﻿ORGANIZATION OF THE UNITED STATES DEPARTMENT OF 

 AGRICULTURE. 



Secretary of Agriculture Henry C. Wallace. 



Assistant Secretary C. W. Pugsley. 



Director of Scientific Work E. D. Ball. 



Director of Regulatory Work 



Weather Bureau Charles F. Marvin, Chief. 



Bureau of Agricultural Economics Henry C. Taylor, Chief. 



Bureau of Animal Industry John R. Mohler, Chief. 



Bureau of Plant Industry William A . Taylor, Chief. 



Forest Service W. B. Greeley, Chief. 



Bureau of Chemistry Walter G. Campbell, Acting Chief. 



Bureau of Soils Milton Whitney, Chief. 



Bureau of Entomology L. 0. Howard, Chief. 



Bureau of Biological Survey E . W. Nelson , Chief. 



Bureau of Public Roads Thomas H. MacDonald, Chief. 



Fixed-Nitrogen Research Laboratory F. G. Cottrell, Director. 



Division of Accounts and Disbursements A. Zappone, Chief. 



Division of Publications John L. Cobbs, Jr., Chief. 



Library Claribel R. Barnett, Librarian. 



States Relations Service A. C True, Director. 



Federal Horticultural Board C. L. Marlatt, Chairman. 



Insecticide and Fungicide Board J. K. Haywood, Chairman. 



Packers and Stockyards Administration "(Chester Morrill, Assistant to the Sec- 

 Grain Future Trading Act Administration. . ) retary. 

 Office of the Solicitor R. W. Williams, Solicitor. 



This bulletin is a contribution from the — 



Bureau oj Plant Industry William A. Taylor, Chief. 



Office of Soil-Fertility Investigations. Oswald Schreiner, Biochemist in Charge. 



31 



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PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS 

 COPY FOR PROFIT. — PUB. RES. 57, APPROVED MAY 11, 1922 



