77 



Recently I collected an undescribed microsporidium 

 (a parasite of S^. invicta in Brazil) that appears to be 

 closely related to B. dimorpha . This dimorphic species 

 also has two sequences of merogony; however, its meronts 

 are diplocaryotic. These observations and reports prompted 

 me to reexamine the life cycle of B. dimorpha , with particular 

 attention to the nuclear condition of early meronts. Addi- 

 tional studies of ultrastructure , including scanning electron 

 microscopy, were also conducted. 



The appearance of sexual castes in colonies of S. geminata 

 is seasonal (unpublished) , and Jouvenaz and Hazard were 

 unable to examine diseased sexual pupae. Spores from sexual 

 pupae have now been examined, and found to differ in one 

 "respect from spores from worker pupae. 



Materials and Methods 

 Light Microscopy 



Specimens were smeared on acid-alcohol cleaned, galss 

 microscope slides, air-dried, and fixed in acetone-free 

 methanol for 5 minutes. Slides were stained with 10% Giemsa 

 stain in phosphate buffer, pH 7.41 (Fisher Gram Pac Buffer) 

 for 12 minutes, rinsed in tap water or acidified deionized 

 water (deionized water adjusted to pH 6.8 with acetic acid), 

 blotted with filter paper, and examined under oil. 



