494 AQUATIC PHYCOMYCETES 



cut off from it by a cross wall at maturity; zoospores up to several 

 hundred in large sporangia, spherical, 3.3-5 \x in diameter, with a 

 colorless eccentric globule and a fiagellum from four to six times the 

 length of the diameter of the body, emerging individually or in a group 

 imbedded in "slime" and remaining motionless for a time, movement 

 hopping, amoeboid; resting spore formed on the endobiotic system, 

 spherical, subspherical, or occasionally pyriform, 24-32.4 \i in diameter, 

 wall smooth, thick, contents with a single large oil globule, upon ger- 

 mination producing an epibiotic operculate sporangium. 



On oogonia and oospores of various species of Oedogonium, Braun 

 (be. cit.), coll. Pringsheim, Braun (1856a: 23), Kny (1871a: 870), de 

 Bary(1884: 177, fig. 76), Germany; Sorokin( 1874b: 8, pi. 1, figs. 29-40; 

 1883:21, fig. 19), Serbinov (1907:77, pi. 5, figs. 9-10), Voronichin 

 (1920:11), European Russia; coll. Haussknecht, Rabenhorst (1871: 

 17), Asiatic Russia; Tokunaga (1934b: 392), Japan; (?) oogonia of 

 Nitella tenuissima (?), Sparrow (1936a: 430, pi. 15, figs. 1-11), Great 

 Britain ; Oedogonium sp.. Lacy (1949: 136, fig. 2, C-C), India; oospores 

 of Oedogonium sp., Sparrow (Massachusetts), Sparrow and Barr 

 (1955: 554), United States. 



Since this species is the unquestioned type of the genus, although 

 apparently not the first chytrid observed by Braun (see Phlyctochytrium 

 hydrodictyi), it is of unusual importance. In it are embodied not only 

 the characters of a Chytridium, but also those which to a degree must 

 be exhibited by all "chytrids." As noted in the diagnosis of the order, 

 these center around the structure of the zoospore. 



The sporangia are extremely variable in size, a fact first pointed out 

 by Kny, who found them ranging from 11.9-100 \i high by 10.6-55 [x 

 in diameter. The more proximal portion of the rhizoidal system is 

 apparently subject to considerable variation, sometimes being evenly 

 tubular and sometimes in Kny's material expanded into an irregular or 

 rounded apophysis. Occasional septations may also occur. Observations 

 on the nature of the rhizoids are difficult within the host contents. Both 

 Serbinov and Sparrow have confirmed the fact, first noted with uncer- 

 tainty by Braun (1856a: 25), that distally the rhizoid becomes divided 

 into a number of more delicate tapering branches. 



The curious production of flamelike refractive outgrowths of the 



