SPONGES 97 
Note differences in elasticity between Commercial 
Sponges and the other forms of Horny Sponges. 
Compare a fine Mediterranean Sponge with an Ameri- 
can Commercial Sponge. 
Note spicules in the specimens and magnified in the 
slide. Show that they are hollow. 
What is the use of spicules? (See habits of Spiculig- 
enous Sponges. 
Notice water system of Spiculigenous Sponge, (page 
63 and 64) and compare with that of Horny Sponge. See 
section of Finger Sponge. 
Note horny fiber inthis and other forms of semr-sili- 
’ 
cious Sponges. 
See fiber in section of Gray Cup Sponge. See Green 
Cup Sponge, Purple Sponge, note color. See section of 
Creeping Sponge with fine fiber. 
Show Fresh Water Silicious Sponge. Note spicules 
as magnified in slide. Make drawings of these spicules. 
Show Limy Sponge, test with acid, then test Fresh 
Water Sponge and note results. 
Show Fleshy Spenge in alcohol; show by section 
