ALCYONELLA. 107 



recollect that the complement of the adult amounts to 42 or 44. Only 

 those of the exterior row are distinct in early stages, the rest are less de- 

 finite.— Fig. 11. 



The nascent hydra? either occupy the sides of their vessel, fig. 12, or 

 remain free in floating groups. But microscopical observation on the 

 latter is somewhat inconvenient, for the heads of all the animals being 

 downwards in their immersion, and a similar rotatory motion advancing as 

 before, perhaps also from the action of the ciliary apparatus, the object is 

 withdrawn from the field of vision. — Fig. 13. The varied forms and cur- 

 vatures, the contrasting brown and yellow of the ova, interspersed with the 

 white of the hydra; in their different stages among them, impart a great 

 degree of elegance, beauty, and interest to the clusters thus borne by the 

 limpid element. 



I have not observed that, in our climate, any ova from the Alcyonella 

 of the preceding year, were hatched after the 3d of June. But the period 

 assigned above for attainment of maturity by the embryo, may be accele- 

 rated or retarded according to the temperature of the season. This will 

 occasion discrepancies in all calculations and conclusions. In truth, no 

 absolute uniformity prevails. As ova seem to escape during summer, it 

 remains to be ascertained whether the term is ever so much abbreviated 

 that their contents are brought to maturity before winter. 



Whether the ova float or adhere they are alike prolific, though many 

 prove abortive on the whole. Each gives birth to only a single hydra ; 

 nor do any others originate from the basis of this nascent animal as with 

 the Cristatella. Therefore, it is by no means obvious how the gelatinous 

 stratum is formed. But the offspring of a number of prolific ova in imme- 

 diate approximation, are connected by some kind of diffusion, which may 

 account for its origin. 



If decay of the parent be almost cotemporary with the maturity of the 

 ovum, and if that be its principal source of liberation, we should conclude, 

 that, by the regular course of nature, the duration of the product is limit- 

 ed to a single season. Whether this conjecture would be supported by 

 the transience of the substance invested, would exact further investigation. 

 But the waste of the hydra, and the distension of the integument for re- 



