THE GERM-CELL CYCLE 

 IN ANIMALS 



BY 



ROBERT W. HEGNER, PH.D. 



ASSISTANT PROFESSOR OF ZOOLOGY IN THE UNIVERSITY 

 OF MICHIGAN 



AUTHOR OF "AN INTRODUCTION TO ZOOLOGY" 

 AND "COLLEGE ZOOLOGY" 



Nefo gorfc 



THE MACMILLAN COMPANY 

 1914 



All rights reserved 



