M 



W 



1/^ 



Fig. 2. Electron micrograph (72 000 x ) of a thin section in the axial plane of 

 Chlorobimn thiosulfatophilmn. The cell wall (W), which tends to appear as two 

 layers, is distinct from the cytoplasmic boundary. The "nuclear" region has a 

 low electron density and contains filaments (F) which ramify. Metaphosphate 

 inclusions (M) appear as circular areas of high electron density. The cytoplasm is 

 filled with small particles which have a maximum diameter of about 150 A. 



