viii INTRODUCTION TO THE AMERICAN REVISED EDITION 



as taxonomy, medicine, travel, embryology, or natural history, that 

 there is little hint even in a good abstract of these significant nuggets ; 

 usually the title reveals no trace of their existence. 



The ripeness of the field of ecological animal geography for sum- 

 mary treatment today is shown by the fact that although, just pre- 

 ceding Hesse's Tiergeographie, Dahl made a similar attempt (also in 

 German), which to our minds was less successful, since that time there 

 has been no further effort to revise or extend our concepts of animal 

 ecology from a strictly geographic point of view. The excellent books 

 on various aspects of ecology by Borradaile (1923), Pearse (1926), 

 Elton (1927), Shelford (1929), and Chapman (1932), are largely con- 

 cerned with other phases of this subject. 



When ecology is approached from its geographic aspects, many of 

 the details of ecological relationships cannot be considered. Notwith- 

 standing the fundamental importance of certain of these details, there 

 are distinct advantages to be gained from looking at ecological prob- 

 lems on a world-wide basis; it is easier to gain a general perspective 

 thus and to obtain sufficient detachment for making and appreciating 

 generalizations. The pedagogical advantages of the approach to eco- 

 logical problems and phenomena from the standpoint of world dis- 

 tribution have grown increasingly evident to teaching ecologists. 



A brief inspection and hurried reading of parts of Hesse's Tier- 

 geographie soon after it appeared convinced the senior editor of its 

 outstanding merit particularly for American students. Here in one 

 volume was an authoritative digest of much European literature which 

 is not accessible in most American libraries even to students with 

 time and linguistic ability. The project for translation was an imme- 

 diate reaction. The junior editor quite independently became seriously 

 interested in the work in connection with other zoogeographic studies. 

 With the stimulus of joint discussion of the book, then new, he under- 

 took to prepare a translation, at first only of selected chapters. 



The work has lagged not because of flagging interest but owing 

 to the pressure of other duties and interests which made this of 

 necessity a secondary project for us both. At times our researches 

 have totally stopped progress on this book; at other times the grow- 

 ing manuscript has been carried afield or laid aside because of trips 

 to Woods Hole or to the Carolinas by one of us and to Brazil, to 

 New Guinea, to Europe, and to Central America by the other. With- 

 out the time for translation furnished the junior editor by his travel 

 in connection with the Marshall Field Brazilian Expedition in 1926 

 and the Crane Pacific Expedition in 1929, this basic translation would 

 probably have failed of completion. 



