The Minimum Temperature for Embryonic Development in the Domestic Fowl (Gallus domesticus)

THE universal opinion of poultrymen and poultry research investigators is that 68.9°F. (20.5°C.) is the temperature above which embryonic development proceeds and below which the embryo remains dormant. This opinion is so well established that no one has questioned it since Edwards in 1902 concluded that 68.9°F. (20.5°C.) was the minimum temperature for development of the embryo of the domestic hen. The authors did not question this widely accepted belief until in the course of some egg quality investigations they measured the development of the blastoderm as one of the indices of deterioration in shell eggs held at different temperatures. They soon found that there was only slight enlargement of the blastoderm at temperatures several degrees above 68°F. and thus they were led to investigate this problem. EXPERIMENTAL Fresh-laid White Leghorn eggs from a mated pen and from an unmated pen were divided into groups and placed in an environment . . .