Growth and metabolism in snake embryos

Since the early papers of Bohr & Hasselbalch (1900, 1903) and Murray (1925), considerable information concerning the growth and metabolic processes in the avian embryo has been accumulated (Romanoff, 1967). Respiratory and growth processes during embryonic life in many species of fishes, amphibians and mammals are also fairly well known. Only a few studies have been reported, however, on the metabolism and growth of the reptilian embryo. Lynn & Brand (1945) presented a detailed description of these processes in four species of turtles. Some data on respiration in the egg of the snake Coluber natrix are given by Bohr (1904). The respiration of four eggs a few days prior to hatching in the snake Liopeltis vernalis was studied by Zarrow & Pomerat (1937). Scattered information on the embryonic growth of snakes may also be obtained from papers dealing with the development of certain anatomical systems in the embryo, such as venom glands and the musculature related to them (cf. Fukada, 1958; Kochva, 1963, 1965). Growth or metabolic curves are not available for snake embryos, however. It is the aim of the present paper to describe the growth and metabolic patterns in embryos of several species of snakes common in Israel, in order to obtain a general pattern for growth and metabolism in snake embryos, and to facilitate comparison among the different species.