Vol. io JUI.Y 19, 1920 No. 13 



JOURNAL 



OF THB 



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 J. FRANnm Mbybr Robekt B. Sosmak S. F. Blake 



BCKBAO 0» ■TAMDAMDB OBOFHTMCAL LABOMATOST BUREAU OF PLANT INDUSTRY 



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BntMcd M Second CUlm Matter. January 25, 1919, at the poat-ofiBce at Ea»to«. Pa., nadar tfc« 

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