Cosmic ray abundances, A$_{cr}$, are compared with those of quiescent matter in the Galaxy, A$_{g}$, for 40 nuclei from Hydrogen to Zirconium via the abundance ratios A$_{cr}$/A$_{g}$. Secondary nuclei generated by spallation reactions in the interstellar medium are removed from the analysis reducing the sample to primary nuclei. The abundance ratios of primary nuclei obey a simple rule depending on the atomic number Z, namely A$_{cr}$/A$_{g}$ = aZ$^{2}$ – b Z where a and b are numerical constants. This study suggests that the physical mechanism giving the correct, quantitative explanation of the above rule is the photoionization of the quiescent, cold interstellar matter. The ultraviolet light spectrum causing photoionization of neutral atoms is highly characteristic and concentrated in a very restricted band, namely 3-250 nm. It is argued that such an ultraviolet spectrum and the related absolute intensity can be generated by O and B stars. It is concluded that the sources of cosmic rays are located in cold zones, at adequate distances from O and B stars beyond the fully ionized Strömgren shells. Previous explanations of the universal A$_{cr}$/A$_{g}$ abundance ratios are discussed.