430 Animal Biology 



The production and roles of intestinal juices and their enzymes in the 

 frog are not well known, but they are probably similar to those in higher 

 animals. Possibly starches may be converted into sugars in the intestine. 

 The various types of foods acted upon by specific enzymes in their proper 

 environments are eventually absorbed by the cells of the intestine and 

 passed into the lymph and blood vessels by which they are transported 

 to body tissues to be utilized. 



External carotid 



Palatine 



Auricularis 



Cutaneous 

 Carotid oiand 



Conus arteriosus 

 Pulmonary 



Systemic arch 



Lateralis 

 Dorsa lis 



Ophthalmic 

 Cerebral 



a^lnternaf carotid 



Brachial 



Vertebral 



Hepatic 



Cocliaco^rn-escnteric 



Left qastric 



PANCREAS 



IRiqht qastric 

 C celiac 

 Anterior 

 mesenteric 



Splenic 



Recto.vesical 

 Sciatic 



/RECTUM I Pac,t^rior mesenteric 



Fig. 214. — Arterial system of the bullfrog (ventral view). (Drawn by Ruth M. 

 Sanders, from Potter: Textbook of Zoology, The C. V. Mosby Co.) 



Circulation. — The heart, located within the thin, saclike pericardium, 

 is three chambered, being made of two thin-walled auricles (right and 

 left) and one muscular, cone-shaped ventricle (Figs. 214, 215, 364, and 

 365). A thick- walled, tubular truncus arteriosus (conus arteriosus) arises 



