8 76 Mockeridge . — Some Conditions influencing the Fixation of 
The acid phosphate was dissolved separately and just neutralized by means 
of a decinormal sodium-hydrate solution before being added to the main 
bulk. The seven flasks used in this case were numbered from 15 to 21 
inclusive. The whole series of 21 flasks was inoculated at the same time 
with the same suspension of Azotobacter , in order that the conditions should 
be as uniform as possible, and Nos. 1, 8, and 15 were sterilized, after 
inoculation, in the autoclave for ten minutes at a temperature of 135 0 C. 
These served as controls, one for each of the solutions used, and by inocu- 
lating the flasks before sterilizing a knowledge of the actual fixation 
of nitrogen was arrived at, and not the nitrogen fixed plus the small amount 
of nitrogen supplied in the bacterial cells. The twenty-one flasks were then 
incubated at a temperature of 28° C. for seven days, at the end of which 
period the contents of each were transferred by means of distilled water 
from a wash-bottle to round-bottomed flasks, to undergo analysis by the 
Kjeldahl process for their nitrogen content. The results of these analyses 
are given in the following table : 
Table I. 
Flask 
No. 
1. 
2. 
3- 
4- 
5- 
6 . 
7* 
8 . 
9- 
10. 
12. 
13 - 
14. 
15 - 
1 6. 
i7- 
18. 
19. 
20. 
21. 
Culture Solution. 
Bottomley’s Solution (I) 1 — sterile 
,, with Azotobacter 
(II) 1 — sterile 
with Azotobacter 
Ashby’s solution — sterile . . . 
,, with Azotobacter 
Gain in 
Nitrogen- 
Nitrogen 
Nitrogen 
fixation 
Content. 
on | grm. 
Mannite. 
on 1 grm. 
Mannite. 
0-14 mg. 
4.78 mg. 
4.64 mg. 
9.28 mg.' 
5.48 mg. 
5-34 mg. 
10.68 mg 
4*92 mg. 
4.78 mg. 
9.56 mg. 
>■9' 
5.20 mg. 
5.06 mg. 
io« r 2 mg. 
4.64 mg. 
4.50 mg. 
9.00 mg. 
4.92 mg. 
0.14 mg. 
4.78 mg. 
9-56 mg.. 
6.18 mg. 
6*04 mg. 
12-08 mg. N 
6-33 mg. 
6.19 mg. 
12.38 mg. 
6*6 1 mg. 
6.47 mg. 
12.94 mg. 
■ 
5.76 mg. 
5.62 mg. 
11-24 mg. 
5.90 mg. 
5.76 mg. 
11.52 mg. 
6-i 8 mg. 
o-i 1 mg. 
6*04 mg. 
12-08 mg.. 
1 
3* IQ mg. 
2.99 mg. 
5-98 mg.’ 
3*30 mg. 
3.19 mg. 
6.38 mg. 
2*81 mg. 
2-70 mg. 
5.40 mg. 
- 6 
3.09 mg. 
2.98 mg. 
5.96 mg. 
3-23 mg. 
3.12 mg. 
6*24 mg. 
3-37 mg. 
3.26 mg. 
6.52 mg. ; 
decided 
fixation 
of nitrogen 
Average 
Nitrogen- 
fixation. 
9.70 mg. 
1 2*04 
6.08 
mg. 
While the results show a v 
the media, yet both of Bottomley’s solutions appear to be better than 
Ashby’s medium, and the presence of basic slag seems to have a beneficial 
effect. The fixations in each series appear to be fairly uniform among 
themselves, and are consistent with other results which have been obtained, 
so that, as a result of these determinations, Bottomley’s solution (II), 
1 ‘ Bottomley’s Solution (I) ’ is the solution containing calcium carbonate, while ‘ Bottomley’s 
Solution (II) ’ is that containing basic slag. 
