-4- 

 developed. A second important problem to overcome is the lack 

 of background information about orchid viruses, most of which 

 are poorly characterized. Indeed, of the 22 viruses listed by 

 Lawson and Horst (1984), only 12 viruses have been assigned to 

 virus groups by the International Committee for the Taxonomy of 

 Viruses (ICTV) (Matthews, 1982). Finally, the resolution 

 limitations of light microscopy makes confirmation by other 

 means necessary regarding the characterization of some of the 

 inclusions observed. The lack of such information, especially 

 for orchid viruses, makes such studies a necessary contingency 

 for this type of investigation. 



