160 



the tentacles are intended to act as a means of diffusion and 

 intromission of the sperma. 



In their shape and structure the Spermatozoa of Campanularia 

 do not differ much from those of Eudendrium, as figured by M. 

 Kolliker. It ought further to be noticed, that, as in other Polyps, 

 the Spermatozoa do not originate within peculiar cells, but fill 

 the whole space of the seminal bag. 



The sexes seem to be entirely distinct. Not only did M. Desor 

 never see but one kind of cells on a branch, either males or 

 females, but whole bunches were either exclusively female or 

 exclusively male, so that a stem which divides by branching 

 is able to produce only branches of its own sex ; thus showing 

 that simple budding does not constitute a true generation. 



The process of furrowing was observed by M. Desor in all 

 its stages, (as was shown by drawings laid before the Society.) 

 The separation of the yolk spheres from each other is com- 

 plete, so that they became easily distinguished. As a peculi- 

 arity of the spheres, it is, however, to be mentioned, that no 

 clear spot could be detected in any of them, either in their 

 early stage, (the division is 4 or 8,) or at a later epoch, when 

 the yolk assumes the mulberry form. As the development 

 goes on, there is seen a transparent zone forming around the 

 yolk ; this is the first indication of the germ, which elongates, and 

 subsequently assumes the form of a little worm hardly per- 

 ceptible to the naked eye, and covered all over with vibratile 

 cilise. It is in this form that the embryo leaves the bag in which 

 it has been developed. It is seen creeping slowly along the 

 bottom of the vase, being in every respect very similar to the 

 PlanulcB, or embryos of Medusa and also of Nemertes. It was 

 noticed that when moving, it advances always with the wider 

 part of its body. This is the so-called infusoria state of the Cam- 

 panularia, and in order to get at the perfect polyp state, the em- 

 bryo has to undergo very remarkable metamorphoses, which 

 have been fully and most satisfactorily investigated by M. Loven.* 



* On page 140 will be found a note containing a list of the various Treatises on 

 this subject, which was added for purposes of reference. It was printed on 

 the responsibility of the Publishing Committee, as M. Desor's absence from the 

 city prevented his being consulted with regard to it while the sheets were passing 

 through the press. To the list there given should be added, — 



Alternations of Generations. By J. J. Sm. Steenstrup. Translated from the 

 German by George Busk. 8vo. London, 1848. — Ftiblishiiig Committee. 



