886 Mockeridge. — Some Conditions influencing the Fixation of 
Flask 
Proportion 
Nitrogen 
Fixation on 
Fixation on 
Average 
No. 
of Slag. 
Content. 
| grm. Mannite. i grm. Mannite. 
Fixation. 
i. 
0*2 % 
°*55 mg. 
11*98 mg. ) 
2. 
0-2 % 
6*54 mg. 
5*99 mg. 
3 * 
0*2 % 
6-86 mg. 
6-31 mg. 
12*62 mg. ) 
12*30 mg. 
4 * 
o *4 % 
0-70 mg. 
5 * 
6. 
0-4 % 
0-4 % 
7- 56 mg. 
8- 12 mg. 
6*86 mg. 
7 H 2 mg. 
13*72 mg. ) 
14*84 mg. j 
14*28 mg. 
7 * 
o*6 % 
077 mg. 
8. 
o-6% 
6-58 mg. 
5 'S 1 mg. 
11*62 mg. ) 
n *34 mg. 
9 * 
o*6% 
6-30 mg. 
5-53 mg. 
11*06 mg. i 
10. 
o*8 % 
0-84 mg. 
11. 
o-8 % 
6*02 mg. 
5‘ l8 mg. 
10*36 mg. ) 
10*78 mg. 
12. 
o-8 % 
6-44 mg. 
5‘6o mg. 
11*20 mg. \ 
13. 
i*o% 
0*98 mg. 
6-58 mg. 
14. 
i*o% 
7-56 mg. 
13*16 mg. ) 
13*02 mg. 
15. 
I-o % 
7-42 mg. 
6-44 mg. 
12*88 mg. i 
16. 
1-2 % 
0*28 mg. 
J 7 * 
18. 
I’2% 
1-2 % 
5-87 mg. 
5-87 mg. 
5*59 mg. 
5*59 mg. 
ii*i8 mg. ) 
1 i*i8 mg. | 
11*18 mg. 
1 9 * 
i *4 % 
0*28 mg. 
20. 
i- 4 % 
5-64 mg. 
5-36 mg. 
10*72 mg. ) 
10*58 mg. 
21. 
i '4 % 
5*5° mg. 
5*22 mg. 
IO *44 mg. j 
22. 
2-0 % 
0-71 mg. 
9*64 mg. ) 
2 3 - 
2-0 % 
5’53 mg. 
4*82 mg. 
io*oi mg. 
24. 
2*0 % 
5’9° mg. 
5’ J 9 mg. 
10*38 mg. \ 
25. 
2*8 % 
071 mg. 
26. 
2*8% 
5-28 mg. 
4*57 mg. 
9 M 4 mg. } 
9*00 mg. 
27. 
2*8% 
5’ J 4 mg. 
4’43 mg. 
8*86 mg. \ 
28. 
4 ‘° % 
0*64 mg. 
29. 
4 -o% 
5*43 mg. 
4*79 mg. 
9*58 mg. ) 
9*29 mg. 
3 °- 
4 '° % 
5'H mg. 
4-50 mg. 
9*00 mg. \ 
3 1 * 
5 * 0 % 
o*74 mg. 
32. 
5 ’° % 
5*H mg. 
4-40 mg. 
8* 80 mg. ) 
8*94 mg. 
33 * 
5 -o % 
5*28 mg. 
4’ 54 mg. 
9*08 mg. j 
34 * 
6*o% 
0-28 mg. 
35 * 
6*o % 
2*86 mg. 
2-58 mg. 
5* j 6 mg. ) 
4*87 mg. 
36. 
6*o % 
2*57 mg. 
2*29 mg. 
4*58 mg. \ 
37 * 
8-o% 
0*43 mg. 
38. 
8*0% 
i-86 mg. 
I *43 mg. 
2*86 mg. ) 
2*57 mg. 
39 * 
8-o% 
i -57 mg. 
1*14 mg. 
2*28 mg. ^ 
40. 
io*o % 
O’ 71 mg. 
41. 
10*0 % 
0*64 mg. 
— 
42. 
10*0% 
071 mg. 
— 
It appears from these results that a proportion of 0-4 per cent, of basic 
slag has the most beneficial effect upon the activity of the organisms. 
Their nitrogen-fixing power declines when more than 0-4 per cent, is used, 
but receives a further stimulation in a medium containing 1 per cent. 
A steady decrease in nitrogen-fixation follows upon increase in the propor- 
tion of slag above 1 per cent., until 5 per cent, is reached, when it begins to 
fall rapidly and is rendered impossible in a medium containing 10 per cent. 
These observations appear to lend support to the hypothesis put 
forward in a previous paragraph, that the effect of basic slag is not limited 
to a simple neutralization of acidity, but that there are at least two con- 
stituents, probably iron and manganese, present in the slag in different 
proportions, which exert a tonic influence upon the organisms ; the maximum 
effect of the one being obtained in a proportion of 0*4 per cent., the other 
being most efficacious in a medium containing i*o per cent. 
