56 THE FROG 



341. Note the heart in its pericardial cavity. On either 

 side find the internal gills, in the opercular cavity. 

 Probe through the opercular aperture. Count the 

 gills, and note the gill (visceral) clefts between 

 Ihem. Probe through the mouth. Deep in the caudo- 

 lateral angles of the opercular cavity find the dimin- 

 utive forelimbs. In the visceral cavity note the long 

 coiled intestine. Lay it to one side after cutting 

 through the rectum at the caudal end and the dorsal 

 mesentery by which it is attached to the body wall. 

 Do not cut through the cephalic end. At the 

 cephalic end, note the stomach and slender yellow 

 pancreas, the liver and gall bladder, and the 

 oesophagus. Compare with the digestive system of 

 the adult. Find the lungs. On the dorsal surface of 

 the coelome, note the conspicuous yellow £at-bodies 

 attached to the kidneys, relatively larger than in 

 the adult, and the rudimentary gonads. 



Drawing 34. Draw (x2) from the ventral surface, 

 showing the intestine displaced to your left, in order to 

 expose the organs normally concealed by it. 



Remove tail by a transverse incision behind the vent. 



342. Examine cut surface and locate: notochord, spinal 

 cord, caudal artery, and muscles. 



Drawing 35. Draw (x4)» 



