Dissection of Common Rat. 185 



The specimen before us being a male, we come next to the 



small whitish bladder in the middle line, and on either side 



of it the pinkish tinted Cowper's Glands, external to which 



. again are the vesiculae seminales : and lastly in the median 



line the Penis and Scrotum. 



On gently pressing away the Liver from the cavity it oc- 

 cupies anteriorly, two structures will be apparent : first, the 

 Diaphragm^ which forms a vaulted moveable partition between 

 the Thorax and the Abdomen, and which, by its movement up 

 and down alternately, during respiration, causes enlargement 

 of the Thoracic cavity in inspiration, and of the Abdominal 

 cavity in expiration ; and, concomitantly, a slight alteration in 

 the position of certain of the Abdominal Viscera, especially 

 the Liver, Stomach, and Spleen ; secondly, in the middle, a 

 reflection of the Peritoneal lining between the Liver and the 

 Diaphragm forming one of the suspensory ligaments of the Liver. 



On raising the posterior free border of the Liver, the whole 

 oi the Stomach is apparent : the left or cardiac portion of this 

 viscus is ovate and strongly recurved ; the (Esophagus will be 

 readily seen to enter near the middle of the anterior or concave 

 border, immediately to the right of which the Stomach will 

 be seen to assume a difierent hue, marking the commencement 

 of the right or pyloric portion whose parietes are thicker than 

 those of the cardiac, and are glandular internally : the Pyloric 

 stricture should also be noted, and the small tendinous spot 

 immediately preceding it, at the end of the pyloric portion of 

 the Stomach whence a ligament proceeds to be attached to the 

 abdominal surface of the large left lobe of the Liver. 



On turning forwards the Stomach, and at the same time 

 gently pulling the Spleen away, the difiused Pancreas* comes 

 into view, spread throughout the Omentum (a process of peri- 

 toneum found only in Mammals), which is attached to the 

 postero- superior segment of the Stomach, and to the Spleen. 



* Cf. p. 187. 



B B 



