242 
PLANT STUDIES 
in rivers and lakes (Fig. 207). The cells are long and 
densely crowded with chloroplasts ; and in certain cells at 
the tips of branches large numbers of zoospores are formed, 
which have two cilia at the pointed end, and hence are said 
to be biciliate. 
166. Vaucheria. This is one of the most common of the 
Green Algae, found in felt-like masses of coarse filaments in 
shallow water and on muddy banks, and often called " green 
FIG. 208. Vaucheria geminata, a Siphon form, showing a portion of the ccenocytic 
body (A) which has sent out a branch at the tip of which a sporangium (E) 
formed, within which a large zoospore was organized, and from which (Z>) it is 
discharged later as a large multiciliate body (C), which then begins the develop- 
ment of a new coenocytic body (E\ CALDWELL. 
felt." The filament is very long, and usually branches ex- 
tensively, but its great peculiarity is that there is no parti- 
tion wall in the whole body, which forms one long continuous 
cavity (Fig. 208). This is sometimes spoken of as a one- 
celled body, but it is a mistake. Imbedded in the exten- 
sive cytoplasm mass, which fills the whole cavity, there are 
not only very numerous chloroplasts, but also numerous 
nuclei. As has been said, a single nucleus with some cyto- 
