84 REPORT OF THE COMMISSIONER OF FISHERIES. 



may be expected to occur. A .small ridge or mound ma3^ in some cases 

 be a satisfactory preliminary plant. If there is an area in Pamlico 

 Sound where a set will not occur it will be encouraging- to know this. 

 On the other hand, if an area should be found where spat will not set, 

 a rare opportunity will thus be discovered for interesting experiments 

 to throw light on important open questions concerning the distance of 

 setting place from birthplace of an oyster, and the value of placing a 

 few spawning oysters in a bed. 



EXPERIMENTS IN SPONGE CULTURE. 



The experiments in sponge culture which this Bureau has been con- 

 ducting for several years, and references to which have been made in 

 previous reports, have been continued during the present year under 

 the direction of Dr. H. F. Moore. The general methods followed 

 have not diverged materially from those employed during the past two 

 years. The sponges are cut into pieces about 1 inch square and 2 

 inches long, with a slit about 1 inch deep in a plane parallel to one of 

 the long sides of the cutting. The slit is placed astride of the wire or 

 line used for a support, and the two faces are bound closely together, 

 with the result that they eventually fuse into an organic whole sur- 

 rounding and closely embracing the line. 



The experiments of the present year have been directed mainly to 

 testing various materials for the supporting wires, which are festooned 

 between stakes planted in the bottom about 25 to 30 feet apart, with 

 the cuttings distributed along them at intervals of about 1 foot. The 

 experience of the preceding fiscal year demonstrated that though the 

 organic adhesion of the young sponge to its support was not essential, 

 it was of very material advantage. When organic attachment does 

 not take place, there is always the liability that the sponges will become 

 loose, owing to the corrosion or loosening of the short lengths of wires 

 by which they are secured to the main supporting wires. When this 

 takes place, it necessitates refastening, otherwise the sponge rotates 

 under the action of the waves, becomes abraded at its point of attach- 

 ment, and if inverted undergoes the necessity of an entire readjust- 

 ment of its circulatory canal system. An inverted sponge tends to 

 reverse the direction of the internal water currents by which it feeds, 

 breathes, and excretes, the original oscula, or openings for the escape 

 of the water, closing up and new ones being formed on the new upper 

 surface. While this is going on, the sponge is apparently at a dis- 

 advantage in the performance of its functions, and there is a retarda- 

 tion of growth. 



Any arrangement, then, which will obviate the expense of refas- 

 tening and insure the maintenance of the cutting's original orientation 

 with respect to its support and to the horizontal, is a distinct advantage. 

 Previous experience had shown that lead possessed this property, but 



