202 VERTEBRATES, 



Divide the peritoneum along the median line, and dis- 

 close the internal organs. 1 



II. Digestive Organs. Trace the digestive system, 

 finding in order : 



1. Esophagus. 



2. Stomach. 



3. Intestine of three distinguishable parts : 



(a) Duodenum, into which ducts from the gall bladder 

 of the liver and from the pancreas open. 



(6) Small intestine. 



(<?) Large intestine ; and at the junction of these two 

 latter parts, a short, lateral, hollow process (the ccecum). 

 The spleen lies near the caecum. 



III. Renal and Reproductive Organs. The reproduc- 

 tive organs cover the kidneys and often other parts. 

 Find a pair of kidneys communicating posteriorly with a 

 bilobed urinary bladder. Make a diagrammatic drawing 

 of all these parts. Make a drawing of the liver, showing 

 its right and left lobes connected with a transverse band. 



IV. Veins and Arteries. Trace the two anterior ab- 

 dominal veins, seen through the peritoneum, before open- 

 ing the body cavity, forward to the liver. Do they unite 

 before entering the liver ? Trace veins from the hindmost 

 parts of the body to the kidneys, thence to the liver, and 

 thence to the venous sinus. Find veins which come from 

 anterior parts of the body, also entering the venous sinus. 



Trace now the principal arteries. Observe that the two 

 aortic arches and the pulmonary artery arise separately 

 from the ventricle, and not from an arterial trunk, as in 

 the frog. Trace the pulmonary artery to the lung, and 



1 After dissecting two other vertebrates, the fish and the frog, the 

 student should not now need further specific directions for finding and 

 studying the nutritive and reproductive organs. He should rather let his 

 knowledge of the structure of those vertebrates serve as a guide to the 

 study of this one , and he should not fail diligently to compare this one 

 with the other two at every point. 



