112 A TEXT-BOOK OF BOTANY 
Vaucheria produces very large asexual spores. The 
tip of a branch becomes separated from the rest of the body 
by a wall (Fig. 101, A). In this improvised chamber the 
whole of the contents form a single large spore. It escapes 
into the water through an opening in the wall, (Fig. 101, B) 
and finally develops a new filament (Fig. 101, C). 
Sex organs (antheridia and odgonia) are also developed. 
In a common form of Vaucheria they appear separately on 
the side of the large ccenocytic body, and are separated 
from the general cavity by walls. The odgonium is a 
globular cell (Fig. 102, 6), usually with a perforated beak 
for the entrance of sperms (Fig. 102, /), and contains a single 
Fic. 102.—Sexual reproduction in Vaucheria: A, a single antheridial branch with 
an empty antheridium (a) at its tip, and also an oégonium (b) containing a 
heavy-walled odspore (c) and showing the beak (f) through which the sperm 
passed; B, another species, in which a single branch bears several oégonia, and 
a terminal coiled antheridium. 
large egg. The antheridium is a much smaller cell, on the 
end of a branch (Fig. 102, a), within which numerous very 
small sperms are formed. The usual escape into the water 
and entrance into the o6gonium is followed by fertilization 
(one sperm fusing with the egg), which results in an odspore. 
The odspore develops a thick wall and is thus protected until 
the next growing season (Fig. 102, c). In another species, 
