A PRACTICAL METHOD OF SPONGE CULTURE. 565 
interfered with the welfare of the cuttings so that they were also difficult to 
keep under observation for experimental purposes. 
Owing to the encouraging early results and the apparent advantages of 
the wire suspension methods previously described, provided a suitable material 
could be obtained, work with bottom planting was suspended for several years 
but was taken up again in 1905 when it became apparent that none of the lines 
and wires previously experimented with was likely to prove satisfactory. About 
the same time a sudden disaster, due to the presence of drainage water near 
the surface on the plantation at Anclote key, made it necessary to transplant 
hurriedly the remaining sponges to the bottom in another locality. Not only 
the plantation of the Bureau of Fisheries was affected, but also that of Messrs. 
Cheyney and Bigelow, who on an adjoining site had been, for two years pre- 
ceding, conducting a similar experiment on a commercial scale. 
Bricks, rocks, and anything available were first used in the hurry to remove 
the sponges from untoward influences, but in the meantime there were being 
made a number of cement disks larger and heavier than those used during the 
first two years of the experiment. These disks (pl. Lxvim) are about ro inches in 
diameter and 114 inches thick, and are composed of a mixture of 1 part cement 
to 3 or 4 parts sand. They are molded in iron rings of the required dimensions 
laid on the sand, and two holes about 4 inches apart are made in each by thrusting 
through the cement before it hardens an iron bar three-eighths inch in diameter. 
The molds are removed as soon as the cement has set and before it hardens, 
the operation being facilitated by running a thin-bladed knife around the inside 
of the rings to break their adhesion to the disk. The disks can be made by 
this method for less than 2 cents each, including material and labor. 
For experimental work hollow triangles (pl. Lxvm) were substituted for the 
disks, six sponges being planted on each. As each triangle was marked or num- 
bered, record could be kept of the growth and behavior of the cuttings, and as 
the large triangles were less easily overlooked than the smaller disks and as each 
was planted with a definite uniform number of cuttings, the rate of mortality 
could be readily determined from time to time. 
These disks and triangles are satisfactory on rocky bottom, but tend to bury 
on sand, marl, or soft mud. They may, however, be used on bottom with a 
sparse growth of grass. When the grass is long and dense it tends to fall over 
the sponges, causing death or irregular growth. Where shifting sands and silt 
are carried by the currents these materials tend to deposit in the eddies on the 
lee side of the disks and triangles, and eventually pile up around the base of the 
sponges and killthem. To obviate this difficulty spindles were placed in some of 
the triangles (pl. Lxvi) and disks, six in each of the former and one in the latter, 
the cuttings being attached near their tops so as to prevent free flow of the currents 
beneath. These spindles project about 8 inches and various materials were tried, 
