INTRODUCTION. xlix 



ova cannot be regarded as the equivalent of the distinct 

 ovary which Van Beneden figures, and which I have 

 myself seen. 



Nitsclie has seen ova produced on the cell-wall in Bicel- 

 laria ciliata, and Smitt in Scrupocellaria scruposa. These 

 cases Joliet is unable thus far to harmonize with what 

 he regards as the general rule ; but he suspects that here 

 also the parietal ova may be in connexion with some off- 

 shoot of the endosarc, perhaps with the threads which 

 pass through the communication-plates from cell to cell. 

 Clearly this branch of the subject requires a much fuller 

 investigation. 



As variations upon what seems to be the more usual 

 plan, Joliet has noted that in a Lepralia [L. Martyi) the 

 ovary is placed at the very base of the funiculus, immedi- 

 ately above the communication-plate ; whilst in a Mem- 

 branipora [membranacea) it occurs on the upper part of 

 the cell-wall, also in immediate connexion with the same 

 structure*. 



On the whole, it may be regarded as established that 

 the testicle is all but universally derived from the funi- 

 culus, invariably from some portion of the endosarc — 

 that the ova are in a considerable number of species 

 also developed in the funiculus — that in one case at least 

 they originate from the endosarc apart from this organ, 

 but in connexion with a communication-plate — and that 

 in several cases they are placed on the cell-wall, but 



* As in some measure eoufirniatory of this writer's view, I may draw 

 attention to Allman's figure of the freshwater PaludiceUa (Freshwater Pol. 

 pi. X. figs. 3, 4), in which the ovary is represented on the cell-wall, but in 

 direct communication with the " superior funiculus," a cord which proceeds 

 from the upper portion of the alimentary canal, while the testicle bears the 

 same relation to the ordinary funiculus below. 



