SERTULARIA. 145 



and the hydra distorted. If the particle be too large, it is retained a long 

 time externally ; nor can it be forcibly removed without the visible reluc- 

 tance of this diminutive being. 



Some authors speak of such creatures as the Animalcula inficsoria 

 being absorbed by the Sertularian, Foliaceous, and Lunate Zoophytes. 



Moderate light and heat, and especially the renovated element, in- 

 vite protrusion of the hydra from the cell to enjoy their refreshing influence, 

 fig. 4. Pertinacious retreat is frequently preserved, perhaps from the 

 state of the atmosphere, as during a cloudy sky, or the greater chill of a 

 north wind ; or an invisible slough may be separating somewhat like that 

 of the Actinia. 



Probably the hydra retreats within its cell to die ; but the life of each, 

 being independent of the rest, the death of one does not affect its neigh- 

 bours. 



The ovaria, or vesicles of this Sertularia, are large in comparison of 

 the cells, and of singular structure, being as if composed of united hoops 

 or belts. The orifice of some is serrated. — Plate XXII. figs. 5, 6. 



Prolific vesicles are rare ; indeed, specimens with any vesicles are far 

 from common. 



Several with living hydrse, and with vesicles scantily distributed, full 

 of yellowish corpuscula, having occurred in September, seemed to promise 

 progeny. All except two had discharged their contents in a few days, as 

 an ovoidal or globular mass, about a line in diameter, adhering to the ori- 

 fice. The mass consisted of from 17 to 20 pale yellow spherules, im- 

 bedded in the most transparent albuminous matter. Some were quite 

 globular, even under the microscope ; of smooth, uniform, shining surface. 

 Others were less regular. But nothing resulted from any of them. — 

 Figs. 7, 8. 



At the distance of several years, the subject was illustrated more sa- 

 tisfactorily. Specimens with lively hydras, and bearing vesicles, scantily 

 distributed as before, were obtained in July. Only one vesicle appeared 

 among twenty cells ; however, three were on a twig. Those prolific ex- 

 tended a line ; the orifice serrated, and the cavity crowded with yellow 



VOL. I. T 



