PERONOSPORALIS 1027 



turing organs, about 20 \x long by 3 u. in diameter, which arise at right 

 angles from the main hyphae, with which they are continuous, fusiform 

 nonseptate or septate gemmae, 80-100 u, by 8-10 \i, sometimes formed; 

 zoosporangium consisting of an undifferentiated portion of the myce- 

 lium and an evacuation tube, 2-3 [i wide, through which the amorphous 

 contents are discharged into a vesicle, within which three to fifteen 

 biflagellate zoospores, 5 by 3 jjl, mature; oogonium spherical, terminal 

 on a lateral branch, brownish at maturity; antheridium single, terminal, 

 clavate, diclinous; oospore single. 



A predaceous parasite of fresh-water rotifers. Sommerstorff (loc. cit.), 

 Gicklhorn (1922), Austria; Gicklhorn (op. cit.), Yugoslavia; Mirande 

 (1920: figs. 1-2), France; Arnaudow (1921: figs. 1-8; 1925: figs. 1-5; 

 1936), Valkanov (1931b; 1931c; 1932: fig. 10), Bulgaria; Sparrow 

 (1929; 1932b: pi. 8, fig. h; 1933c), Karling (1936c), Rattulus sp., Sparrow 

 (1952d: 771), United States; Barnes and Melville (1932: 94), Sparrow 

 (1936a: 465), Distyla sp., Monostyla sp., Dip'ois sp., Dip/axis sp., Prowse 

 (1954b: 137, figs. 3-5), Great Britain. 



The description of Zoophagus insidians above is drawn mainly from 

 Sommerstorff (loc. cit.) and Arnaudow (1921, 1925). A comparison of 

 the accounts of zoospore formation in this species as given by Arnaudow 

 (1921) and Gicklhorn (1922) makes it quite evident that two different 

 fungi were involved, one (Arnaudow's) with a filamentous sporangium 

 and the other (Gicklhorn's) with a globular or saccate sporangium. 

 Both produced biflagellate zoospores, it is true, but in Gicklhorn's 

 material the zoospores appeared to be formed in the sporangium before 

 discharge, whereas they were matured outside the sporangium in Ar- 

 naudow's fungus. A study of the second account by Arnaudow (1925) 

 of Z. insidians, derived from material collected in Germany rather than 

 Bulgaria, and the description of Z. tentaclum by Karling (1936c) reveals 

 a striking similarity between their two fungi with respect to the method 

 of formation and the shape of the conidia or "gemmae." Furthermore, 

 Karling states that he was unable to obtain zoospore formation, and 

 Arnaudow reports finding it in only one instance in the German mate- 

 rial. From these considerations the interesting possibility arises that 

 Karling and Arnaudow (German material) may have been dealing with 



