A PRACTICAL METHOD OF SPONGE CULTURE. 573 
banks covered with vegetation, while at Soldier Key the bottom consists of 
clean rock, the adjoining banks are sandy, and the current is probably less rapid, 
though of the latter Iam not certain. The difference in the rate of growth may 
be due to the strength of the current or to the larger amount of food in the 
waters adjacent to marine vegetation. That the latter is the probable reason 
is indicated by recent observations that sponges planted on bottom covered by 
short grass at Soldier Key exhibit a more rapid rate of growth than those 
planted on bare rock. 
The slower rate of growth in the warmer waters of Sugar Loaf Sound was a 
surprise, and it may possibly be accounted for by the general absence of strong 
currents or by the character of the seed sponges. These were all small specimens 
rarely over 5 inches in diameter, obtained from the waters of the sound, which 
while formerly producing large ones now rarely do, possibly as a result of over- 
fishing in former years. In these shallow waters the spongers have been able 
rigidly to select out all marketable sponges, a process which would logically tend 
to eliminate those which grew rapidly and had an inherited tendency to reach 
larger dimensions, while leaving a preponderance of those of slower or stunted 
growth to perpetuate their kind. The inevitable tendency of an intensive fishery 
of this character would be to breed a race of more or less dwarfed sponges of slow 
growth, an assumption which is in a measure confirmed by the fact that Sugar 
Loaf Sound formerly produced a much greater proportion of large sponges than 
it does at present. This could not be due to the intensity of the fishery during the 
period within which I have been familiar with it, as the sound was then closed to 
promiscuous fishing and the sponges had ample opportunity to grow to larger 
size than the average attained. 
In Biscayne Bay and at Anclote Key the seed sponges were obtained from 
partially depleted beds, but owing to tlie greater depth and the more frequent 
prevalence of turbid water these have never been so thoroughly scoured of mar- 
ketable sponges. The specimens from which cuttings were made were larger, 
and presumably more virile, and in any event the cuttings grew more rapidly. 
At Sugar Loaf and Anclote Keys the planted sponges were measured at intervals 
after the first year by means of calipers, and occasionally specimens of average 
size were taken and cleaned. In Biscayne Bay local conditions prevented the 
systematic measurement of the sponges while growing. 
Text figures 4 and 5 exhibit graphically the rates of growth in volume of the 
cuttings at Anclote Key and Sugar Loaf Sound, respectively. The dotted lines 
indicate the theoretical increase in volume, assuming a uniform annual increase 
in diameter of 0.8 inch at Sugar Loaf and 1 inch at Anclote Key, while the 
heavy lines show the average growth of a number of measured specimens of the 
ages indicated by the position of the small circles. It will be observed that the 
