Crystal violet binding capacity and the Gram reaction of bacterial cells.

Kennedy and Barbaro (1953) presented data suggesting that crystal violet adsorption values correlated directly with the gram staining character of bacterial cells, and implied that such quantitative dye uptake studies might prove a basis for a much needed quantitative index of gram positivity. Their results are consistent with a popular theory of the mechanism of gram differentiation presented by Steam and Steam (1926). In a previous paper, the authors (Finkelstein and Bartholomew, 1953) presented a colorimetric method for measuring the maximum dye uptake of bacterial cells. This method then was used to determine whether or not a correlation existed between the gram reaction and dye uptake. The conclusions to be presented here, however, differ from those of Kennedy and Barbaro (1953).