280 UTILIZATION OF MINUTE LIFE. 



The exact time required for the growth, of the 

 rigid portion or skeleton of the sponge, and the 

 duration of this skeleton, is not known with accu- 

 racy; but it appears, from recent investigations, 

 that beds of sponges spring up and increase rapidly 

 where they were not before observed, and that a 

 period of two years is generally sufficient to renew 

 the crop of sponges on rocks that have been laid 

 almost bare by the sponge fisheries. It has also 

 been asserted that of all the numerous varieties of 

 sponge already known, that which possesses the 

 most precious qualities for the toilet grows in the 

 Mediterranean. The places where its growth is 

 most abundant are in the Grecian archipelago, the 

 coasts of Syria and those of Barbary. The sponge 

 fishery there is a profitable trade, and although 

 perfectly free, it is scarcely practised by any others 

 than the Greeks and the inhabitants of the shores 

 on which sponges grow luxuriantly. 



A strong constitution and a certain intrepidity 

 being required, the sponge fishery is almost com- 

 pletely monopolized by the Greek and Arabian 

 divers. 



The coarser varieties of sponge are brought up 

 from a comparatively slight depth, but for the soft, 

 delicate varieties it is sometimes necessary to dive 

 down thirty fathoms or more. 



As soon as they are taken from the water, the 



