LETTER OF TRANSMITTAL. 



U. S. Department of Agriculture, 



Bureau of Plant Industry, 



Office of the Chief, 



Washington, D. 0., May 23, 1903. 

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

 " The Physiological Role of Mineral Nutrients in Plants," by Dr. Oscar 

 Loew, formerly an Expert in this Department, and recommend its 

 publication as Bulletin No. 45 of the series of this Bureau. The 

 paper is a revision of a former bulletin of the Department on this 

 subject and was submitted b}^ the Pathologist and Physiologist. 

 Respectfully, 



B. T. Galloway, 



Chief of Bureau. 

 Hon. James Wilson, 



Secretary of Agriculture. 



