AMPHITRITE. 221 



then, as the turbid matter descends gently from above, the creature will 

 forsake its concealment, display its plume, and renew its labours. 



More than mere instinct must be ascribed to all this, for the archi- 

 tect can certainly testify a certain discrimination, both of what is essen- 

 tial to be done, and in the mode of doing it, whether in simple prolonga- 

 tion of its dwelling, or in repairing attainable breaches. Thus its revo- 

 lution is either partial, complete, or repeated ; it advances and returns, 

 plastering the same portion once and again ; nor is it satisfied with a 

 single application of its trowels in moulding the work ; their office is 

 varied and appropriately resumed. 



To obtain satisfactory exhibition of the process above detailed, a 

 tall vessel, little exceeding three inches in diameter, should be employed, 

 which will bring the whole within the focus of an ordinary lens ; or a 

 smaller vessel may suffice, according to the specimens. The water should 

 rise considerably above the object, that the muddy drops may descend 

 in gentle dispersion. 



The softest earthy particles are the most congenial to the delicate 

 structure of the ciliated funnel. Nevertheless grains of sand enter the 

 lower part of large tubes, in the natural state, while the higher consists 

 of the wonted materials. Short tubes, those under six inches, have con- 

 sisted exclusively of mud and gluten. Long tubes, those of twenty or 

 twenty-four inches, have consisted, first, of the finest sandy particles, for 

 a third upwards, of agglutinated or silky matter ; next, of mud and 

 gluten as usual, for the remainder. Their foundation was never obtain- 

 ed, and although some, extending two feet, seemed of this latter com- 

 pound exclusively, they were also ruptured below. They appear to en- 

 large gradually from a line in diameter near the foundation, to about 

 three lines at the orifice. The substance of the tube is no doubt depen- 

 dent on its situation. Possibly where originating near a quantity of 

 sand, a portion of that ingredient becomes affixed externally with the 

 glutinous secretion from the animal, while there is nothing but mud 

 above to be purposely employed in the fabric. It is from the forcible 

 means adopted for recovering the tubes that they are ruptured in the 



