234 BOTANICAL GAZETTE [MARCH 
DucGeGar (loc. cit.). In the course of an experimental review of 
previous work on nitrogen fixation by fungi, DuccGarR has repeated 
and extended the observations of earlier workers on this subject, 
taking extraordinary precautions to avoid experimental methods 
open to criticism on the score of inaccuracy. Among the species 
thus investigated are Penicillium spp., Aspergillus niger, Macro- 
sporium commune, Glomerella Gossypii, and Phoma Betae, as well 
as three forms of Azotobacter isolated from different soils. With 
regard to the four first named genera, DuGGAR’s work confirms that 
of previous observers, namely, that these fungi can utilize atmos- 
pheric nitrogen to a very slight extent. The amounts recorded are 
very small, and in DuGGar’s opinion cannot be accepted as con- 
clusive evidence of ability to fix atmospheric nitrogen. On the 
other hand, the values obtained by Duccar for Phoma Betae range 
from 3.022 mg. to 7.752 mg. per s5occ. of culture fluid, a known 
amount of combined nitrogen being supplied. These values are 
of special interest for comparison with those recorded by TERNETZ 
for the forms of Phoma radiciis extracted from the roots of ericaceous 
species. Indeed, the evidence appears to be conclusive that ability 
to continue to fix atmospheric nitrogen exists in varying degree in 
Phoma. 
The experimental results obtained by the writer indirectly 
support this view, and provide a basis for an intelligible explana- 
tion of one physiological aspect of the relation between green 
plant and fungal symbiont in Ericaceae; incidentally, they throw 
light on the proved ability of species such as Calluna and Vaccinium 
to thrive in soils deficient in nitrates. The degree of nitrogen 
fixation by the endophyte doubtless varies with the species con- 
cerned, and may operate as an important survival factor for the 
plant growing under competitive conditions. 
Summary 
1. In 1907 TERNETZ provided evidence that certain strains of 
Phoma, isolated from the roots of ericaceous plants, could utilize 
atmospheric nitrogen. 
2. In 1915 the necessary proof that the fungi extracted by 
TERNETZ were actually the endophytes was provided by the 
