Dr Grant on the Ova of Zoophytes. 151 



bit signs of life ; they appeared to us to be evidently young living 

 polypi, which extended in a circular order, the tentacula proceed- 

 ing from their head, as in other polypi. While examining them, 

 some of the ova, after detaching themselves, fell to the bottom 

 of the glass of water in which we had placed them ; they then 

 began to move and stretch themselves out like fresh water po- 

 lypi ;" (Ellis, Hist. Nat. des Cor., p. 116). This statement of 

 Mr Ellis, though not altogether correct in its detail, is satisfac- 

 tory as to the motions of the ova which he saw escape from the 

 vesicles. As this species of Campanularia occurs abundantly 

 on Leith rocks, and, at this time (May) presents the ova in a 

 state of maturity, I have examined their singular motions under 

 the microscope, in presence of some friends conversant with the 

 structure of these animals. The moving ova which Mr EUis 

 observed, were not, as he supposed, the same with the polypi- 

 like bodies he has represented (PL xxxviii. Fig. 3. B, B, B,) 

 hanging from the mouths of the vesicles, but were ova which 

 had fallen from these polypi-like bodies. The polypi-like bo- 

 dies, viewed under the microscope, are found to be thin, trans- 

 parent, motionless capsules, containing each three distinct ova, 

 and presenting at their free extremities several stiff, straight, di- 

 verging pointed processes, which Mr Ellis mistook for the ten- 

 tacula of a young polypus ; and was thus led to believe, that 

 the polypus is the first formed part of a young zoophyte, which 

 I have found by experiment to be contrary to fact. This mode 

 of generation in Sertularice, by the detachment of numerous 

 capsules, containing ova enveloped in a viscid matter, was known 

 to Cavolini, who, forty years ago, detected the fallacy of Mr 

 Ellis's statement regarding the polypi-like bodies, and suspected 

 that the true ova contained in these exterior capsules, would be 

 found to exhibit the same kind of motions which he had ob- 

 served in the ova of other zoophytes ; but he did not succeed 

 in obtaining the ova after their expulsion from the capsules, so 

 as to verify or refute his conjecture. As I had already observed 

 through the transparent vesicles of the Plumulariajhlcata the 

 motions, and even the cilias, of the ova contained in them, I 

 placed one of the polypi-like capsules hanging by umbilical 

 cords, from the vesicles of the Camp, dichotoma entire under the 

 microscope, and I could distinctly perceive the vortex-like cur- 



