The Mesosome of Bacillus Subtilis as Affected by Chemical and Physical Fixation

The reliability of structures observed with electron microscope techniques represents a general problem in ultrastructure research . Obviously, every technique employed will have its limitations . Unfortunately the limitations are incompletely understood, and the eventual image obtained by electron microscopy deviates to an unknown extent from reality . The experimental approach to this problem is not an easy one . However, the effects of chemical fixation on the preservation of ultrastructure can, within limits (9), be studied by means of freeze-fracturing. In previous studies (8, 9) some of these effects were studied on young cells of Bacillus subtilis, strain Marburg . Freeze-fracturing after chemical fixation according to the Ryter-Kellenberger tech-