1 92 CYSTOSPERME^. 



inflcated cells occupied with sporangia or globules, is quite 

 consistent with the idea of these bodies being formed by the 

 contents of two cells, since each may be in contact on either 

 side with au inflated cell. In the very rare instances in which 

 three or four contiguous cells occur, I have never noticed 

 a perfect globule in each of these, and even if such ever exist, 

 each globule yet might be formed not indeed of the entire 

 contents of two cells, but still of a portion of the green matter 

 of two. 



M. Leon le Clerk thus defines the genus Prolifera. 

 ** Filamentis loculatis simplicibus, materia viridi granulis 

 fulgidis aspersa totaliter repletis. Singulo loculo, fructifica- 

 tionis tempore, projyriis viribus in glohulam suam efformante. 

 Isto globulo intense viridi ex loculo demisso novam plantam 

 emittente." 



This definition of M. Leon le Clerk is exceedingly faulty. 

 It is not in each cell that the round globule is formed, but only 

 in occasional cells, or at most in alternate cells; and the asser- 

 tion that this globule really gives origin to a new plant, is 

 by no means established. Even INI. J. Decaisne, who has 

 separated the Conjugates from the Alg(R zoospore of Agardli, 

 does not state that he has Avitnessed their developement, but 

 Infers this from the fact that the filaments of the Conjugated;, 

 whether young or old, in the same species, invariably present 

 the same diameter, and thus, as he supposed, could not pro- 

 ceed from organs so minute as the zoospores. 



M. Decaisne combats the idea of the disintegration of the 

 sporangia of the Conjugates and VesiculifercB into zoospores, by 

 the fact that their contents are at all times fluid. This argu- 

 ment is, however, by no means conclusive, the contents of 

 the cells of the Vesiculiferce, &c., are also generally fluid ; but 

 this fluid, when the proper period arrives, becomes fashioned 

 into distinct organs or zoospores, and the same may be the 

 case with the contents of the spores of the Zygnemata, as 

 asserted by Agardh. 



M. Decaisne also repudiates the idea of a double mode of 

 reproduction ; the spores he regards as the true and only re- 

 productive bodies of those AlgcB Vvdiich possess them ; but it 



