6 PREFACE. 
monographs, and microscopes. Natural History has out- 
grown the limits of a single book. Trial has proved the 
folly of giving the student so many things to learn that he 
has no time to understand, and the error of condemning 
the student to expend his strength upon the details of 
classification, which may change in the coming decade, 
instead of upon structure, which is permanent. Of course, 
specialists will miss many things, and find abundant room 
for criticism in what they regard as deficiencies; but the 
work should be judged by what it does contain, rather than 
by what it does not. 
What is claimed, in the language of inventors, is the 
selection and arrangement of essential principles and typ- 
ical illustrations from the stand-point of the teacher. The 
synthetic method is employed, as being the most natural : 
to begin with complex Man, instead of the simplest forms, 
would give a false idea. Man is not a model, but a mon. 
strosity, the most modified of Vertebrates. But these out- 
lines must be filled up, on the part of the teacher, by lect- 
ures, and by the exhibition of specimens, and, on the part 
of the student, by observation (noting, above all, the char- 
acteristic habits of animals), and by personal work with 
the knife and microscope. No text-book can take the 
place of nature, or supersede oral instruction from a com- 
petent teacher. 
Suggestions and corrections from naturalists aud teach- 
ers will be thankfully received. 
In a work of this character, which is but a compend of 
the labors of all naturalists, it would be superfluous to 
make acknowledgments. The works referred to on page 
385 have been specially consulted. 
