PORIFERA 395 



6. Heredity. — How would you define heredity, and what evidence do 

 you see of it in the Protozoa f 



7. Which do you consider the more important factor in the hves of ani- 

 mals, heredity or environment? Which factor or force do you consider 

 the stronger one in their existence? Why? 



8. Mind (p. 8). — Do you see any evidence of mind in Protozoa? 



9. Multiplication. — Give examples, from the text, of multiplication, 

 asexual and by conjugation in Protozoa. 



10. Colonial Protozoa. — Gonium, for example, has "a group of sixteen 

 cells, each cell a complete perfect animal capable of living independently, 

 but all holding together to form a tiny, flat colony" (Jordan). What 

 is the difference between a colony and an individual, for example, 

 a bee? 



11. Whether the animal body is one celled, as in Atneha, a colony of cells, 

 as in Gonium, or many celled, as in the higher forms, does not the living 

 protoplasm of Protozoa foreshadow the animal world, with all its com- 

 plexity of body and animal behavior? (Mind, p. 8.) 



12. Show clearly that the Ameha is the hmit of simphcity for an animal in 

 body and behavior (Mind, p. 8), but that it has all the essential .elements, 

 or is potentially all that any of the higher forms are as to animal body and 

 animal behavior. 



PORIFERA 



1. Body, many celled. The plan of arrangement of these many cells 

 is in layers around a hollow center. Hence, sponges and the following 

 branch, Coelenterata, are sometimes called "hollow animals." See Fig. 4. 



2. Symmetry of .sponge body? Body layers? (p. 10). Body differen- 

 tiation? (p. 10). 



3. Discuss increasing complexity of body structure of sponges over that 

 of the protozoan body. 



4. Compare the threefold .struggle for existence and the fivefold en- 

 vironment of Porifera and Protozoa. Which branch shows the better 

 preparedness for existence? Wh}'? 



5. Behavior of Sponges (p. 8, Mind). — Do you discover any increasing 

 complexity (advance) in mind in sponges over mind in protozoans? Would 

 increasing body complexity necessitate more mind manifestations? 



C. Discuss variation in shape, size, color, structure, and use of 

 sponges. 



7. Economic use of sponges to other animals and to man. See "Har- 

 vesting Sponges," pp. 14, 1.5. 



8. Skeleton. — Comment on structure and advance over that of proto- 

 zoans. 



9. Name some enemies of sponges. Why enemies? 



