(1) Water vapor conductance (gH2O) of the shell was widely altered at the beginning of incubation, and blood gas and hematological variables were determined on day 16 of incubation. (2) Changes in blood gas tensions (PaO2 and PaCO2), hematocrit and mean corpuscular indices were expressed by quadratic regression equation of inverse gH2O. (3) In connection with lowered gH2O, the reduced PaO2 might contribute to increases in both cell count and macrocytes and concurrent hypercapnia, increase mean cell volume (MCV). (4) The marked increase in MCV along with small decrease in mean corpuscular hemoglobin at lowered gH2O accounted for prominent decrease in mean cell hemoglobin concentration. The whole blood hemoglobin concentration was however maintained high by increased cell count.