103 



we have cited abo\'e. As Moore and Webster haxe put it, 

 authority has too long held sway over logic and experimental 

 fact. It is high time to let those considerations rule." 



These words will appear all the more opportune to-da>' if it 

 be remembered that about 70 years ago there took place in 

 France the famous controversy between Ville and Boussingault, 

 which impassioned the physiologists and the agronomists of the 

 whole world. At the end of this controversy the victory was 

 unjustly gi\'en to Boussingault, who supported the theory that 

 plants do not assimilate free nitrogen from the air. Notwith- 

 standing this decision the experiments of Ville twenty years 

 later received, in part at least, a victorious confirmation frcm 

 Hellriegel and Willfarth's discovery of the assimilation of 

 nitrogen from the air by the legumes. And if the numerous 

 works published afterwards in Germany and in France did not 

 make it possible to reach a definite conclusion as to whether or 

 not all cases of the positive assimilation of free nitrogen were due 

 to the presence of microorganisms, or if attributable to the direct 

 aerial assimilation by the green cells, the results presented in 

 various papers published by Prof. Pollacci and myself from 191 1 

 until the present (which completely exclude the causes of error 

 not taken into account by preceding investigators) together 

 with those obtained by the authors cited in the present article, 

 appear to us sufficient ground for abandoning the old error 

 and concluding this debated question definitely as follows: 



The property of assimilating jree nitrogen from the air is more 

 general than heretofore admitted, as all plants, from the algae to the 

 angiosperms , can, according to their condition of life, use this 

 power with more or less activity. Notwithstanding this it is natural 

 that some cultivated species cannot do without the combined nitrogen, 

 which for so long a time has been supplied by the soil. It is also 

 natural that there should exist plants which have a special power 

 to assimilate free nitrogen: real nitrogen accumulators: and this 

 not solely by the presence in their tissues of symbiotic microorgcniims, 

 as in the case of legumes and other plants, but also by direct assimi- 

 lation, as shown by the results of analysis obtained by Pollacci and 

 m^y self with the following species: Raphanns sativus, Acer negundo, 

 Cucurbita pepo. Polygonum fagopyrum , and various other species. 



