THE STOMACH. 
275 
the cardia it is continuous Numerous small openings a rt> 
visible upon its inner surface, through which issues a mucoug 
tiuid, the product of follicular glands underneath, which is 
useful in the process of digestion, and where it may be said 
properly to commence. This is called the gastric juice, which 
mixes with the food already softened, and converts it into that 
fluid substance called chyme. 
, c. The margin which separates the cuticular from the villous 
portions. 
d The entrance from the gullet into the stomach. The circular 
layers of muscles which invest this part are very strong and 
thick. By their powerful contractions they assist in rendering 
it difficult for the food to be returned or even vomited. This 
orifice is called the cardiac orifice, in consequence of its con¬ 
tiguity to the heart. It is constantly closed by strong muscular 
fibres, except when the food is passing through it into the 
stomach. Although this assists materially in preventing the 
return of the food, it is the construction of the soft palate 
which mainly contributes to the prevention of vomiting in the 
horse. 
f. The oesophagus, or gullet, through which the food is conducted 
from the pharynx into the stomach. It has its commencement 
in the pharynx, and is there placed at the upper and back part 
of the larynx, the first part of its course being behind the 
trachea, between it and the cervical vertebra*. After proceed¬ 
ing a short way down, it inclines to the left, and soon after 
makes its appearance altogether on the left side of the trachea, 
and continues so in its passage down the neck. This will 
explain what has puzzled many, why we look for the bolus 
during the act of swallowing on the left, and not on the right 
side of the animal. Accompanying the trachea, the oesophagus 
enters the chest between the first two ribs, at which part, 
running above that tube, it diverges from the trachea, and in 
connexion with the superior mediastinum, and traversing thai 
cavity a little way below and to the right of the aorta. 
g. The communication between the stomach and the first intestine. 
i. A small orifice through which a portion of the secretion of the 
pancreas enters the intestines Its direction will be seen bv 
the probe which is passed through it. The pancreas, othe? 
