174 
AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
results are expressed, however, on the basis of 250 grams of soil. A curve 
constructed from these data is shown in figure 15. 
Table 8. The Effect of Hydrochloric Acid and Sodium Hydroxide on the Reaction of the Soil 
Used in Experiment 5 
Treat- 
ment 
Cc. 2N HCl per 250 G. of Soil 
Cc. 2N NaOH 
10 
7 
5 
4 " 
3-5 
3 
2.5 
2 
1.5 
I 
0 
2 
5 
10 
13 
Ph 
3-5 
3-8 
4.47 
4-25 
5-12 
5.3 
5-43 
5-47 
5-47 
5.6 
5-74 
6.4 
6.98 
7.18 
7.83 
7.83 
SIS 
m 
m 
i 
m 
Fig. 15. Titration curve of soil used in experiment 5 with 2N HCl and 2N NaOH. 
Inoculation and planting were carried out as in experiment 4. The 
seeds planted in the sixteen uninoculated flats were soaked in sterile water 
for the same length of time that the others were immersed in the spore 
suspension. 
The appearance of the seedlings at the surface of the soil was first noted 
three days after planting. A larger number of seedlings was found in the 
inoculated series. In the latter series seventeen seedlings were counted, 
as compared with seven in the inoculated series. The total number of 
seedlings up in the uninoculated flats continued to be larger than in the 
inoculated set. The relation between the two series and the relation of 
each to the acidity are brought out in table 9 and also in the graphs in figures 
16 and 17. At this time it is not certain whether or not this difference is 
due to infection by Gihherella Sauhinetii. The pn values given are the 
averages of two series of determinations made one day before and four 
days after this period respectively. 
