78 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



nia locally vesicular or paunchy ; antheridia lack- 

 ing. Oospores numerous, parthenogenetic, formed by 

 the contraction and encystment of the oogonium 

 content; spherical, 12 p, with a bright-golden, thick, 

 smooth or warty wall, and a large central refractive 

 globule ; germination unknown. 



Parasitic in the zygospores of Spirogyra sp. 

 (Pringsheim, Zopf, I.e.), Euastrum humerosum and 

 Microasterias mahabuleshwarensis var. wallichii 

 (Schultz-Danzig, '23) in Germany; Spirogyra sp. 

 in Belgium (de Wildeman, '91, '93, '95) ; S. varians, 

 S. calospora, and S. insignis in New York, U. S. A. 

 (Atkinson, I.e.), and Spirogyra sp. in Wales and 

 England (Cook, '33, '35). 



This species appears to have been described and 

 figured first by Carter ('56; pi. 9, figs. 9-10) as a 

 developmental stage of an Astasia-like flagellate in 

 the zygospores of Spirogyra, and later by Pring- 

 sheim as a species of Pythium. It differs primarily 

 from L. rabenhorstii by its shorter, thicker, more 

 crooked and irregular thallus, parthenogenetic 

 oospores, and its localization to the zygospores of 

 the host, although de Wildeman ('95) claims that 

 L. rabenhorstii also may occur rarely in zygospores 

 of Spirogyra. On the other hand, L. entophytum is 

 strikingly similar to L. gracile which inhabits the 

 same cells, and there is a strong possibility that the 

 two species may be identical. 



Pringsheim figured and described the zoospores 

 of his fungus as being formed exactly as in Pythium 

 within a definite vesicular membrane, but Cook re- 

 ported that the latter structure is missing and that 

 the extruded mass of protoplasm is naked. Atkinson 

 likewise failed to observe a membrane and reported 

 that the protoplasmic mass may float away from the 

 exit tube before cleavage. Cook further regarded 

 the contraction and encystment of the oogonium con- 

 tents as the differentiation of an egg cell or oosphere 

 as in L. rabenhorstii. 



In view of the fact that no other workers have 

 found this species in other but Spirogyra zygospores 

 it is perhaps questionable whether Schultz-Danzig's 

 fungus in Euastrum and Microasterias relates to 

 L. entophytum. His fungus may possibly belong to 

 Petersen's Mysocytium irregulare or the unidenti- 

 fied species of Lagenidium reported by de Wilde- 

 man ('95) in Euastrum oblongum. Whether Atkin- 

 son's L. americanum is identical to L. entophytum 

 or L. gracile, or distinct from both is at present 

 largely a matter of personal interpretation, but the 

 author is inclined to agree with Minden that it re- 

 lates to L. entophytum. 



L. ENECANS Zopf, I.e., p. 154. Scherffel, 1925. Arch. 

 Protistk. 52: 20. PI. 2, figs. 60-09. 



Thallus sparingly branched with short plump, 

 finger-like branches, 6-12 ft X 37-156 /x; attached 

 to host cell by infection tube; apparently continu- 

 ous, transformed completely into a zoosporangium 

 at maturity. Exit tube cylindrical, 3—6 p. X 9-36 p, 

 extending only slightly beyond the surface of the 

 host; thickened and inflated at base to form a 

 "spreading apparatus" which enables it to pass be- 



tween the valves of the host cell. Zoospores egg- and 

 kidney-shaped, elongate with a ventral groove, 

 5.7 yu X 8-12.5 p; secondary swarmers heterocont 

 with the short flagellum directed forward; vesicular 

 membrane not clearly evident. Oospores spherical, 

 18 /x, broadly oval, 15—22 /x X 20-24 p, and irregu- 

 lar with a smooth thick wall, large central refractive 

 globule, and finely granular protoplasm ; germina- 

 tion unknown. 



Parasitic in Stauroneis phoenocenteron, Cocco- 

 nema lanceolatum and Pinnularia sp., in Germany 

 (Zopf, I.e.) ; various diatoms in Belgium (de Wilde- 

 man, '93) ; Gomphonema constrictum, Cymbella 

 cymbiformis var. parva, C. gastroides, Cymato- 

 pleura solea, Stauroneis phoenocenteron, Amphora 

 ovalis, and Cocconema lanceolatum in Hungary 

 (Scherffel, '02, '25); Navicula cuspidata var. am- 

 bigna and Stauroneis phoenoceuteron in China 

 (Skvortzow, '31 ). 



Inasmuch as Zopf and none of the subsequent 

 workers except possibly de Wildeman had figured 

 this species, Scherffel was not certain that the form 

 which he found relates to L. enecans, although he 

 described it as such. 



L. PYGMAEUM Zopf, 1887. Abh. Naturf. Ges. Halle 

 17: 97. PI. 1, figs. 21-39; pi. 2, figs. 1-12. 



Thalli usually solitary, sometimes 2-4 in a host 

 cell, oval, spherical, ellipsoidal and Olpidium-like, 

 or elongate, irregular and lobed with one or several 

 short branches or protuberances ; often completely 

 filling the host cell; unicellular or dividing into an 

 antheridium and oogonium at maturity. Exit tubes 

 short, thick, tapering, and rarely branched, usually 

 extending but a short distance beyond the host cell. 

 Zoospores bean-shaped, 5 X 8 /x, tapering at the 

 anterior and more rounded at the posterior end with 

 a ventral groove and several small refractive gran- 

 ules; delimited in the sporangium, emerging in suc- 

 cession, and completing their development in an ex- 

 tramatrical vesicle ; swarming in the latter and freed 

 by its rupture ; intermittently amoeboid. Oogonia 

 oval, paunchy and slightly irregular with protuber- 

 ances ; antheridia smaller with none or fewer and 

 less conspicuous protuberances; conjugation canal 

 usually well developed. Oospores predominantly 

 spherical and oval, sometimes ellipsoidal and slightly 

 elongate, 18-29 p in diameter, hyaline, smooth, and 

 thick-walled, with a large refractive globule; germ- 

 ination unknown. 



Parasitic in pollen grains of P. sylvestris, P. aus- 

 triaca, P. laricio, P. pallasiana, Pinus sp., and Cos- 

 marium pyramidatum in Germany (Zopf, I.e.; 

 Schultz-Danzig, '23). pollen grains in Switzerland 

 (Maurizio, '95) and conifer pollen in Belgium (de 

 Wildeman, '95) and Denmark (Petersen, '09, '10). 



The author ('41) collected this species in pollen 

 of P. austriaca in New York City and succeeded in 

 transferring it to pollen of P. sylvestris, P. bank- 

 siana, P. densiflora, P. thunbergii, P. strobus, P. 

 austriaca var. nigra and hemlock. Attempts were 

 also made to infect living and killed cells of Nitella 

 fle.vilis, Char a coronata, Cladophora glomerata, 



