SAPROLEGNIALES 823 



tents by its numerous irregular refractive bodies. As growth proceeded 

 the disintegrated chloroplast material became more granular, whereas 

 the algal protoplasm assumed a vacuolate character. Coincident with 

 the increase in size of the fungus there was a strong distention of the 

 host cell accompanied by a pronounced thickening of the wall. In 

 addition, certain adjacent nodal cells were stimulated to divide, and 

 there was produced in the vicinity of the infected cell a number of curved 

 stunted lateral branches which gave a "bushy" appearance to the region. 

 Such places could easily be detected with a hand lens. Apparently, some 

 sort of substance was produced in infected cells which diffused to 

 adjacent ones and stimulated them to abnormal growth. Apical cells 

 infected with what was presumably the same fungus showed little 

 hypertrophy. 



It is not known whether the myriad of zoospores produced in a 

 single sporangium emerge by action of the flagella or are forced out. 

 Once discharged, they form a dense cloud around the infected part of 

 the filament, each spore being surrounded by an angular wall (Fig. 62 

 G, p. 821). These cystospores are not connected with one another as 

 in Eurychasma but are loosely disposed in the medium (Fig. 62 H). 

 After a varying period of quiescence the protoplasm of each of the cysts 

 emerges, probably through a small pore ; it exhibits a rocking motion near 

 the empty shell and undergoes fashioning which terminates with the 

 production of the fully formed bifiagellate zoospore. Further observa- 

 tions are needed on the orientation, length, and place of attachment of 

 the two flagella. 



The fungus is apparently a true parasite but, unlike certain other 

 marine fungi, does not seem able to continue its destruction of the alga 

 after the latter has been noticeably weakened or killed. The remainder 

 of the host plant, save in the immediate vicinity of the infected cell, 

 appears unaffected by the incursion of the fungus. 



See remarks under Olpidiopsis magnusii (p. 953), where J. and G. 

 Feldmann (1955) have segregated the fungi found by Magnus in the 

 rhizoids of Ceramium from those in the nodal and cortical cells. 



