CHYTRIDIALES 229 



arising in empty sporangia by internal proliferation, lntramatrical 

 haustorium polydigitate or polylobate. Zoospores amoeboid upon liber- 

 ation, spherical when actively swimming, 3.7 to 3.9 u. in diameter, 

 with a single posterior flagellum 26 \x long, one posterior highly re- 



Explanation of Figure 1 7 



A. Rhizophydium karlingii, sp. nov., on U/othrix, sporangium discharging 

 zoospores. B. Rhizophydium subaugulosum (Braun) Rabenhorst, sporangium 

 with discharge papillae, resting on tip of filament of Oscillatoria. C. Rhizo- 

 phydium megarrhizum Sparrow, on Lyngbya, discharging sporangium with 

 its broad undulating rhizoid. D-E. Rhizophydium sphaerotheca Zopf: D, 

 mature sporangium with protruding discharge papillae, on pine pollen; E, 

 sporangium with two discharge papillae, on microspore of Isoetes. F. 

 Rhizophydium constantiueani Saccardo on Vaucheria, sporangium discharg- 

 ing its few zoospores. G. Rhizophydium cyclotellae Zopf on Cyclotella, 

 sporangium discharging its zoospores through two pores. H. Rhizophydium 

 asymmetricum (Dang.) Minden on Tribonema, mature sporangium. /. Rhizo- 

 phydium sp., germination of resting spore by formation of sporangium. /. 

 Rhizophydium pollinis-pini (Braun) Zopf on pine pollen, empty pyriform spo- 

 rangium above at left, resting spore below; rhizoidal system not shown. 

 K. Rhizophydium sciadii (Zopf) Fischer on Ophiocytium, mature sporangium. 

 L-M. Rhizophydium sphaerocarpum (Zopf) Fischer on Spirogyra and Mou- 

 geotia: L, empty sporangium; M, resting spore. N. Rhizophydium vermicola 

 Sparrow, on nematode, empty sporangium. O. Rhizophydium zoophthorum 

 (Dang.) Fischer on rotifer, group of sporangia on carapace. P-Q. Rhizo- 

 phydium gramdosporum Scherffel on Tribonema: P, mature sporangium; Q, 

 spiny resting spore on smooth-walled basal male cell. R. Rhizophydium mischo- 

 eocci Scherffel on Mischococcus, mature sporangium. S. Rhizophydium sim- 

 plex (Dang.) Fischer on cyst of Cryptomonas, discharging sporangium. T. 

 Rhizophydium clinopus Scherffel on diatoms, sporangium. U-V. Rhizophydium 

 goniosporum Scherffel on Tribonema: U, sporangium with opposed discharge 

 papillae; V, angular resting spore with adherent male cell. W. Rhizophydium 

 gibbosum (Zopf) Fischer on rotifer egg, maturing sporangium. X. Rhizophy- 

 dium fusus (Zopf) Fischer on Melosira, mature sporangium. Y. Rhizophydium 

 messanense Morini on Cladophora, sporangium. 



(A, Karling, 1938e; B, Braun, 1856a; C, after Dangeard, 1886a; D-E, 

 G, K, Zopf, 1887; F, after Constantineanu, 1901; H, after Dangeard, 1890- 

 91c; /, Karling, 1939c; J, after Braun, 1856a; L-M, after Zopf, 1884; N, 

 U-V, Sparrow, 1936a; O, S, Dangeard, 1889b; P-Q, Scherffel, 1925b; R, 

 Scherffel, 1926a; T, Scherffel, 1931; W, after Zopf, 1888; Y, Morini, 1896) 



