6 How do the similarities found among the vertebrates in the early stages 

 compare with those found in adult stages? 



7 What theories can explain the presence of useless structures within the 

 bodies of living things? Which explanations agree best with established facts and 

 most widely accepted assumptions? 



8 How can we account for the fact that forms living today are different 

 from their predecessors? 



9 How did Lamarck explain the origin of new species? What support is 

 there for his explanation ? What are its limitations ? 



10 How did Darwin explain the origin of new species? Upon what observ- 

 able facts was his explanation based? What support is there for his explanation? 

 What are its limitations? 



471 



