16 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



long with a few small refringent granules in the 

 center or near the posterior end; flagella apparently 

 laterally inserted (?) ; zoospores active for twenty- 

 four hours or more, or rounding up and encysting. 

 Resting spores unknown. 



Parasitic in Phytophthora cryptogea and P. 

 megasperma, London, England, causing occasional 

 hypertrophy of the host sporangia and supporting 

 hyphae. 



Miss Waterhouse discovered this parasite in ma- 

 terial collected from the Hogsmill River, a Surrey 

 tributary of the Thames, and gave an excellent ac- 

 count of its development and infection of the host. 

 She succeeded in inoculating P. megasperma with it, 

 but all attempts to infect Rhiphidiiim continum and 

 R. americanum were unsuccessful. This species dif- 

 fers from R. inflata by its pyriform zoospores and 

 the fact that it causes only slight hypertrophy of 

 the host. Because of its similarity in other respects 

 to Butler's species, Miss Waterhouse, however, did 

 not diagnose it as a new species. 



Septigenous Polysporangiate Species 



R. SEPTIGENA (Fischer) Karling, I.e., p. 34. 



Rozella septigena Fischer, 1883. .Tahrb. wiss. Bot. 

 13:331. PI. 14, fig. 19; pi. 15. (Not R. septigena Cornu, 



181-2.) 



Sporangia up to 20 in a linear row in delimited 

 segments of the host hyphae, of the same size and 

 shape as the hyphal segments, with 1-2 apical or 

 lateral exit papillae. Zoospores elongately pyriform, 

 4 ii X 6-8 /x, hyaline, with a minute central refrac- 

 tive spot; shorter flagellum anteriorly attached, 

 longer flagellum lateral. Resting spores solitary in 

 segments of the hyphae or in short swollen side 

 branches or "false oogonia," spherical, 20/*, with a 

 hyaline endospore and spiny brown exospore, spines 

 2/i long; contents coarsely granular, including a 

 large refractive globule; germination unknown. 



Parasitic in Saprolegnia monoica and »S'. thureti 

 in Germany (Fischer, I.e.; Minden, I.e.) causing 

 hypertrophy and septation of the host hyphae. 



Fischer's attempts to inoculate Achlya with this 

 species failed, and he accordingly concluded that it 

 is limited in host range to Saprolegnia. His results 

 have not been confirmed experimentally. 



R. SIMULANS (Fischer) Karling, I.e., p. 34. 



Rozella simulans Fischer, I.e., p. 331 ; Minden, I.e., p. 371, 

 fig. 11a; Tokunaga, 1933. Trans. Sapporo Nat. Hist. 

 Soc. 13:25. PI. 3, figs. 13-14. 



Sporangia up to 15 in a linear row in delimited 

 segments of the host hyphae, cylindrical, barrel- 

 shaped, 25-90 ix X 60-250 /x, with 1-2 apical or lat- 

 eral exit papillae. Zoospores elongate, ellipsoidal, 



2.4 ii X 6 ix, hyaline, with a small refractive spot 

 and two unequal flagella attached at the anterior 

 end. Resting spores solitary in short swollen side 

 branches or "false oogonia," of the same size, shape, 

 content, and appearance as those of the previous 

 species ; germination unknown. 



Parasitic in Achlya polyandra and A. racemosa in 

 Germany (Fischer, I.e.; Minden, I.e.), Achlya sp., 

 in Switzerland (Mauricio, '95), and A. flagellata in 

 Japan (Tokunaga, I.e.), causing hypertrophy and 

 septation of the host hyphae. 



According to Fischer, this species is similar to R. 

 septigena and differs only by its limitation in host 

 range to species of Achlya. Subsequent workers who 

 reported its occurrence, however, did not make cross 

 inoculations but accepted Fischer's observations 

 without question. Inasmuch as Minden apparently 

 did not determine the number, relative lengths, and 

 position of the flagella of his fungus, it is just as 

 probable that the resting spores which he figured 

 relate to R. septigena as to the present species. Like- 

 wise, it is not certain that Tokunaga's species is R. 

 simulans, although the host reactions and sporangia 

 are similar. He figured the zoospores as anteriorly 

 biflagellate and narrow, while Fischer described 

 them as large and exactly similar to those of R. sep- 

 tigena with the short flagellum anteriorly and the 

 long one laterally attached. Consideration, however, 

 must be given to the difficulty of determining the 

 exact position of the flagella on active zoospores, 

 and it is possible that these differences in observa- 

 tions are due to this factor. If this species is identical 

 to R. septigena, as Fischer maintained, and will in- 

 fect only Achlya, it may possibly be a physiological 

 race of the former species. 



bibliography: woroninaceae 



Cook, W. R. I. 1933. New Phytol. 31, 133. 



, and W. H. Nicholson. 1933. Ann. Bot. 47: 851. 



Couch, J. N. 1939. Jour. Elisha Mitchell Sci. Soc. 



Dangeard, P. A. 1890. Le Bot. 3:63. 



Hartog, M. M. 1890. Rept. 6th Meeting Brit. Assn. Adv. 



Sci. 1890:873. 

 Karling, J. S. 1943. The Plasmodiophorales. New York. 

 Maurizio, A. 1895. Jahrb. Nat. Gesell. Graiibundens. 38:9. 

 McLarty, D. A. 1941. Bull. Torrey Bot. Club. 68:49, 75. 

 Petersen, H. E. 1909. Bot. Ark. 39:5. 



. 1910. Ann. Mycol. 8:494. 



Pringsheim, N. 1860. Jahrb. Wiss. Bot. 3:305. 



Scherffel, A. 1935. Arch. Protistk. 53:1. 



Smith, A. L. and J. Ramsbottom. 1917. Trans. Brit. Mycol. 



Soc. 6:331. 

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. 1889. Rev. Mycol. 11:74, 81. 



Sparrow, F. K. 1933. Mycologia, 24:373. 1933, Ibid., 



25:515. 1942, Ibid. 34: 113. 

 . 1936. Jour. Linnean Society. London, Botany, 



50: 425. 

 Valkanov, A. 1931. Arch. Protistk. 73:361. 

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