Packard G C, Taigen T L, Packard M J, Shuman R D
Respir Physiol. 1979 Sep;38(1):1-10. doi: 10.1016/0034-5687(79)90002-1.
Flexible-shelled eggs of snapping turtles (Chelydra serpentina) have conductances to water vapor that are 55 times higher than predicted for avian eggs of similar size, whereas rigid-shelled eggs of softshell turtles (Trionyx spiniferus) and American alligators (Alligator mississippiensis) have conductances that are only five times higher than expected for comparable eggs of birds. The differences between empirical and predicted values result from the much higher effective pore areas in reptilian eggshells than in those of birds. The relatively high porosities of these reptilian eggs presumably facilitate the transport of oxygen and carbon dioxide eggshells in later stages of incubation when air trapped inside nest chambers may become hypoxic and hypercapnic, yet seem not to lead to excessive transpiration of water vapor owing to the high humidities in nests where incubation occurs.
鳄龟（蛇鳄龟）的软壳蛋对水蒸气的传导率比类似大小的鸟类蛋预测值高55倍，而鳖（刺鳖）和美国短吻鳄（密西西比鳄）的硬壳蛋传导率仅比鸟类同类蛋的预期值高5倍。实测值与预测值之间的差异是由于爬行动物蛋壳的有效孔隙面积比鸟类蛋壳大得多。这些爬行动物蛋相对较高的孔隙率大概有助于在孵化后期蛋壳内氧气和二氧化碳的传输，此时巢穴内被困的空气可能会变得缺氧和高碳酸血症，但由于孵化发生的巢穴湿度较高，似乎不会导致水蒸气过度蒸腾。
