Growth and Development of Chick Embryos Supplied with Various Concentrations of Yolk

When small amounts of yolk were supplied to chick embryos deprived of their own yolk after three days of incubation, survival, developmental stage, and body weight, measured at 8 or 9 days, were related directly to the amount of yolk provided. Embryos that were sacrificed, or that died of yolk exhaustion, show no characteristic abnormalities except for some edema among those of 11 to 13 days' incubation. Body weights of embryos sacrificed at 8 days were found to have increased as yolk increased to a maximum at 1 ml/embryo; for normal weight at 9 days, 2 ml of yolk were required. Yolk concentration affected allantoic development and the Na/K ratio in the amniotic fluid of 8-day embryos.