THE EFFECT OF THYROXIN UPON THE GENERAL METABOLISM OF THE INTACT CHICK EMBRYO

Abstract

Eggs from a Barred Columbian stock of Gallus domesticus were injd. with 0.025 ug. of thyroxine at the preincubation stage. The Og uptake was measured manometrically and the wet and dry wts. during progressive stages were obtained. From these data the metabolic rate of normal and exptl. embryos was calculated. Several conclusions are drawn from this study: An increase occurs in both wet and dry wts. of the embryo starting by the 4th day of development; an increase in the O2 uptake/embryo during all stages of development of the embryo; no significant increase in the metabolic rate of the chick embryo during any part of its embryonic development; a proportional increase of wt. and O2 uptake resulting in a metabolic rate equivalent to that of the control animals; a decrease in the incubation period of from 1-1.5 days.