$\eta$ and ${\eta }^{\prime }$ Production in $e^{+}{e}^{-}$ Annihilation at 29 GeV. Evidence for the $D_s^{}{}_{}{}^{\pm }$ Decays into $\eta {\pi }^{\pm }$ and ${\eta }^{\prime }{\pi }^{\pm }$

$\eta$ production has been investigated by the Mark II collaboration at the SLAC $e^{+}{e}^{-}$ storage ring PEP. $\eta$ particles are reconstructed by their $\gamma \gamma$ decay mode. The $\eta$ fragmentation function has been measured and found to be in good agreement with the Lund-model prediction. ${\eta }^{\prime }$ production has been measured for the first time in high-energy $e^{+}{e}^{-}$ annihilation. There is evidence at the $3\sigma$ level for $D_s^{}{}_{}{}^{\pm }$ decay into $\eta {\pi }^{\pm }$ and ${\eta }^{\prime }{\pi }^{\pm }$.