VERTEBRATES 135 



crop. If the pigeon chewed its food, would it have a crop ? 

 Why ? How does a pigeon drink ? How does the chicken 

 drink ? 



Respiration. 10. What parts move in breathing ? 



II. Compare roughly the body temperature (by touch) 

 of man, the pigeon, and the frog. Which has the highest 

 temperature 1 which the lowest 1 How can you account 

 for the higher temperature of the bird ? (Which of 

 the three must be able to endure long-sustained effort .' 

 What is the effect on your own body of long-continued 

 effort ?) 



Sense Organs. 12. Identify the eyes, ears, and nostrils, 

 and describe their location. What are the advantages in 

 having the eardrum at the bottom of a canal.? Is there 

 any disadvantage } What is the probable function of the 

 inner thin eyelid .' How does it work } 



1 3. Investigate the power of response of the special 

 senses. Which seems to be the most alert } State the 

 experiments which you used and your reasons for your 

 answers to this question. Which senses are most service- 

 able in finding food .■' in protecting against enemies .' 



Protection. 14. In what different ways are feathers 

 protective to the bird.? Study the arrangement of the 

 feathers to find how protection is increased in this way. 

 How do the feathers and parts of feathers which lie next 

 the body differ from those which are on the outer surface 1 

 What parts of the body are unprotected by feathers 1 How 

 are these protected, if at all .' 



15. Note the flexibility of the neck. Through what 

 part of the arc of a circle can the pigeon turn its head .' 

 How is this especially important to birds ? 



16. What means of defense has the pigeon when 

 attacked .' 



