600 BULLETIN OF THE BUREAU OF FISHERIES. 
Allemand announces practical experiments in this matter. The informa- 
tion published by him on this subject is, however, quite elementary: 
A larva, fixed to a support which we afterwards immersed in flowing water in 
May, 1905, has developed this summer, but gave in September only a large spot with 
an oscule, not a completely formed sponge; this fact ought to be ascribed to the manipu- 
lations necessary in the transportation of the larva. 
Evidently we can not deduce anything from this solitary failure. 
In view of the absence of positively established facts, we are forced to study 
this method in a purely theoretical manner. The choice of the collectors deserves 
first consideration. Breeding effected in aquaria shows that collectors of various 
kinds may be utilized for the larve of sponges, and we know that such is the 
case in nature, the larvee of commercial species attaching themselves to plants 
(branches of Posidonias) as well as to shells and stones. It should not be for- 
gotten, on the other hand, that these coilectors must be easy to manipulate and 
very inexpensive. We need not expect such a number of sponges to attach to 
these collectors as might be observed on oyster collectors. Are there not found 
in Arcachon over 300 young ones on one tile? After the young sponges are 
attached they should be preserved, and we know that they must adhere to a 
support. If small stones or shells have been utilized as collectors this support 
will not be of a sufficient size to be considered permanent, and it will have, in 
its turn, to be attached to another support. Should tiles be used? Tiles 
would be durable, as there could be no question of disintegration, but the use 
of tiles would be expensive. It seems that a good collector might consist of 
wooden branches tied in fagots and immersed in the vicinity of sponges that 
have attained their sexual maturity. The branches possess great resistance 
to sea water, and by using them, as is being done in Italy in deep-water 
oyster culture, it would be possible to divide them and to tie them to ropes 
or to apparatus similar to that used for sponge culture by means of cuttings. 
The use of fagots presents another advantage. It is generally admitted 
that the larve of sponges possess a marked negative phototropism. My 
observations, made on Reniera simulans, do not concur with those of other 
authors in this respect, and I found, on the whole, that the larve of this 
species are quite indifferent to light. Allemand has stated that the larve of 
a commercial species, Hippospongia equina elastica, seek a feeble light. It 
is certain that a negative tropism theoretically may be very useful to the species 
by impeding the larve from rising to the surface and by making them descend 
to less lighted regions, i. e., to the bottom, where they may find supports in 
great numbers; the opinion of a sponge diver would be quite useful, and it 
would be wise to ask him whether young sponges are not often attached above 
their mother to vertical walls of rocks. Should there really exist a negative 
phototropism the fagots would present the advantage of offering in their lower 
