Experiments on Amphibian metamorphosis and pigment responses in relation to internal secretions

Abstract

The problem of metamorphosis in Amphibia attracts attention from many points of view. These organisms have, one may say, acquired interest as being indicators for the action of certain internal secretions; the underlying mechanism of metamorphosis is still imperfectly understood; and the general biological problems involved, especially with respect to the neotenous and perennibranchiate forms, are remarkably fascinating. The experiments here recorded were undertaken with a view to elucidating these issues more fully, and in the course of them data relevant to the pigmental responses of Amphibian larvae also emerged. For various reasons it was deemed desirable to publish an account of the observations so far completed. Acknowledgment is made to Mr. D. F. Leney of New College for assisting in the care of animals, to the Royal Society and the Trustees of the Dixon Fund for grants in aid of the expenses incurred by the authors respectively, and to Prof. E. W. MacBride, F. R. S., for his kindness in reading the MS. 1. Metamorphosis of the Axolotl by Thyroid Administration . ( a )When a note (Huxley, ‘Nature,' 1920) on the metamorphosis of medium-sized but immature Axolotls by means of thyroid feeding was published by one of the authors a year ago, and confirmed a few months later (Hogben,‘ P. Z. S.,' 1920), our attention had not been called to Jensen’s work (1916). Since this appears to be little known and is not readily accessible to English-speaking workers, it is proposed to give a short of some of his most important findings.