THE GENERAL ANIMAL FUNCTIONS 89 



appear differently because of their differing functions, are 

 homologous. 



1 1 6. Topics for Investigation, in Library and Field. 



1. What are the advantages and the disadvantages of divi- 

 sion of labor and differentiation? Illustrate your views very 

 fully. 



2. Illustrate the variety of foods used by different animals 

 with which you are acquainted. Classify the animals you know 

 on the basis of their food preferences. 



3. Compare the ways in which animals known to you cap- 

 ture and prepare their food for swallowing. What special 

 structures arise in connection with this function ? 



4. Do animals have any power of storing food within the 

 body for future use ? Compare with plants. 



5. Compare gills and lungs as to general form and arrange- 

 ment and see in what ways they appear to you to be suited to 

 their particular media, i.e., gills to water and lungs to the air. 

 Why might not the conditions be reversed ? 



6. What seem to you to be the comparative advantages and 

 disadvantages of the exoskeleton and endoskeleton. 



7. Devices to accomplish locomotion in animals known to the 

 student. Find as many variations as possible. 



8. Select four animals, as diverse as possible, representing 

 each of the following conditions of locomotion : through the air, 

 through the water, on the earth, and through the soil. Compare 

 the problems which each must solve, and the organs by which 

 the work is accomplished. 



9. Compare known animals as to rate of locomotion. Do 

 you find a satisfactory explanation in any case ? 



10. Let the student attempt to prove that the dog experi- 

 ences the same sensations which we have. Hold him rigidly to 

 his evidence. 



11. Report on the general differences between the eyes of 

 insects and of vertebrates, with a statement of their structure 

 and the work done by each. 



12. In what way could the statocysts possibly act as organs 



