SPONGE CULTURE. 601 
region a zone of lesser light, where a greater number of larvae would attach them- 
selves; these would be attracted at this point less imperiously by the darkness 
of the bottom. 
Supports for young sponges would be attached with advantage to bodies 
which the waves might put in motion—ropes treated so as to resist putrefac- 
tion, ete. Bidder luckily demonstrated the advantage derived by sponges 
living on mobile supports. Thanks to the renewing of food and aerated water, 
a consequence of their oscillations, the rapidity of growth of young sponges is 
increased. It should not be lost from view that in such cases the skeleton is 
coarser, as stated by several authors; the advantage gained on the one hand 
is decreased by the diminution in value of the product obtained. 
The sponge cutting should be immersed at a certain depth, and it seems 
rational from this point of view to choose the depth preferred by the spontaneously 
grown sponges of the species it is desired to cultivate. Experimenters have 
noticed that sponge cuttings seem to fear too intense a light; this is a thing to 
be remembered and may find its application. 
Sponge culture appears to us then as an operation fraught with difficulties, 
which can be attempted, without involving too high expenditure, only in 
localities offering an exceptional combination of favorable conditions. It 
should not be forgotten that if the sponges are to be immersed at a sufficient 
depth they must be attached so firmly that a wave shock can not detach them. 
They should also be protected against marauders, and the question of guarding 
the pares and inclosing these arises again in connection with the expenditure 
involved. 
It is possible to attempt the combination of this method of sponge culture 
with that undertaken in parcs by placing the collectors in the parcs themselves 
where the adult sponges are kept. There would thus be no interruption in the 
future gathering of sponges, since those maintained in the parcs would furnish 
the larve before being garnered, and the young sponges attached to the collectors 
would be taken care of until the time when, in their turn, they would emit 
larvee and reach the necessary size. 
It is to be regretted that this method has not been the object of serious 
study and has been neglected by the cultivators of sponges.* In the mean- 
while we are reduced to simple hypotheses where it is concerned, and it is 
impossible to know whether it is indeed a practical method for purposes of 
profit. It might be possible that, at the present state of our knowledge, such 
an operation would not pay nor cover not only the expenditures involved by 
@ It will shortly be attempted along the French coast of the Mediterranean. I have been asked 
for information on this subject. Without concealing my skepticism from my interviewer, I told him 
that sponge culture by collectors alone or combined with parcage was the only method worth attempting. 
