64 THE SAPROLEGXIACEAE 



The species has been found only a few times. Recently Hayr6n 

 has reported it from Finland and Giiumann from Lapland. Fischer 

 has a good description with measurements ('92, p. 340, fig. 52b). He 

 gives the eggs as up to a good many in an oogonium, 14-22}!, thick, round 

 or at times irregular; antheridia mostly absent, when present androgy- 

 nous or diclinous. He thinks that Lindstedt's plate 4 ('72) of an un- 

 named species is really this. For another supposed figure of this see 

 Lechmere ('na), fig. i. Lechmere found that the plant he studied formed 

 no oogonia on egg albumen. 



15. Saprolegnia asterophora deBary. Jahrb. f. wiss. Bot. 2: 189, pi. 20, 

 figs. 25-27. i860. 



Plate ig 



Mycelium extensive, but thin and delicate. Hyphae slender, un- 

 even, much or little branched, about 5-iI[jl thick, rapidly thickening 

 towards the sporangia which are typically very scarce and often entirely 

 absent in cultures on insects. They are up to 401J. thick, sub-cylindrical 

 to clavate, and proliferate from within, or rarely laterally frorn below 

 as in Achlya. Spores I4-I5'j<. in diameter, emerging and swimming 

 slowly and aimlessly in the neighborhood for two or three minutes, then 

 encysting and after a few hours emerging in the usual form and in a 

 more active state. Gemmae not abundant, often absent on insects, 

 peculiar, shaped like the sporangia or pear-shaped, tuberous, knotted, 

 etc. Oogonia numerous, usually thickly set with blunt papillae which 

 are usually 2-4;j:, rarely up to 8iJL, long; oogonia about 30-571J. thick, 

 including the papillae, most about 37-451J., borne on even more slender 

 lateral branches of small ordinary hyphae (the stalks rather long), or 

 occasionally intercalary or terminal; walls thin and unpitted. Eggs 

 one or often two, rarely three (very rarely 4 or 5 — deBary), i8-35'iA 

 in diameter, dark, often a large and a small one together; structure 

 subcentric, /. e., with the protoplasm completely surrounded by small oil 

 drops, which are in a double layer on one side and a single layer on the 

 other. Antheridial branches varying greatly in abundance, often nearly 

 absent at low temperature, appearing close to the oogonium and usually 

 from its stalk, rarely from neighboring hyphae, often branched and 

 several arising in a twiggy group, but only one or two becoming fully 

 developed. Antheridia short-tuberous or pear-shaped; antheridial tubes 

 not seen. 



Found only three times out of more than two thousand collections in 

 Chapel Hill, twice on the same day (Nos. 4 and 5, February 14, 1918) in 

 two places on New Hope Creek margin south of the Durham bridge ; again 

 in a wet weather branch in Strowd's lowgrounds, February 8, 1922. For 

 other illustrations see deBary ('81), pi. 6, figs. 18-29; Humphrey ('92), 

 pi. 17, figs. 54 and 55; Minden ('12), fig. if on p. 520; Istvanffi ('95), 

 pi. 35. figs. 19-21, and pi. 36, fig. 22. 



