INTRODUCTION 



Biennial appearance 



In the 1953-issue we announced that suggestions have been made from 

 several sides to publish the General Embryological Information Service bien- 

 nially. The inquiry which we held in the beginning of this year in order to 

 obtain an objective judgment of the desirability of either an annual or a bien- 

 nial publication of the G.E.I.S., served its purpose very well. We feel very 

 much obliged towards all subscribers and collaborators of the G.E.I.S., who 

 sent us their answers and often very valuable suggestions. We received a total 

 number of about two hundred answers, which clearly demonstrates the general 

 interest in our enterprise. The far greater majority. 143 out of 198, supports a 

 biennial appearance of the G.E.I.S. and only 55 want to see the G.E.I.S. 

 published annually. Particularly a great number of American collaborators are 

 in favour of a biennal appearance, viz. 56 out of 68. which represents about 

 82 %. In Europe this percentage is about 71 % (70 out of 98) and in the 

 remaining countries including many more isolated countries the percentage is 

 about 53 % (17 out of 32). Thus, even there the majority supports a biennial 

 appearance. 



We will try as much as we can to meet the objections necessarily attended 

 with a biennial appearance by publishing a supplement in the interjacent years, 

 and by making the full issue as complete and up to date as possible. 



Contents o[ the supplement 



This supplement will contain the following chapters: 



a) Introduction P- 5 



b) Changes of address and new addresses of collaborators . 



c) ,, Supply and Demand" Service for laboratory animals . . 



d) General questions and announcements 



I The Hubrecht Laboratory 



II The Central Embryological Library (C.E.L. ) 



III The Central Embryological Collection of slides and 

 material 



IV The Normal Table of Xenopus laevis 



e) Communications of the ,,Institut International d'Embryologie" 

 (Embryological Section of the I.U.B.S.) . • 



f) Reviews of recently published textbooks on embryology 



We decided that these chapters should be published annually in order to 

 guarantee actuality of the published data. 



..Supply and Demand" Service 



The chapter "Supply and Demand" Service for laboratory animals has been 

 changed, since the original form missed the required clearness and was typo- 

 grafically unsatisfactory. In order to avoid the necessity of using two different 

 systems the data of the 1953-issue are included in the supplement. 



