THE JOURNAL 



OF 



EXPERIMENTAL ZOOLOGY 



EDITED BY 



William E, Castle 



Harvard University 



Edwin G. Conklin 



Princeton University 



Charles B. Davenport 



Carnegie Institution 



Herbert S. Jennings 



Johns Hopkins University 



Frank R. Lillie 



University of Chicago 



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 



Charles R. Stockard 



Cornell University Medical College 



and 



Ross G. Harrison, Yale University 

 Managing Editor 



VOLUME 33 

 MAY— JULY, 1921 



THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY 

 PHILADELPHIA, PA. 



