Abstract
1. Methods have been developed for the extraction and purification of bacterial basic proteins. These proteins were initially examined by a micro-method of starch-gel electrophoresis and were then characterized more fully. 2. Although it was found that most of the DNA in both Bacillus megaterium and Escherichia coli must be free from combination with basic protein, there was some evidence that a small portion might be in the form of a typical nucleohistone complex. 3. The ribosomes of both B. megaterium and E. coli were shown to contain approximately 2% of basic protein. On the basis of ultraviolet-absorption curves, partial amino acid analyses and their behaviour on electrophoresis in polyacrylamide gels, it was concluded that some of these ribosomal basic proteins may be extremely similar to typical histones. 4. These results are discussed in relation to those of other authors, and the possible functions of basic proteins present in micro-organisms are considered with reference to those that have already been proposed for the histones of higher organisms.