14 ECONOMIC ZOOLOGY 



have become scarcer prices have advanced, so that even if a vessel does not 

 secure as large a quantity in a given time as formerly the financial result is 

 about the same. 



" Several varieties of sponges are caught in Florida waters. They are 

 first, sheep's wool, which sell for $2 to $5 a pound; second, yellow 

 sponges, which sell for 50 to 60 cents a pound; and third, grass sponges, which 

 are coarse in texture and not durable, and sell for 15 to 25 cents per pound. 

 Other coarse grades are boat and glove sponges. When these are marketed 

 they are cleaned of sand and shells, and then pressed into small bales of 

 100 to 120 pounds each, in which form they go to the wholesale dealers. 

 The yellow sponge especially is subjected to a bleaching process to improve 

 the color, but the process ordinarily employed greatly weakens the fibre. 



" Owing to the rapidly decreasing supply of the finer grades and the 

 rising price the problem of propagating sponges artificially has been taken 

 up seriously by the United States Bureau of Fisheries. It has been 

 found that sponges may be raised successfully both from the egg and from 

 cuttings but, owing to the much shorter time required for the latter to reach a 

 marketable size, the first method has been abandoned. The technical prob- 

 lems of sponge raising have been largely solved and there is every promise 

 that .their culture on a commercial scale can be undertaken in the near future, 

 and that the depleted grounds will be restocked. 



"In 1900 the Florida sponge fisheries employed 2225 persons, with 156 

 vessels and other apparatus valued at $594,598. The product aggregated 

 418,125 pounds of all kinds of commercial sponges, which sold for $567,685. 

 To this total sheep wool sponges contributed 181,131 pounds, valued at 

 $483,263 "(36). 



Besides the above, sponges are of economic importance in that the 

 silicious spicules of some species form large flint deposits. Negatively, 

 certain sponges are of economic importance because of their destruc- 

 tiveness to oyster beds, either by smothering the oysters or by boring 

 (certain "Boring Sponges" have this curious power) through their 

 shells and thus destroying them. 



