3l6 ZOOLOGY. 



can be given them it is scarcely worth while to try to feed 

 them. They seem to do quite as well without food for a 

 reasonable length of time. 



A. The Living Animal (chiefly physiology). Record what 

 you know from observation of the animal's general haunts 

 and habits. To what extent is it a terrestrial animal? 

 Aquatic? What is the natural position when at rest? What 

 are its modes of locomotion on land? Place on the floor, and 

 test. Describe its motions in water, and the use made of the 

 parts of the body in swimming and in its other methods of 

 locomotion. Can it rest at the surface of the water? How 

 much of the body protrudes from the water? How does it 

 dive? Can you find any evidence that it does any thing to 

 increase its specific gravity when diving? 



Feed by placing living grasshoppers or flies in the vessel 

 with a frog, or by dangling a piece of meat in front of it at 

 the end of a string. Note the action of the tongue in making 

 the capture. Examine the mode of attachment of tongue, 

 and suggest its possible advantages. 



Watch the animal while floating at the surface of water or 

 out of water. Can you detect any signs of breathing? Note 

 carefully the nostrils, the cheeks and the sides of the ab- 

 domen, and determine how it gets air into its lungs. De- 

 termine what senses are represented in the frog. How 

 does it react to salines, acids, sweets, bitters? Judging from 

 the position of the eyes and from experiment, can a frog on 

 the ground see objects in all directions? Can it do so while 

 floating on the surface of the water? Are the eyes movable? 

 Can the frog see any point with both eyes at the same time? 

 Select a small frog and chloroform it until quiet, but do not 

 kill it. Wrap it in a wet cloth, and place on a support of such 

 height as will allow the web to be stretched over the opening 

 in the stage of the microscope. With the low power note the 

 pigment cells and blood vessels. Determine which are arteries 

 and which veins; present your evidences. By placing a little 

 water and a cover-glass on the web the high power may be 



