204 BOTANICAL GAZETTE [OCTOBER 
acid (fig. 18). The bell jars were sealed by means of vaseline to 
ground glass plates and water was kept in the pan enough to cover 
the lower edge of the bell jars at all times. These all developed 
some growth, not perceptibly different from the aerated cultures. 
Each fungus developed its specific characters. Analysis was made 
of only one of these cultures, but the dry weight of the mycelium 
was found for all. A control was also analyzed. The develop- 
ment period was the same as for those in investigation III (70 
days). A comparison was also made in this investigation between 
the growth in ammonia-free water, prepared by another distilla- 
tion of distilled water acidulated with sulphuric acid, and in the 
“conductivity water” obtained from the chemical laboratory. 
As seen from the dry weights in the table, no perceptible difference 
could be detected. Very little growth occurred in either. The 
data are given in table IX. 
It is evident, by a glance at table IX, that these cultures showed 
no evidence of nitrogen-fixing power. The dry weights of the last 
four are too small to give any expectation of finding nitrogen by 
analysis. Repeated analyses of such amounts have shown no 
appreciable nitrogen present. Moreover, the one analyzed (no. 1) 
fully confirms this idea. 
INVESTIGATION V 
An attempt was made in this investigation to see whether fungi, 
which were supplied with sufficient combined nitrogen to start 4 
good growth, would not under such conditions show a power to 
fix some free nitrogen. This was especially desirable, since the 
results of BERTHELOT (13), PuRtewirscH (16), and LATHAM (20) 
have shown such decided nitrogen-fixation in such solutions. 
The medium used was exactly the same as that employed in the 
last two investigations, except that varying amounts of ammonium 
nitrate were added. These solutions were made as follows: First, 
Erlenmeyer flasks of 150 cc. capacity were selected and cleaned 
ready for the solutions. Then a solution exactly like that used 1 
investigation TIT was made up, using only half as much water, thus 
giving a solution of double the strength of all the constituents. 
This was called solution A. Then a solution of ammonium nitrate 
