172 

 A NORMAL TABLE OF XENOPUS LAEVIS. 



The anuran species Xenopus laevis, which has already been introduced 

 into several Institutes for pregnancy tests, appears to be very suitable 

 for experimental embryological work. At a number of institutes experi- 

 mental work has already been started, but it has met one great impediment 

 up till now, viz., a general deficiency of our knowledge of normal 

 development. We will, therefore, try to solve this problem by the com- 

 position of a Normal Table of this very interesting anuran species. This 

 project was already started at the beginning of 1948. 

 The elaboration of a complete normal table from the beginning of 

 development up to the end of metamorphosis is, however, an enormous 

 project. We, therefore, asked a number of embryologists already working 

 with this species to cooperate. 



As the Hubrecht Laboratory tries to stimulate international cooperation, 

 and a project like this one appeared to be very suitable for elaboration 

 by a group of embryologists working at different institutes, we chose 

 the form of international team-work. The general interest in our enterprise 

 allowed us to found an international team of more than 20 collaborators, 

 spread over 8 countries on three continents. 



At the present moment the material for this extensive project has been 

 collected in South Africa, the native country of Xenopus laevis, and 

 will be distributed among the collaborators in the early part of 1950. 

 We hope that the elaboration of this material can be carried out in the 

 course of 1950, so that we can publish the Normal Table in 1951. 



Communication of the ,,Institut International 



d'EmbryoIogie" (Embryological Section of the I.U.B.S.) 



A meeting of the I. I.E. was held in the Zoological Laboratory of the 

 university of Berne, Switzerland on September 10th — 11th, 1949. It was 

 preceded by a Symposium on September 6th — 9th, organised by Prof. 

 F. E. Lehmann under the auspices of the I. I.E. and with the financial 

 aid of the I.U.B.S. and the Cantonal Direction of Education of Berne. 



The theme of the symposium was: Organised field actions (induction 

 and competence) and cellular genetic factors in embryonic development. 



The program comprised the following papers: 

 I. The experimental data. 



A. Neural induction. 



1. A. M. Dalcq, Bruxelles: La genese du complexe inducteur 

 chez les chordes. 



2. P. D. Nieuwkoop, Utrecht: Neural competence and neural 

 fields. 



3. S. Toivonen, Helsinki: Stoffliche Induktoren. 



4. J. Brachet, Bruxelles: Characteristiques biochimiques de la 

 competence et de l'induction. 



5. Tr. Gustafson, Stockholm: Survey of the morphogenetic action 

 of the lithium ion and the chemical basis of its action. 



