PRACTICAL ZOOLOGY 



BY 



ROBERT W. HEGNER, PH.D. 



ASSISTANT PROFESSOR OF ZOOLOGY IN THE UNIVERSITY OF MICHIGAN 

 FORMERLY TEACHER OF NATURE STUDY IN THE SCHOOL OF EDUCA- 

 TION, UNIVERSITY OF CHICAGO, AND PROFESSOR OF BIOLOGY IN 

 THE STATE NORMAL SCHOOL AT RIVER FALLS, WISCONSIN; 

 AUTHOR OF " INTRODUCTION TO ZOOLOGY," " COLLEGE 

 ZOOLOGY," AND " THE GERM-CELL CYCLE IN ANIMALS " 



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THE MACMILLAN COMPANY 

 1922 



All rights reserved 



