THE FROG 163 



sides how they grade into each other. Is the color of the 

 lower surface the same in all frogs ? Does it change as does 

 the color of the upper surface? 



(3) Observe the frog in a sitting posture. Note the 

 position of the front limbs, and also the hind limbs. Note 

 the disposition of the toes of both front and hind feet. Ob- 

 serve the well defined hump on the back. Pass the fingers 

 down the back and see what makes the hump. Is it similar 

 to the hump on the back of a cat in a sitting posture? 



(4) Notice the general shape of the head. Is it joined 

 to a neck? Observe and describe the articulation of the head 

 with the body and the motions resulting from such articu- 

 lation. Note the position and shape of the eyes. Discuss 

 these items with reference to the safety of the animal. 

 Have the eyes eyebrows or eyelids? Touch an eye with 

 the finger or a pencil. What follows? Describe the eye 

 cover. It is called the nictitating membrane. Do other ani- 

 mals have such a membrane? Compare the frog's eye and 

 the human eye in this particular. Notice the throat, nos- 

 trils, and the sides of the body. Can you detect the process 

 of respiration? Describe the process as it appears from 

 this view. What do the movements of the nostrils and throat 

 indicate? Look over the body for indications of heart 

 action. How does it compare with your own pulse? 



(5) See the frog jump and study the process of move- 

 ment. Does it jump straight forward or at an angle? 

 Is there any advantage in this ? Is the body adapted for such 

 a movement? In what ways? Watch the swimming pro- 

 cess. How do the movements of the legs compare in the 

 two methods of locomotion ? Is the body adapted for swim- 

 ming? In what ways? 



