A formalism introduced previously is used to calculate the shape of an absorption line in a gas, considering the "resonance" interaction between like atoms. The most serious approximation is the neglect of the effect of translational motion. An asyrnmetric line is obtained, with the maximum shifted slightly toward the red. Some simple classical considerations agree qualitatively with the results. Various properties of the line shape obtained are discussed. The neglect of translational motion makes it impossible to compare the results with experiments performed up to the present time. (auth)