244 



POLYZOA. 



take a portion of one of these very common pro- 

 ductions, and bring it under a lens of high magnify- 

 ing power, its entire surface is found to be made up 

 on both sides by an assemblage of cells of a somewhat 

 horny texture, the margins" of which are beset with 

 spines arranged with great regularity. Should the 

 specimen happen to be alive, it will be seen, on 

 placing it in a glass of sea-water, that every cell is 

 inhabited by a little hungry, active animal, polype- 



FlG.. 184. CELLS OF FLUSTRA MAGNIFIED. 



like in its form, but displaying a much more com- 

 plicated structure. Around its mouth are set 

 numerous long tentacles; but these are not mere 

 smooth filaments, or petal-like appendages, like those 

 of the true polypes, described in a former chapter, 

 but they are furnished with innumerable cilia arranged 

 in rows, which being set in rapid vibration at the 

 will of the animal, produce strong and constant 

 currents in the surrounding water, all of which con- 



