METABOLISM OF THE BLACK SNAKE EMBRYO II. RESPIRATORY EXCHANGE

Bohr (1904) reported CO2 production of an embryo of Natrix natrix, weighing 0-46 g., to be 120 mm.3/g./hr. at 14-2 ° C; the CO2 produced at 280 C. was 3 times that at 150 C, and production by a newly hatched snake at 15 ° C. was approxi-mately 90 mm.3/g./hr. Other data are given, but they are not related to stage of development, and oxygen utilization was not measured. Zarrow & Pomerat (1937) made rather exhaustive studies of the effect of temperature on various aspects of respiratory behaviour of the smooth green snake during the last week of develop-ment. It appeared profitable, therefore, to obtain details of respiratory exchange throughout the developmental period of snake embryos. Such data were available from the same embryos which served for the excretion studies reported elsewhere in this Journal by the author (1953). MATERIALS AND METHODS Data on oxygen consumption, CO2 production and R.Q. were obtained by use of a special flask (Aminco 5-210) with a standard Warburg apparatus. Temperature was maintained at 23-9 ° C. during the determinations, although the environmenta