THE GERM-CELL CYCLE 

 IN ANIMALS 



BY 



ROBERT W. HEGNER, Ph.D. 



ASSISTANT PROFESSOR OF ZOOLOGY IN THE UNTVERSTTT 

 OF MICHIGAN 



AUTHOR OF "an INTRODUCTION TO ZOOLOGY" 

 AND "college zoology" 



Neijj gorit 



THE MACMILLAN COMPANY 



1914 



All rights reserved 



