FEOG ' 243 



find the inferior mesenteric artery. Look 

 also for the splenic artery. Trace one of the 

 iliac arteries back to the sciatic artery, which 

 eventually divides into peroneal and tibial ar- 

 teries. 

 Make a diagram of the arrangement of the blood- 

 vessels which communicate with the heart by means of 

 the systemic arch. 



Examine the pulmo - cutaneous arch, and trace its 

 branches, the cutaneous artery, to the skin, and the 

 pulmonary artery, to the surface of the lung. Draw 

 this arch and its branches. 



Compare the above arches as regards the extent of 

 the distribution of their branches. 



ly. The internal anatomy of the heart. 



In frogs killed with chloroform it will be 

 found that the heart is distended with blood. 

 The heart of any of the specimens thus far ex- 

 amined may be used, or one may be especially 

 prepared by killing a frog with chloroform, open- 

 ing the body so as to expose the heart, and plac- 

 ing the entire specimen in alcohol. In a day 

 or so remove the heart by cutting it away from 

 the lungs and severing its attached blood-vessels 

 at a sufiBciently remote distance from the organ. 

 Examine its external anatomy again so as to get 

 the various regions of the organ clearly in mind. 

 Select three small bristles of different colors, and 

 gently thrust one of them into the carotid, an- 

 other into the aortic, and the third into the 

 pulmonary arch. Then fasten the heart down, 

 dorsal side uppermost, in a dissecting -pan by 

 thrusting small pins through the apex of the ven- 



