1 14 SPONGES 



Do you see the spicules? What seems to be their office? 

 Do you find the radial canals, or incurrent orifices extending 

 outward from the body wall? Draw one half of the sponge 

 as it appears now and show the parts studied. 



(4) Examine a slide made according to direction and 

 trace out the parts studied, i. e., the cloaca, radial tubes and 

 fleshy portion. Study the arrangement of spicules and note 

 how they are disposed about the openings. Make a large 

 drawing of the section. 



(5) The spicules mounted according to direction may 

 now be studied and the different forms noted. Note in 

 what part of the body each shaped spicule is found? Can 

 you suggest any reasons for these shapes? Draw spicules. 



The Compound Sponge (Fresh Water). — (i) Ex- 

 amine a fresh-water sponge. Note the general appearance 

 and compare with the simple sponge just studied. Is it at- 

 tached or free? Study its surface. Can you find the open- 

 ings? Of what use are they? Are they all the same size? 

 Do you think they all carry water in the same direction? 

 Explain how a simple sponge may grow into this form. Draw 

 complete form. 



(2) Is this sponge soft like the commercial sponge? 

 What causes the difference? Has it fibers or spicules? 

 Remove a small portion of it and find out the nature of 

 its framework. Study the spicules as in the simple sponge. 

 Are they siliceous or calcareous ? Why ? Draw spicules. 



(3) Observe the mottled appearance of the sponge. The 

 small round bodies are called gemmules. Where are they 

 located? Remove a few and study them under the low 

 power of the microscope. Note the shape, size and ar- 

 rangement. Do you find spicules of a peculiar nature 



