Caknegie Institution of Washington. Publication No. 179. 



\PERS NOS. 18 AND 19 OF THB-StATION FOE EXPERIMENTAL EVOLUTION AT CoLD SPBING 



Hahbok, New York. 



Copies of this BooV 

 w«re first issued 



SEP 131913 



PRESS OF GIBSON BROTHERS 

 WASHINGTON, D. C. 



