404 BOTANICAL GAZETTE [june 
added to 2000°¢ of 5 per cent. sugar solution, which was divided into 
portions of 200° each; one series, containing boiled and unboiled 
samples, was placed in an incubator at 49° C; the other was left at 
room temperature. After twenty-four hours no change could be noted 
in either series. It appeared that Deglet Noor contained no invertase. 
A series of comparative extracts of Deglet Noor and three invert 
sugar dates was then prepared, using five parts of glycerin and seven 
parts of date, and pressing after digesting together for twenty-four 
hours or longer. In the tests the same quantities of 5 per cent. sugar 
solution and of date extract were used in each case. The preserva- 
tive used throughout was thymol. The figures show the reading on 
the saccharimeter when portions of the solution were weighed off 
and treated in the usual manner. It will be noted that the inversion 
in the case of the three invert sugar dates follows, in a general way, the 
mass law as found by O’SuLLIVAN and THompson?s for yeast inver- 
tase. In another series all the invert sugar date extracts were found 
to work better at 35° C, but the optimum was not determined. 
INVERTING POWER OF DATE EXTRACTS 
Date Hour Deglet Noor Rhars Birket el Haggi| Row 12, no. 7 
Nov. 6 2 P.M. 14 4.51 4-47 4-49 
es 5 P.M. .05 4.32 4-33 4.26 
ee Q A. M. chy 20) 2.02 3-95 
aN 4 P. M. -19 3.01 SOF 2.72 
‘i 8 9 A.M. 18 o.81 a dee I .04 
ee, 9 A. M. 16 =z 69 —o.65 1-41 
one QA. M. 15 at di —1.99 =. 5° 
12 9 A. M. 15 —1.92 ~~ <'79 ata by 
The question then arose as to whether the Deglet Noor contained 
no invertase or whether an inhibiting substance was present. The 
first experiment had already shown that the failure to invert was not 
due to low temperature. Accordingly a series of tests with equal 
amounts of invert sugar date extract were arranged and increasing 
amounts of Deglet Noor extract added until roo°* of the latter were 
present to 25° of the former. In no case could a diminution of the 
inverting power of the invert sugar date extract be observed. To 
make this matter more certain, a concentrated aqueous extract of 
35 Invertase, a contribution to the history of an enzyme or unor; ganized ferret 
Jour. Lond. Chem. Soc. 5'7:834. 1890 
eg! & = — 
a 
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