Digestive Organs of the Ox and Sheep. 
33 
Fig. 1. 
o. The Parotid Duct. 6, Its Opening into the Mouth, 
c, The Entrances of the Submaxillary Ducts. rf, The Parotid Gland. 
The Sublingual Glands. 
the first of these is voluntary, the second but partly so, and the 
third altogether involuntary ; the first conveys the food from the 
tip to the dorsum of the tongue, the second from thence to the 
pharynx placed at the upper part of the gullet, and the third from 
this to the stomach. The velum palati, or veil which guards the 
openings of the nostrils at the back part of the mouth, is large in 
the horse, and so situated as to direct the current of air, in ordinary 
respiration, through the nostrils. An equal development of this 
structure in the ox or sheep would interfere with the return of 
the ingesta from the pharynx in rumination, and consequently 
in them the veil is of smaller size, and takes a somewhat altered 
course ; hence these animals are enabled to breathe both through 
the mouth and nostrils. 
The entrance to the oesophagus is by the pharynx, which is 
defined by anatomists to be a funnel-shaped receptacle for the 
food, composed of several pairs of muscles, and lined by a conti- 
nuation of the membi ne of the mouth. The oesophagus may be 
viewed as a canal extending from the mouth to the stomach ; 
being also constituted of muscular fibres, and lined with a mucous 
membrane. These fibres possess an action independent of the 
will, as is the case with all muscles belonging to organic life. 
Their arrangement v.u ies in different classes of animals ; but we 
shall speak principally of it as observed in ruminants. The 
oesophageal tube has a loose cellular connection to the parts by 
which it is surrounded, so as to allow of its dilatation in the acts 
of deglutition and rumination. The muscular coat is composed 
VOL. IX. D 
