164 Linnean Society. [Feb. f, 



of Conferva by the subdivision of their cells ; but he states that his 

 views of the mode in which this subdivision is effected differ consi- 

 derably from those of M. Morren. He does not believe that wdien 

 the endochrome of a cell has become separated into two masses, 

 leaving a transparent space between them, this space is occupied by 

 a formative intercellular matter such as M. Morren describes. On 

 the contrary, he states that the first indication of the partitions which 

 are to divide the parent cell into two consists of a solution of the 

 continuity of a portion of the periphery of the cell, the divided edges 

 of which become inflected and gradually approach the centre, where 

 they coalesce. 



After dismissing as unphilosojjhical the doctrine of spontaneous 

 generation, as well as the more recent theory which attempts to de- 

 duce the origin of productions so widely differing in their structure 

 and modes of growth as Mosses and Confervce from the same germ 

 developed under different circumstances or in different media, the 

 author proceeds to pass in review the mode of reproduction of the 

 several genera of freshwater Confervce, adopting for the most part 

 the divisions of Vaucher, and comparing his own observations with 

 those of that distinguished algologist. 



In his account of the reproduction of the genus Vauchcria, he dif- 

 fers from Vaucher, who states that the horns (which he regards as 

 the anthers) approach the globular cell containing the future spore. 

 On the contrary, he affirms that it is the spore which approaches the 

 horn, in contact with which it remains for some hours ; and he adds 

 that the sporiferous cell is perforated or prolonged into a tube at the 

 place where it comes in contact with the horn. Of the function at- 

 tributed to the latter by Vaucher he has no doubt. He finds also, 

 in contradiction of Vaucher's statement, that enlargements of the 

 filaments, distinct from the reproductive apparatus, occur in all the 

 species of Vaucheria ; but he regards their presence as unconnected 

 with reproduction, their purpose being possibly to assist in sustain- 

 ing the plant on the surface of the water. 



The most important of Mr. Hassall's observations on the genus 

 Conjugata of Vaucher (including the more modern genera Zygnema, 

 Tyndaridea and Mougeotia), viz. the development of the spores with- 

 out conjugation of the filaments by the confluence of the contents of 

 two adjoining cells of the same filament, was published by him in the 

 ' Annals and Magazine of Natural History,' vol. x. p. 34. To his 

 account of the reproduction of this genus he adds, that the filaments 

 of the different species never grow in an entangled manner, but on 

 ♦;he contrary always lie, when undisturbed, parallel to each other, 



