the cells form a beautiful mosaic of tolerably 

 regular hexagons (the bases of the wedges), whilst the internal 

 surface exhibits a similar mosaic of hexagons elongated in 

 the direction of the length of the tube, but appearing very 

 slender in its transverse diameter (the acute border of the 

 wedge). Such a mosaic is most distinctly seen in specimens 

 preserved in Midler's fluid. 



* Loc. cit., figs. 538 and 539. 



f Kolliker, Handbuch der Gewebelehre, 5th edition, 1867. 



j Loc. cit., Taf. iii., fig. 10. 



Loc. cit. ** Loc. cit. 



|| LOG. cit. ft Loc. cit. 



IT Loc. cit. 



