SAPROLEGNIALES 



159 



members of the family (reaching four microns), and is prom- 

 inently pitted. The antheridial branches arise immediately 

 below the oogonium, or if the oogonia occur in chains, as is fre- 

 quently the case in A. androgynus, then the antheridial branch 

 arises near the top of one oogonium and applies itself to the 

 next one above. Since a fourth species, Saprolegnia hypogyna 

 Pringsheim, with a similar sexual stage is retained by Coker in 



Fig. 55. — (a-c) Aplanes androgynus (Archer) Humphrey, (a) Tip of oogon- 

 ium showing single germinating oospore. (6) Two oogonia with oospores and 

 pitted wails; antheridial branch in each case attached to the cell beneath, (c) 

 Sporangium in which sporangiospores are germinating in situ; and two oogonia 

 each accompanied by an antheridial branch, (d) Aplanes treleasanus (Hum- 

 phrey) Coker. Oogonium, oospores, and antheridial branches, {a-c, after 

 deBary 1888; d after Coker 19-23.) 



Saprolegnia on the basis of sporangial characters the status of 

 the genus Aplanes would seem to be doubtful at best. Coker 

 states in the case of A. treleaseanus, that though the sporangio- 

 spores usually germinate in situ by tube, they sometimes emit 

 swarmspores as in Achlya or more rarely as in Dictyuchus. Fur- 

 ther investigation of the sporangial stage of the species incorpo- 

 rated in Aplanes is desirable, and may result in the abandonment 



