1843.] lAnnean Society. 165 



thus allowing of the regular tinion of the filaments, which could not 

 otherwise take place. So remarkable is this arrangement, that Mr, 

 Hassall states it to be alone sufficient to enable us at once to recog- 

 nize a species as belonging to the Conjugating Confervce. 



On the reproduction of Hydrodictyon and Polysperma (Lemania, 

 Bory) Mr. Hassall offers no observations of his own. The account 

 given by Vaucher of that of Batrachospernnim (including also Chceto- 

 phora and Draparnaldia) has been since doubted, but Mr. Hassall 

 thinks that he has verified it by obsen^ations on B. plutnosum. On 

 the other hand, he believes Vaucher's account of the reproduction of 

 ProUfera to be in a great measure inaccurate. The enlargements of 

 the filaments are doubtless connected with reproduction, but not, he 

 thinks, in the manner supposed by Vaucher, while what Vaucher re- 

 garded as the young proliferous offspring appear to him to be para- 

 sitic growths, to which Confervce are peculiarly liable. 



Having completed his review of the genera of freshwater Confervce 

 noticed by Vaucher, Mr. Hassall next proceeds to call attention to 

 the mode of reproduction occurring in a group of which he believes 

 himself to have first ascertained the true characters, and which 

 he has denominated VesicuUferce. His observations on this group 

 have been already published in the ' Annals and Magazine of Natural 

 History,' vol. x. p. 336, &c. In these obser^-ations he had described 

 as the usual mode of reproduction in that group the formation of the 

 si)ores without union of the filaments by the intermingling of the 

 contents of two contiguous cells in the same filament ; and had 

 questioned the motion and development of the zoospores as described 

 by M. Agardh the younger. In his communication to the Society 

 he adds some extracts from letters which he had since received from 

 Mr, Ralfs, who describes the disintegration of the sporular masses 

 and the vivid motion of the separated granules in Draparnaldia tenuis 

 and Sphceroplea crispa, and adduces the testimony of Mr. Borrer and 

 Mr. Berkeley to the same fact. And Mr. Hassall himself, in a note 

 under date of the 7th of April, retracts his objections to the motion 

 and development of zoospores in the Vesiculiferce, and states his be- 

 lief that they possess a double mode of reproduction, that which he 

 had described as occurring by means of true spores being the perfect 

 form. 



Mr. Hassall's observations on the reproduction of the branched 

 Confervce have been published, since the reading of his paper before 

 the Society, in the ' Annals and Magazine of Natural History,' vol. xi. 

 p,360, &c. With regard to the genus Meloseira, Mr. Hassall believes, 

 from the occurrence of vesicles in the filaments similar to those of the 



