252 J. G. WALLER ON CLIONA CELATA, ETC. 



One thing is made manifest, that the living elements before you do 

 not belong to a creature with much motive power. 



Perhaps I may here be called in question, and be reminded of 

 the monad-form Sponge animal, the more perfect knowledge of 

 which is one of the latest developments of science in this depart- 

 ment. But this helps but little ; the cihated monad which may leave 

 the parent stock, and set up for itself, is but a feeble creature, and 

 soon settles down to a state of rest. To give this being, or a col- 

 lection of these beings, the power of excavating a limestone rock, 

 or the shell of a mollusc, is one of the difficulties before us. To 

 assume that it does this, and then to bend the mind to find out some 

 expedient by which it may be accomplished, does not commend itself 

 to my mind as a true and philosophical mode of enquiry : yet, 

 nevertheless, this is as the case at present stands. 



When one reads what has been written on the subject, we find all 

 sorts of surmises, as to the how it is performed. Mr. Hancock, to 

 whom we owe the theory of a " boring sponge," thought he had found 

 the instruments by which the operation was accomplished, which was 

 easily disproved. One suggests acid, others deny its presence. The 

 course followed by some would be amusing, if it did not painfully 

 suggest a royal road to error. For instance, one tells us of the 

 Sponge attacking the oyster, which, on its defence, bars him out 

 by the formation of new shell, and thus escapes the burglarious 

 intent. The same writer then philosophizes on the possibility of 

 this creature, in the economy of nature, being for the purpose of 

 assisting in the breaking up of such portions of organic structure.* 

 Once, in this room, it was accused of attacking the oyster spat, and 

 of even assailing an infant oyster, only a fortnight old. A ferocious 

 oyster-loving Sponge is a novelty in Natural History, and its pro- 

 pensities somewhat alarming. The story is almost pathetic, but, is 

 it true ? When science condescends to such dreams as these, it is 

 necessary to give it a reminder, and to awaken it to common sense. 



To an opponent of the theory, it is certainly satisfactory, as well 

 as remarkable, to notice the vacillation in those who support it. 



* The pi'Ogress of assumption when once the ball is set rolling is seen in 

 the following passage : — " The greatest enemy of oyster-banks is a Sponge 

 (CUona), which eats into the valves, both of dead and living shells ; at first 

 only small round holes, at irregular intervals, and often disposed in regular 

 patterns are visible; but ultimately the shell is completely mined and falls 

 to pieces." (" Manual of the Mollusca," by S. P. Woodward, F.G.S., 1850, 

 }). 254.) It really seems as if on this subject proofs for a statement were 

 never held to be necessary. The falling to pieces is purely gratuitous. 



