ABSTRACT
Xenopus laevis has become a common laboratory animal since the detection of its usefulness for pregnancy tests and other hormonal reactions. It has turned out to be a very good laboratory animal, which, being an aquatic form, can easily be kept and reproduces readily in captivity after hormonal stimulation. Although only very fragmentarily known, the development of Xenopus laevis is quite interesting from a descriptive and comparative as well as from an experimental embryological point of view. Any national, but particularly any international project set up with a large number of collaborators, faces the difficulty of special time requirements, which difficulty in this project was greatly increased by the technical troubles met with in working out the older stages, the animals being of considerable dimensions.
