150 UNIT AND DIVISION OF LABOR 



4. Which one is the better organized, and therefore the 

 higher animal ? Reasons for your answer ? 



Questions 



1. Where are the sponge cells in an ordinary commercial 

 sponge ? 



2. How are toilet sponges prepared for the market ? 



3. How and where are toilet sponges obtained ? 



4. How do the individual sponge cells get their food and 

 oxygen ? 



5. How does a sponge show division of labor ? 



6. Where are the most important sponge fisheries ? 



7. Tell, step by step, how a fertilized sponge egg becomes 

 a blastula, then a gastrula, and finally a stationary sponge. 



8. Show how there is division of labor in a hydra. 



9. What are the functions common to all animals ? 

 10. What is the cell theory ? 



Special Reports 



1. The sponge industry. 



2. The development of Metazoa to the gastrula stage. 



3. Division of labor in a metazoan. 



4. The cell theory of Schleiden and Schwann. 



References 



Hunter, Essentials of Biology. Chap. XVI. 



Elements of Biology. Chap. XIV. 



Potts, E. Fre.sh-wat&r Sponges, 



Miner, R. W., A Guide to the Sponge Alcove. Guide Leaflet 23, 

 American Museum of Natural History, New York, October, 1906. 



Moore, " A Practical Method of Sponge Culture." Bureau of Fisheries. 

 Document 669, 1910. 



Jordan, Foot-Notes to Evolution. 



