SAPROLEGNIALES 837 





or more or less simple, straight or crooked, usually tapering gradually 

 outward, more or less pointed, springing from an intricately branched, 

 in part rhizoid-like mycelium within the substratum; hyphae not septate 

 nor constricted until the approach of reproductive stages. Sporangia at 

 first terminal on main hyphae, typically long-clavate and thicker toward 

 the distal end, or at times slender-fusiform, often irregular and polymor- 

 phic in older cultures, typically proliferating within the older ones in a 

 "nested" fashion, but often also as in Achlya; at maturity opening 

 typically by an apical mouth. Spores emerging rapidly one by one 

 through pressure from within, diplanetic, at first pip-shaped with two 

 apical cilia and swimming away as soon as discharged, soon coming to 

 rest and encysting, after a few hours emerging from the cyst and 

 swimming again more actively in a somewhat kidney-shaped form with 

 two lateral cilia, finally coming to rest and germinating; gemmae (chla- 

 mydospores) of variable shape and size formed in greater or less number, 

 often in chains, after resting a few days either becoming sporangia di- 

 rectly or indirectly or sprouting into a mycelium. Oogonia terminal on 

 main hyphae or on lateral branches, or in some species intercalary 

 singly or in chains, spheric or oval or pyriform or when intercalary 

 sometimes fusiform, the wall smooth or papillate, often pitted; eggs 

 one or many in an oogonium, smooth, the protoplasm entirely surround- 

 ed by one or two layers of fatty food material (centric or subcentric), 

 undergoing a rest period before sprouting. Antheridia present or absent, 

 androgynous or diclinous, usually terminating slender antheridial branch- 

 es which are short or long, simple or branched; antheridia when 

 present often forming one or more slender tubes, these entering the 

 oogonia through thin places and reaching the eggs" (Coker and Mat- 

 thews, 1937). 



Type species: Saprolegnia ferax (Gruith.) Thuret. 



with mature oospore. P. Calyptralegnia achlyoides (Coker and Couch), Coker; 

 discharging sporangium. Q-R. Aphanomyces laevis de Bary : R, tip of spo- 

 rangium with cluster of encysted zoospores; Q, sex organs. S-U. Leptolegniella 

 keratinophilum Huneycutt : S, intricate sporangial apparatus ; T, resting spores ; 

 U, zoospores. V. Geolegnia septisporangia Couch, multinucleate spores in 

 sporangium. 



(A-B, N-O, Coker, 1927; C-K, Q, R, Coker, 1923; L-M, Couch, 1926b; 

 P, Coker and Couch, 1923; S-U, Huneycutt, 1952; V, Couch, 1927) 



