114 WORMS, MOSS-POLVPS, SPONGES, ETC. 



SPONQES. 

 Among the lowest forms of life that drift to our 

 shores are sponges of one kind or another, many 

 of them, doubtless, wafted northward on the cur- 

 rent of the Gulf Stream, and then distributed by 

 local storms. Some of these are of the horny 

 character seen in the ordinary sponge of commerce, 

 but usually they are of a much looser texture, and 

 with a distinct disposition to branch. In the living 

 condition of the animal this fibrous mass is envel- 

 oped in a soft jelly-like substance, frequently most 

 brilliantly colored in tints of yellow, brown, and 

 red, which constitutes the active or vitalized mat- 

 ter of the organism, the horny fibres themselves 

 being merely an accessory in the way of an internal 

 support or skeleton. The entire mass is then per- 

 meated by inmjmerable canals, into which the sea- 

 water gains access by a multitude of external pores, 

 and from which it is expelled into a number of 

 larger channels, into which the canalulse open, 

 and thence into the open sea again. A series of 

 perpetual circulations is thus kept up within the 

 substance of the animal, the cilia lining the chan- 

 nels helping along the water, and with it the 

 microscopic food-particles that may be contained 

 therein. The excurrent orifices (oseula) are of 

 much larger size than the incurrent pores, and are 

 frequently situated, crater-like, on special emi- 

 nences. In our ordinary wash-sponges their posi- 

 tions are clearly indicated in the larger spaces left 

 on the surface between the fibres. 



