PLATE io 
Photomicrographs of Phytophthora parasitica var. rhei. 
A. —(Center) oospore, with focus on stalks of antheridium and oogonium. 
B. —Same with focus on oospore wall. 
C. —Another oospore, showing attachment of the oogonium and its relation to the 
antheridium. 
D. —Another oospore. 
E. —A sporangium, showing granular protoplasm and papilla. 
F. —A laterally attached chlamydospore. 
O.—An intercalary 1 sporangium. 
H. —A sporangium killed with osmic acid fumes just before emergence of the zoo¬ 
spores would have taken place. After killing the slide was treated with chloroiodid 
of zinc, which stained the walls a light blue and the protoplasm yellow. Note the 
cleavage at this stage into distinct individuals. The papilla also is clearly shown. 
I, J.—Intercellular hyphae and cell wall penetration. Note in both the slender 
hypha at point of penetration and enlargement afterward. J shows what appears to 
be a typical haustorium. 
K, L, M.—Various stages in zoospore germination. 
