170 THE FISH AND FROG 



4. Compare breathing, in the fish, in the frog, and in your own 

 body. What especial adaptation do you note ? 



5. Why do some fishes lay more eggs than others? 



6. What have life habits of fishes to do with their possible 

 extermination through overfishing? 



7. What is artificial propagation of fishes? 



8. Some kinds of fish eggs are provided with a minute drop 

 of oil in each egg. Of what use might this be in the development 

 of the egg ? 



9. Why are many more sperm cells manufactured than egg 

 cells in a cod ? Explain with reference to the egg-laying habits of 

 the fish. 



10. Name ten food fishes that are cheap in your locality ; ten 

 that are expensive. Why are they either cheap or expensive ? 



11. What are the amphibia and why are they so called? 



12. How is a frog fitted to live in water ? On land? 



13. Do fishes and frogs lay their eggs at any especial time of 

 year? Give examples. 



14. How does the development of a frog differ from that of a 

 fish? 



15. Explain the term metamorphosis. 



16. What are the chief enemies of the frog? How is it pro- 

 tected from these enemies? 



17. How may frogs and toads be useful to man ? 



18. How are the eggs protected and from what enemies ? 



19. Of what use is the yolk of an egg in development ? 



REFERENCE BOOKS 



Hunter, Civic Biology, Chap. XVI. American Book Company. 



Hunter, Elements of Biology, Chaps. XXII, XXIII. American Book Company. 



Hunter, Essentials of Biology, Chap. XXII. American Book Company. 



Bulletins of the U. S. Commission of Fish and Fisheries. (Write to the Com- 

 mission.) 



Butler, The Codfish its Place in American History. Transactions Wisconsin 

 Academy of Science, Vol. IX, p. 261, 1898. 



Green and Roosevelt, Fish Hatching and Catching. Rochester, N. Y. 



Johnstone, Conditions of Life in the Sea. G. P. Putnam's Sons. 



Jordan, Fishes. Henry Holt and Company. 



