LAGENIDIALES 973 



Thallus uni- or multicellular, lying free in the host cell or adherent to 



the persistent penetration tube; parasites of algae, microscopic 



animals, etc. 



Thallus unbranched, occupying one cell of host, strongly constricted 



at the cross walls, segments regular, appearing linklike; anther- 



idial cell poorly differentiated Myzocytium, p. 973 



Thallus unbranched or branched, occupying one or more cells of host, 

 little or not ac all constricted at the cross walls, segments often 

 irregular; antheridial cell usually well differentiated 



Lagenidium, p. 982 



MYZOCYTIUM Schenk 



Uberdas Vorkommen contractiler Zellen im Pflanzenreiche, p. 10. Wurzburg, 



1858 



(Fig. 79 A-C, F-H, p. 977) 



Thallus endobiotic, tubular, unbranched, holocarpic, at maturity one- 

 celled or more commonly divided by transverse septa into a linear series 

 of linklike sporangia or gametangia; zoosporangium with a single 

 discharge tube; zoospores grape-seed-like, laterally biflagellate, incom- 

 pletely cleaved within the sporangium and undergoing final maturation 

 often in an evanescent vesicle at the tip of the discharge tube or occasion- 

 ally emerging completely formed; female gametangium without peri- 

 plasm, the contents after fusion with the male gamete forming a thick- 

 walled resting spore, germination not observed; male gametangium like 

 the female, conveying its contents to the female by a pore or tube formed 

 in the cross wall. 



Parasites of fresh-water algae and microscopic animals. 



KEY TO THE SPECIES OF MYZOCYTIUM 



Sporangia in regular beadlike chains, extramatrical part of the discharge 

 tube narrowly cylindrical ; in algae 

 Discharge tube narrowly cylindrical throughout. . . . M. proliferum, p. 974 

 Discharge tube with a more or less well defined swelling beneath the 



inner face of the host wall M. megastomum, p. 978 



Sporangia in somewhat irregular chains or forming an intricate com- 

 plex, extramatrical part of the discharge tube broadly conical; in 

 microscopic animals or their eggs 

 Sporangia in chains, broadly pyriform, oblong or more or less spher- 

 ical; fertilization tube formed; in eel worms . . . M. vermicola, p. 979 



