Feb. 24,1923 
Stimulating the Growth of Azotobacter 
673 
Examination also reveals that 42 per cent of the original amount of 
dextrose was consumed within two days, 22 per cent within four days, 
17 per cent within six days, and 13 per cent within the eighth-day period, 
while 6 per cent was not fermented. 
It also appears from these data that 31.6 per cent of the total nitrogen 
is fixed within two days, 33.8 per cent within the second period, 10.9 
per cent within the third period, and 23.5 per cent within the fourth 
period. The amount of dextrose consumed in four days was 64 per cent 
of the sugar originally present, while the amount of nitrogen fixed within 
the same period was 65 per cent of the total nitrogen fixed. This periodi¬ 
cal rate of nitrogen fixation and dextrose fermentation is noted in figure 
3 by the curves plotted from these data. 
Resummarizing the data in Table III as noted in Table VI shows that 
the rate of azofication per gram of dextrose per day is very uniform. 
On the sixth day the amount of nitrogen recorded is greater than the 
amount actually fixed for this period as the nitrogen determinations were 
lost on the fifth day. The figures, therefore, in reality give the amount 
of nitrogen fixed between the fourth and sixth days. 
During the first three days a fixation of 78 per cent of the total nitrogen 
occurred. The amount of dextrose fermented in the same period was 95 
per cent of the original amount present. 
The curves in figure 4, plotted from these data, exhibit curves 
similar to those noted in figure 3. 
Table IV .—Rate of nitrogen fixation and dextrose fermentation 
Culture. 
9 B. ■ 
2 B. . 
9 A. . 
S»- 
11 B. 
8 B. . 
3 A.. 
213. . 
6 A. . 
Average 
2 days. 
4 days. 
6 days. 
8 days. 
Gm. 
dex¬ 
trose. 
! 
j Mgiu. 
i N. 
Gm. 
dex¬ 
trose. 
Mgm. 
N. 
I'll 
Mgm. 
N. 
Gm. 
dex¬ 
trose. 
Mgm. 
N. 
0. 70 
i 
1. 
O. 49 
6.6 
0. 28 
6. 7 
O. IO 
7.0 
• 70 
i -5 
•49 
8. 6 
•34 
7.0 
• 13 
7-4 
• 54 
2.8 
. 24 
8.0 
.08 
O 
11. 6 
. 61 
i -5 
•49 
5-6 
•30 
6.8 
. 2 
9.8 
.70 
3-2 
•49 
4.9 
6. 21 
5-3 
O 
10.0 
•54 
3 - 8 
•49 
4-9 
•34 
8. 4 
•3 
• 50 
2.9 
. 18 
5-3 
.04 
7 - 7 
.63 
5-2 
•32 
5-6 
. 18 
8. 0 
•38 
5-3 
•05 
4.9 
0 
6. 1 
0 
• 58 
2.9 
•36 
6. 0 
. 19 
7.0 
. 06 
9. 16 
Table V .—Rearrangement of data from Table IV 
2 days. 
4 days. 
6 days. 
8 days. 
Total grams dextrose consumed. 
O. 42 
O. 64 
j 
0.81 ; 
O. 94 
Total milligrams nitrogen fixed. 
2. 90 
6. 00 
7.00 ! 
9. 16 
Grams dextrose consumed each 2 days. 
• 42 
. 22 
• *7 I 
• 13 
Milligrams nitrogen fixed each 2 days. 1 
Rate of azofication per gram dextrose each 2 j 
2. 90 
3. 10 
1. 00 
2. l6 
davs.; 
6. 90 
9-37 
8. 64 j 
9 - 74 
