NATIONAL FISHERY CONGRESS. 
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large area might eventually be stocked. This subject has been discussed to some 
extent by those interested in the sponge industry, and the United States Fish Com- 
mission has been urged to make the experiment. The transplanting of Mediterranean 
sponges to the Bahamas has also been under consideration in Great Britain. 1 
The transportation of Mediterranean sponges to this country would involve 
difficulties which readily suggest themselves. There seems little doubt, however, 
that the project would be practicable by the use on the transporting vessel of tanks 
in which water could be kept aerated and of a suitable temperature. 
If the acclimatization of Mediterranean sponges in Florida waters were accom- 
plished the ultimate results of the experiment would still be problematical. It is a 
question whether, under the changed and less favorable environment, the introduced 
sponges would retain their superiority, or at least exhibit it in their offspring. Mr. 
Bidder states that the calcareous sponges exhibit a remarkable susceptibility to 
changes in environment, and thinks it not impossible that the progeny of the imported 
sponges would be similar in quality to the native sponges. The experiment is, 
however, worthy of the attempt. 
There is a remarkable similarity between the marketable sponges of Europe and 
those of America. Hyatt thinks it evident that the Mediterranean sponges originated 
in the Caribbean Sea. The three leading American species (sheepswool, yellow, and 
glove) correspond respectively with the leading sponges of Europe (horse, Zimocca, 
and bath). 
As to the cause of the superiority of the best Mediterranean sponges over our 
native sponges, there is some diversity of opinion, and different factors probably 
have their influence. An eminent American authority in considering this question 
expresses the opinion that the superiority may be due in part to the greater depth at 
which the Mediterranean sponges are taken, the deeper water being of better quality 
than the shallower, because freer from sediment, which is detrimental to the growth 
of the finest grades of sponge. Milky water (i. e., water made opaque by sediment) 
is incompatible with the best quality of sponge. While the coral reefs of the Florida 
coast, as in the Mediterranean, furnish excellent material for the attachment of 
sponges, the reefs in our own country are more exposed than in the Mediterranean, 
and large quantities of limy sediment are washed from them by the waves, a condition 
which does not exist to a conspicuous degree in the Mediterranean, where the coarsest 
species of sponges are found at those depths and in those situations exposed to the 
injurious influence of suspended matter. In the case of different grades of the same 
sponge the coarsest are in the shallower water. Coarseness consists in the greater 
stiffness and harshness of the skeleton, and is usually associated with a looser or more 
open structure — that is, a greater number of canals. It is this latter feature that is 
perhaps the most constant difference between the best Mediterranean sponges and the 
best Florida sponges. 
The finest Mediterranean sponges grow in water having a surface temperature in 
winter of 50° to 57°, the mean air temperature at that season being from 63° to 70°. 
The sponges which occur in deeper water off' the coast probably are not exposed to a 
colder temperature than 60° or perhaps 50° in January. 1 This differs considerably 
from the conditions on the southern coast of Florida, as shown by the following table, 
‘Note on projects for the improvement of sponge fisheries, by George Bidder. Journal Marine 
Biological Association of the United Kingdom, iv, No. 2, Feb., 1896. 
