462 
DE. HERBERT WATNEY ON THE MINUTE 
On examining villi which have lain three or four days in weak bichromate of potash, 
if the epithelium be removed, we see the cells forming the membrana (as in fig. 9). If 
the tissue is then stained in strong hsemtoxylin for some hours and afterwards teased, 
the membrane with its attached blood-vessels can be isolated, and we obtain similar 
appearances to those in fig. 6, which was drawn from a section of a hardened villus. 
It has been mentioned that the blood-vessels are always attached to the membrana ; 
the reason for this will be evident by referring to fig. 13 (e), where it is seen that the 
cells forming the membrana are not altogether flat plates, but partially surround the 
blood-vessels and form a kind of adventitia to them. 
In examining sections of the villi of the following animals, a membrana propria, very 
similar to that of fig. 6, is seen — i. e. in the sheep, rabbit, rat, hedgehog, dog, cat, 
and frog. 
The Membrana of Lieberkuhn’s Cryjpt. 
If in sections this membrane be completely isolated from the surrounding structures 
and viewed from above, it is seen to be a structureless membrane w 7 ith nuclei imbedded 
in it at regular intervals (see Plate 40. fig. 7). 
On viewing an oblique section of a Lieberkuhn’s crypt, however (see Plate 39. fig. 5), the 
membrane is seen to be composed of large cells, the reticulum (r) resting on these cells 
( e ), and sending processes between them. The cells have all the characters of an endo- 
thelium, and (as is the case with the membrana of the villi) the endothelial plates 
are really contained in the meshes of the reticulum. 
The disposition and terminations of the Muscles in the processes of the Mucous 
Membrane of the Babbit's Colon. 
On viewing a slightly oblique section of one of the processes of the mucous membrane 
of a rabbit’s colon (see Plate 39. fig. 10), we recognize the epithelium, the dark line below 
it, and the separate large cells of the membrana, as oval or roundish bodies ; we observe 
also bands of muscle running up between the Lieberkuhn’s crypts, and separating into 
individual fibres. Many of these fibres will be seen apparently to end in the large cells 
below the epithelium (m, fig. 10) ; others will be found to end in connective-tissue 
processes, which are also seemingly attached to the cells of the membrana (m', fig. 10). 
At first sight we are tempted to conclude that the muscles end in these cells ; this is, 
however, not the case. In order to understand the relations of the muscle-fibres to the 
surrounding tissues, they must be studied in cross sections. This will best be done in 
sections at right angles to the muscularis mucosa (see fig. 12). Here we find certain 
points of resemblance to the transverse sections of the epithelial cells. Thus small 
branched bodies are seen which are attached to one another by their processes, the 
muscle-fibres being contained in their meshes. Is this appearance, then, due again to 
a reticulum ? and, if so, can this reticulum be shown to be in anatomical continuity with 
that of the mucosa 1 Both these questions are answered by observing sections in which the 
