VERTEBRATES 117 



Questions. 



1. Describe the probable action of the frog's tongue in 

 catching a bug. 



2. What advantage can you ascribe to the peculiar 

 mode of attachment of the tongue ? 



3. Of what use is the notch in the inner end of the 

 tongue ? (Note its position when the tongue lies at rest 

 in the mouth.) 



4. If the frog chewed its food, how would the existing 

 structure of the nostrils be very inconvenient .' 



5. Recall either the frog's habit of feeding or the 

 structure of the nostrils. Do you think the nostrils are of 

 much service in smelling .? State the reason for your answer. 



6. Of what use are the vocal cords and why are they so 

 muscular ? Consider their use in sound making and also 

 their condition during swallowing. 



7. Of what use are the teeth .' Recall the form and use 

 of the fish's teeth. 



Suggested drawings. 



a. The mouth, wide open and with tongue extended. 



b. A diagram showing the path of air and of food 

 through the frog's mouth. 



The Organs of Digestion, Absorption, and Excretion 



Materials. 



Freshly killed or preserved frogs in dishes or shallow 

 pans of water, forceps, and, if the pupil is to do any dis- 

 secting, scissors. 



Directions and Observations. 



The specimens may have been opened by the teacher, or 

 may be dissected by the pupil as follows : — 



