AMERICAN SCIENCE SERIES 



AN INTRODUCTION 



TO 



GENERAL BIOLOGY 



BY 



WILLIAM T. SEDGWICK, PH.D. 



Professor of Biology in the Massachusetts Institute of Technology, Boston 



AND 



EDMUND B. WILSON, PH.D. 



Professor of Zoology in Columbia, College, New York 



SECOND EDITION, REVISED AND ENLARGED 



NEW YORK 



HENRY HOLT AND COMPANY 



1895 



