576 BULLETIN OF THE BUREAU OF FISHERIES. 
It should be stated also that 50 cuttings made from a 6-inch sponge would 
be smaller than has been found advisable and the rate of increase in diameter 
during the first year would be somewhat smaller than has been assumed, though 
thereafter it would be fully equal to that of the larger cuttings. 
MORTALITY. 
The data upon the highly important question of the death rate among 
sponges grown from cuttings are not satisfactory. Buccich estimated it at about 
Io per cent in seven years, but my results indicate a somewhat higher rate. 
Owing to the unsatisfactory character of the supports which were employed 
during the early years of the experiment, it was necessary to shift the sponges 
from time to time, each handling resulting in some loss, and moreover the break- 
age of the lines often allowed the plants to fall to the bottom, where they were 
much injured by adverse conditions. The mortality was highest at Anclote 
Key, where the plantation was exposed to the full force of the waves and the 
parting of the lines was frequent, and it was least at Sugar Loaf Key, where the 
greatest shelter was afforded. At Anclote there also was always more or less 
fall in the salinity during the heavy rainfall of summer, and the greatest mor- 
tality on the lines which remained intact was invariably coincident with this. 
Cuttings planted in the fall frequently reached the late spring months with a 
mortality of but 1 or 2 per cent, a rate increased to 8 or 10 per cent by fall. 
The observations made at that place are of value only as indicating the necessity 
for establishing the plantations in places not subject to the influence of freshets 
in neighboring streams. At Cape Florida, in Biscayne Bay, the plantation was 
more sheltered from boisterous seas, but the surface water was liable to fall in 
salinity during summer with a coincident increase in the death rate, though here 
the results were not so uniform. At this place various lots of sponges planted 
at different times and all subject to more or less of the vicissitudes of experi- 
mental work mentioned above, exhibited mortalities of 32 per cent at the end 
of fifty-three months, 29 per cent at the end of forty months, and 15 per cent at 
the end of twenty-six months, respectively. The first two lots were subject to 
damage from the breaking of the wires, but the last did not have this condition 
to contend with and the mortality during the last twenty-one months was equal 
to but 4 per cent of the original number planted. The heavy death rate of the 
first five months was due to the sagging of the wire so that the cuttings lay 
among the dense vegetation, none of those raised above the top of the grass 
dying during that period. 
At Sugar Loaf Sound no difficulty was experienced with fresh water, and 
the death rate was correspondingly decreased. The lot of 400 cuttings having 
the longest period of growth at that place—thirty-five months—exhibited at the 
end of that time a mortality of 14 per cent. All of these were transplanted at 
