Fig. 13. Sections of Chlorobium limicola strain R grown at low light 

 intensity. The median section at the lower right shows clearly the com- 

 plex wall (w), with its rod-shaped extensions and the cell membrane 

 (m) of this organism. The large oblong chlorobium vesicles (Cv) sur- 

 rounded by an electron-dense membrane are clearly seen in the me- 

 dian section. Their general distribution through the cortex of the cell 

 is well shown by the tangential section at the upper right. At upper 

 left, a tangential section has passed transversely through some of the 

 rod- shaped extensions from the cell wall. Main fixation 2 hours, post 

 staining with lead hydroxide. X 135,000. 



