  We take a closer look at our published results of determination of ages,
metallicities, helium mass fractions and abundances of chemical elements in
Galactic globular clusters in order to find possible signatures of the
phenomenon of multiple stellar populations in these data. Our analysis reveals
that carbon abundances in the atmospheres of stars in the studied clusters
change gradually during their evolution. The changes of the helium mass
fraction and C, O, Mg and Na abundance anomalies caused by the effect of
multiple stellar populations on the analyzed integrated-light spectra are
detected through the comparison of our results with models of chemical
evolution and literature data for Galactic field stars.
