THE SECRETION OF INVERTASE BY PLANT ROOTS 375 
Table 2. Corn. Duration, Dec. ji, igi8 to Feb. 10, igig: 42 days. 
Dry Weight 
Total 
Sugar at 
Sugar 
Reducing 
s 
End of 
1 
Water Trans- 
Experi- 
Calcu- 
lated as 
Sucrose 
Used 
Culture Solution 
u 
s 
3 
pired (Cubic 
Centimeters) 
Green W 
(Granr 
Roots 
(Grams) 
Tops 
(Grams) 
Total 
(Grams) 
Calcu- 
lated as 
Sucrose 
ent at End 
of Experi- 
ment 
(Grams) 
(Grams) 
Pfeffer's + sucrose . . . 
6 
300 
21.5 
0.220 
0.970 
1. 19 
3769 
0.984 
0.583^ 
+ " ... 
7 
326 
27.0 
0.410 
1.420 
1.83 
4-314 
0.439 
0.434 
+ " ... 
8 
29.0 
0.540 
1.620 
2.160 
3-657 
1.096 
0.976^ 
+ " ... 
9 
340 
29.0 
0.290 
1.30 
1.590 
4.217 
0.535 
0.3125 
+ " ... 
10 
270 
23.0 
0.270 
1.250 
1.520 
4-595 
0.158 
0.328 
+ " ... 
Control solution no plant 
4-753 
trace 
Pfeffer's 
II 
300 
13.2 
0.120 
0.610 
.0.730 
12 
310 
16.5 
0.230 
1.050 
1.280 
1 
No 
13 
190 
II-5 
0.220 
0.650 
0.870 
reducing 
14 
168 
10.5 
0.130 
0.520 
0.650 
1 
sugar 
15 
300 
20.0 
0.190 
1. 100 
1.290 
J 
^ Kept in laboratory in diffused light for 10 days before analysis. 
2 Contaminated. 
toluene was used. At the end of the 14 days, analyses were again made for 
reducing sugars. No increase was shown in any case after incubation except 
in number 3. In this case the amount of reducing sugar had nearly doubled, 
due undoubtedly to the enzyme invertase derived from the Penicillium 
contamination. 
In the Canada field pea cultures only one of the sucrose cultures re- 
mained uncontaminated. The duration of growth in this case was 50 
days, the green weight 14.95 grams, and the amount of reducing sugar 
present 0.448 gram. The total sugar present calculated as sucrose was 
3.71 1 grams, and the amount of sugar as sucrose used was 1.042 grams. 
The non-sucrose cultures did not show any reducing sugars in the culture 
medium. As in the experiment with corn, 500 cc. of the culture solution 
was incubated for 14 days at a temperature of 32° C. No increase in 
reducing sugar was found at the end of that period. 
Experiment j. A white dent variety of corn was used and the plants 
were grown as before in the greenhouse. The duration of the experiment 
was from June 27 to July 29, a period of 32 days. The concentration of 
sucrose was }4 percent. In this experiment the hydrogen-ion concentration 
of the culture solution was again accurately determined by the indicator 
method, using anhydrous KH2PO4 and Na2HP04 according to Soerensen 
and using neutral red as the indicator. In addition to determining the 
hydrogen-ion concentration, several cultures were provided, to each of 
which was added i cc. of a >^ percent solution of neutral red, the purpose 
being to follow the reaction during plant growth. This was possible for 
only about ten days, for the plant by the tenth day had absorbed all the 
indicator. From the outset the solution became increasingly alkaline, so 
that it was only at the outset that an acid reaction prevailed and then the 
hydrogen-ion concentration was only io~^-'^ normal. 
