THE JOURNAL 
OF ‘ 
EXPERIMENTAL ZOOLOGY 
EDITED BY 
WILLIAM E. CastTLE Jacques LoEB 
Harvard University The Rockefeller Institute 
Epmunp B. WILSON 
Columbia University 
Epwin G. CONKLIN 
Princeton University 
THomas H. MorGan 
CHARLES B. DAVENPORT 
Columbia University 
Carnegie Institution 
GEORGE H. PARKER 
HERBERT S. JENNINGS es Una ceveiee 
Johns Hopkins University 
RAYMOND PEARL 
FRANK R. LILLIE Maine Agricultural 
University of Chicago Experiment Station 
and 
Ross G. HARRISON, Yale University 
Managing Editor 
VOLUME 25 
1918 
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY 
PHILADELPHIA, PA. 
