Aug. 19, 19x8 
Reaction on Nitrogen-Assimilating Bacteria 
33i 
Table VII .—Effect of concentration of hydrogen ions on the reproduction of legume 
bacteria after 21 days —Continued 
Result after 21 days. 
No. 
Ph. 
Soy¬ 
bean x6. 
Soy¬ 
bean 17. 
Velvet 
bean x8. 
Lu¬ 
pine 19. 
Lu¬ 
pine 20. 
Lu¬ 
pine 21. 
Lu¬ 
pine 22. 
1. 
3 -o 
None.... 
None.... 
None.... 
None.... 
None.... 
None.... 
None. 
jt.. .. 
3 -x 
...do_ 
...do.... 
...do.... 
...do.... 
...do.. .. 
.,.do.... 
Do. 
3. 
3• 3 
.. .do_ 
...do.. .. 
...do.... 
Growth. 
Growth. 
Growth. 
Growth, 
4... 
3-4 
.. .do_ 
Growth. 
Growth. 
...do.... 
.. .do.. .. 
...do.... 
Do. 
5.. 
3 - S 
Growth. 
. ..do_ 
.. .do.... 
...do.... 
...do.... 
...do.... 
Do. 
6.. 
3-6 
...do_ 
...do.. .. 
.. .do.... 
...do_ 
...do.... 
...do.... 
Do. 
7 . 
3*7 
.. .do_ 
...do,. .. 
.. .do- 
...do.. .. 
.. .do.... 
...do_ 
Do. 
8....... 
3-8 
. ..do_ 
...do.... 
...do.... 
...do.. .. 
...do.... 
.. .do.... 
Do. 
9. 
4.0 
...do.... 
...do_ 
.. .do.... 
...do.... 
...do.... 
...do.... 
Do. 
10.. 
4.1 
...do.... 
...do.... 
...do_ 
...do_ 
.. .do_ 
...do.... 
Do. 
11. 
4-3 
...do.... 
.. .do.... 
...do_ 
...do.... 
.. .do_ 
...do.... 
Do. 
12. 
4.6 
. ..do_ 
...do_ 
...do.. .. 
...do.... 
...do_ 
...do.... 
Do. 
13.. 
4.8 
.. .do,.... 
...do.... 
.. .do_ 
.. .do.... 
...do.... 
.. .do_ 
Do. 
14. 
5 -0 
...do_ 
. ..do_ 
. ..do_ 
.. .do.... 
.. .do.... 
.. .do_ 
Do. 
15.,. 
5*2 
...do.. .. 
...do_ 
...do.... 
.. .do_ 
.. .do.... 
...do_ 
Do. 
16..... 
5*4 
.. .do_ 
.. .do.... 
...do.... 
.. .do.... 
, ..do_ 
.. .do_ 
Do. 
17. 
5*5 
...do_ 
.. .do.... 
...do.... 
...do.... 
...do.... 
. ..do_ 
Do. 
18. 
5*6 
...do_ 
. ..do_ 
...do.... 
.. .do.... 
...do.... 
...do_ 
Do. 
19. 
5-7 
...do_ 
...do.... 
...do.... 
. ..do_ 
...do.... 
...do.... 
Do. 
20. 
5*9 
...do_ 
...do.. .. 
...do_ 
.. .do_ 
.. .do.... 
.. .do_ 
Do. 
21. 
6. t 
...do_ 
...do_ 
...do.. .. 
.. .do.... 
., .do_ 
.. .do.... 
Do. 
22. 
6* 2 
...do- 
...do..., 
...do.... 
...do.... 
.. .do_ 
...do_ 
Do. 
23. 
6.3 
.. .do_ 
. ..do_ 
...do.,.. 
...do_ 
.. .do.. .. 
...do.. 
Do. 
24. 
6.4 
...do,. .. 
...do.... 
. ..do_ 
. ..do_ 
...do.... 
...do.... 
Do. 
25. 
6.6 
...do.... 
...do.... 
. ..do_ 
...do.... 
.. .do.... 
...do.... 
Do. 
26. 
6.8 
.. .do..., 
...do.. .. 
...do.. .. 
.. .do.... 
.,.do.... 
..'.do_ 
Do. 
27. 
7 -o 
...do.... 
...do.... 
...do.... 
.. .do.. .. 
...do.,.. 
.. .do.... 
Do. 
2 8.. 
Do. 
The limit of growth and critical P H values for the legume bacteria and 
Azotobacter are about as follows: 
No. 
Organism. 
Acid value 
. of Ph 
which 
allows 
growth. 
Add value 
of Ph 
which 
inhibits 
growth. 
Mean value 
of Ph 
or the 
critical 
Ph. 
I 
Rhizobium leguminosarum from alfalfa. 
5*° 
4. 8 
4*9 
2 
Rhizobium leguminosarum from sweet clover... 
5-o 
4*8 
4*9 
3 
Rhizobium legunimosarum from garden pea. 
4*8 
4.6 
4* 7 
4 
Rhizobium leguminosarum from field pea...... 
4*8 
4*6 
4*7 
5 
Rhizobium leguminosarum from vetch. 
4*8 
4.6 
4*7 
6 
Rhizobium leguminosarum from red clover. 
4*3 
4* I 
4. 2 
7 
Rhizobium leguminosarum from bean. 
4*3 
4* I 
4. 2 
8 
Rhizobium leguminosarum from soybean....... 
3*4 
3*2 
3*3 
9 
Rhizobium leguminosarum from velvet bean. . . 
3*4 
3*2 
3*3 
10 
Rhizobium leguminosarum from lupine. 
3*2 
3* 1 
3* 15 
11 
Azotobacter.. 
6.6 
6.4 
6* 5 
If the critical P s value of the legume bacteria be compared with the 
growth of the leguminous plant in soil of varying reaction, it will be noted 
that the bacteria in relation to acidity behave similar to their host plants. 
Here, then, is a characteristic of the legume bacteria which separates 
these organisms into different groups, acid sensitive, acid resistant, and 
no doubt a long list of organisms intermediate between the two extremes. 
