212 



FAM. X. MONOCYSTE.E. 



The reproduction of this family agrees precisely with that 

 of Chcetophora and Draparnaldia, and perhaps Batrachosper- 

 mum, which genera it would perhaps have been more natural 

 that it should have been made to follow. 



It consists of three genera of freshwater Alga, Cladophora 

 Kiitzing (a genus synonymous with my genus Microspora), 

 Coleochcete, and Lyngbya. 



In the species of this family we have no union and inter- 

 mingling of the contents of two cells, but each cell contains 

 all the requisites for the perpetuation of the species, viz. 

 zoospores and the fertilizing vesicles. 



When the zoospores have been fertilized, the cells swell 

 up, the increase in the size of the cells being determined by 

 the developement of the zoospores, and which developement 

 proceeds to such an extent as to occasion the rupture of the 

 membranes of the cells, the zoospores escaping through the 

 apertures thus formed. 



This inflation of the reproductive cells of the branched 

 Conferva and of the Lyngbya does not appear to have been 

 noticed by any other observer save Vaucher, and by him only 

 in the Batrachosperms ; and yet it is of frequent occurrence, 

 and affords a character whereby species may be often dis- 

 tinguished from each other, although at the same time it 

 changes the ordinary appearance of the species so much as to 

 lead sometimes to the description of specimens so altered as 

 distinct species ; and this has doubtless been the case with 

 Conferva fracta of the " Flora Danica," which is C. crispata 

 in a state of reproduction. 



The species of this family are for the most part attached, 

 and present the double mode of growth described in the In- 

 troduction, viz. that of longitudinal and lateral developement 

 of the cells. 



