874 AQUATIC PHYCOMYCETES 



(1901 ; 1903), Minden (1915: 582, fig. 14b [p. 580]), Germany; Dillwyn 

 (1809: pi. 79), Great Britain; Dangeard (1 890-91 b: 118, pi. 6, figs. 

 24-31), Radais (1898: 144), Guilliermond (1922), France; Humphrey 

 (1893: 135, pi. 14, fig. 6), Coker (1923: 170, pi. 58), Kevorkian (1935: 

 pi. 19, figs. 10 a-b), United States; Tulloch (1934), Alaska. 



Numerous references are found in the older literature to ""Leptomitus" 

 one of the earliest-studied members of the water fungi, and exsiccati 

 are quoted by Minden (1915: 582). Fischer (1892: 371) has discussed 

 these older records. A careful morphological study of this species is 

 greatly needed. Kolkwitz (1903: 34), Schade (1940), and Schade and 

 Thimann (1940) have made investigations of the physiology of the 

 organism. 



APODACHLYA Pringsheim 

 Berichte Deutsch. Bot. Gesell., 1 : 289. 1883 

 (Fig. 69 C-E, G-K, p. 875) 



Thallus filamentous throughout, the hyphae constricted and pseudo- 

 septate at intervals, monopodial, often richly branched, the branches 

 arising at the constrictions, apparently without specialized holdfasts, 

 contents faintly refractive, bearing from one to three cellulin discs in 

 each segment; zoosporangia terminal or sympodially arranged along 

 the hyphae, rarely in basipetal succession, pedicellate, ovoid, pyriform, 

 or occasionally cylindrical, zoospores few, diplanetic, primary spores 

 apically biflagellate, formed in the sporangium, encysting at once at the 

 orifice after discharge or swimming directly away, secondary spores 

 laterally (?) biflagellate, emerging from the cysts after a period of 

 quiescence; oogonia borne singly, terminally or laterally, subtended by 

 a linklike antheridial cell, fertilization tube lacking; oospore thick- 

 walled, with one or more large globules, borne singly in the oogonium, 

 which it nearly or entirely fills, upon germination forming from one to 

 two germ tubes. 



The five known species are primarily inhabitants of twigs and sub- 

 merged fruits. 



The slender slightly refractive or gray lustrous filaments are readily 

 distinguishable from the coarser ones of Achlya, with which they often 

 occur. 



