STRUCTURE OF SPONGES. 169 



water. Most of the species are unfit for that pur- 

 pose ; they are very numerous, and appear to inhabit 

 indifferently every sea, being more abundant, how- 

 ever, near the equator. 



The Ked Sea, the coasts of Syria, the seas of 

 America, the Middle Atlantic, and the Southern Seas, 

 are rich in sponges capable of serving for domestic 

 purposes. 



Sponges are torn from the rocks to which they are 

 attached by divers, who pursue their trade more par- 

 ticularly in the seas of Asia. Should we not feel 

 astonished by the low price at which they can be 

 sold, when we reflect that every sponge collected in 

 the submarine forest has been gathered at the risk ot 

 death to one of these unfortunate men, to whom ]i c 

 is nothing but one long agony ? 



At certain periods of the year certain ovoid or 

 spherical corpuscles are developed in the spongy 

 mass, and thence pass into the channels with which 

 the sponge is pierced. Carried out into tlie sea by 

 the currents of water which circulate in these chan- 

 nels, they propagate the sponge in the manner de- 

 scribed above. 



When the spongy mass, for any reason whatever, 

 decays or breaks up, the spiculse are scattered upon 

 the bottom. In some seas, such as the Indian Ocean, 

 the sea of coral, the specimens of the bottom, taken 



