LAG EN 1DI ALES 949 



fusiform or reniform, with broad rounded ends, 15-50 \x long by 5-8 u, 

 in diameter, the long axis parallel with that of the algal cell, with a 

 single lateral median (rarely otherwise placed) tapering discharge tube 

 4-6 [x long by 3-4 [i wide which, funnel-like, projects slightly extrama- 

 trically, wall thin, colorless, smooth; zoospores oval in outline, dorsally 

 arched, with hyaline plasma containing refractive granules and a bright 

 spot, 5 [jl long, with two equal, opposed flagella arising from the flattened 

 ventral surface, generally emerging from the sporangium as partly 

 formed bodies which undergo their final maturation at the tip of the 

 discharge tube, escaping rarely as distinct attenuated biflagellate motile 

 spores which encyst at the mouth of the discharge tube and after a period 

 of rest emerge from the cysts (3 [jl in diameter) as biflagellate zoospores 

 with a single globule, (shape?), 5 \i long, movement "dancing" or an 

 even swimming; resting spore spherical or subspherical, 13 \x by 10 [j., 

 lying loosely within a saclike smooth oogonium, with a thick smooth 

 colorless wall, the contents with numerous small refractive globules and 

 a single large eccentric lustrous fat body, without periplasm, germi- 

 nation not observed; companion cell elongate, saclike, or subspherical, 

 10 ij. in diameter, smooth-walled, attached to the wall of the oogonium 

 by a beaklike projection or sessile on it. 



In Oedogonium sp., Sorokin (Joe. cit.), Asiatic Russia; Oecfogonium 

 sp., de Wildeman (loc. cit.), France; Oedogonium sp., Scherffel (be. 

 cit.) Berczi (1940:80, pi. 2, figs. 2-3), Hungary; Oedogonium sp., 

 Sparrow (1933c: 516, text fig. I, 9-10), United States. 



According to Scherffel, the infecting zoospore after coming to rest 

 on the host wall forms a hemispherical appressorium, from the base 

 of which a delicate penetration tube is produced. After discharge of 

 the contents into the host the external parts of the infecting zoospore 

 disappear and the naked fungous plasma, free from the infection tube, 

 passively moves, no doubt carried by the host contents, to the vicinity 

 of the nucleus. Here it becomes surrounded by a membrane, in- 

 creases in size, and assumes an ovoid shape. In the early stages of 

 development the host cell is not appreciably altered, but, from the 

 figures given, presumably all or nearly all of the algal contents arc 

 eventually consumed. Details of the changes undergone by the fungous 

 contents, which include strong vacuolization and the formation ot a 



