6 i 8 
Journal of Agricultural Research 
Vol. XXI, No. 9 
inoculated they served as a control. Maceration was carried out at 
37.5 C. The results of these experiments are shown by Table I. 
Table I .—Time in hours required by the mycelium and the solution on which it grew 
to macerate sweet-potato disks after growth in sweet-potato decoction for stated intervals 
of time 
Hours required to macerate after growing in culture— 
1 
2 
3 
4 
5 
6 
days. 
10 
1 r 
12 
13 
16 
day. 
days. 
days. 
days. 
days. 
days. 
days. 
days. 
days. 
days. 
days. 
Powdered hyphae: 
Enzym powder. 
O 
4- OO+ 
4- 5 
4- 75 
c c 4- 
5-5 + 
5- 5+ 
5- 25 
. 
Q „ 
Water (control), no 
O' w 
4* 5 
5- 5 ■ 
7- 0 “i 
0. 5 
19. 0 
maceration. 
Solution: 
Not steamed. 
t- 75 
i- 75 
i- 75 
i- 75 
i- 75 
i- 75 
2. 0+ 
2.25+ 
4- 5 
6. o-f- 
Steamed (control), no 
maceration. 
No fungous growth (con¬ 
O' v 
i- 5 
trol), no maceration. 
From Table I it is seen that the macerating power of the liyphae per 
unit of dry weight is greatest on the first and second days of growth 
and becomes gradually weaker thereafter. The enzym of the solution, 
on the other hand, is equally powerful from the second to the seventh 
day of growth, inclusive. The writers have arbitrarily adopted three 
days as the standard length of time for growth. Somewhat discordant 
results were obtained in the steamed solutions and in the solutions on 
which the fungus was not grown. No maceration was apparent in such 
solutions at the end of the time required to macerate completely the 
disks in the solutions containing the active enzym. On the other hand, 
in some cases if they were exposed for some hours longer maceration was 
evident, and it was often completed in 24 hours. 
RELATION OF VARIOUS FACTORS TO MACERATION 
The writers have previously discussed the method used in carrying 
out macerating experiments with the enzym contained in the mycelium 
and with that exuded into the substratum. Experimental data have 
also been submitted which show that Rhizopus tritici produces both 
a powerful intracellular and extracellular pectinase which dissolves the 
middle lamellae of raw sweet-potato disks in from two to five or more 
hours (Table I), depending upon the length of time the organisms grew 
in the culture. It was shown that the most vigorous enzym was con¬ 
tained in cultures 1 to 3 days old. 
In investigations of this kind the methods used in the treatment 
of the fungous material or of the solution might conceivably greatly 
influence the activity of the enzym. To obtain reliable data it was, 
therefore, necessary to make a careful study of the physical, mechanical, 
and other factors involved in the various steps in the process of manipula- 
