84 REPORT OF THE COMMISSIONER OF FISHERIES. 
may be expected to occur. A small ridge or mound may 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 these 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 
