568 BULLETIN OF THE BUREAU OF FISHERIES. 
efficiency with which he works. The attachment of sponges to the disks by 
means of wires is slow under the best conditions and must be much slower 
under water where work is done at a disadvantage, but the cuttings can be 
slipped on to the spindles as readily under water as in the air. 
The same considerations apply to cuttings planted on long spindles (pl. Lxvm) 
which will hold them above the bottom and in deep water. Especially in a 
locality requiring the transport of the disks or triangles for considerable dis- 
tances, the second planting can be carried on more economically than the first. 
Holes should be punched in the disks, however, even when spindles are used, 
so that a wire attachment can be employed should the spindle eventually be 
broken off. 
The density with which sponges can be planted on the bottom in any 
given locality is a subject which will require actual experiment on a commercial 
scale for its elucidation. That ordinary waters will support a dense growth of 
miscellaneous sponges is well known, and among the Florida keys I have 
observed an average of several to a square yard over considerable areas. 
Though nothing is known of the actual facts concerning the food of sponges, 
it can hardly be doubted that all horny sponges feed on essentially similar 
material. If this be true, it is fair to assume that an area which will support 
a large number of useless horny sponges should support and produce an equal 
volume of the commercial kinds. Unfortunately the shoal-water beds of our 
coast are now so depleted that present day observations are useless and the 
distribution of the valuable kinds on the deep water grounds is so unequal, 
owing to the irregular and sporadic occurrence of suitable bottom, that nothing 
definite can be learned. I am informed by Dr. H. M. Smith, however, that 
in very shoal waters in the Philippine Islands he has seen commercial sponges 
somewhat similar to the Florida grass sponge averaging one to every square 
foot of the bottom over areas many acres in extent. The commercial experi- 
ment carried on at Anclote Key by Messrs. Cheyney and Bigelow showed that, 
even in an unfortunately selected locality, cuttings would grow rapidly when 
planted with a density of about one per square yard over an area of about 15 
acres, and that the growth was no less satisfactory than upon the government’s 
neighboring plantation covering but a few acres. In no case, on any of the 
plantations under observation, did the density of planting, up to a maximum 
of a little over one sponge per square yard, have any apparent effect upon the 
rate of growth. In bottom planting on a small scale sponges have been planted 
in some cases as densely as 5 or 6 per square yard without apparent bad effect, 
but with extensive areas so thickly planted it is possible that there might be 
an insufficiency of food. Experiments in Biscayne Bay appear to indicate that 
sponges grow more rapidly in strong currents, and presumably the same con- 
dition would permit denser planting than where the currents are weak. 
