LHTTHR OF TRANSMITTAL. 



U, S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 



Washington, D. C, April 28, 1911. 



Sir: I have the honor to transmit herewith a paper entitled 

 "Dimorphic Leaves of Cotton and Allied Plants in Relation to 

 Heredity," by Mr. O. F. Cook, Bionomist in Charge of Crop Acclima- 

 tization and Adaptation Investigations of this Bureau, and to recom- 

 mend its publication as Bulletin No. 221 of the Bureau series. 



Numerous agricultural applications of the facts of dimorpliism 

 have been described in Bulletin No. 198 of tliis Bureau, entitled 

 "Dimorpliic Branches in Tropical Crop Plants: Cotton, Coffee, 

 Cacao, the Central American Rubber Tree, and the Banana." The 

 present paper reports additional information regarding the dimor- 

 phic characters and variations of cotton and other plants and points 

 out their relation to problems of heredity and breeding. It is 

 believed that more definite knowledge of the characters and habits 

 of growth of our cultivated plants will be of assistance in many lines 

 of agricultural investigation. 



Respectfully, Wm. A. Taylor, 



Acting Chief of Bureau. 



Hon. James Wilson, 



-Secretary of Agriculture. 



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