NATIONAL FISHERY CONGRESS. 239 



large area might eventually be stocked. This subject lias been discussed to some 

 extent by those interested in the sponge industry, and the Tnited 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 (JO or perhaps 50 in January. 1 This differs considerably 

 from the conditions on the southern coast of Florida, as shown by the following table, 



1 Note on projects for the improvement of sponge fisheries, by Ueorge Bidder. Journal M urine 

 Biological Association of the United Kingdom, iv, No. 2, Feb., 1896. 



