EXERCISES 521 



3. Circulation, as pertaining both to the nature of circulat- 

 ing fluid and to the organs moving it; the relation of the whole 

 process to the organs and function of digestion and respira- 

 tion in the types chosen. 



4. Respiration: the medium containing the oxygen, and the 

 contrivances for securing it. 



5. Excretion: note and classify the chief modes of elimin- 

 ating waste materials observed in the animal phyla. 



6. The body cavity (ccelom) in relation to digestion, cir- 

 culation and excretion. 



7. Physical support and protection (skeletal structures); 

 their position, structure, and mode of formation. 



8. Motion and locomotion: degree of each; relation of the 

 muscular or contractile elements to the skeletal. The medium 

 used in locomotion; the principal special devices in each group 

 for the solution of the problems presented by the medium. 



9. Sensitiveness: the kinds of stimuli to which the organ- 

 isms in the various groups react; the differences in the differ- 

 ent phyla in each of the various classes of sense organs, as to 

 structure, position, and manner of action; the number, position 

 and perfection of the nerve centres; and the relation of the 

 nerve centres to the sense organs and to the muscles. 



10. Reproduction. The various methods, and the special 

 ends accomplished by each; rate; number of offspring; paren- 

 tal care; sex dimorphism; alternation of generation; partheno- 

 genesis. 



III. Ecology and Adaptations to the Environment. Com- 

 pare the animal groups from the following points of view. 



1. General habitat: aquatic, fresh or salt water; terrestrial; 

 aerial. 



2. Migration or other special means of effecting distribution 

 from the point of origin. 



3. Degree of connection, organic or social, between the in- 

 dividuals of a species; gregarious, social and communal life; 

 resulting social qualities; degree of division of labor; poly- 

 morphism. 



4. Power of regenerating lost parts. 



5. Growth; rate, and ultimate size; longevity. Special 

 hindrances to growth. 



