PERONOSPORALES 1039 



antheridial cell only slightly swollen, clavate, mak- 

 ing moderate oogonial contact; oogonium when 

 intercalary sometimes two to rive in series, 19.6- 

 37.8 y. (av. 28.3 pi) in diameter; oospore 13.8- 



31.1 [i. (av. 24.6 a) in diameter, wall moderately 

 thick, with a single reserve globule; sporangia 

 spherical, elliptical or pyriform, 24-48 u. (av. 



38.2 jx) in diameter, terminal or intercalary, occa- 

 sionally catenulate; encysted zoospores 1 1-16 [i in 

 diameter; soil and water on plant and animal 

 substrata (Fig. 87 F) P. pulchrum Minden, p. 83m 



Antheridium typically monoclinous or diclinous 

 Antheridium one, typically sessile, arising imme- 

 diately below the oogonium, sharply incurved, 

 or sometimes two, then often of diclinous origin 

 and straight, antheridial cell swollen, making 

 narrow apical contact with base of oogonium; 

 oogonium spherical, terminal, rarely interca- 

 lary, 19.6-22.9 \l (av. 20.6 fx) in diameter: 

 oospore 14.7-18.3 [x (av. 16.3 jjl) in diameter, 

 with thick (at least 2 ;jl) wall and single globule; 

 sporangia chiefly terminal and spherical, 12- 

 28 [j- (av. 20 \j.) in diameter, or occasionally 

 intercalary and barrel-shaped, 14-17 \l, to 22.9 

 by 27.8 [x, germinating only by germ tubes (Fig. 



87 H) P. ultimum Trow, p. 86m 



Antheridium one to six, typically stalked mono-and 

 diclinous, when monoclinous arising some 

 distance below oogonium not immediately 

 adjacent to it, crooknecked, clavate, the apex 

 obtuse, narrowly applied to the oogonium; 

 oogonium spherical, 15-28 |x (av. 21 ;x) in 

 diameter, terminal or intercalary; oospore 

 12-20 \x (av. 17 [x) in diameter; sporangia 

 spherical to oval, terminal or intercalary, 15- 

 26 [x (av. 19 [x), germinating by germ tubes or 

 zoospores; in soil (Fig. 87 G) 



P. debaryanum Hesse, p. 98m 



Oospores typically several in an oogonium, aplerotic, 10.5- 

 29.4 [x (av. 21.6 jx) in diameter, with moderately thick 

 smooth wall; antheridia monoclinous and diclinous, 

 one to several, usually two, stalk of variable length, 

 antheridial cell clavate to swollen, closely to moder- 



