Classification of Green Alga. 167 
Family Qldogoniachaf.. 
Thallus fixed, consisting of simple or branched filaments 
uninucleate cells. Cell division accompanied by the intercalation of a 
new piece of membrane to form the side wall of the upper danghtcr-ccll, 
giving rise to the characteristic “capping” of the upper cell. 
Chromatophore consisting of parietal, anastomosing longitudinal 
bands, which may fuse to form a continuous parietal layer. Pyrenoids 
one or more. 
Reproduction by Stephanohontan zoospores, each produced singly 
from a vegetative cell, and by oogamy. 
Genera. 
1. CEdogonium. Link, 1820. 
Thallus an unbranched filament, fixed by a special 
basal cell. All cells, except the basal, capable of 
division. End cell of the filament sometimes 
becoming a hair-cell. 
Reproduction by zoospores and by oogamy, the 
antheridia, producing Stephanokontan antherozoids, 
either formed directly from vegetative cells, or 
in minute few-celled plants (dwarf males), which 
arise from special Stephanokontan swarmers 
(androspores), themselves produced from vegetative 
cells. The round or elongated oogonia develop from 
newly iormed vegetative ceils by swelling, contain a 
single egg-cell and open by a lateral pore or by a lid. 
Germination of zygote gives rise to zoospores, each 
of which forms a new vegetative plant. 
2. Bulbochcete. Agardh, 1817. 
Thallus a fixed, repeatedly branched filament, each 
branch terminating in a long sheathed bulbous hair¬ 
cell. The basal cell of each branch is alone capable 
of adding cells to its branch by division; each newly 
cut-off segment functions in its turn as the basal cell 
of a new branch, and grows out to form first the 
terminal hair-cell and then the vegetative cells. Cell 
division and reproduction as in CEdogonium. 
3. CEdocladium. Stahl, 1891. 
Thallus terrestrial, consisting of a creeping filament 
bearing aerial assimilating, and subterranean colour¬ 
less absorptive branches (“ rhizoids”). Cell-division 
almost confined to the apical cells of the branches. 
Intercalation of new membrane at cell-division as in 
CEdogonium. 
Reproduction by Stephanokontan zoospores, and by 
uni- or multicellular bulbils (specialised akinetes) 
borne as branches of the subterranean “rhizoids.” 
Gametes unknown, 
