Fig. 1. Portion of a large mononuclear cell in a 14-day myeloid leukaemia spleen culture in 

 the second passage generation. Large numbers of virus-like particles (V) are present at the 

 outside of the cell, and an increased number of granular bodies (GB) are present in the 

 cytoplasm, one of which contains a similar particle (V^). (P = plasma membrane; F = fat 

 bodies.) x 30,000. (From Parsons et al., 1962.) 



Fig. 2. Part of another large group of particles found in the same tissue culture as shown in 

 Fig. 1. The outer membrane is 35 A thick and appears single when sectioned normally (Mi). 

 In other particles it appears double (M2), but this may be due to oblique sectioning and to the 

 thiclmess of section. The dense centre (N) appears to have no definite membrane and to 

 contain filaments (F) of 40 A diameter and fibrils of 20 A diameter (indicated by arrow). 

 X 240,000. (From Parsons et al, 1962.) 



