X INTRODUCTION TO THE AMERICAN REVISED EDITION 



holarctic origin of vertebrate life which was not mentioned in the 



original text. 



We have eliminated many scientific names of animals given in 

 illustration of various points, not because they are unimportant for 

 the careful student interested in the particular phase under discussion, 

 but because such students can find them all in the German text and 

 their inclusion would tend to slow down and discourage the general 

 and perhaps more casual student. We have added American examples 

 sufficiently to give American readers a feeling of closer contact with 

 the world problems under discussion. 



We have also omitted many names of observers from the text, 

 leaving only the reference numbers by means of which they may be 

 recovered from the chapter bibliographies, and we have added signifi- 

 cant names and citations in an attempt to secure a more complete 

 discussion. We have not hesitated to eliminate repetitions where pos- 

 sible and have shifted material from one chapter to another in order 

 to concentrate discussions. The cross references added to the text, 

 together with the extensive index, will allow ready reference to related 

 parts of the discussion which may be unavoidably separated by the 

 reorganization of the book. The terminology has been made more 

 objective and less anthropomorphic, and technical ecological terms 

 have to some extent been replaced by non-technical language. 



The last chapter has been changed more than any other. It has 

 been entirely rewritten in an attempt to concentrate there materials 

 originally somewhat scattered and to expand these in the light of 

 American experiences with the rapid and recent advances of civiliza- 

 tion upon primeval communities of plants and animals. In our opinion 

 this change and the changes throughout the book have sharpened 

 rather than blunted Professor Hesse's discussion. 



A distinct need exists for a new book on animal geography in 

 English. It is now twenty years since Lydekker's Wild Life of the 

 World appeared in three large volumes only to go out of print in a 

 few years, and still longer since Newbigin's small Animal Geography 

 was published. These are the only fairly recent books known to us in 

 English that are devoted to the description of animal distribution on 

 a world scale, and even if both were available and otherwise entirely 

 satisfactory, they lack the ecological approach furnished in this book. 

 This need could have been filled either by a completely new compila- 

 tion, or by a carefully revised translation. We have chosen the latter, 

 course as the more practical and as a tribute richly merited by the 

 importance of Hesse's pioneer work. 



A need still remains for a new discussion of animal distribution 



