1048 AQUATIC PHYCOMYCETES 



intercalary forms with somewhat spherical sporangia indistinguishable 

 specifically from the bursiform types. 



The material Wolf (1944) doubtfully assigned to this species showed 

 considerable variability with respect to the position of the sporangia. 

 Some of them were terminal and not transversely inserted, others inter- 

 calary. They measured 87-128 [x by 20-24 \i. 



Pythiogeton autossytum Drechsler 

 J. Wash. Acad. Sci., 22: 447, figs. 1-5. 1932 



'intramatrical mycelium composed of hyphae branching mostly at 

 rather wide angles and at moderate intervals, measuring 1 .6 to 7.0 [i. in 

 diameter, each element maintaining usually a nearly uniform width 

 from origin to tip, the wider axial hyphae of straightforward course, the 

 shorter branches usually with somewhat abrupt changes in direction, 

 and often bearing appressoria in groups ol 5 to 10 or more ; the individual 

 appressorium distended clavate, mostly 10 to 13 \i in diameter and 20 

 to 30 [x in length, after functional frustration often growing out into 

 irregular processes of somewhat crescentic parts. Under aquatic condi- 

 tion extramatrical mycelium rather meager. Aerial mycelium on dry 

 substrata generally meager, arachnoid, yet often spreading rather exten- 

 sively over surfaces of adjacent bodies. 



"Sporangium terminal or intercalary, when intercalary mostly borne 

 only a short distance from the tip of the supporting filament, the distal 

 element mostly 3 to 30 \i in length remaining as an empty appendage; 

 when produced under conditions suitable for zoospore production 

 sometimes subspherical or ellipsoidal, but more often markedly ven- 

 tricose, utriform, or bursiform, with the expanded part free and its axis 

 directed athwart the axis of supporting hypha, or occasionally bilocular 

 as through fusion of two parts, either of which may be subspherical 

 or bursiform; measuring 16 to 226 ;jl, mostly 50 to 150 jx (average 96 y.) 

 in length and 1 3 to 68 \l, mostly 30 to 54 \x (average 42 \x) in greatest 

 diameter; when formed under conditions unsuitable for zoospore for- 

 mation, mostly subspherical measuring usually 32 to 51 [x (average 

 40.4 \x) in diameter. Evacuation tube arising often from position 

 opposite attachment of supporting filament and directed in approximate 



