I.] THE FROG. 39 



the shoulder girdle thus liberated and remove it, with 

 care, together with the rest of the ventral portion 

 of the body- wall. 



A spacious cavity (pleuro-peritoneal cavity) will be 

 laid bare. Note the general characters and mutual 

 relations of the undermentioned organs of the viscera 

 which lie within it, as seen in the undisturbed state. 

 They will be found severally connected with the body- 

 wall and each other by a delicate membrane or 

 mesentery. 



a. The liver: a great brown two-lobed mass, its left 

 lobe the larger and subdivided into two, lying in 

 the anterior end of the cavity. 



b. The lungs: the posterior ends of these may be seen 

 as sacculated pouches, one on each side of the liver, 

 but they are frequently not visible until the latter 

 organ has been displaced. 



c. The stomach: a small portion of this is seen pro- 

 jecting beyond the lower left border of the liver. 

 Note that it lies exclusively to the left side. 



d. The intestine: a convoluted tube, continuous with 

 the stomach, and occupying the middle third of the 

 cavity. It can be resolved into 



a. The small intestine; a yellowish-white tube, con- 

 voluted and situated wholly to the right side. 



ft. The large intestine; a short straight greyish-green 

 tube, of greater calibre than a, passing obliquely 

 backwards in the middle line. 



e. The urinary bladder (urocyst}, a thin-walled bilobed 

 sac (which may or may not be distended) lying just 

 in front of the pelvis, immediately above (ventral 



