352 
MR. YOUATTS VETERINARY LECTURES. 
fluid. We are not yet prepared for the inquiry into the power 
or influence by means of which the gastric juice is secreted ; but 
we can no longer doubt that it is by the stimulus of the par vagum 
on the muscles of the stomach that the elementary mass is 
brought into repeated and sufficient contact with this juice. 
The Muscular Coat of the Stomach .—I need not tell you that 
the second or central coat of the stomach is a muscular one, and 
of singular construction, consisting of two layers of fibres, 
intersecting each other; the one small and few in number, 
running longitudinally, and the other large and numerous, 
running circularly. You may plainly perceive how these fibres 
are multiplied and strengthened around the cardiac orifice, so as 
to form not precisely a sphincter muscle, nor a valve, but a 
strong, and, in the horse, an almost insuperable obstacle to the 
regurgitation of the food. At the pyloric orifice they are also 
increased in number and strength, constituting to the required 
extent, and, as it regards solid matter, a true sphincter muscle. 
These muscles effect some important purpose, or they would not 
be placed around the stomach and so curiously arranged there; 
and they are supplied by the gastric portion of the cerebro-visceral 
nerve alone. While the filaments from the semilunar ganglion, 
diffused likewise over the stomach, pass with the arteries through 
the coats of this viscus, and are lost in its interior surface, the 
cerebro-visceral is seen pursuing its course between the perito¬ 
neal and muscular parietes, and evidently expending and losing 
itself on the muscular coat. 
Illustrations of the Influence of the Cerebro-Visceral Nerve on 
the Stomach . It prevents Vomiting .—The oesophagus is not 
inserted into the stomach of the horse vertically, nor does it at 
once penetrate the parietes; but it runs obliquely between the 
muscular and cuticular coats for some distance, so that the 
contraction of the muscles at the base of the oesophagus, or 
around the cardiac orifice, will obliterate, as it were, the canal, 
and render the regurgitation of the food almost impossible. 
Every contraction also of the circular fibres of the stomach gene¬ 
rally, and particularly of those about the cardiac region, unite in 
producing the same effect, and preventing the act of vomiting; 
a liability to which would be inconvenient in a slave, the utmost 
exertion of whose pow r ers is required at every call of necessity, 
or freak of caprice, in sickness or in health, or whether the 
stomach is full or void. 
The difficulty of vomiting in the horse depends not upon any 
construction of the velum palati, or posterior part of the mouth, 
but simply upon the ureter-like manner in which the oesophagus 
