THE GREEN ALGiE loi 



in many species of GLdogoniiun and in all of those of Bidbochaic), 

 which are formed from modified zoospores (androspores), settling 

 down in the immediate neighbourhood of the oogonia and pro- 

 ducing a small unicellular or few-celled plant, which gives rise 

 to a limited number of spermatozoids. These dwarf-males 

 may possibly have arisen from zoospores, forming antheridia 

 precociously (cf Eritsch 27). 



Recent advocates (Oltmanns 54, p. 13) of an Ulotrichaceous 

 affinity of the (Edogoniacese have attempted to connect up the 

 two groups by way of the rare freshwater genus Cylindrocapsa 

 (Cienkowski 14). This forms unbranched filaments (fig. 4, d), 

 the cells of which are very similar to those of an Ulothnx, which 

 Cylindrocapsa resembles also in its marked faculty of forming 

 palmelloid stages. Zoospores have not yet been observed, but 

 in its sexual reproduction Cylindrocapsa diverges widely from 

 Ulothrix, inasmuch as it is oogamous (fig. 4, d) like that of 

 CEdogonium. The spermatozoids, however, are biciliate and not 

 multiciliate like those of the latter genus. Cylindrocapsa certainly 

 helps to a slight extent to bridge the gap between Ulotrichaceae 

 and (Edogoniacese, but there are still many difficulties in the 

 way of such a connection, and for the present we must regard 

 the Stephanokontas, even if of Isokontan affinit}^, as standing 

 markedly apart from the remainder of the Isokonta?. 



Long before the division of the Akonta^ became established 

 under this name, the Conjugatae, with which they are synony- 

 mous, were separated off as a distinct group from the remainder 

 of the Chlorophyceae (Wille 6"^). The main basis for this 

 separation was the special character of the sexual process 

 (familiar to all in the case of Spirogyra) and the absence of 

 motile reproductive units of any kind, and there can be no 

 doubt that in view of these marked peculiarities such a separa- 

 tion is warranted, just as in the case of the Stephanokontae. No 

 one, however, has ever seriously suggested a distinct Flagellate 

 origin of the Akontas, and most, if not all, authorities consider 

 them to be connected in some way with the Isokonta, either 

 as a collateral group arising from the same Flagellate ancestry 

 or even branching off from the Isokontan stock itself There 

 are not very many points of analogy between present-day 

 Conjugatae and Isokontas, but the most important are the 

 similarity between the sexual process of the former and that 

 of Chlaniydomonas Braunii and some other species of the same 



