INTRODUCTION 



The editors apologize for the fact that the eleventh main issue is several 

 months overdue. The reason for this is twofold: 1 ) unforeseen alterations have 

 occurred in the administrative personnel of the Hubrecht Laboratory; 2) the 

 preparation of the new Subject Index has brought a considerable amount of 

 extra work. 



The main change that has been made in the set-up of the periodical is in the 

 Subject Index. So far the arrangement of the Index was systematical, which 

 entailed the use of twelve different "keys" for the location of research subjects. 

 It was felt that this made the use of the Index unnecessarily cumbersome. 

 Moreover, it was sometimes difficult to fit work carried out with modern 

 methods into the system in such a way that it could be easily retrieved. There- 

 fore, it was decided to replace the systematical Index by an alphabetical Index. 

 Great pains have been taken to make the new Index as efficient as possible. 

 For more details the reader is referred to page 277. Suggestions for impro- 

 vement are solicited. 



As far as the Directory of Institutes is concerned, addresses of Institutes are 

 now omitted. This makes for better surveyabiHty; the full address of an 

 Institute can always be found in the Directory of Names and Addresses. 

 Furthermore, names of Institute members who are not explicitly engaged in 

 developmental biology are as a rule not listed. 



New contacts were established with Algeria, Ceylon, Hawaii (U.S.A.). Ja- 

 maica, and Nigeria. The contacts with Argentine, India, and Mexico were 

 extended. Moreover, several European countries, particularly France and 

 Western Germany, show a marked increase in the number of Institutes listed. 



The steadily increasing costs of printing have rendered a rise of the sub- 

 scription unavoidable. Unfortunately, it was impossible to notify our subscribers 

 earlier. Starting with the present main issue the subscription for two years has 

 been fixed at $ 10. — . Moreover, the costs of shipment will henceforth be 

 charged separately. At present these amount to $ 0.50 for two years. 



Information concerning the Hubrecht Laboratory may be found on page 329. 

 For information concerning the ,,Institut International d'Embryologie", please 

 see page 331. 



P. D. NIEUWKOOP 

 J. FABER 



