THE GERM-CELL CYCLE 

 IN ANIMALS 



A/V- 



BY 



ROBERT W. HEGNER, PH.D. 



ASSISTANT PROFESSOR OF ZOOLOGY IN THE UNIVERSITY 

 OF MICHIGAN 



AUTHOR OF "AN INTRODUCTION TO ZOOLOGY" 

 AND "COLLEGE ZOOLOGY" 



THE MACMILLAN COMPANY 



1914 



All rights reserved 



