1843.] Linnean Society. 163 



from the collection of Dr. Wood of Cork, was obtained by him from 

 very near the original locality named by Mr. Drummond. Mr. Hincks 

 stated that he had taken some pains in comparing the specimen, not 

 only with the description, but also with the original sketch made by 

 Mr. James Drummond on a blank leaf of the pocket-book in which 

 he noted down the occurrences of the tour upon which he made the 

 discovery of this curious plant. The specimen now exhibited was 

 marked by Dr. Wood when fresh, and he had no doubt of its identity ; 

 and the result of Mr. Hincks's examination was a confirmation of 

 this opinion. 



Read the conclusion of Mr. HassaU's " Essay on the Distribution, 

 Vitality, Structure, Modes of Growth and Eeproduction, and Uses 

 of the Freshwater ConfervcE." 



The author commences his memoir by a general notice of the cir- 

 cumstances under Mhich the freshwater Conferv<z are found, and the 

 distribution of various species. As regards their vitality he is in- 

 clined to think that the lives of fevv' species, if any, extend beyond 

 the period of a year ; while it is certain that very many perish after 

 a few months or even weeks, and are reproduced, under favourable 

 circumstances, twice or thrice in the course of the year : their tena- 

 city of hfe is also verj- great. 



In structure they exhibit great uniformity. An outer transparent 

 membrane destitute of markings, but whose ultimate structure Mr. 

 HassaU beUeves to be fibrous, invests a simple series of cells placed 

 end to end, and containing a turbid almost colourless fluid, in which 

 float a number of vesicular bodies of various sizes, the uses and na- 

 ture of which are not satisfactorily ascertained. In some of them 

 Mr. HassaU has noticed a dark central nucleus ; and it is supposed 

 that they are connected with the function of reproduction, and that 

 they supply the material for the formation and growth of the cells 

 and their investing membrane. Each cell, the author thinks, may 

 be regarded as possessing a separate and independent existence; and 

 consequently the entire Conferva is to be looked upon, like the asso- 

 ciated zoophytes, as a compound or aggregated being. 



The principal part of Mr. Hassall's observations on the growth of 

 Confervce has been already published in the ' Annals and Magazine 

 of Natural History,' vol. ix. p. 431-2 ; and he has, since the reading 

 of the present paper, published his obser\-ations on a mode of deve- 

 lopment not previously noticed by him, in the same Journal, vol. xi. 

 p. .359. At the period of the former publication he was not aware of the 

 observations of M. Morren, M. Dumortier and M. Mold on the growth 



