ABSTRACT
This chapter gives a systematic description of the internal development of Xenopus Laevis. In the early development, no distinction between organ systems can be made, so that up to stage 10 the embryo is described as a whole. From stage 10 to stage 15 the formation and subsequent development of the germ layers are followed. In some divisions an anatomical description has been given of a certain stage, either at the beginning (the fertilized egg), in the middle (just before metamorphosis) or at the end of development, as a link between larval and metamorphic development and when the complexity of the system concerned made it desirable. This is reflected in the subdivision and heading of the text. The subdivision of the text into successive periods of development leads inevitably to a certain scattering of the data concerning the development of certain structures over successive subdivisions.
