Abstract

The effect of sodium fluoride on Rana temporaria tadpoles was investigated by adding it in the doses of 1, 2 and 10 mg/lilre to the aquaria where the tadpoles were kept. In all three groups the time of metamorphosis was delayed as compared with that of the controls. Histological examination of the thyroid glands revealed that in the three experimental groups the thyroids were less active than those of the controls.

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