A PRACTICAL METHOD OF SPONGE CULTURE. 585 
the value of pure sponges is $4 per pound, which is less than the average of 
recent years. These assumptions are all regarded as very conservative. 
From this must be deducted the cost of harvesting, which, in shallow water 
such as is to be found among the keys, should not exceed about $25 if proper 
conditions of weather and water be availed of. The net return, therefore, from 
an original investment of about $225 per acre would be an average of about 
$200 per year. In deeper water the cost of harvesting the crop would be some- 
what greater, but as the operations would be carried on on a larger scale econ- 
omies could be practiced which would reduce the expense. 
In conclusion it should be plainly stated that the above calculation, though 
based on the actual results of experiment, is largely theoretical and that definite 
data can not be attained until the work is actually undertaken on a commercial 
scale. It is confidently believed, however, that if directions are followed in a 
suitable locality the actual net returns per acre will be considerably greater than 
those stated. 
