312 SEA-SIDE STUDIES. 



buds spring not from ova, but from a detached portion 

 of the medullary substance ; '' and in a note he adds, 

 " Although they are described by Van Beneden as 

 developed from ova, yet it is clear from his own 

 account that such is not the case ; and that what he 

 called the vitellus is continuous with the medullary 

 substance of the stem and branches of the zoophyte." 

 Not having seen Van Beneden's Memoire, I am unable 

 to say whether that admirable naturalist has imperfectly 

 described what he has seen, or Dr Carpenter imperfectly 

 comprehended what he has read ; but I have no hesi- 

 tation in asserting that direct study of the phenomena 

 will disclose the fact of the Medusa being, at any rate, 

 sometimes developed from ova, although the vitellus 

 is " continuous with the medullary substance of the 

 stem/' The ova are there, unmistakable by any eye 

 familiar with the ova of zoophytes ; and by cutting off 

 the tips of the capsules we can gently press these ova 

 out, revealing the germinal vesicle in each, and the 

 vitelline mass surrounding it. Not only are ova there, 

 but in some instances spermatozoa may be observed 

 in great activity, and this at a time w^hen the circula- 

 tion, or more properly oscillation, of medullary granules 

 from the stem into the interior of the capsule is per- 

 fectly visible. Sometimes, instead of these, we find 

 simply a mass of granules and nucleated cells ; at 

 other times, ova in various stages of segmentation, the 

 germinal vesicle having disappeared, and a vitelline 

 membrane being formed ; at others, we find embryos 

 nearly ready to escape. 



