(1) Some factors affected to ovulation from fragments of the ovaries of spinous 10aches immersed in frog pituitary suspension during the breeding season in vitro were researched.
(2) On density of hormone suspension，1/2 or 1/4 of frog pituitary per 1 cc of Ringer's solution were effective for ovulation.
(3) On treating duration by hormone suspension， it was the most effective for ovulation that fragments of the ovaries of spinous loaches were immersed in frog pituitary suspension between 3 or 5 hours and then were removed in pure Ringer's solution regulated value of pH.
(4) The most effective value of pH was 8.8 for ovulation.
(5) The value of pH in the ovary of the spinous loaches which were injected with frog pituitary suspension were between 6.6 or 6.8.
(6) Thus the eggs ovulated from the fragments in vitro cleaved normally after insemination.