REt>OtlT OF OOMMISSIONeR OF FISPI AND FISHERIES. 167 



Edible Mollusks. 



Mr. K. Ct. Harrison and Mr. J. L. Kellogg, of Jolms Hopkins Uni- 

 versity, were employed at the Woods Holl laboratory during tlie sum- 

 mer of 1890, under the direction of Prof. W. K. Brooks, to investigate 

 certain natural-history problems relative to the oyster and other edible 

 mollusks, and bearing upon their artificial cultivation. They worked 

 conjointly on the embryology of the oyster, and made experiments re- 

 specting the elBfects of density, temperature, sunshine, etc., on the oyster 

 larva during its free-swimming and lixative stages. Tbey also collected 

 material for a study of the trematode parasites of the oyster and other 

 bivalves. Dr. Brooks having been led to believe that these organisms 

 may have been instrumental in causing the deterioration of oyster beds 

 in some cases. The general investigation of the anatomy, histology, 

 and embryology of lamellibranchs was taken up by Mr. Kellogg and 

 was conducted by him in accordance with modern methods of biological 

 research. It is expected that these inquiries will furnish many imiior- 

 tant facts regarding the mori)hology of the common edible bivalves which 

 will be of service to the fish-culturist. They will be continued during 

 the summer of 1891. Dr. Wilson has also, during his investigations at 

 Woods Holl, recor<led many valuable observations respecting the breed- 

 ing habits and organs of the long clam, quahog, mussel, and scallo}). 



Sponges. 



Preliminary to a study of the life history of the Florida com^ner- 

 cial sponges, which it is intended shall soon be taken up, Dr. H. V. 

 Wilson began at Woods Holl, in the summer of 1890, an investi- 

 gation of the breeding habits of certain species occurring in that vi- 

 cinity. His observations were continued during the following winter 

 and spring, most attention being paid to a silicious form which is com- 

 mon on the wharf at the Fish Commission station. Dr. Wilson found 

 that during tlie summer and early fall this species, instead of reproduc- 

 ing by means of eggs, does so asexually through the formation of in- 

 ternal buds or gemmnles, solid oval bodies which swim about by means 

 of cilia. Similar means of reproduction have l)een detected in the 

 fresh- water sponges and in the genus Chalinula. The formation of 

 these gemmnles in the silicious species referred to, the character of the 

 swimming larvai, and its metamorphosis into the adult sponge, were 

 carefully studied by Dr. Wilson, who, judging also from observations 

 made at the Bahama Islands, is led to believe that this method of 

 propagation is common among marine sponges. Should this hold true 

 with tlie commercial species, three possible methods of accomplishing 

 their artificial cultivation would thereby be presented, namely, by 

 means of the eggs, by means of the gemmules, and by cuttings. All 

 the practical experiments made in this direction uj) to the present time 

 have dealt only with the cuttings, and while that method may still 

 prove to be the more satisfactory one, the others might present certain 

 advantages i*n any attempt to improve the grade of sponges or to dis- 

 tribute them over new grounds. 



