168 INTRODUCTION TO ZOOLOGY. 



An examination of the foregoing table shows us 

 what is meant by a more complex structure. In gen- 

 eral, each animal named in the table possesses the 

 positive characteristics of the several animals preced- 

 ing it and some special peculiarities of its own. 



We aj-e ready also from a study of this table to 

 make a logical definition of each branch; e.g., an 

 Arthropod is an animal that is composed of many cells, 

 has a hollow body cavitjj- and separate digestive system, 

 is bilaterally symmetrical, has specialized breathing 

 organs, jointed appendages, and an exoskeleton. 



Compare this definition with the one derived from 

 the table of resemblances on page 77. Have we 

 learned anything about the grasshopper since we 

 ceased studying it? 



GENERAL REVIEW TOPICS. 



1. Define Ontogenetic series. 



2. Define Phylogenetic series. 



3. Define Taxonomic series. 



4. What is a notochord? 



5. What is meant by homologous organs? 



6. What is meant by bilateral symmetry? 



7. What is radial symmetry? 



8. What is a parasite? 



9. How many methods of breathing have you found? 



10. What is the essential process in breathing? 



11. What is the essential organ in breathing? 



12. How many methods of locomotion have you found? 



13. What is meant by protective resemblance? 



14. What is meant by mimicry? 



15. What are warning colors? 



16. What classes of animals have no nervous system? 



17. What are vestigial organs? Give examples. 



18. What methods of escape from their enemies do 



animals employ? 



