Age factor in the induced metamorphosis of thyroidectomized tadpoles

SUMMARY Three age-groups of thyroidectomized tadpoles of Rana catesbeiana were treated with a series of the same graded increasing concentrations of thyroxin. Normal froglets were formed from the three groups at the end of the induced metamorphosis. Growth and metamorphosis were compared. It was found that while the growth rate was a function of ageing, the pattern and rate of metamorphosis were not affected by senile processes. Therefore a case of differentiation independent of age was presented.