THE HUMAN INTESTINAL CANAL. 



317 



The gullet (oesophagus) passes do^Ynward through the 

 thorax, along the vertebral column, behind the lungs and 

 the heart, and enters the ventral cavity, after penetrating 

 the diaphragm. The latter (Fig. 16, 2;) is a membranous, 

 muscular, transverse partition, which in all Mammals (and 

 only in these) completely separates the chest-cavity 

 {thorax, c) from the ventral cavity (c^J. As has been said, 

 this division does not originally exist; at first a common 

 chest and ventral cavity, the cceloma, or the pleuro- 

 peritoneal cavity, is formed in the embryo. It is only 

 afterwards that the diaphragm forms a muscular, horizontal 

 partition between the chest and the ventral cavities. This 

 partition then completely separates the two cavities, and 

 is penetrated only by separate organs, passing through the 



Fig. 275. — Human stomach and gall-intestine in longitudinal section : 

 a, cardia (limit of the oesophagus) ; b, fundus (blind sac of the left side) ; 

 c, pylorus fold; d, pylorus valve; e, pylorus-cavity ; /g ^, gall-intestine ; 

 i, mouth of the gall-duct and of the pancreas duct. (After H. Meyer.) 



chest-cavity into the ventral cavity. One of the most 

 important of these organs is the gullet [oesophagus). After 

 this has passed through the diaphragm into the ventral, 

 cavity it enlarges into the stomach in which dioestion 



