VERTEBRATES 115 



What will it eat ? How is the mouth adapted to this 

 manner of feeding ? 



Respiration. 5. The frog has no diaphragm, and there- 

 fore no chest cavity ; watch very carefully the movements 

 of the mouth, the nostrils, the throat, and the sides of the 

 body to determine how the problem of breathing (how 

 the air is gotten into and out of the lungs) without a 

 diaphragm is solved. Write a detailed account of the 

 frog's method of breathing which shall explain just how 

 the air is forced into the lungs. 



6. What would be the effect of propping open the 

 mouth of the frog } Why } Does the frog breathe in 

 the usual manner while under the water } If not, how 

 do you explain its ability to remain under water for a 

 long period of time } 



Sense Organs. 7. Investigate the efficiency of the five 

 special senses in the frog by devising experiments to test 

 each sense ; as, for example, giving a frog its liberty on 

 the floor and trying to catch it again, to test the sense 

 of sight. Write an account of your experiments and their 

 results. Which of the senses is best developed.' Give 

 reasons for your answer. 



8. Compare the eye of the frog with respect to its 

 shape, movements, parts, and protective structures with 

 that of the fish. In what respects are they similar? in 

 what respects different .' Why should they differ .■' 



9. Where are the frogs' ears located .' What do you 

 think of the efficiency of an eardrum situated on the 

 surface of the body ? Why .■' 



10. The frog has certain other responses. Try turn- 

 ing the jar or cage containing a frog around to face the 

 frog in another direction. What happens ? How do you 

 explain this response on the basis of use } What other 

 responses have you noticed t 



