226 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



siliceous matter in greater or less numbers and having a variety of forms. The fibers 

 consist of a network of fibrils whose softness and elasticity determine the commercial 

 quality of a given sponge. The horny framework is perforated externally by very 

 many minute pores and by a less number of larger openings. These are parts of an 

 interesting double-canal system, an external and an internal, or a centripetal and a 

 centrifugal. 



At the smaller openings on the sponge surface, channels begin which lead into 

 dilated spaces (sacs or ampulla;); in these, in turn, channels arise which eventually 

 terminate in the large openings (craters or oscula). Through these channels or canals 

 definite currents are constantly maintained which are essential to the existence of the 

 sponge. The currents enter through the small apertures and emerge through the 

 large ones. 



The active part of the sponge that is, the part concerned in nutrition and growth- 

 is a soft, fleshy mass partly filling the meshes and lining the canals. It consists largely 

 of cells having different functions some concerned in the formation of the framework, 

 some in digestion, some in reproduction. Lining the dilated spaces into which the 

 afferent canals lead are cells surmounted by whip like processes (cilia); the motion of 

 these processes produces and maintains the water currents, which carry the minute 

 food products to the digestive cells in the same cavities. 



Sponges multiply by the union of sexual products, certain cells of the fleshy pulp 

 assuming the character of ova and others that of spermatozoa. Fertilization takes 

 place within the sponge. The fertilized eggs, which should now be called larva 1 , pass 

 out with the currents of water; and, being provided with cilia, swim actively for a 

 while, like larval oysters. In a comparatively short time, probably in 24 to 48 hours, 

 they settle and become attached to some suitable surface, where they in time develop 

 into mature sponges. 



THE FLORIDA COMMERCIAL SPONGES. 



The merchantable sponges of the waters of Florida fall under five heads the 

 sheepswool or "wool" sponge, the velvet sponge, the grass sponges (two species), the 

 yellow sponge, and the glove sponge. Numerous varieties have been described by 

 naturalists and many grades are recognized by dealers, but all are included in the 

 foregoing designations. 



The principal center of the industry is Key West, where more than seven-eighths 

 of the business is carried on. Other places at which sponges are landed are Apalachi- 

 cola, St. Marks, and Tarpon Springs. About 100 registered vessels and L'OO unreg- 

 istered vessels and boats are employed in the fishery, which, with their outfit, are 

 worth about 821)0,000, and are manned by upward of 1,100 fishermen. 



Sponges are by far the most important of the fishery products of Florida, repre- 

 senting about one-third of the annual value of the fishing industry. 



In the calendar year 1895 the Florida sponge .fishery yielded 300,070 pounds of 

 sponges, of which the first value was $380,871. In 18% the catch, as represented by 

 the purchases of the wholesale buyers, who handled practically the entire output, was 

 234,1 11 pounds, having a value of $273,012. In 1897 the product was 331,540 pounds, 

 valued at $28 1,640. 



The quantity and value of the yield of the different grades in each of the tlm-e 

 years named are shown in the following table. This information is compiled from the 



