1. Turkey eggs which are incubated under chicken hens lose from 11 to 13 per cent of their original weight during the first 24 days of incubation. Small turkey eggs lose relatively more weight than large eggs incubated under the same conditions. 2. Considerable variation was observed in the weight loss during the first 24 days of incubation of eggs of approximately the same size when incubated in the same environment. The range was from 7 to 24 per cent of the original weight. Differences in shell texture may account for these variations, although care was taken to select only apparently normal eggs with good texture for these experiments. 3. Variations in the weight loss during incubation within the limits of our observations as herein reported apparently have no significant correlation with the growth rate during the first eight weeks of the life of the poult. 4. Rate of air movement and humidity as environmental factors apparently influence hatchability more during the last four days than during the first twenty-four days of the incubation period. 5. It is probable that for turkey eggs cabinet incubators require conditions during the last four days of the hatch that are somewhat different from those which have proved satisfactory for hatching chicken eggs