PERONOSPO RALES 1049 



alignment with that filament, but at other times originating from other 

 positions; measuring mostly 3.5 to 7.0 \x (average between 5.5 and 6.0 u.) 

 in diameter, and 5 to 300 \i in length; in cases of frustration often 

 becoming septate, and discharging from a branch. Zoospores formed 

 up to approximately 100 from a single sporangium, broadly reniform, 

 the longitudinal furrow bearing the two cilia well-marked, the forward 

 end more pointed than the rounded rear end, measuring mostly 18 to 

 20 \x in length and 11 to 13 ij. in width in motile state; after rounding up 

 measuring mostly 13 to 17;jl (average 15 u.) in diameter; germinating 

 individually by the production of 1 to 4 delicate germ tubes, or giving 

 rise to a secondary zoospore after proliferating an evacuation tube 

 approximately 2 \± in diameter, and 2 to 27 (j. in length" (Drechsler, be. 

 cit.). 



On dying and decaying leaves of Typha latifolia, United States. 



Pythiogeton uniforme Lund 



Kgl. Danske Vidensk. Selsk. Skrift., Naturv. Math., Afd. IX, 6(1): 54, tig. 



28a-c. 1934 



"Hyphae about 3-5 \x thick, much branched, sometimes divided by 

 septa. Sporangia subspherical or slightly oval, 40-56 x 30-40 \l, ter- 

 minating the main hyphae or on side branches, mostly with their long 

 axis at nearly right angles to the hyphae, filled with a granulated plasma. 

 Tube of discharge about 39-70 x 5.6 \x, filled with refractive plasma 

 when young. At maturity the plasma of the sporangium passes through 

 the tube of discharge as a long flowing stream; after some time about 

 20 biciliate zoospores are differentiated. When the sporangium has 

 emptied, the walls collapse; proliferations frequent. Sexual organs not 

 observed" (Lund, he. cit.). 



On hempseed in water, Denmark. 



The sporangial stage of what is probably this species has been report- 

 ed by Waterhouse (1942: 323) from Great Britain. 



Pythiogeton dichotomum Tokunaga 

 Trans. Sapporo Nat. Hist. Soc, 14 (1): 12. 1935 

 Mycelium intra- and extramatrical, hyphae branched, hyaline, slender, 



