VOLUME LVI NUMBER 4 
LHE 
BOTANICAL (GAZETTE 
OCTOBER 1913 
CAN FUNGI LIVING IN AGRICULTURAL SOIL ASSIMI- 
LATE FREE NITROGEN? 
H. N. GopDARD 
(WITH EIGHTEEN FIGURES) 
I. Historical introduction 
As early as the middle of the nineteenth century it was known 
to Boussincavtt (cited by Sacus 1) that plants cannot make use 
of atmospheric nitrogen in their nutrition, but are dependent on 
combined. nitrogen which they ordinarily get from the soil. This 
idea has become so thoroughly established in all later works that 
any evidence of nitrogen-fixation by plants is received with unusual 
interest. Such evidence has come almost entirely from studies of 
lower organisms, such as bacteria, algae, and fungi. 
The full establishment of the nitrogen-fixing power of certain 
bacteria calls for little discussion in this paper. The important 
and now classical studies of HELLRIEGEL (2), BEYERINCK (3), 
HILTNER (4), WinocRapskKI (5), and SroxLasa (6) have put on 
a sure scientific basis the fact that a number of bacteria, including 
not only those associated with root tubercles, but several others, 
have the power to assimilate free nitrogen, especially when deprived 
of sufficient quantities in the combined form. It is perhaps worthy 
of note, also, that this power has been found in many cases to be 
much augmented by a symbiotic relationship with other organisms, 
such as algae, Leguminosae, and with other bacteria. A good 
résumé of the literature of this subject has been given by CHESTER 
(7), Kocu (8), and Hetzer (9). 
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