408 BULLETIN OF THE BUREAU OF FISHERIES. 
of artificial bleaching. Sponges of the same species will frequently differ in 
color in different localities. The sheepswool of the Florida Keys, for instance, 
has a deep reddish brown ‘‘root” and interior, while this is lacking in Rock 
Island specimens, and the latter are also more grayish externally. As these 
color characteristics are correlated with differences in other qualities, especially 
durability, they are of value in distinguishing the grades. In general the 
sponges of commerce, i. e., the skeletons, are yellow, light brown, or brownish 
gray. 
Size and shape-—The most desirable size and to some extent the shape 
depend upon the purpose to which the sponges are to be put. For surgical 
purposes small ones are required, for toilet use a medium size, while for clean- 
ing vehicles and cars a large sponge holding a considerable quantity of water 
is necessary. Sponges up to about 8 inches in diameter are commonly used 
entire and called “forms,” but above that size they are usually cut into pieces 
and known commercially as ‘“‘cuts.”” Most or all American sponges of a less 
diameter than 4% to 5 inches are of comparatively little use and value, but 
the Mediterranean grades find a market in even the smallest sizes. Some 
species possessing all the other requisites are debarred from the markets solely 
by their shape. 
Whatever the form of a sponge, to be of commercial value it must be regu- 
lar, moreor less massive, and free from long processes and digitations. Certain 
of the inferior Cuban sheepswool sponges are about the only exception to this 
rule, and in the case of these the long, teat-like projections which carry the 
oscula at their summits are usually cut off more or less close to the massive 
base from which they rise. Under normal conditions all commercial sponges 
are either spheroidal, cake shaped, conical, or cupped. The gradations between 
these shapes are infinite and each species presents great variety, due to age, 
environment, and perhaps individual tendency. ‘The shapes assumed by the 
various species will be considered in the descriptions of the several commercial 
varieties. 
For general purposes the most desirable forms are the spheroidal and cake 
shaped. In applying the glaze to pottery, however, and in other similar werk, 
a smooth, flat surface is desired, and this is generally obtained either by cutting 
up the more massive forms or by taking pieces from a smooth-surfaced cup- 
shaped sponge like the Mediterranean elephant’s ear. The American rough- 
surfaced conical and cup-shaped sponges, like the Anclote grass, are usually 
cut, invariably so when they are of large size. 
Softness.—The more desirable grades of sponges, other things being equal, 
are those which are softest, the cheaper, inferior grades being generally, though 
not always, more or less harsh. This quality depends upon the thickness and 
arrangement of the fibers, the amount of foreign matter included in them, and 
