7s SPOXGES 
HABITS OF FLESHY SPONGES. 
These spouges grow attached to rocks, often spreading completely over 
them. They appear to propagate partly by bads which are hable to appear 
on any portion of the sponge. When hving and undisturbed, they are very 
soft and compressible, but shrink very perceptibly wpon being handled, and 
then become hard and rigid. In fife, the excurrent ortfi¢es are plainly visible, 
Fig. 39, 
A. section of Spiculigenous Sponge, 
life size. B, single spicule of same 
greatly enlarged. Cand D, spic- 
ules of Fresh Water Sponge. 
: ge 4 Bie 
appearing as round openings, each surrounded by a mound-like clevatiatt, 
These close so completely that all traces of them are lost when the specimens 
are placed in formalin. 
