Acta Scientiarum Universitatis Pekiniensis (Naturalum)

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a1 ake Rana nigromaculata FURR S — 105

THE EARLY DEVELOPMENT OF THE COMMON

FROG, Rana nigromaculata. Wang Ying-tien (Department ot Biology) ABSTRACT This paper deals with the study of the early development of Rana nigromaculaia, the mest common species of frogs in this country. It includes a description of the external forms, internal anatomy, a normal developmental time table at 18°C of the embryos and a comparism with those of other species of Rana. In addition, a series of photographical records of the developing embryos was taken as a suppliment. Beginning with the artificial fertilization of the completion of the operculum of the tadpole 307 hours are needed. On the basis of the morphological and the physiological characteristics of the embryos, the whole cours: of development is devided into 25 stages, and in certain aspects, the development of

this frog closely resembles to that of Rana pipiens.