Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 48196-h.htm or 48196-h.zip: (http://www.gutenberg.org/files/48196/48196-h/48196-h.htm) or (http://www.gutenberg.org/files/48196/48196-h.zip) Transcriber's note: Text enclosed by underscores is in italics (_italics_). [Illustration: Photo, American Museum of Natural History] [Illustration: _Giraffes in their native African haunts_] POPULAR SCIENCE LIBRARY EDITOR-IN-CHIEF GARRETT P. SERVISS AUTHORS WILLIAM J. MILLER HIPPOLYTE GRUENER A. RUSSELL BOND D. W. HERING LOOMIS HAVEMEYER ERNEST G. MARTIN ARTHUR SELWYN-BROWN ROBERT CHENAULT GIVLER ERNEST INGERSOLL WILFRED MASON BARTON WILLIAM B. SCOTT ERNEST J. STREUBEL NORMAN TAYLOR DAVID TODD CHARLES FITZHUGH TALMAN ROBIN BEACH ARRANGED IN SIXTEEN VOLUMES WITH A HISTORY OF SCIENCE, GLOSSARIES AND A GENERAL INDEX _ILLUSTRATED_ [Illustration] VOLUME TWELVE P. F. COLLIER & SON COMPANY NEW YORK Copyright 1922 BY P. F. COLLIER & SON COMPANY MANUFACTURED IN U. S. A. ZOÖLOGY THE SCIENCE OF ANIMAL LIFE BY ERNEST INGERSOLL [Illustration] P. F. COLLIER & SON COMPANY NEW YORK PREFACE