抄録
When black-headed Munia, Munia malacca malacca, were subjected to different photoperiods, testes started developing practically immediately under constant short (8 or 9 hrs.) days, but after a delay of three months under long (15-hr.) photoperiod. Under both the photoperiods, gonads were maintained permanently in a full breeding condition. Under natural photoperiod, tests began to grow six months later than those of short-day brids and attained their maximal size four months after their recrudescence. However, thereafter they showed a rapid regression in size.
It is suggested that while day-length may induce gonadal development, in nature, some other environmental factor (s) is responsible for bringing about annual gonadal regression.
