THALLOPHYTES : FUNGI 267 
One of the ordinary life processes which seems to be 
seriously interfered with by the saprophytic and parasitic 
habit is the sexual process. At least, while sex organs 
and sexual spores are about as evident in Phycomycetes 
as in Algae, they are either obscure or wanting in the 
Mycomycete groups. 
1. PHYCOMYCETES (Alga-Fungi) 
180. Saprolegnia, This is a group of "water-moulds," 
with aquatic habit like the Algae. They live upon the dead 
bodies of water plants and animals (Fig. 233), and some- 
times attack living fish, one kind being very destructive 
to young fish in hatcheries. The hyphae composing the 
mycelium are ccenocytes, as in the Siphon forms. 
Sporangia are organized at the ends of branches by 
forming a partition wall separating the cavity of the tip 
from the general cavity (Fig. 233, B). The tip becomes 
more or less swollen, and within it are formed numerous 
biciliate zoospores, which are discharged into the water 
(Fig. 233, (7), swim about for a short time, and rapidly form 
new mycelia. The process is very suggestive of Cladophora 
and VaucJieria. Oogonia and antheridia are also formed 
at the ends of the branches (Fig. 233, F), much as in Vau- 
cJieria. The oogonia are spherical, and form one and some- 
times many eggs (Fig. 233, Z>, E). The antheridia are 
formed on branches near the oogonia. An antheridium 
conies in contact with an oogonium, and sends out a deli- 
cate tube which pierces the oogonium wall (Fig. 233, F). 
Through this tube the contents of the antheridium pass, 
fuse with the egg, and a heavy-walled oospore or resting 
spore is the result. 
It is an interesting fact that sometimes the contents of 
an antheridium do not enter an oogonium, or antheridia 
may not even be formed, and still the egg, without fertiliza- 
tion, forms an oospore which can germinate. This peculiar 
