CHYTRIDIALES 569 



lateral place of attachment on the sporangium wall; zoospores spherical 

 or somewhat elongate, 3-5 \x in diameter, posteriorly uniflagellate, with 

 a colorless centric globule, escaping upon the dehiscence of an oper- 

 culum 7 [x in diameter and forming for a few moments at the orifice an 

 ellipsoidal motionless mass; resting spore spherical, 20-35 \l in diameter, 

 with a smooth faintly brownish wall 2.5-3 [i. thick, contents with a large 

 central and several small peripheral globules, germination not observed. 



Weakly parasitic or saprophytic in Cladophora sp., United States; 

 vegetable material, Shanor (1944: 331), Mexico; saprophytic on grass- 

 leaf bait, from soil, Sparrow (1952b: 69), Cuba. 



Resting spores were found in abundance in old cultures in dead 

 Cladophora. These were associated in filaments with the nonsexual stage 

 and were even formed inside evacuated sporangia. 



Karling (1937a) has identified the species with one found by him that 

 is saprophytic in various algae and cysts of monads, and considers both 

 to be identical with Rhizophlyctis operculata de Wildeman and Ento- 

 phlyctis maxima Dangeard. On the basis of the sporangial stage alone 

 this is justifiable. In Karling's fungus, however, the spherical, ovoid, or 

 slightly ellipsoidal resting spores are 4.5-18 y. in diameter or 5 by 7 to 

 12 by 16 [j., and the wall is predominantly rough or warty, only occasion- 

 ally smooth (Hillegas, 1940). In Endochytrium ramosum, on the other 

 hand, the resting spores are spherical and larger (20-35 [z), and the wall 

 is always smooth. Since the character of the wall of the resting spore is 

 ordinarily remarkably constant in a particular species of chytrid and, 

 indeed, in the Phycomycetes as a whole, variation in this respect is 

 unusual and worthy of further study. 



To which of these two fungi de Wildeman's Rhizophlyctis operculata 

 belonged is problematical, since only the sporangia were found. The 

 same may be said of Dangeard's Entophlyctis maxima, which Karling 

 considers synonymous with de Wildeman's and his own fungi. 



Endochytrium operculatum (de Wild.) Karling 

 Amer. J. Bot., 24: 353, figs. 1-53. 1937 



Rhizophlyctis operculata de Wildeman, Ann. Soc. Beige Micro. (Mem.), 



19: 108, pi. 4, figs. 1-9. 1895. 

 (?) Entophlyctis maxima Dangeard, Le Botaniste, 24: 242, 1 fig. 1932. 



