The extent of tolerance to immersion in water probably depends on the stage of development, the temperature, the oxygen content of the water and other factors. One egg was fully immersed for ten minutes on July 20, 1951, then returned to a container with damp soil in the laboratory, where it seemed to develop normally. On July 30 it was opened and found to have a living fetus, which was a week short of hatching. On July 22 another egg of the same clutch was immersed and left in water for 23 hours. On July 30 it was ruptured in handling and found to contain a living fetus. On July 31 two eggs were placed in a dish of water in a refrigerator. On August 5 they were removed and opened. Fetuses were dead and were not appreciably larger than the one of the same clutch in the egg opened on July 31. On August 5 two of the remaining eggs of this clutch were placed in a Petri dish, partly immersed in water, with approximately one-fourth of the surface of each protruding and exposed to the air. Forty-eight hours later it was found that both eggs had hatched. Evaporation had reduced the water in the dish to an amount sufficient to cover only about the lower one-third of each egg. One hatchling was missing, evidently having climbed out of the shallow dish and escaped to the floor. The other was found still standing in the water with its head protruding, and it was lively and in good condition. The remaining four eggs in this clutch, which had been kept in a container of damp earth, were also hatching on this date. On July 10, 1952, an egg in a late stage of incubation was immersed in water in the laboratory. On July 14 when removed, it had fungus growing on it, and was found to have a dead fetus, nearly full-sized. The range of temperature tolerance of the embryo is wide, probably comparable to that of the adult. Time required for incubation is dependent on temperature. Persistently wet and cloudy weather in the summer of 1951, keeping temperatures relatively low in nests, was a contributing cause to late hatching that summer. As compared with 1952, hatching was about one month delayed in 1951, but later emergence and breeding accounts for part of the difference. The extent to which low temperature may delay incubation was indicated by the effect of refrigeration on several experimental eggs, as recorded below. 1. July 8, 1952 Egg transferred from natural nest to jar of damp soil in refrigerator at 13.8°C. July 14, 1952 Seems to be in good condition. July 19, 1952 Partly collapsed. Weight and measurements same as on July 8; opened and found to contain a dead fetus. Snout-vent length 23 mm., forehead bulging, skin delicate and membranous. Colors somewhat dull, indicating that it was not quite fully developed, although it had attained the minimum hatching size.