THE JOURNAL 
OF 
EXPERIMENTAL ZOOLOGY 
EDITED BY 
William E. Castle 
Harvard Unive; ' 7 
Edwin G. Conklin 
Princeton University 
Charles B. Davenport 
Carnegie Institution 
Herbert S. Jennings 
Johns Hopkins University 
Frank R. Lillie i 
University of Chit'ago 
Jacques Loeb 
The Rockefeller Institute 
Edmund B. Wilson 
Columbia University 
Thomas H. Morgan 
Columbia University 
George H. Parker 
Harvard University 
Raymond Pearl 
Johns Hopkins University 
and 
f.OSS G. Harrison, Yale University 
Managing Editor 
VOLUME 32 
JAIIUARY— APRIL, 1921 
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY 
I PHILADELPHIA, PA. 
