448 Hartog. — The Alleged Fertilization 
The c sexual * reproduction in the Saprolegnieae is briefly 
this : — The hyphae swell into rounded enlargements, which 
become partitioned off ; these are the ‘ oangia.’ The proto- 
plasm in these oangia aggregates into rounded masses, the 
oospores, which, instead of escaping like the zoospores, round 
off, become invested with a thick laminated cell-wall within 
the oangium, and remain for a long time in a resting con- 
dition. This is complicated by the fact that in most, but not 
all the forms, smaller hyphae, which we may call ‘ male ’ 
hyphae, grow into contact with the oangia ; and the dilated 
end of the male hypha is shut off as an ‘ antheridium 5 by 
a septum closely attached to the oangium. On the loss of 
turgor by the oangium,, the antheridium emits tubes which 
grow from the antheridium into the cavity, and press closely 
against some or all of the young oospores, without contracting 
any permanent adhesion to them, as may be clearly seen when 
the laminated wall is formed round the oospores. On com- 
parison with allied forms the tubes appear clearly identical 
with the fertilizing tubes of the Peronosporeae, and may 
receive the same name. 
We have first to consider the appearances in the maturing 
oangium. In this a central vacuole is established, if not 
already present at the moment of closure and septation ; 
and vacuoles appear at fairly regular intervals in the peri- 
pheral protoplasm, which disappear by opening into the 
central cavity, as I showed, so that the layer of plasma is 
gradually and steadily thinned down. At the commence- 
ment it is multinucleate ; and as the plasma shrinks the 
nuclei are brought closer to one another ; in Achlya they 
may be seen approximated in files ; and their total relative 
number now steadily decreases. At the same time they 
show changes of form and structure ; many are seen to 
become ovoid, instead of spherical or lenticular. Again, at 
first the staining material of the single central nuclein-mass 
is in the form of a fairly large central body suspended by 
threads of linin ; but as the process goes on its size diminishes 
and several are seen in each nucleus ; in the oval nuclei we 
