One of the major distinctions between bacterial and eukaryotic genetics stems from the bacteria's lack of membrane-bound organelles (this is true of all prokaryotes.
The differences in morphology and other properties were attributed by Nageli in 1877, to bacterial pleomorphism, which postulated the existence of a single, a few species of bacteria, which possessed a protein capacity for a variation.
With the development and application of precise methods of pure culture, it became apparent that different types of bacteria retained constant form and function through successive generations.
[1] In transformation, a cell takes up extraneous DNA found in the environment and incorporates it into its genome (genetic material) through recombination.
Other elements, however, may be viewed as bacterial parasites and conjugation as a mechanism evolved by them to allow for their spread.