VAUCHERIA 317 
but there are a number of species living in fresh water and some 
on moist shaded soil. 
Vaucheria. — Vaucheria (Fig. 272) is one form of the Sipho- 
nales that is common in fresh water and on moist shaded soil. 
The long filaments, usually much coarser than those of Spiro- 
gyra and usually branched, interlace and form felt-like masses, 
on which account Vaucheria is often called Green Felt. The 
green or yellowish green felt- 
like mats of the species grow- 
ing on moist soil are common 
in flower pots andon and under 
the benches in greenhouses. 
Other species are common in 
ponds and sluggish streams. 
Vaucheria forms zodspores 
and heterogametes. In form- 
ing a zodspore a portion of pro- 
toplasm at the end of the fila- 
ment is cut off from the rest 
by across wall. This severed 
mass of protoplasm escapes 
from the filament as a multi- 
nucleate and multiciliate zo- 
ospore, large enough to be seen Fic. 273. — Botrydium granulatum. 
with the naked eye. After atthe left, the vegetative plant body, 
swimming about for a time showing the root-like projections be- 
the zodspore comes to rest and low and the balloon-like top above 
elongates into a new filament. round; at the right, a plant in which 
. zoospores have formed and are escap- 
Sexual reproduction shows ing; between the enlarged plants, 
advancement in that the plants about natural size. Drawn with 
gametes are borne in well-de- modifications from Wolle. 
fined sex organs, which are 
special structures for bearing sex cells. The odgonium, oval in 
shape, bears one large egg, and the antheridium containing many 
sperms is near it and is the end cell of a short curved branch. The 
sperms escape, reach the egg through a special opening in the 
oégonium, and one of them fertilizes the egg. The heavy-walled 
odspore upon germination forms a new filament directly. 
There are, however, some Siphonales in which sexual reproduc- 
tion is of asimpler type. For example, in Botrydium (Fig. 278), 
