The 



Plant World 







j\ Magazine of General Botany 







VOLUME 12 







NUMBER 6 







JUNE 1909 







Containing 







Darwinism and Experimentation in Botany 







By D. T. MacDougal 12 1 







An Advance in Root Physiology 







By B. B. Livingston 127 







The Fixation of Nitrogen by Means of Bacillus radicicola 







By K. B. Fred and W. H. Kllet 131 







A Peculiar Specimen of Arctium 







By H. B. Bn.wn 135 







Books and Current Literature .138 







Notes and Comment 141 







Tucson, Arizona 







Entered as Second Class Matter, Dec 1 7, 1907, at the Post-Office, Tucson, 

 Aritemn. under the Act of Conoress of March 3. 1R7Q 



