By application of minor variations in the usual method of centrifugal elutriation, we have been able to separate a nuclear suspension from rooster testes. We have obtained a population of elongated or late spermatid nuclei (98% purity), a Key terms: Centrifugal elutriation, nupopulation of round or early spermatid clei separation, rooster spermatogenesis nuclei (90% purity), and, finally, a mixed population of meiotic and pre-meiotic nuclei.