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On Clioxa celata (Grunt), Hymeniacidon celata (Bowerbanh). 

 Does the Sponge make the Burrow ?^ 



By J. G. Waller. 



PLATES XX, XXI. 



{Read March loth, 1881.) 



It may perhaps be thought that, in renewing this subject, I am 

 somewhat of a pertinacious disposition, nor am I disposed to deny 

 such imputation. But I can assure you, nevertheless, it is not a 

 pertinacity to hold to error, but an endeavour to seek the truth. 



To dogmatize by asserting, this cannot be done by a Sponge or 

 that by an Annelid, is to no purpose whatever. You may go on 

 thus until the day of doom, and then be no nearer to a solution. It 

 is to base a calculation upon nothing, and to expect a result. Facts 

 alone, carefully studied, with a mind free from foregone conclusions, 

 are our only safe guide, and to bring the subject, as far as possible, 

 under the dominion of an a priori reasoning, is my object in again 

 addressing you. 



The problem before us ought to be capable of solution. Whether 

 it will be when we indulge in theories, in place of demonstration, 

 is a matter open to doubt. A theory may be plausible, it may be 

 possible, but it advances little to an end without it be submitted to 

 the stern conclusion of experiment. Whether the Cliona bores the 

 cavities it inhabits, or whether the cavities are made by another 

 creature, are both hypotheses. We must endeavour to interpret 

 by analogies. It matters little whether Sponges are to be relegated 

 to the Protozoa or to the Metozoa, it is clear enough we are deal- 

 ing with a condition of life imperfectly understood, or its classifica- 

 tion would not be the subject of contest. Even in its most active 

 state, it has at best but a vegetative or quiescent existence. You 

 may see it forming spicules before your eyes, from day to day ; a 

 mysterious operation, just as a plant may open its bud by an ex- 

 panding leaf, and you go from the contemplation as wise as before. 



