460 
DR. HERBERT WATNEY ON THE MINUTE 
If the epithelium which has lain in weak bichromate of potash is teased (and it is 
best to select the intestine of the rabbit, as in that animal the epithelial cells are more 
easily separated), the idea that they have processes will soon be refuted. They are seen 
to be somewhat conical, the lower smaller end being slightly broadened at its termina- 
tion, as was first shown by Billroth (36). Attached to them are shreds of the reti- 
culum* *, which always separate with the epithelial cells from the rest of the mucosa. 
In these preparations rarely, if ever, will an epithelial cell with two nuclei be found : 
the lymph-corpuscles attached to individual cells may give that impression, but in such 
a case, by pressing on the cover-glass, and so rolling over the epithelial cells, the 
attached corpuscles will be seen indenting the wall (see fig. 3). This indentation 
of the wall has been shown in the drawings of Eberth (33) (fig. viii. a and b) and 
Arnstein (40). 
The epithelial cells are closed : perhaps the easiest way to show this is to add weak 
acetic acid to epithelium of a freshly killed animal, examined in saline solution. If the 
action be pushed far enough (i. e. until the cells are almost transparent and the nuclei 
very much marked) the well-known seam will be pushed up in the form of a segment 
of a circle, as has been shown by so many observers, or it may be raised up en masse. 
Sections of frog’s intestine show great differences in the length of the epithelial cells 
in the same animal ; and, as a rule, the epithelium in the rectum is longer than that of 
the upper parts of the intestine. Any good section will show epithelial cells with pro- 
cesses nearly, if not quite, as long as those figured by Heidenhain (37) and others (see 
Plate 42. fig. 34, of the epithelium of the stomach of the frog). Considerable differences 
of length will also be met with in the epithelial cells of the intestine of mammals, partly 
due to the presence of structures which will be discussed hereafter, under the title of 
“ Epithelial Buds ” (see Plate 39. fig. 13), and partly due to the fact that the epithelium 
covering the upper surface of the villi and the upper surfaces of the processes in the 
large intestine is much shorter, as a rule, than elsewhere. 
On examining the projections of the mucous membrane in a section of the vermiform 
process of the rabbit, fine, almost thread-like processes from the dark line on which the 
epithelium rests may be seen running among the epithelial cells. This dark line (see 
figs. 9 and 13, r), as we shall see afterwards, is due to the sectional view of the con- 
nective-tissue reticulum, which lies surrounding the epithelial cells, and on which 
they rest. 
Again, if sections of villi or folds of the mucosa be examined where the epithelial cells 
have been cut horizontally near their base (see Plate 40. fig. 4), the polygonal areas of the 
epithelial cells are seen, and between them very deeply stained bodies (fig. 4, r), which 
rabbit’s intestine (see Plate 39. fig. 1) for concluding tbat tbey are ever contained in the epithelial cells ; 
but, on the contrary, they are probably situated between the cells, the latter being pressed to one side by the 
invading Psorospermise. 
* This reticulum will shortly be discussed. 
