186 



AQUATIC PHYCOMYCETES 



Fig. 15. Achlyogetonaceae 



A-B. Achlyogeton entophytum Schenk in filaments of Cladophora: A, thal- 

 lus, showing segmentation into a linear series of zoosporangia; B, discharged 

 zoosporangia with clusters of encysted zoospores at orifices of discharge 

 tubes; in left-hand cluster zoospores are all encysted, in middle one they 

 are emerging from cysts, and in right-hand group all but one have emerged, 

 leaving the empty cysts behind. C-H. Septolpidium lineare Sparrow in dia- 

 toms: C, discharge papilla just before moment of discharge; D, first zoospores 

 emerging en masse; E, zoospores swimming directly away from sporangium; 

 this behavior is not usual, but is occasionally observed; F, immature thallus 

 in diatom, showing progressive segmentation of tubular body into sporangia; 

 G, group of sporangia produced from single thallus; sporangium on left has 

 formed a papilla; remainder have discharged their zoospores, which form 

 motionless clusters at orifices of discharge tubes; //, chain of empty sporangia. 

 / ./. Bicricium in algae and eelworms: /, Bicricium transversum Sorokin, 

 two-linked thallus in Cladophora; a resting structure is present in one seg- 

 ment; J, Bicricium lethale Sorokin, two pairs of empty sporangia in body of 

 eelworm. 



I I fi, Schenk, 1859a; C-H, Sparrow, 1936a; I-J, Sorokin, 1883) 



