CGELENTERATES. 



THE FRESH-WATER SPONGE. 



(Myenia fluviatilis.) 



Study of Live Specimens. Examine fresh specimens. 1 

 Note: 



1. Their form. 



2. Their attachment: upon what kind of surfaces they 



are found growing. 



3. Their color. 



4. Their odor, pecul- 

 iar, not unpleasant in 

 life, but rapidly becom- 

 ing very disagreeable if 

 any specimens have died. 

 This rapid decomposi- 

 tion of the sponge flesh 

 betrays its animal na- 

 ture. 



Examine the surface 

 of the sponge with a 



SPICULES OF FRESH-WATER SPONGE (My- d leng t find th t 



enia fluviatilis) : a, skeleton spicules ; & 



the others, gemmule spicules seen sidewise oles (or exlialent open- 

 at 6 and d, endwise at c and e. Qut of 



life, currents of water are continually flowing. 



Examine it still more closely to find the minute but 

 multitudinous pores (or inhalent openings) which cover 



1 Directions for collecting are given in Appendix, p. 279. 

 22 



