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 ampullae); 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 larvae, 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 200 unreg- 
istered vessels and boats are employed in the fishery, which, with their outfit, are 
worth about 8260,000, and are manned by upward of 1,400 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 306,070 pounds of 
sponges, of which the first value was $386,871. In 1896 the catch, as represented by 
the purchases of the wholesale buyers, who handled practically the entire output, was 
234,111 pounds, having a value of $273,012. In 1897 the product was 331,546 pounds, 
valued at $28 1, 640. 
The quantity and value of the yield of the different grades in each of the three 
years named are shown in the following table. This information is compiled from the 
