SPONGE WEAVERS. 131 



to the living sponge consists in the minute organisms, 

 whether animal or vegetable, which are suspended 

 in the water carried down the inflowing canals. A 

 curious speculation has been indulged in by some 

 authors, whether certain forms of the spicules, which 

 enter into the composition of the flinty sponges, may 

 not be instrumental in the capture and detention of 

 little worms, and other animals, so that in fact they 

 may be devoured for the sustenance of the sponge. 

 One writer says : " I have for a long time entertained 

 the idea that these elaborate and varied forms of 

 defensive spicules, probably subserved other purposes 

 than that of the protection of the digestive surface 

 against the incursions of minute annelids, and other 

 predacious creatures. They are admirably fitted to 

 retain, and make prey of any such intruders. No 

 small animal could become entangled in the sinu- 

 osities of the interstitial cavities of sponges, thus 

 armed, without extreme injury from the numerous 

 points of these spicules, and every contortion, arising 

 from its struggles to escape from its painful and 

 dangerous entanglement, would contribute to its 

 destruction, and it may then, by its death and de- 

 composition, eventually become as instrumental to 

 the sustentation of the sponge as if actually 

 swallowed by the animal." 1 Although there is little 



1 Bowerbank's "British Spongiadce," vol. i. p. 122. 

 K 2 



