I will briefly discuss the arangement of chapters b — e and the contents 

 of chapters f — h. 



Chapter b gives the alphabetical list of names with addresses. 

 The present collaborators of the G.E.I. S. have been marked with *. 



Chapter c contains the list of institutes and has been arranged according 

 to a geographical order, which forms the best supplement to the alpha- 

 betical list of chapter b. The institutes have been grouped according to 

 continent, country, district, town and street. Within each of these groups 

 we use an alphabetic arrangement. 



Members of the staff have been placed in the left column, embryologists 

 not belonging to the staff in the right column. 

 Three groups of institutes can be distinguished: 



a. Those institutes which are mainly concerned with embryology or 

 which have a separate embryological department with a rather 

 extensive staff of embryological workers. 



b. Those institutes, in which only a small number of embryologists are 

 working (individual workers). 



c. Those institutes, from which we have not yet received information. 

 They are included in order to give as complete a survey as possible 

 of all embryological Institutes. They have been marked "data not 

 yet received". 



The size of this issue compelled us to restrict the data concerning the 

 composition of staffs to the embryological workers and directors only. 



In chapter d you will find the names of embryologists and the subjects 



on which they are working. This chapter has given us some trouble. 



especially in those cases, in which forms have not been filled in 



completely. 



The indices at the end of each subject refer to the arrangement in the 



next chapter. 



Chapter e with the classification of data according to subjects has, 

 however, given the greatest trouble, again especially when forms have 

 not been filled in completely 1 ), or when investigations deal with more 

 than one of the main groups distinguished in our general classification. 

 Sometimes it was necessary to divide a subject into two separate ones, 

 and in a few cases it was even impossible to classify an investigation 

 in the right place. We, therefore, urgently request every collaborator to 

 give us complete data! 



The order of classification into subjects is of course a more or less 

 arbitrary one. We have tried to develop the most practical system. We 

 classified the investigations according to general group, general subject, 

 special subject and only finally according to systematic group. The 

 arrangement according to subject could be followed out completely in 

 the case of special investigations, but was soon exhausted in the case of 

 general investigations, so that here we soon fell back upon the systematic 

 order (cf. the general rubrics I. 2, II. 2, Ilia. 2 and Illb. 2). This was 

 also the case with investigations on Invertebrates, as the classification 



1 ) Incomplete data give rise to wrong classifications and can be classified in main 

 groups only. 



