CARNEGIE INSTITUTION OF WASHINGTON, PUBLICATION No. 241 



PAPER No. 26 OF THE STATION FOR EXPERIMENTAL EVOLUTION 

 AT COLD SPRING HARBOR, NEW YORK 



FROM THE LABORATORY OF GENETICS 

 OF THE BUSSEY INSTITUTION 



Copies of this Book 



were first issued 



SEP 20 1916 



f *f U 



PRESS OF GIBSON BROTHERS, INC. 

 WASHINGTON 



