654 AQUATIC PHYCOMYCETES 



sparingly septate hypha, with rhizoids. Hypha 4-15 \x thick, swelling at 

 more or less regular intervals to form zoosporangia or resting bodies 

 connected by narrow one- or two-celled isthmuses and thus catenulate. 

 Zoosporangia pyriform or subpyriform in fluke eggs, 25-36 x 38-71 \l 

 or considerably smaller when crowded, emergence papillae 5-8.6 x 8- 

 several hundred microns long, connecting isthmuses 5-5.4 x 4-14 u.; 

 in nematodes zoosporangia oval or elliptic, 9-20 x 12-34 u., the emer- 

 gence papilla only projecting through the nematode skin ; on liver agar 

 zoosporangia subglobose with very long emergence tubes, up to a mm. 

 long; zoospores completely formed within the sporangium, usually 

 showing rocking motion before discharge; first spores usually emerging 

 to form a spherical mass enclosed by a gelatinous substance at the tip; 

 this gelatinous envelope soon dissolves and the first spores swim away, 

 the rest of the spores swim away as soon as they reach the exit, or first 

 spores may swim away immediately; zoospores 3.8-5.4 x 6.7-8 \x 

 tapering toward the anterior end, with 3-4 anterior fat (?) globules, a 

 distinct nuclear cap and nucleus to one side of which is a side body 

 and several fat ? globules; with one posterior whiplash cilium; rounding 

 up and encysting before germinating, 4.6-5.4 ;j.; germinating in water 

 or nutrient agar by sending out a delicate rhizoid and then forming a 

 tubular growth from the opposite pole, which may form a dwarf spo- 

 rangium with a small, sterile basal part, or may grow into a new myceli um 

 if sufficient food is available [on fluke eggs, zoospore leaves empty cyst 

 on outside of egg membrane (Butler and Buckley, 1927)]. Resting bodies 

 formed on nematodes, fluke eggs, leaf tissue, and nutrient agars; formed 

 within zoosporangial membrane and conforming somewhat to its shape, 

 resting spore protoplasm retreating from the old sporangial wall and 

 forming a new thick pale brownish wall of its own; on nematodes oval 

 or oblong ovate, 16-18 x 20-33 u., in fluke eggs spherical, subspherical, 

 ovoid or irregular in shape, 21-42 \x when spherical, 20-33 x 40-55 \x 

 when subspherical; on boiled leaves spherical, pyriform, lobed, or 

 cylindrical with rounded ends frequently conforming to the leaf cells 

 except for a cone-shaped part through which the emergence tube 

 sprouts, 30-50 38-100 u.; on agar spherical or subspherical, except 

 for a small or large cone-shaped elongation up to over 100 \x long, on 

 agar No. 5 1 up to 138-176 \i thick when spherical or subspherical; wall 

 1 See Couch, 1945a. 



