



CARNEGIE INSTITUTION OF WASHINGTON 

 Publication No. 144 



Paper No. 17 of the Station for Experimental Evolution at 

 Cold Spring Harbor, New York 



Contributions from the Laboratory of Genetics, Bussey Institution, 



Harvard University, No. 8. 



Copies of this Book 

 first issued 



, 141911 



THE CORNMAN PRINTING CO. 

 CARLISLE, PA. 



