I.] THE FROG. 87 



a. The cwliaca-mesenteric artery, to the alimentary- 

 organs; the cut end of this will be seen arising 

 either at the point of union of the two aortic 

 arches or, more generally, from the base of the 

 left arch. 



Very rarely this is represented by distinct coeliac 

 and mesenteric trunks. 



b. The renal arteries, to the kidneys ; variable in 

 number, arising from the aorta as it passes between 

 the kidneys. 



c. The genital arteries, to the reproductive glands; 

 usually arising from the anterior renal vessels. 



d. The inferior mesenteric artery; a small vessel 

 arising far back and supplying the base of the 

 large intestine. 



e. The common iliac arteries; arising as an apparent 

 bifurcation of the dorsal aorta. 



Very rarely, the aorta is continued back, beyond 

 the point of origin of the above, as a delicate 

 median sacral or caudal artery, 

 a. The hypogastric arteries; arising, one on each 

 side, from the iliacs, just before they leave the 

 body-cavity, and distributing branches to the 

 urinary bladder and body-wall adjacent. 

 1 o. The hepatic-portal system in detail. 



Pin a newly-killed Frog down upon its left side, 

 and remove the body-wall and arm of the right one. 

 Reflect the skin of the back and remove the genera- 

 tive organs; dissect off the pericardium and liberate 

 the right lung. Displace the alimentary canal 

 turning the stomach and liver forwards and the 

 large intestine well back; and pin down under water. 



