play important role for disks with high content of dust decreases the luminosity of a galaxy and simultaneously increases its color index shifting the points practically along the theoretical correlation.

\[h!\] ![Diagram “$(M/L_B)_d$—$(B-V)_0$”, plotted for (a) the entire sample of galaxies and (b) for the galaxies of types later than $S0/a$. Milky Way is marked by open circle, pair members are shown by asterisks. Straight line corresponds to model relation obtained for old stellar systems with different history of star formation by Bell, de Jong (2001). Here and in other figures the error bars correspond to the errors of velocity dispersion data used to estimate the disk masses.](pic1.jpg "fig:"){width="12cm"} ![Diagram “$(M/L_B)_d$—$(B-V)_0$”, plotted for (a) the entire sample of galaxies and (b) for the galaxies of types later than $S0/a$. Milky Way is marked by open circle, pair members are shown by asterisks. Straight line corresponds to model relation obtained for old stellar systems with different history of star formation by Bell, de Jong (2001). Here and in other figures the error bars correspond to the errors of velocity dispersion data used to estimate the disk masses.](pic2.jpg "fig:"){width="12cm"}

In Fig. 1a the entire sample of galaxies with known color indices is 