Embryogenesis in 100% O2 at reduced pressure

Fertile chicken eggs were incubated in an altitude chamber in a near 100% O₂ atmosphere at 225 torr. Both N₂ and CO₂ were kept under 0.5%. Temperature was a standard 37.5° but a high relative humidity of 90% was required to prevent dehydration. In ten trials involving 382 eggs, hatchability averaged 21% of controls and weight of chicks was 11% less than controls, but embryo mortality was distributed similarly. Low pressureper se and small differences in O₂ tension may have affected the results, but similarities to incubation in 21% O₂-79% He call attention to absence of nitrogen as a possible explanation.Supported in part by NASA grant NGR-008-004.