Development of Homeothermy in Birds

Abstract
Chick embryos were cultivated in opened eggs. A curve was plotted which demonstrated that the developing egg at first behaves as a poikilothennic animal; the temp. of the egg stays slightly above that of the incubator. The embryo gradually becomes a homeothermic animal, but complete homeothermy is not acquired by the chick until the 4th or 5th day after hatching.