66 Proceedings of the 



stolons and gemmse ; the plant puts forth flowers, the polypary 

 medusae, which alone have true reproductive organs.* 



* Note on dioecious reproduction in Zoophytes. — I have stated the development 

 of medusee from polypes, in accordance with the elegant expression of the fact 

 first given hy Dr Carpenter, hut there is still some obscurity with regard to this 

 subject. It r? not correct to state generally, that Gampanularia, Tubularia, 

 Coryne, and Clava produce medusa-buds, although some varieties of all these 

 species do so. Schultze has observed in Campanularia geniculates, in place of 

 medusa-buds, the production of capsules filled with spermatozoa. The pro- 

 duction of ova, and their direct development into young polypes, has been noticed 

 in the ovarian capsules of Tubularia indivisa by Mummery. I have repeatedly 

 seen large polyparies of Coryne glandulosa, all the polypes of which bore buds 

 containing spermatozoa, developed from a stalk traversing the axis of the bud, 

 the whole polypary being, in each case, unisexual and male. While in other 

 polyparies of the same zoophyte, the reproductive buds were filled with ova 

 also developed from the exterior of a hollow central stalk, a diverticulum of 

 the alimentary canal ; the entire polypary in these cases being female. In some 

 species of Clava, the polypes (which are not separate as hitherto described, but 

 attached together by a fleshy basis, investing a horny polypidum somewhat 

 similar to that of Hydractinia, or by a slender creeping thread inclosed in a 

 membranous sheath) bear reproductive capsules, some of which contain sper- 

 matozoa and others ova; but the polypes bearing male capsules are never found 

 grouped on the same polypary with those carrying female capsules. I may 

 state that many, if not all, the composite hydroid zoophytes are not only uni- 

 sexual with regard to their individual polypes, but also dioecious, the male and 

 female reproductive organs being always situated on different polyparies. I 

 have already observed dioecious reproduction in Coryne glandidosa (Daly ell), 

 Clava, two species, Hydractinia echinata, Sertularia cupressina, Plumularia 

 falcata, Campanularia lacerata, Sertularia rosacea, and several others. I hesi- 

 tated for some time to agree with Drs Allman and Carpenter in considering the 

 marcescent reproductive capsules, which in some of these zoophytes appear at 

 first sight to be mere sacs, filled with spermatozoa or ova, as homologous with 

 the budding medusas, in which the organs of sensation, locomotion, nutrition, 

 and even of reproduction, are highly developed and distinctly differentiated, 

 which maintain an independent life long after the decay of the polype from 

 which they have budded, and some of which multiply themselves indefinitely 

 by gemmation before their true sexual organs appear; but I am convinced, 

 after careful examination of many genera, that this is nearly a correct view of 

 the case. The peduncle of the medusa-bud appears to me to be homologous 

 with the entire reproductive capsule (of Coryne glandulosa, &c), and the um- 

 brella to be a superadded organ, having the nature of a polypary or ccenosarc 

 (Allman). Very lately I have found at the Scougal Rocks, near North Berwick, 

 a very interesting Coryne, in which each polype of the cluster bore a single 

 long cylindrical medusa-bud without tentacles. The peduncle consisted of a 

 thick white mass nearly filling the umbrella, and was found to consist of an 

 inner and outer coat (endoderm and ectoderm) widely separated from each other 



