192

CYSTOSPERME^E.

inflated cells occupied with sporangia or globules, is quiteconsistent with the idea of these bodies being formed by thecontents of two cells, since each may be in contact on eitherside with an inflated cell. In the very rare instances in whichthree or four contiguous cells occur, I have never noticeda perfect globule in each of these, and even if such ever exist,each globule yet might be formed not indeed of the entirecontents of two cells, but still of a portion of the green matterof two.

M. Leon le Clerk thus defines the genus Prolifera.“ Filamentis loculatis simplicibus, materia viridi granulisfulgidis aspersa totalitcr repletis. Singulo loculo, fructifica-tionis tempore, propriis viribus in globulam suam efformante.Isto globulo intense viridi ex loculo demisso novam plantainemittente.”

This definition of M. Leon le Clerk is exceedingly faulty.It is not in each cell that the round globule is formed, but onlyin occasional cells, or at most in alternate cells; and the asser-tion that this globule really gives origin to a new plant, isby no means established. Even M. J. Decaisne, who hasseparated the Conjugates from the Algce zoospores of Agardh,does not state that he has witnessed their developement, butinfers this from the fact that the filaments of the Conjugates,whether young or old, in the same species, invariably presentthe 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 thesporangia of the Conjugates and Vesiculifera into zoospores, bythe fact that their contents are at all times fluid. This argu-ment is, however, by no means conclusive, the contents ofthe cells of the Vesiculifers, &c., are also generally fluid; butthis fluid, when the proper period arrives, becomes fashionedinto distinct organs or zoospores, and the same may be thecase with the contents of the spores of the Zygnemata, asasserted by Agardh.

M. Decaisne also repudiates the idea of a double mode ofreproduction; the spores he regards as the true and only re-productive bodies of those Algs which possess them; but it