Classification of Green A Igce. 2 r 7 
approximately equal in length, but one directed forwards and the other 
backwards. Resting cells occur. 
Genus. 
Vacuolaria. Cienkowski, 1870. 
Cells large with numerous parietal chromatophores. The 
flagella arise in a pit at the anterior end close to which 
are two contractile vacuoles. A large non-contractiie 
sap-vacuole is often present. 
Fam. III. Ch LOROS ACC AC EAE. 
Cells predominantly non-motile and united to form a mucilaginous 
colony in which abundant cell-division takes place. In the motile phase 
(zoospore) the cells have two lateral chromatophores and two unequal 
flagella arising close to the apex. 
[This family forms a transition from the typically flagellate to the 
typically algal type, in respect of the dominance of the non-motile con¬ 
dition and the differentiation of a cell-wall.] 
Genera. 
1. Chlorosaccus. Luther, 1898. 
Colony a large mucilaginous aggregate formed by 
repeated quartering of the. constituent cells. Cells 
oval, each with a special wall which is dense towards 
the surface of the colony and thin or discontinued at 
the opposite pole. Short flagellum one-third to one- 
sixth the length of long one. 
2. Chlorobotrys. Boldin, 1901. 
Cells spherical, 2 (-8) in mucilage. Cell-walls siliceous, 
but not brittle. Life-history uncertain, neither cell- 
division nor swarmers yet observed. 
Series II. Confervales. 
Plant-body unicellular, multicellular or coenocytic. Cells strictly 
algal in organisation with several discoid parietal chromatophores. 
Reproduction by zoospores with two 'unequal flagella (the short one 
often only demonstrable by special methods); and by similar iso- 
planogametes. A pianos pc res occur in most genera. 
[Until 1898 the zoospores of genera placed in this series were 
described as having only one long flagellum, which is the appearance 
they present when alive or when killed with most reagents. In that 
year Luther proved that the zoospores of Conferva and Botrydiopsis 
possess also a second, short flagellum which had been overlooked because 
it is generally pressed against the body. This brought the Confervales 
into line with the Chloromonadales in this most fundamental character 
as well as in many others, so that their phylogenetic connection seems 
now indisputable. The zoospores of most of the genera have not jet 
been re-examined in this matter, but a second short flagellum is assumed 
to be present in all cases and also in the gametes which were previously 
described as uniflagellate. Such gametes have been observed in the 
best known genera, but to some others gametes possessing clearly two 
flagella of approximately equal length have been attributed ; this is, how¬ 
ever, not yet established beyond doubt.] 
