248 A STUDY OF VERTEBRATES 



ished by milk furnished by the mother until they are able to take 

 other food. Thus we see as we go higher in the scale of life fewer 

 eggs formed, but those few eggs are more carefully protected and 

 cared for by the parents. The chances of their growth into adults 

 are much greater than in the cases when many eggs are produced. 



REFERENCE BOOKS 



ELEMENTARY 



Hunter, Laboratory Problems in Civic Biology. American Book Company. 



Bigelow, Introduction to Biology. The Macmillan Company. 



Cornell Nature Study Leaflets. Bulletins XVI, XVII. 



Davison, Practical Zoology, pages 185-199. American Book Company. 



Hodge, Nature Study and Life, Chaps. XVI, XVII. Ginn and Company. 



Sharpe, Laboratory Manual, pp. 195, 204-209. American Book Company. 



ADVANCED 



Dickinson, The Frog Book. Doubleday, Page and Company. 



Holmes, The Biology of the Frog. The Macmillan Company 



Jordan, Fishes. Henry Holt and Company. 



Morgan, The Development of the Frog's Egg. The Macmillan Company. 



Needham, General Biology. Cornstalk Publishing Company. 



