[Evidence of a circadian sequence of photogonadsensitivity in the ferret].

Using "skeleton" photoperiods with a primary photofraction of 3 hrs. 30 min. and secondary photofraction of 30 min. located at various intervals after the onset of darkness, the occurrence of a photoinducible phase in the androgenic function has been evidenced in the Ferret. This photo-inducible phase seems to be located around 12 hrs. after the onset of the primary photofraction, since the ferrets who received the 30 min. photofraction 8 hrs. after the onset of darkness responded with a maximal increase in plasma testosterone.