1006 AQUATIC PHYCOMYCETES 



reaction with chlor-iodide of zinc. The protoplasm has the pale whitish 

 gleam as in the Ancylistales [Entomophthorales — Ancylistaceae]. Any 

 segment may become a sporangium. The sporangium empties its content 

 in an undifferentiated, naked mass (or sometimes several masses) 

 through a tube, the dimensions of which are 6-10 x 50-300 \x. This 

 mass becomes differentiated into a variable number of laterally biciliate 

 zoospores. Zoospores 8-9 x 9-10 \x, their movement as in Achlya but 

 rather sluggish. Monoplanetic. Sexual reproduction not observed. 



"Weakly parasitic on mosquito larvae, copepods and Daphne. Also 

 culturable as a saprophyte" (Couch, loc. cit.). 



The species is of exceptional interest, as Couch has indicated, in the 

 hypha-like nature of the thallus — resembling strongly in this an Aphrag- 

 mium type of Pythium — and in being readily cultured an a variety of 

 artificial media. He suggests that, from the character of the thallus 

 development, it is intermediate between the filamentous and nonfil- 

 amentous Phycomycetes. Observations on the sexual organs, thus far 

 not reported, will probably determine to which group it is more nearly 

 related. A highly opganized sexual apparatus — for example, an oogo- 

 nium containing periplasm and a well-defined antheridium — might 

 indicate that the species is closer to Pythium, perhaps to P. daphnidarum 

 (Petersen, 1909, 1910), than to Lagenidium. 



Infection experiments on living mosquito larvae were inconclusive 

 in demonstrating the parasitic ability of the species. 



In the course of cultural studies a mycelial sector appeared which 

 was composed of irregularly branched hyphae mostly 12 u. in diameter 

 and which formed an open ramose rather than a compact type of growth. 

 Further transfers indicated the stability of this mutant. 



The fungus termed Pythium dictyosporum by Rieth (1954: 176, fig. 8) 

 on Oedogonium more closely resembles a species of Lagenidium allied 

 to L. giganteum than a Pythium. 



Lagenidium callinectes Couch 



J. Elisha Mitchell Sci. Soc, 58: 158, pi. 18, 19. 1942 



"Mycelium developing entirely within the egg and eventually pretty 

 well filling the egg, or body of the young crab, consisting of branched 



