960 



AQUATIC PHYCOMYCETES 



Fig. 76. Olpidiopsidaceae 



A. Pseudosphaerita euglenae Dangeard in Euglena, parasitized host con- 

 taining mature sporangium; to the right are two zoospores, enlarged, showing 

 their hifiagellate nature. B. Olpidiopsis gracile (Butler) Karling on Pythium 

 intermedium, mature sporangium, with four discharge tubes and a resting 

 spore, within hypertrophied part of host. C. Petersenia pollagaster (Petersen) 

 Sparrow, empty sporangium with three discharge tubes. D-I. Petersenia lobata 

 (Petersen) Sparrow in the red seaweed Spermothamnion: D, portion of frond 

 of host showing thalli of fungus in various stages of development; E-G, empty 

 sporangia within host showing various types of lobulations; H, discharging 

 zoosporangium (zoospore at left is a free-hand enlargement); /, tetraspores 

 of host containing nearly mature sporangia of parasite. 



(A, Dangeard, 1933; B, Butler, 1907; C-I, Sparrow, 1934c) 



