620 IMPROVEMENT OF LIVING THINGS BY MAN 



greater than are the young of lower animals which produce many 

 eggs but take no care of them. 



Practical Exercise 8. Make a series of colored diagrams for your workbook 



to show stages in development in (1) fish, (2) frog, (3) bird, (4) mammal. Use 

 the same colors in each series to show the same parts. Get help from as many 

 sources as you can. 



What would you say were the outstanding differences in development in the 

 groups just mentioned? 



Self-Testing Exercises 

 Check the correct statements for your workbook. 



T. F. 1. Cells grow in size in order to have more food-absorbing 

 surface. 



T. F. 2. Starfish and earthworms regenerate lost parts. 



T. F. 3. Vegetative propagation means producing new plants 

 from parts of others. 



Grafting and budding are examples of sexual repro- 



If we have an arm amputated, we will regenerate another 



Sexual reproduction involves the fusion of eggs and 



An ovule is an egg cell. 



Birds reproduce asexually as well as sexually. 



All animals are produced from eggs and sperms. 



The endoderm is the outer layer of a developing animal. 



The lower the animal the more eggs are produced. 



Mammals' eggs develop within the body of the mother. 



PROBLEM III. WHAT ARE THE LAWS OF HEREDITY? 



Heredity and the work of Gregor Mendel. By far the most 

 important discovery for the plant and animal breeder was made by 

 Gregor Mendel, the abbot of a monastery at Brunn, in what 

 is now Czechoslovakia. About 1865, Mendel bred peas in his 

 monastery garden and found that certain characters, such as color 

 of seeds, color of flowers, smooth and wrinkled coats, and other 

 characters, are inheritable. Then he began a long series of experi- 

 ments in which he crossed or hybridized peas having some of these 



T.F. 



4. 



duction. 





T.F. 



5. 



one. 





T.F. 



6. 



sperms. 





T.F. 



7. 



T.F. 



8. 



T.F. 



9. 



T.F. 



10. 



T.F. 



11. 



T.F. 



12, 



