2 o 8 Tuttle . — Induced Changes in Reserve 
cause the formation of starch, for the outside material gave no reaction to 
the iodine test. The effect of changing temperature was watched, and it 
was found that the enzyme response diminished after a fortnight of lower 
temperature, although at that time a slight reaction was given despite the 
fact that the material was gathered when the temperature was lower than 
o° F. (— 1 7 0 C.). 
The important point, however, was that the material undergoing con- 
version gave a strong enzyme reaction. The next step was to determine 
whether or not this was due to the fat-splitting enzyme lipase. The test 
applied was that used by G. J. Fowler (3) and Reynolds Green (4) in work 
with germinating Ricinus seeds. Here the solution which is to be tested 
for the presence of the enzyme is allowed to act on an oil emulsion caus- 
ing (if lipase be present) the hydrolysis of the oil and the formation of a 
fatty acid. 
An extract of the leaves was made by grinding them in a mortar with 
a solution containing 5 per cent, sodium chloride and 0-2 per cent, thymol 
as an antiseptic. This was allowed to stand for twenty-four hours and then 
filtered. The filtrate was treated as follows : an emulsion of olive oil with 
a little gum arabic was made, and to this was added a small amount of the 
extract, phenolphthalein being used as an indicator. As the leaf extract and 
oil emulsion were both slightly acid, they were carefully neutralized with 
a few drops of very dilute caustic potash. From two to five experiment 
tubes were made up in this manner. A control was made up in a similar 
manner, except that the extract was boiled for two or three minutes before 
it was added to the emulsion. Both experiments and control were placed 
in an oven at 95 0 F. (35 0 C.). Table V gives the results of several tests for 
lipase in extracts from material of different conditions. The test made on 
January 9 shows that fresh material from outside without exposure to 
higher temperature does not respond to the test for lipase. 
Table V. 
Date . 
Dec. 4 
„* § 
Jan. 2 
>> 9 
L 16 
Feb. 8 
A ction of L ipase . 
Exposure to Higher 
Temperature . 
4 days 
4 » 
2 „ 
None (material tested 
when brought in) 
2 days 
2 
11 
Experiment. 
Acid reaction after 
4 hours 
Acid reaction after 
4 hours 
Acid reaction after 
2 hours 
No reaction 
Acid reaction after 
2 hours 
Acid reaction after 
4 hours 
Boiled 
Control. 
No reaction 
Slightly acid 1 
No reaction 
Indicator. 
Litmus 
Phenolphthalein 
1 Due to insufficient boiling. 
