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Note on Projects for the Improvement of 

 Sponge-Fisheries. 



By 

 George Bidder. 



For Summary see under title of preceding article. 



A. Sjwnge-cultivation. 



In considering the experiments of Buccicli (6) on propagation of 

 sponges by cuttings, two main questions present themselves : — 



(1) If a sponge be divided into many fragments, will the total 

 increase of such fragments and their progeny be greater than the 

 increase of the intact sponge and its progeny would have been in 

 the same time ; the conditions of water, &c., being identical ? 



(2) Are sponges, grown as recommended by Buccich, more or less 

 favourably situated than those on the sea-bottom ? 



(1) The first of these questions I should, according to our present 

 knowledge, answer in the negative. We have no evidence whatever as 

 to the rate of growth of the sponge of commerce at Lesina, under 

 natural conditions. So far as I am aware, there is no observation in the 

 literature of the subject which throws any light whatever on the 

 probable age of sponges of given size, their probable future rate of 

 increase, or the dimensions at which increase stops.* 



When, therefore, Buccich records that his cuttings grew to two 

 or three times their size in the first year, we have no reason for 

 supposing that an equal increase would not have taken place had they 

 remained intact in the surface of the parent sponge. A jynori, I should 

 suppose that a greater increase would have taken place. For the life of 

 a sponge depends on a most interesting system of hydraulic canals, on 

 the mechanical perfection of which depends the quantity of its food. 

 Each cutting contains only the fragment of such a system, broken into, 

 with direction of currents confused or inverted, and pressure-chambers 



* A discussion of the question of growtli will be found in the Appendix. 



