THE JOURNAL 
OF 
EXPERIMENTAL ZOOLOGY 
EDITED BY 
Wi.uiaM E. Caste FRANK R. LILLIE 
. Harvard University University of Chicago 
EpwIin G. CONKLIN JacquEs LorsB 
Princeton University Rockefeller Institute 
CHARLES B. DAVENPORT Tuomas H. Morean 
Carnegie Institution Columbia University 
Horace JAYNE GeorGE H. ParKER 
The Wistar Institute Harvard University 
HERBERT §. JENNINGS Epmunp B. WIitson, 
Johns Hopkins University Columbia University 
and 
Ross G. Harrison, Yale University 
Managing Editor 
VOLUME 12 
1912 
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY 
PHILADELPHIA, PA. 
