298 Wager . — On the Structure and 
on the mycelium. Branches of the mycelium which do not 
carry oogonia apply their obtuse extremities against the 
oogonium, swell up and are cut off to form the antheridia. 
When the oosphere is formed, the antheridium puts out 
a narrow and erect tube from the middle of its face which 
is pressed against the oogonium, which perforates the wall 
of the oogonium, and traverses the peripheral protoplasm 
towards the oosphere. As soon as it touches the oosphere 
it ceases to elongate ; the oosphere becomes surrounded by 
a cellulose membrane and takes a regular spheroidal form. 
The tube put out by the antheridium must be regarded as 
a fertilizing tube, but it is remarkable that it never opens, 
effecting fertilization by contact only ; until the maturation of 
the oospore the antheridium retains the aspect which it 
presented at the moment of fertilization. 
The membrane of the oospore becomes thickened : the 
epispore is derived from the peripheral protoplasm, which 
gradually disappears, and finally there remains only a quantity 
of granules suspended in a watery transparent liquid. At the 
period of maturity the epispore is a thickened membrane, 
very resistant, coloured yellowish brown and finely punctate. 
The surface of it is nearly always furnished with brownish 
warts, large and obtuse, sometimes isolated, sometimes con- 
fluent, forming irregular crests. The warts are composed of 
cellulose and are coloured deep blue by the known reagents, 
while the membrane which carries them retains its primitive 
colour. One of the warts larger than the others forms a 
sheath around the fertilizing tube. The endospore is a thick 
membrane, smooth and uncoloured, composed of cellulose; it 
encloses a layer of protoplasm finely granular, which surrounds 
a large central vacuole. 
The conidial sporangia form zoospores. When sown in a 
drop of water so that they become soaked, they absorb water 
rapidly and swell ; an obtuse papilla is developed on one side, 
and vacuoles are formed in the finely granular protoplasm, 
which disappear later : fine lines of demarcation at the same 
time divide all the protoplasm into five to eight polyhedral 
