ANATOMY OF THE ALIMENTAKY CANAL. 
459 
stained in a solution of hsematoxylin. They were left in a strong’ solution from six to 
twelve, or even thirty hours. The solution of hsematoxylin was made in accordance with 
the receipt given by Dr. Klein in the ‘ Quarterly Journal,’ Oct. 1873. 
Structure of the Mucous Membrane of the Intestine. 
The Epithelium, and the Reticulum and Lymph-Corpuscles among the Epithelial Cells. 
On viewing a section of the vermiform process of the rabbit, many small round cells 
will he noticed among the epithelium covering the apices of the lymphatic follicles. 
These cells are exactly similar to those in the follicles. They may be situated among 
the epithelium, as if that tissue "were to some extent infiltrated by them ; or they may 
have possession of at least the lower half of the space which ought to be occupied by the 
epithelium, as in Plate 39. figs. 1 & 2, where they are seen as two or more layers above the 
basement membrane, the epithelium being apparently eaten away at its lower extremity 
by the round cells. If the section be a favourable one, and very deeply stained, it will 
he seen that processes from the’ dark line on which the epithelium appears to rest run 
up between the epithelial cells ; and where this is the case the epithelium which covers 
the follicle contains a tissue similar to that found within the follicles. (Identical appear- 
ances are met with in the epithelium covering the follicles of the tonsil *.) Thus we 
find that the epithelium contains a tissue consisting of a reticulum containing in its 
meshes lymph-corpuscles. 
If, now, sections of the epithelium covering the villi or the villus-like processes of 
the large intestine be examined in any animal, it will easily be seen that the epithelium 
contains lymph-corpuscles similar to those in the follicles (see fig. 13). It is specially 
easy to demonstrate this fact in the intestine of the rabbit and sheep. In preparations 
treated by chromic acid and stained in hgematoxylin, these cells are seen to consist of a 
small zone of unstained protoplasm surrounding a very deeply stained spherical nucleus. 
In the following pages I intend to apply the term “ lymph-corpuscles ” only to these cells. 
Again, if the villi of a recently killed rabbit be examined (either in the fresh state, in 
saline solution of three quarters per cent., with the addition of weak acetic acid, or after 
having remained in one per cent, bichromate of potash from two to six days), it is easy 
to show that the lymph-corpuscles are scattered everywhere among the intestinal epi- 
thelium ; and it is equally easy to show, if the epithelial cells be separated from one 
another by teasing, that the lymph-corpuscles are not found within the epithelial cells, 
hut lie between them. Thus Arnstein (40) was mistaken in supposing that these cor- 
puscles were ever contained within the epithelium f. 
* Henle long ago noticed that the epithelium which covers much developed “ agmmated glands ” of the 
conjunctiva is thinner from an infiltration of the gland-substance (‘ Eingeweidelehre,’ 1862). 
f Some observers have described Psorospermiae as existing within the epithelial cells (Krebs, Virchow’s 
* Archiv/ Bd. xvi.). There is considerable difficulty in deciding the exact relations in tissue so abnormal a s 
that where Psorospermiae are present in any great number ; hut there is no evidence in my preparations of 
3 S 2 
