U. S. DEPARTMENT OF AGRICULTURE. 



BUREAU OF PLANT INDUSTRY— BULLETIN NO. 221. 



B. T. GALLOWAY, Chief of Bureau. 



DIMORPHIC LEAVES OF COTTON AND ALLIED 

 PLANTS IN RELATION TO HEREDITY. 



BY 



O. F. COOK, 

 Bionomist in Charge of Crop Acclimatization and Adaptation Investigations. 



Issued Novembkr 22, 1911. 



WASHINGTON : 



GOVERNMENT PRINTING OFFICE. 



1911. 



