ANATOMY OF THE ALIMENT AEY CANAL. 
477 
placed both in the submucosa and in the mucosa. Follicles were found at the com- 
mencement of the duodenum in the dog and cat. 
Schlemmer (107), 1869, showed that Brunner’s glands are tubular. 
Schwalbe (72), 1871, confirmed Schlemmer, and proved the great similarity between 
the epithelial cells of the tubes of the pylorus and those of Brunner’s glands. He said 
that the cells of Brunner’s glands are like those of the stomach-glands in active secretion. 
Heidenhain (108), 1871, agreed with Schwalbe as to the tubular character of 
Brunner’s glands, and their great analogy to the stomach-glands of the pylorus. 
If the point of union of the stomach and intestine in the dog be examined with the 
naked eye, lymphoid follicles are seen to be present in varying number. In some dogs 
they are so numerous that they form a ring of about half an inch in breadth at the 
commencement of the intestine, the surface being almost completely covered by them. 
In sections made at right angles to the plane of union of the stomach and intestine, 
it will be seen that the character of the epithelium of the surface changes quite suddenly. 
This change in the character of the epithelium indicates the point of transition between 
the stomach and intestine. In specimens hardened in chromic acid and stained in 
haematoxylin, we see on one side the regularly arranged cylindrical epithelium of the 
stomach, which in its upper part is clear and almost unstained ; on the other we find 
the granular epithelium of the intestine, with goblet-cells at intervals. This change of 
epithelium is found not only on the surface but in the tubes, so that at this point the 
glands of Lieberkuhn may be said to commence. There is, therefore, no gradual change, 
but suddenly the ducts of the stomach-tubes leave off, and the Lieberkuhn’s glands 
begin. This opinion is confirmed by preparations hardened in osmic acid, where it can 
plainly be seen that the ducts of Brunner’s glands do not open into the crypts of 
Lieberkuhn, but run up between them, as has been represented in the figure. 
In viewing the section made at right angles to the plane of union, we notice that the 
stomach-glands near the point of union are slightly different to those of the rest of the 
portio pylorica, the proper glands (coiled tubes) are more branched and convoluted, 
and the ducts are somewhat shorter. It will be further noticed that the coiled tubes 
are found penetrating (or even to some degree extending below) the muscularis mucosa. 
At about the point of union between the stomach and intestine, the coiled tubes will be 
found to break through the muscularis mucosa to a greater degree ; and at the com- 
mencement of the intestine we shall find that there are as many of these tubes in the 
submucosa as in the mucous membrane. At this point the muscularis mucosa is gene- 
rally rather indefinite, as it splits up, and portions of it run among the lobes of the 
coiled tubes. These tubes, from their situation, must now be called Brunner’s glands. 
On examining the section still further down the intestine, but few coiled tubes will be 
found above the still somewhat irregular muscularis mucosa ; while below it, Brunner’s 
glands are more regularly arranged in the form of separate lobes. Still further in the 
section we find a continuous muscularis mucosa with numerous Lieberkuhn’s crypts 
