The Gaseous Environment of the Chick Embryo in Relation to Its Development and Hatchability

TESTING an assumption that the developing chick embryo may have different requirements at different stages of incubation, a series of experiments has been projected to determine the optimal levels of carbon dioxide (CO2) and oxygen (O2) during short segments of the total period of incubation. Previous investigations and much practical testing have been concerned almost exclusively with the effect of conditions maintained uniformly throughout the entire incubation period or with cumulative effects produced by the increasing rate of metabolism of the embryo. The results from such experiments may reflect either a response by the embryo to conditions obtaining at all times during incubation or a limitation of development at certain stages when the embryo is particularly sensitive to its gaseous environment. Evidence from many sources has been accumulating that may be interpreted as indicating varying optimal requirements according to the stage of development of the embryo. The present report is …