118 THE DIGESTIVE SYSTEM. 



.shaped op)ening. The oesopliagns, on leaA'ing the pharynx and 

 entering the chest cavity, diminishes in calibre, expanding again 

 &s soon as it has passed through the diaphragm or midriff. It does 

 not actually terminate in either of the stomachs, but ends in a 

 pouch called the oesophageal canal. This is about 4 to 4^ 

 inches in length, formed superiorly by the oesophagus and in- 

 feriorly by muscular pillars or duplicatures of the upper por- 

 tions of the first and second stomachs. So it will be apparent 

 tlist the oesophageal canal or furrow is a sort of passage, having 

 r.onnections with the different stomachs, and which, with the 

 exception of the second and fourth, are the only openings these 

 stomachs are endowed with. The food passing from the oeso- 

 phagus enters the first stomach, called the rumen, the entrance 

 to which is close to the termination of the oesophagus and the 

 entrance of the canal. The rumen is of enormous extent, oc- 

 cupying when full of food nearly three-quarters of the whole of 

 the abdominal cavity. 



By reference to the illustration on opposite page it will be 

 seen that the oesophageal furrow or food duct commences at the 

 entrance to the rumen, its floor being composed of muscular 

 pillars formed by the upper part of the second stomach, the en- 

 trance to which is between these grooves. The pillars are con- 

 tinued within the cavity of the second stomach for nearly an 

 inch and a half to the entrance to the cavity of the third, Avhich, 

 being situated above, forms the roof of the oesophageal furrow. 

 The entrance to the fourth stomach is 2^ inches in length, 

 formed by the turning back of the mucous and muscular coats 

 of the visciis, which at times are in close apposition one with the 

 other, as the necessity of nature may require. The food on 

 passing through the oesophagus usually falls into tlie rumen or 

 first stomach. This stomach, the largest of the four, occupies 

 the left flank; by a constriction across its middle it is almost 

 ■di^aded into two compartments. Externally lining it is the 



