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PREFACE 
Courses in field zodlogy usually lack the convenient background of 
organization which one finds in the doctrine of evolution when presenting 
the animal series from a structural standpoint. The need of some 
logical and philosophical background for the organization of natural 
history instruction into something more unified than haphazard dis- 
cussions of such animals as were encountered in chance localities, was 
keenly felt at the beginning of the author’s experience as a teacher of 
field zodlogy. Evolutionary background was tried, but failed and was 
rejected; genetics and faunistics proved inadequate. Behavior as 
presented and studied by zodlogists was incomplete. Plant ecological 
methods were, when unadapted, applicable only in part, while much 
of physiology dealt with organs and internal processes. 
The organization of the data here presented is the result of many 
attempts and failures which at times made the task seem hopeless. The 
literature relating to this subject has been written almost exclusively 
from points of view which are very different from the one here presented. 
It is scattered, and the bibliography has never been brought together. 
Accordingly its incorporation here has called for the expenditure of 
much time, and often for reinterpretation, which is always fraught with 
danger of error. The time consumed in working over the literature has 
been great, but, for the reason stated, the amount covered has been rela- 
tively small, and the literature in foreign languages has not received its 
share of attention. Furthermore, since the bulletin is not written 
primarily for investigators, much of the literature not in English has 
been omitted from the Bibliography but some of it will be found in the 
papers cited. To present such a subject as we have before us without 
constant reference to the writings of such naturalists as Buffon, White, 
Darwin, Wallace, Bates, Belt, Hudson, Romanes, Audubon, Brehm, 
Fabre, Claude Bernard, Huber, Giard, Forel, Schmarda, Janet, Haase, 
Mobius, Dahl, and others (35a) seems at first thought quite unjustified, 
but a complete study of the works of such men would be almost a life’s 
work in itself. The writer does not claim to have a detailed knowledge 
of all the articles written by these men. He knows them only in part. 
Their facts, in so far as they are known to him and relate to the questions 
at hand, tend to support the main contentions. But the successful 
organization of such a subject depends more upon the investigation of 
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