1018 



A Q UA TIC PH YCO M YCETES 



Fig. 84. Sexual reproduction in Pythium 



A-B. Two stages in development of oogonia and antheridia of Pythium 

 adhaerens Sparrow: A, antheridial rudiments encircling central oogonial 

 rudiment; B, antheridia delimited from their hyphae by cross walls. C-H. 

 Sex organs of Pythium angustatwn Sparrow and germination of oospore: C, 

 terminal oogonium to which is attached a cluster of diclinous antheridia with 

 their fertilization tubes piercing the contracted ooplasm: D, mature oospore 

 with one monoclinous (lower) and one diclinous antheridium persistent on 



