280 ZOOPHYTES. 



The external action of the cilia is notably excited by the visible pre- 

 sence of foreign matter, and by this the whole energies of the animal 

 seem to be aroused. 



A fine example is shewn by another creature, a thousand times larger 

 than the inhabitant of any of the zoophytes. Elsewhere we shall perhaps 

 have an opportunity of detailing the facts more at large. 



I speak of the Amphitrite ventilabrum, which is not an ascidian 

 hydra indeed, but is at present incorporated with another race, known by 

 rather an indefinite name, the Annelides. The anterior extremity is de- 

 corated with a beautiful plume, consisting of many ciliated ribs, disposed in 

 similar arrangement as tentacula. A row of cilia fringes each side of sixty 

 or seventy ribs or tentacula in adult specimens, the central rib being two 

 or three inches long. While the Amphitrite is quiescent below in its 

 tubular dwelling, apparently regardless of every thing, let a few muddy 

 drops fall amidst its element, over the orifice of the tube, it quickly 

 ascends, displays the beautiful plume, and immediately thousands of cilia 

 are in motion. Attracted to their sphere, the muddy particles are accu- 

 mulated, received into the mouth, prepared as paste, and applied to the 

 upper edge of the tube, where it is moulded into shape, and beaten down 

 by two organs, bearing a rude resemblance to trowels, accomplishing, as 

 it were, the work of human hands. 



Here the functions of the cilia are definite. 



Later naturalists finding cilia in many unexpected places, testify 

 some earnestness to assign them a peculiar office, though their real use 

 has probably to be postponed for future discovery. 



The Hydra and the Actinia being carnivorous, it might be inferred 

 that the hydraoid zoophytes, including the Tubularia, should be of the 

 like nature. However, we cannot speak positively to that point. We only 

 know that some of the race are voraciously and promiscuously carnivorous. 



Admitting the probability of the hydras of the zoophytes being so 

 likewise, it should be recollected, that none of the Ascidiae manifest any 

 such propensity. Therefore it may be logically deduced, that the same 

 principles should govern the nature of the ascidian hydra, as I have ven- 

 tured to denominate it, when in this compound form of a zoophyte. 



