CHYTRIDIALES 91 



2. Swarmspores freed l>y disintegration of the sporangial wall 

 and remaining together for a time as a rotating sphere. 



20. Nowakowskia, p. 99 



B. Individual functioning as a prosporangium, its contents extruded 

 into a thin-walled vesicle in which the spores are formed. Rest- 

 ing spore formed as a result of the copulation of two individuals. 



1. Sporangiospores non-motile, germinating in the sporangium 



as in Aplanes. 



21. Sporophlyctis, p. 100 



2. Sporangiospores ciliated and escaping before germination 



22. Polyphagus, p. 100 



1. Rhizophidium Schenck (tJber Vorkommen Kontraktiler 



Zellen 1858). 



A large genus of about thirty species occurring in the water 



on algae, lower fungi, lower animals, pollen grains (Fig. 20), and 



similar substrata. A key to most of the known species is given 



Fig. 20. — Rhizophidium pollonis (A. Braun) Zopf, on pollen grains, (a) 

 Swarmsporangium and swarmspores. (6) Two resting spores and four swarm- 

 sporangia, two of which have freed their spores. {After Zopf 1888.) 



by von Minden (1911: 316). Notes of particular interest to 

 American students are given by Atkinson (1894; 1909 a), Coker 

 (1923: 186), Martin (1922), Melhus (1914 a), and Zeller (1918). 

 In the search for chytrids in algae, members of this genus are 

 more often encountered than other forms, R. globosum (Fig. 21) 

 being particularly common. 



The genus Latrostium Zopf (1894), erected on L. comprimens 

 Zopf occurring on Vaucheria, resembles Rhizophidium in the 

 form of the swarmsporangium. The statement that the cilium 

 precedes the swarmspore in swimming raises a question as to 

 the actual relationships of the form, and it is here treated as 

 doubtful (see key, p. 48). 



