title: Some effects of manipulation of daily photoperiod on the rate of onset of a photorefractory state in canaries (Serinus canarius).
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D002940:Circadian Rhythm; D003624:Darkness; D008027:Light; D008297:Male; D013737:Testis / Q000033:anatomy & histology / Q000502:physiology*; D013997:Time Factors