174 PHYLUM II. CHLOROPHYCEAE 
producing 4-ciliate zoospores, or 2-ciliate gametes. The 
irregularly tubular Enteromorphas resemble the Sea 
Lettuces and are common in brackish ponds. 
245. In the Oedogoniums (Oedogoniaceae) the plants 
are attached below, and are simple or branched above. 
They propagate by means of multiciliated zoospores which 
are formed singly in the cells, and generate by hetero- 
gametes, consisting of small multiciliated sperms, and 
large non-ciliated eggs. The sperms are 
formed (1) in certain cells in the filament 
which produces the eggs, or (2) in some- 
what smaller filaments, or (3) in very 
small, few-celled filaments (“dwarf males’’). 
The eggs are formed singly in oogones that 
Row are merely transformed and considerably 
" enlarged vegetative cells. When the egg 
reaches maturity the oogone wall opens to admit the 
sperm, after which the egg becomes a thick-walled rest- 
ing spore. In germination the resting spore divides into 
four multiciliated zoospores which soon come to rest and 
develop into ordinary vegetative filaments. 
246. The little Disk Algae (Coleochaetaceae) are minute 
branching plants closely related to the Oedogoniums, 
whose radiating filaments usually fuse later- 
ally into small disks or cushions, a milli- 
meter or so in diameter, and occurring on 
the stems and leaves of larger water plants. 
They propagate by biciliated zoospores 
formed singly in the cells, and generate by 
heterogametes. ‘The biciliated sperms are 
formed singly in the antheridial cells. cocaine. 
The oogones are terminal and each contains 
a single egg, and is supplied with a tubular prolongation, 
the “trichogyne.”’ 
