LAG ENID] ALES 991 



Careful studies of the development have been made by both Scherffel 

 and Couch. Each of these investigators noted the production of a small 

 appressorium by the infecting zoospore and the formation of a protec- 

 tive layer of callus by the host. The parasite reduces the chloroplasts to 

 a brownish residue, the cytoplasm and starch being almost completely 

 consumed. 



Lagenidium pythii Whiffen 

 J. Elisha Mitchell Sci. Soc, 62: 54, pi. 7, figs. 6-14. 1946 



"Thallus intramatrical, causing hypertrophy of the hypha of the host. 

 Zoosporangial thallus hyaline, smooth-walled, spherical to pyriform, 

 16-25 [jl in shortest diameter. Zoospore [cleaved out within the sporan- 

 gium] ovoid, 2.1-2.8 >: 3.5 4.2 \x, isocont, encysting on surface of the 

 host hypha and discharging contents into the host through an evanescent 

 penetration tube. Antheridial cell smooth-walled, spherical to ovoid, 

 8-13 [jl in shortest diameter. Oogonium spherical to ovoid, smooth- 

 walled, 12-23 (j. in shortest diameter. Oospore spherical, smooth- 

 walled, 7-15 [j. in diameter/' (Whiffen, he. cit.). 



Parasitic on Pythium sp., Cuba. 



Whiffen was impressed by the great similarity of Lagenidium pythii 

 to a species of Olpidiopsis, specifically in its possession of a simple 

 thallus, endogenously formed zoospores, and lack of fertilization tube 

 in the antheridial cell. She says (op. cit., p. 56), "If the oogonium of 

 this species were to be filled completely by its oospore, then the resting 

 body in its form and simplicity would be indistinguishable from the 

 typical resting body of Olpidiopsis. One is thus led to believe that L. 

 pythii may be a transitional form connecting Olpidiopsis and Lageni- 

 dium.'''' 



Lagenidium destruens Sparrow 



J. Wash. Acad. Sci., 40: 54, figs. 15-24. 1950 



(Fig. 82 A-E, p. 1004) 



Thallus consisting of a complex of short, finger-like, irregular and 

 contorted branches of variable size which may fill the strongly hyper- 



