June 9,1923 
Substrate and Hydrogen-Ion Concentration 
871 
solution, sweet-potato decoction) would have on the secretion of pecti- 
nase. The methods used in these experiments have been outlined 
already. The results of these experiments are shown in Tables III to VI. 
Table III gives the results of experiment i, in which the Ph values 
of the original control solutions (column i) varied from 1.04 to 8.53. 
In this experiment the fungus grew for 5 days. 
Table III. —{Experiment i) showing hydrogen-ion concentration and dextrose content 
of the control and inoculated Czapek’s solution, the time required by them to macerate 
sweet-potato disks, and the dry weight of the mycelium produced 
Pnof 
con¬ 
trol. 
Pnof 
inocu¬ 
lated. 
Dextrose 
in con¬ 
trol. 
Dextrose 
in inoc¬ 
ulated. 
Per cent. 
Per cent. 
1.04 
1.01 
14. 7 
IS* 25 
I. 71 
I. 76 
14 - 95 
15* 25 
2.62 
2. 27 
14 - 95 
14* 55 
3 - 58 
2.18 
14*95 
13* 75 
5. 82 
2.17 
14*95 
13.40 
6. 01 
2.18 
14* 95 
13*30 
6.57 
2.15 
14* 95 
13*00 
7. 28 
2.20 
14* 95 
12. 55 
7.61 
2.32 
14.90 
12. 20 
7.91 
2.39 
14. 8s 
12. 00 
8.12 
2.59 
14. 70 
12.40 
8. S 3 
2.66 
14*55 
12. 40 
Time required to cause macer¬ 
ation in control. 
Time required to cause macer¬ 
ation in inoculated. 
Dry 
weight 
of my¬ 
celium. 
Complete in s hours. 
Complete in 24 hours. 
Some in 48 hours. 
Nearly complete in 48 hours... 
.do 
Complete in 48 horns 
.do 
.do 
Some in 48 hours 
Very little in 48 hours. 
Doubtful if any in 48 hours.... 
None. 
Complete in 5 hours. 
Complete in 24 hours. 
Some in 48 hours. 
Complete in 48 hours. 
do. 
do. 
do. 
do. 
do. 
Nearly complete in 48 hours... 
Very little in 48 hours. 
Practically none in 48 hours,.. 
Gnt. 
None. 
Do. 
o. 0283 
. 0728 
.0972 
• 1005 
. 1147 
• 1357 
• 1553 
. 1620 
. 1748 
. 1780 
In experiment 2 (Table IV) the fungus was allowed to grow for seven 
days. Carrot disks were macerated in about the same time as the sweet- 
potato disks. If there was any measurable difference the carrot disks 
were macerated in a little less time than the sweet-potato disks. 
Table IV. —{Experiment 2) Showing the hydrogen-ion concentration and dextrose con¬ 
tent of the control and inoculated solutions, the time required by them to macerate sweet- 
potato and carrot disks, and the dry weight of the mycelium produced 
Pnof 
con¬ 
trol. 
Ph of 
inocu¬ 
lated. 
Dex¬ 
trose in 
control. 
Dex¬ 
trose in 
inocu¬ 
lated. 
Per 
Per 
cent. 
cent. 
1.67 
1.63 
15*9 
15*9 
2.67 
2.22 
15*9 
14.9 
3.22 
2.09 
15*9 
14. 0 
4*39 
2.18 
15*9 
14. 0 
4 . 8 x 
2.18 
15*9 
14. 0 
5*69 
2.12 
15*9 
13*5 
< 5.46 
2.18 
15*9 
12.8 
6. 78 
2.46 
15*8 
12. 2 
6.97 
2 .47 
15*4 
II. 7 
7 * 33 
2 .59 
15*4 
II. I 
7.80 
2.58 
15*4 
9. 2 
Time required to cause 
maceration in control. 
Time required to cause 
maceration in inoculated. 
Dry 
weight 
of my¬ 
celium. 
Complete in 22 hours. 
Slight maceration in 30 hours. 
A little maceration in 30 hours. 
.do. 
.do. 
.do. 
.do. 
No maceration in 30 hours. 
.do. 
.do. 
.do. 
Complete in 22 hours.. 
Slight maceration in 30 hours. 
A little maceration in 30 hours. 
.do.. 
.do. 
.do.. 
.do.. 
No maceration in 30 hours_ 
.do—... 
.do. 
.do.. 
M, 
None, 
o. 0340 
.0766 
.0812 
. 0814 
. 1040 
• 1283 
• 1539 
. 1679 
. 1718 
• 1734 
