QUESTIONS AND SUGGESTIONS 291 



parts of the mother organism, through which the developing em- 

 bryos are fed. In the case of many plants, ducts and sieve tubes 

 pass through the placenta and through the seed stalk and thus 

 carry nourishment to the seed. In the case of mammals, the 

 blood vessels of the embryo extend into the placenta through 

 a cordlike structure somewhat similar to the seed stalk. 



QUESTIONS AND SUGGESTIONS 



1. Name three differences between seeds and eggs. 



2. Describe the spawning of frogs. 



3. Give the following facts concerning the reproduction of the frog : 

 reproductive organs, the names of reproductive gametes, where ferti- 

 lization takes place (use the word external or internal), where the 

 organism develops, and the food of the developing embryo. 



4. Discuss the complete development of the frog embryo. 



5. Name the germ layers of the embryo and state the organs devel- 

 oping from each layer. 



6. Using the outline headings given in question 3, fill in the out- 

 line for a flower, bird, and mammal. 



SUPPLEMENTARY READINGS 



Atwood, Wm. H., and Heiss, El wood D., Educational Biology (P. Blakiston's 



Son & Co.). 



Haupt, Arthur W., Fundamentals of Biology (McGraw-Hill Book Co.). 

 Holmes, S. J., General Biology (Harcourt, Brace & Co.). 

 Jewett, F. G., The Next Generation (Ginn and Co.). 

 Scott, George G., The Science of Biology (T. Y. Crowell Co.). 

 Wiggam, A. E., Fruit of the Family Tree (Bobbs-Merrill Co.). 



