964 
Journal of Agricultural Research voi. xxx, No. 10 
and 30° C. produces a pectinase which, 
though not as active as that from 
Rhizopm tritici, will macerate raw 
sweet potato disks. 
Diploma tubericola.— Numerous 
attempts were made to demonstrate 
the production of pectinase by Diplodia 
tubericola. This fungus was grown in 
10 different substrates, among them 
sweet potato decoction, and in no case 
could the secretion of a macerating 
principle be demonstrated. In this re¬ 
spect the organism differs essentially 
from the other fungi studied. In view 
of the negative results obtained, the 
investigations with this fungus need 
not be detailed. 
* AMYLASE 
The presence of amylase was dem¬ 
onstrated by the use of potato starch- 
paste solution to which a weighed 
quantity of dried mycelium ground in 
quartz sand was added. Hydrolysis 
was carried out for 19 hours at a tem¬ 
perature of 35° C. The reducing 
sugars were determined quantitatively 
by the method of Clark (/). All starch- 
paste solutions were tested before the 
addition of the ground mycelium for 
the presence of reducing sugars, and in 
no case were any found. A control in 
which ground mycelium was added to 
the starch-paste solution and the 
enzymes inactivated by immediately 
steaming, was carried in each experi¬ 
ment. The reducing sugars of the con¬ 
trol preparations were determined, the 
amount of sugar found being probably 
due to autolysis of the mycelium and 
to such starch digestion as would 
probably take place before inactiva¬ 
tion was accomplished by the steam¬ 
ing. The reducing sugars found were 
calculated in milligrams per 10 c. c. of 
solution. 
Mucor racemosus. —The produc¬ 
tion of amylase by Mucor racemosus 
was demonstrated by the use of one- 
fourth gram of the ground mycelium 
in 50 c. c. of a 0.5 per cent starch- 
paste solution. The mycelium used 
was grown on sweet potato decoction 
for 37 days at a temperature of 5° C. 
After incubation for 19 hours at 35° 
the controls averaged 3.14 mgm. and 
the solutions containing the active 
enzymes 19.87 mgm. of reducing 
sugars in each 10 c. c. of solution. This 
seems to demonstrate clearly that the 
mycelium contains an enzyme which 
has the power to hydrolyze starch. 
Diploma tubericola. —The experi¬ 
ments with Diplodia tubericola were 
conducted the same as with Mucor 
racemosus , except that a 2 per cent 
starch-paste solution was used with 
0.5 gm. of powdered mycelium in 50 
c. c. of solution. The mycelium was 
grown for 8 days on Czapek’s modified 
solution at 30° C. The controls 
averaged 2.133 mgm. and the active 
enzyme preparation 52.96 mgm. of re¬ 
ducing sugars for each 10 c. c. of 
solution. 
INVERTASE 
The production of invertase by 
Mucor racemosus and Diplodia tuber¬ 
icola was determined by the use of 
mycelium from the same source as that 
employed in the demonstration of 
amylase. The amount of saccharose 
hydrolyzed was measured quantita¬ 
tively by a determination of the re¬ 
ducing sugars. 
Mucor racemosus. —To 50 c. c. of a 
0.5 per cent saccharose solution was 
added one-fourth gram of powdered 
mycelium. After incubation for 19 
hours at 35° C. the controls averaged 
1.42 mgm. and the active enzyme prep¬ 
arations 16.47 mgm. reducing sugars 
per 10 c. c. of solution. 
Diploma tubericola.— With this 
organism 0.5 gm. mycelium in 50 c. c. 
of a 2 per cent saccharose solution was 
used. At the end of the incubation 
period the controls averaged 6.09 mgm. 
and the active enzyme solution 175.88 
mgm. reducing sugars per 10 c. c. of 
solution. The amount of reducing 
sugars in the control is somewhat 
larger than that usually found, which 
may possibly be accounted for by auto¬ 
lysis, or by some of the saccharose 
having been broken down in heating to 
inactivate the enzyme, or both of these 
reasons may be adduced. The sugar 
solution alone before the powdered 
mycelium was added or heated con¬ 
tained only 0.95 mgm. of reducing 
sugars. 
RAFFINASE 
The secretion of ratlinase by Mucor 
racemosus and Diplodia tubericola was 
demonstrated by the hydrolysis of 
raffinose by the powdered mycelium. 
One-fourth of a gram of the powdered 
mycelium was suspended in 50 c. c. of 
0.5 per cent raffinose solution and incu¬ 
bated for 21 hours at 35° C. A 
steamed control was carried at the same 
time. At the end of the incubation 
period further hydrolysis was stopped 
by steaming the solutions in an Arnold 
sterilizer. The reducing sugars were 
determined quantitatively. 
Mucor racemosus. —The controls 
gave an average of 3.55 mgm. and the 
active solutions 13.75 mgm. of reduc¬ 
ing sugars per 10 c. c. of solution, thus 
demonstrating the presence of raffinase. 
