THE FOUNDATIONS OF ZOOLOGY

A COURSE OF LECTURES

DELIVERED AT COLUMBIA UNIVERSITY

ON THE PRINCIPLES OF SCIENCE

AS ILLUSTRATED BY ZOÖLOGY

Columbia University Biological Series.

EDITED BY

HENRY F. OSBORN AND EDMUND B. WILSON.

1. FROM THE GREEKS TO DARWIN.

By Henry Fairfield Osborn, Sc.D. Princeton.

2. AMPHIOXUS AND THE ANCESTRY OF THE VERTEBRATES.

By Arthur Willey, B.Sc. Lond. Univ.

3. FISHES, LIVING AND FOSSIL. An Introductory Study.

By Bashford Dean, Ph.D. Columbia.

4. THE CELL IN DEVELOPMENT AND INHERITANCE.

By Edmund B. Wilson, Ph.D. Johns Hopkins.

5. THE FOUNDATIONS OF ZOOLOGY.

By William Keith Brooks, Ph.D. Harvard, LL.D. Williams.

THE

FOUNDATIONS OF ZOÖLOGY

BY

WILLIAM KEITH BROOKS, PH.D., LL.D.

PROFESSOR OF ZOÖLOGY IN THE JOHNS HOPKINS UNIVERSITY

PUBLISHED FOR THE COLUMBIA UNIVERSITY PRESS BY

THE MACMILLAN COMPANY

COPYRIGHT, 1899,

BY THE MACMILLAN COMPANY.

Norwood Press

J. S. Cushing & Co. - Berwick & Smith

Norwood Mass. U.S.A.

To Hobart College

WHERE I LEARNED TO STUDY, AND, I HOPE, TO PROFIT BY BUT NOT TO BLINDLY FOLLOW, THE WRITINGS OF THAT

GREAT THINKER ON THE PRINCIPLES OF SCIENCE

GEORGE BERKELEY

I HAVE, BY PERMISSION, DEDICATED THIS BOOK