76 F. B. BANG 



Amies, 1938), it was generally accepted that they were composed of varying 

 proportions of homogeneous material in the cytoplasm and that within the 

 consequent "inclusion," numerous "elementary bodies" might sometimes be 

 identified by appropriate staining. The studies of Bland and Robinow (1939) 

 on rabbit corneal cells infected in vitro with vaccinia clearly showed that the 

 virus particles could be recognized as they developed into colonies within the 

 cell. These authors inoculated small explants of corneal epithelium with 

 purified and concentrated virus for 5 minutes, then washed away the free 

 virus. The cultures were removed at intervals, fixed with osmic acid vapor, 

 and stained with Giemsa. 



1. Identification 



In the first stage of infection, small homogeneous bodies were found which 

 varied in dimension from the size of an elementary body to that of a staphy- 

 lococcus. As many as 67 of these were found in one cell. The larger and more 

 distinctly homogeneous bodies appeared later. Small and medium-sized 

 networks then developed within the inclusions and became progressively 

 larger and more numerous during 24 hours after infection. Quantitative data 

 on the different types and numbers of inclusions prevailing at different 

 periods of infection were presented. The elementary bodies, which were 

 readily distinguishable at the start of the infection, disappeared during the 

 middle portion of the cycle and reappeared later, exclusively within the 

 large networks. Feulgen-staining characteristics were not consistent. The 

 elementary bodies were found Feulgen-negative, the inclusions Feulgen- 

 positive, and the larger networks Feulgen-negative, with deep purple rods 

 and granules within. The presence of Feulgen-positive material as part of the 

 matrix of the inclusion was also found by Matumato and Dohi (1956) in 

 ectromelia. In some cells infected with vaccinia the elementary bodies 

 appeared to be released individually from the ends of long stalks (Bland and 

 Robinow, 1939). 



Eisenberg-Merling (1940) studied the same cell system but followed the 

 development of these events in the living cells obtained by resecting bits of 

 cornea from an infected rabbit. The cells were studied under a dark field in 

 Tyrode's solution or saline. Changes were detectable as early as 24 hours 

 after inoculation. The whole surface of a cell was sometimes studded with 

 elementary bodies, which were immobile or adherent to the gel of the cyto- 

 plasm. At a later stage these seemed to be oscillating aggregations of elemen- 

 tary bodies, which were also found in rapid Brownian movement in different 

 parts of the cytoplasm. Some cells had several inclusions; the smallest either 

 contained single elementary bodies, or they were filled with dancing elemen- 

 tary bodies. Phase microscope studies of ectromelia in sarcoma cells have 

 shown similar events before cell destruction sets in (Ozaki et al., 1956). 



