354 ON THE ANATOMICAL PECULIARITIES 
desirous to communicate as distinct an idea of its configu- 
ration, as mere verbal description is adequate to convey. 
The inner surface of this intestine further presents cer- 
tain peculiarities of structure, which, so far as I am aware, 
have not been recognised by anatomists. When inspected 
with care, the portions which are on the right side of the 
axis, are entirely different in structure from those on the 
left. In the latter, they are smooth and uniform, like a 
mucous membrane void of villi, and destined, like that 
of the respiratory organs in the mammalia, to secrete 
merely thin serous mucus. On the right side of the axis, 
the portions of the bowel interposed between the spiral 
membranous slips present a distinct, though modified form, 
of the reticular structure exhibited by the duodenum. It 
is not uninteresting to mark the transition of these two 
forms of structure into each other The winding slips of 
the valve divide the tube, as it were, into a series of sinuo- 
sities or cells of an irregular eUiptical shape. 
The membranous lining of the first of these cells, on the 
right side, is, like the beginning of the intestine, smooth 
and uniform * but as it approaches the slip, it assumes the 
reticular or honeycomb arrangement. At the margin of 
the slip, again, and at the plane of the axis, this ceases, 
and it passes to the other side, in the shape of a smooth, 
polished, mucous surface. On the opposite side, and at the 
lower margin of this slip, however, the honeycomb texture 
again commences, and extends over the whole surface of 
the r>iuuosity between the two slips ; but on the mesial 
plane the smooth poKshed aspect of the membrane is re- 
sumed. This alternate arrangement of reticular and smooth 
structure is observe'd the whole way down the tube. The 
number of the cells thus formed, is eight, with reticular 
structure, on the right side of the axis, — and nine, with 
smooth surfaces, on the left side. It is a remarkable proof 
