WEST OF SCOTLAND VETERINARY MEDICAL ASSOCIATION. 443 
rather, is formed into the anterior or left half of the organ (for I think there 
can be no doubt as to thq anterior half of the stomach of the horse being a 
continuation and a dilatation of the oesophagus), the muscular fibres become 
increased in number and thickness, and the tube itself considerably nar¬ 
rowed in its calibre. This narrowing at the cardiac end is so marked that 
the loose folds of mucous membrane in the non-dilated or quiescent state of 
the tube fill it to repletion, and, moreover, to the extent that neither fluid 
nor solid can enter from the stomach into the oesophagus. 
If, for example, we introduce—as I have repeatedly done—the nozzle of 
a water-pipe into the oesophagus, the stream of water will wash out the 
contents of the stomach into t he duodenum; but when we reverse the order 
of procedure—that is, insert the nozzle into the duodenum—neither liquids 
nor solids can be forced into the oesophagus. In short, if we tie the pipe 
within the duodenum, the pressure will rupture the walls of the stomach, 
and yet not a drop of liquid has forced an entrance through the cardiac 
orifice into the oesophagus. In all other of our domestic animals, and in 
the human subject, the oesophagus is as wide, if not wider , at its cardiac 
extremity as elsewhere, distinctly funnel-shaped , and the contents of the 
stomach can be washed into the oesophagus, or vice versa, as desired. 
Stomach. —The stomach of the horse is a single organ, but at the same 
time it might be affirmed, with equal truth, that this animal has two 
stomachs as that the ox has four. Veterinarians are familiar with the fact 
that internally the one half of the mucous membrane of the organ differs 
from the other; that the anterior half does not secrete gastric juice’; beyond 
this, little more has been recorded. 
If we carefully dissect and trace out the arrangement of its muscular 
and other structures, several important additions reveal themselves. When 
we distend the walls of the stomach with water or air, and ligature the 
cardiac and pyloric orifices, we observe that the organ is constricted in the 
middle , divided into two compartments, and the line of cleavage almost 
corresponds to the points where the cuticular and villous portions of the 
mucous membrane blend with each other. In some stomachs this line of 
division is very marked ; in all it exists and divides the stomach into a left 
and right cul-de-sac, or cardiac and pyloric fundi. This division of the 
stomach into two parts results from a difference being observed in the dis¬ 
tribution of the muscular fibres forming its walls, and is the reason for the 
statement made—that the left, or cardiac portion of the stomach is a con¬ 
tinuation of the oesophagus, and nothing more. Now, what is the arrange¬ 
ment F If we boil a stomach, macerate another, and have at the same time 
a fresh stomach at command, with care we make out that the muscular 
tissue is arranged in three layers, or planes, as most accurately described in 
‘ Chauveau’s Anatomy,’ and to which I refer those members who may 
desire to study the subject in detail. The superficial plane is a continua¬ 
tion of the longitudinal fibres of the oesophagus, or, if you prefer it, they 
are continuous with it. This layer more or less envelopes the whole 
organ, and is thickest upon the cardiac portion. In the middle layer 
the fibres run in a circular direction, and spread over all the 
stomach, and are thickest around the pylorus to form the sphincter. 
The deep layer is by far the thickest of the three, and is principally 
concerned in forming the cardiac portion. The structure and distribution 
of these muscular fibres, and their lacing and interlacing, explains 
why the stomach is and must be constricted in the centre; how the walls 
of the cardiac compartment are thicker than those of the pyloric fundus, 
and distinctly points to the conclusion that considerable more muscular 
power is needed to press or propel the food through the cardiac orifice, and 
along the left than the right cul-de-sac. In support of the inference which 
