108 ANIMAL BIOLOGY 



c. Draw the lungs in position to show their situation, 

 size, and shape. 



4. On the frog's right side, and behind the heart and 



lungs is the reddish, several-lobed liver. Lay 

 the liver over to one side and find between the 

 lobes on the underside a thin-walled, green sac, 

 the bile sac (or gall bladder). Sketch in your 

 drawing the liver to show it in this position 

 together with the gall bladder. 



5. On the frog's left side and under the liver in its 



natural position is a whitish,, oblong body, 

 which narrows at its hinder end. This body is 

 the stomach. Push the handle of the dissecting 

 needle down the gullet into the stomach. 



a. Tell what you have just done. 



b. What organ does the handle enter? 



c. Push the stomach to the frog's left and draw it 



in this position to show its shape and relative 

 size. 



6. Extending from the stomach is a tubular structure 



of considerable length, the small intestine. At 

 the lower end of the small intestine the tube 

 becomes larger and then disappears between 

 the two thighs. This last part of the tube is 

 called the cloaca or large intestine. 

 Draw the small and large intestines. 



7. Between the stomach and the first loop of the small 



intestine is a thin pink body, the pancreas, 

 which is a very important digestive gland. 

 Draw the pancreas. 



8. Label heart, lungs, liver, stomach, small intestine, 



large intestine, bile sac, pancreas. 



9. Push the small intestine to one side and find two red 



bodies on either side of the spinal column. 

 These bodies are the kidneys. The kidneys 

 remove the nitrogenous waste (urea) from the 

 blood. 



Make a sketch of the kidneys twice the natural 

 size. 



