ANATOMY OF THE ALIMENTARY CANAL. 
463 
muscularis mucosa is cut obliquely to the direction of its fibres ; we there find that the 
reticulum surrounding the fibres is continuous with that of the rest of the mucous mem- 
brane. The same thing may be noticed in cross sections of those fibres which are found 
in immediate contact with the chyle-vessel. Thus each muscle-fibre is ensheathed in a 
reticulum ; and it is by this reticulum that the muscle-bands running up towards the 
surface are attached to the cells forming the membrana, or, more correctly, to the reti- 
culum surrounding the cells forming the membrane. The method of their attachment 
to these large endothelial cells is well shown in fig. 11, where the ensheathing tissue (r) 
is seen to envelop one of the cells of the membrana (e). The reader will notice that the 
reticulum must be considered not only as a network of threads , but as forming, to some 
extent, membranous investments. Thus the muscle-fibres have membranous coverings, 
which are continuous with and are really part of the reticulum ; and the same may be 
said of the endothelial plates of the membrana. 
The Disposition of the Muscle-bundles and the Muscle-endings in the villi. 
In those villi of the monkey, hedgehog, or rat where there is only one chyle-vessel, 
the muscle-bundles run by its side, giving oif individual fibres towards the side of the 
villus ; and finally they either run straight on and end by being attached to the mem- 
brana at the apex of the villus (see fig. 13), or they may be arched slightly over the 
vessel, and then they will be attached to the membrana at a point on the opposite side 
of the villus. In the monkey the involuntary muscles form a membrane at least half- 
way round the chyle-vessel, and it is doubtful whether they do not entirely surround it ; 
but of this I am not sure, as I have no good horizontal sections. This membrane, which 
is composed of a single layer of fibres dovetailing into one another, is in contiguity with 
the endothelium*. 
In the hedgehog the muscle-bands contain very few fibres, generally only two or 
three, so that only a small portion of the wall of the chyle-vessel is in contact with 
muscle-fibre. 
In the rat the bands are reduced to the smallest dimensions, sometimes even to rows 
of single muscle-fibres slightly overlapping at their ends. 
In the broad villi, as those at the commencement of the duodenum, in the dog and 
cat, and in the villi of the sheep, there are many bands running up the villi, which 
branch, anastomose, and finally end by being attached to the membrana f. I have one 
preparation of the sheep’s intestine where one of the uppermost anastomosing bands, 
running nearly parallel to the surface epithelium, gives the appearance of a transverse 
band of muscles. 
* It is difficult at first_sight to understand how fat can pass through this membrane to the chyle-vessel ; 
we have, however, seen that each muscle-fibre is surrounded by the reticulum, and it will be further shown 
that the fat travels by that reticulum. 
t Kollikee (61) noticed that in the broad villi of the commencement of the duodenum and jejunum the 
muscle-bands are spread out like a membrane, and run from the base of the villus to the top. 
