STUDIES ON THE OXYGEN CONSUMPTION AND WATER METABOLISM OF TURTLE EMBRYOS

Abstract

1. The average period of development of the Mud Turtle egg at 25.0 to 25.5° C. is 76 days; that of the Painted Turtle egg, 63 days; and that of the Snapping Turtle egg, 72 days.2. Measurements of the carapace lengths of developing embryos of the Painted and Snapping Turtles indicated a relatively slow growth rate during early development, a rapid rise during the period between the thirtieth and sixtieth days, and almost no increase in length from the sixtieth day up to hatching.3. The figures for the oxygen consumption of the developing eggs of the Mud Turtle, Painted Turtle and Three-toed Box Turtle agree closely and can be expressed by a single curve while those for the Snapping Turtle egg, though they give a fundamentally similar curve, show a significantly higher rate of metabolism. This is to be attributed to the greater bulk of the Snapper embryo.4. During the first 50 days of development the oxygen consumption was a little less than doubled every 10 days; later on the curves flatten out.5. While the increase in oxygen consumption is quite regular during the first 40 to 50 days of development irregular values were obtained at later stages, probably as a result of muscular activity of the embryos.6. Young hatched turtles have about the same rate of oxygen consumption as do advanced embryos. The highest values for oxygen consumption were obtained from eggs studied while in the process of hatching.7. The eggs of the Snapping Turtle, Painted Turtle and Three-toed Box Turtle showed a definite water intake during development as evidenced by a progressive weight increase but no such phenomenon was found in the case of the Mud Turtle egg.8. The Snapping Turtle egg shows an average loss, during development, of 0.46 gram of dry substance. Fat is consumed in the amount of 61 mg. per egg. These data in conjunction with those on the oxygen consumption make it appear possible, though not yet certain, that large amounts of protein are catabolized during the development of this animal.