PERONOSPORALES 1037 



16.2-23 \j. in diameter, wall 3 u. thick; sporangial appa- 

 ratus consisting of feebly inflated elements and discharge 

 tube; zoospores 8.1-10 <j.; on animal substrata bait, 



saline soil P. aquatile Hohnk l 



Wall of oogonium spiny, spines slightly tapering to a blunt apex, 

 terminal, occasionally intercalary, spherical to subspherical, 

 body 25-40 \x (mean 33 \£) in diameter; oospore aplerotic, 20 - 

 34 a (av. 29.5 <x) in diameter, wall moderately thick; anther- 

 idia diclinous, one to three, usually on a single stalk, rarely on 

 two stalks, the stalks intricately involved with oogonium; 

 antheridial cell oblong clavate, markedly lobed, making 

 broad ventral contact with the oogonium; sporangia interca- 

 lary, rarely terminal, the basal digitations often aggregated 

 into massive complexes, in old cultures the contents retract- 

 ing to form thin-walled resting spores; zoospores 8-11 by 

 9-10 \j. when swimming, 8-10 a when encysted; in water 



P. periplocurn var. coimbatorensis Balakrishnan 2 

 Sporangium spheroidal 

 Sex organs present 

 Oogonium wall smooth 

 Oospore wall smooth 

 Oospore plerotic 



Sporangium producing zoospores, not proliferating 



Antheridia single, rarely two, monoclinous, originating 

 in close proximity to the oogonium, crooknecked or 

 sometimes reduced to a hypogynous cell or short 

 lateral process, fertilization tube short and stout; 

 oogonium typically intercalary, 13-29.4 \i (av. 21 \i) 

 in diameter; oospore with a moderately thickened 

 wall, 12-27 [j. (av. 20 |x) in diameter; in soil 



P. rostratum Butler, p. 71m 

 Antheridia single or several, monoclinous or diclinous, 

 arising from the oogonial stalk and from the oogo- 

 nial hypha, the antheridial branch sometimes encir- 

 cling oogonium which is smooth, 16-21 \i in diam- 

 eter; oospore thin-walled, 14.9-17.6 [t in diameter; 



in saline soil P. salinum Hohnk 3 



Sporangium producing only hyphae, never zoospores, ter- 

 minal or intercalary, globose, ellipsoidal, or pyriform, 

 18-41 [j. in diameter; antheridia one to four, clavate, 



1 Veroff. Inst. f. Meeresforsch. Bremerhaven, 2:94, rig. 4. 1953. 



2 Proc. Indian Acad. ScL, Sect. B, 28: 31, fig. 3. 1948. 



3 Veroff. Inst. Meeresforsch. Bremerhaven, 2: 89, fig. 7. 1953. 



