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 C 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 pressure per 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.