SERTULARIA. 139 



shelter them. There are neither too many nor too few. The dwelling 

 of each is coeval with the other,— originating jointly, but not invari- 

 ably corresponding in duration ; though in the hydraoid Sertularia, it is 

 not, as many believe, a portion of the living tenant's substance. The cell 

 serves as its proper habitation during life, and sometimes subsists perma- 

 nently or temporarily afterwards. It is a place of refuge, always in ready 

 preparation, whither the animal can retire for safety, or to undergo such 

 organic changes as are incident to its nature ; and from whence it can ad- 

 vance in quest of food, or to enjoy the salubrity imparted by its reno- 

 vated element. The vigour and the disposition of the tenant are sensibly 

 modified by these provisions for security. Unlike the inactive langour of 

 hydrse, deprived of such receptacles, here it is quick and lively, — as if con- 

 scious of danger, it lurks below : it is cautious of advance, and precipitate 

 in retreat. While completely unfolded, the whole organs suddenly col- 

 lapse, it sinks within the cell in a moment, and crouching still lower and 

 lower, lies quiescent, until, the dreaded peril over, it rises slowly as be- 

 fore, again to expand itself. All this is amply exposed by the transpa- 

 rence of the most capacious of the cells allotted for the dwelling of these 

 timid diminutive creatures. 



How interesting is the view of a luxuriant specimen of the Sertula- 

 rian race, — one resembling the richest productions of the vegetable crea- 

 tion, shorn of its flowers and foliage in the winter season. Now the whole 

 is still and lifeless : it seems hastening to decay, — to approaching dissolu- 

 tion. Let it remain undisturbed, and in a few moments it will be covered 

 by innumerable animated blossoms, issuing forth from their cavities to the 

 light. Then, after seeking their enjoyments in the plenitude of evolution, 

 do they again vanish in instant retreat. Infinitely more than mere sensa- 

 tion, however, is manifested by this marvellous host. All have a common 

 perception of what affects their common condition, while each has an inde- 

 pendent sense, deduced by some comparative means, of the real circum- 

 stances peculiarly afiecting itself. 



All the inorganic parts of the Sertularia are of a tough and elastic 

 texture ; they are hollow, and occupied by a kind of pith, less evident 

 than in the Tubularia indivisa. During its subsistence, the more minute 



