[Chronobiological patterns in the course of amphibian metamorphosis]

Metamorphic rates in Rana temporaria larvae treated with thyroxine and prolactin were observed in different phases of the light-dark cycle. Different hormonal effects on tadpole development were demonstrated depending on the light-dark phases. Thyroxine always accelerated the development. Thyroxine employed at L-D and D-L phases was more effective than in T and D phases. Prolactin retarded metamorphosis in D phase and accelerated in L-D phase. This work demonstrated some temporal relief of hormonal sensitivity of anuran metamorphosis.