78 



Scanning Electron Microscopy 



Spores from a suspension in deionized water were attached 

 to carbon-stabilized, formvar coated grids with polylysine 

 (Mazia et al. , 1975), fixed overnight in buffered 1% osmium 

 tetroxide, and dehydrated in 2 , 2-dimethoxypropane. Specimens 

 were critical point dried, sputter coated with palladiiim- 

 gold, and examined in a Hitachi H-6010A high resolution 

 scanning electron microscope at an accelerating voltage 

 of 50 kV. 



Results 



Jouvenaz and Hazard (1978) were correct in their state- 

 ment that B. dimorpha has two sequences of merogony; however, 

 I am now convinced that these cells are diplocaryotic and 

 bidiplocaryotic , rather than uninucleate and binucleate. 

 The cells of the first merogonic sequence are very small, 

 and their compact nuclei are very closely appressed; the 

 cells of the second merogonic sequence are larger, and their 

 nuclei are rather diffuse. The diplocaryotic condition 

 of these nuclei is not readily apparent, and the published 

 diagrammatic life cycle adequately reflects their appearance 

 in stained smears. 



Jouvenaz and Hazard also stated that the surface of 

 both spores is smooth. This is correct only with respect 

 to the NMB spore (Figs 28 and 30). The surface of the MB 

 spore has a reticular pattern of ridges that are evident 



