602 AQUATIC PHYCOMYCETES 



irregularly lobed holdfast which anchors the plant to the outer surface 

 of the substratum, mature thallus polycentric, eucarpic, hypha-like 

 consisting of the holdfast, main axis, and two dichotomously branched 

 secondary axes, one of the branches of each secondary axis terminating 

 in an operculate sporangium, the other remaining sterile; zoospores 

 posteriorly uniflagellate, with a single globule, formed outside the 

 sporangium in a delicate evanescent vesicle which envelops the extruded 

 protoplasm after the dehiscence of the operculum; resting spore sur- 

 rounded by an epispore and an endospore, formed after the conjugation 

 of the tips of two short lateral opposite branches of the same thallus 

 which became walled off from the branches, germinating by means of 

 a hypha. 



On submerged cadavers of insects. 



Because of the remarkable combination of chytridiaceous sporangia 

 and zoospores (Fig. 38 A-E,) and the zygomycetous type of sexual 

 reproduction (Fig. 4 R-T), Sorokin's genus has been almost universally 

 rejected by monographers and mycologists in general. This rejection 

 has been strengthened by the lack of further observations on the organ- 

 ism. Sorokin's description and figures of the development and repro- 

 ductive processes are unusually clear and distinct, and there seems no 

 reason for doubting them. Since it is now apparent that the chytrids 

 have evolved a variety of types of sexual reproduction it is not surprising 

 to find a form having a method like that observed in another group of 

 Phycomycetes. Such parallelism is frequent in all types of biological 

 material. No one doubts the relationship of Polyphagias to the chytrids, 

 and yet it possesses an unmistakably "zygomycetous" type of sexual 

 reproduction. Such instances, however, do not mean that Polyphagus 

 and Zygochytrium are related to the Zygomycetes or are even in the 

 same line of fungous evolution. 



Repeated collections on the same substrata at the same time of year at 

 the same locality will probably result in the rediscovery of Zygochytrium. 



Zygochytrium aurantiacum Sorokin 



Bot. Zeitung, 32: 308, pi. 6, figs. 1-22. 1874; Bull. Soc. Nat. Kazan, 4(3): 12. 



pi. 2. figs. 1-22. 1874 



Thalli occurring in orange-red gelatinous masses on the surface of 



