The Collaborative International Dictionary of English v.0.48:

Eugenesis \Eu*gen"e*sis\, n. [Pref. eu- + genesis.] (Biol.)
   The quality or condition of having strong reproductive
   powers; generation with full fertility between different
   species or races, specif. between hybrids of the first
   generation.
   [Webster 1913 Suppl.]