374 LEWIS KNUDSON 
Table i. Canada field pea. Duration, Nov. 2 to Dec. ij, IQ16: 42 days. 
Water 
Trans- 
pired 
(Cubic 
Centi- 
meters) 
Dry Weight 
Roots 
(Grams, 
1 ops 
(Grams) 
Total 
(Grams) 
Total 
Sugar in 
Culture 
Solution 
at End 
of 
Experi- 
ment, 
Calcu- 
Ipted as 
Invert 
Sugar 
(Grams) 
Sugar 
Ab- 
sorbed 
by 
Plant, 
Calcu- 
lated as 
Invert 
Sugar 
(Grams) 
Reduc- 
ing 
Sugar in 
Culture 
Solution 
at End 
of 
Experi- 
ment, 
Calcu- 
lated as 
Invert 
Sugar 
(Grams) 
Pfeffer' 
' + Vi per cent sucrose 1 i 
+ 3^ per cent " 2 
+ 3^ per cent 
+ 3^ per cent 
+ ^ per cent 
210 
230 
170 
120 
150 
0.130 
0.170 
0.082 
0.140 
0.100 
0.375 
0.368 
0.215 
0.140 
0.280 
0-505 
0.538 
0.297 
0.280 
0.380 
4-584 
4-544 
4.652 
4-572 
0.216 
0.256 
0,148 
0.228 
0.541 
0.600 
0.497 
0.491 
is there not a greater production of reducing sugars? The maximum 
increase in reducing sugar is only one fifteenth of the sucrose present. 
Circumstances prevented at this time any incubation experiment with 
the culture solutions to determine whether or not there would result an 
increase in reducing sugars which might be taken as evidence of the presence 
of invertase. 
Experime?it 2. The culture methods and conditions were essentially 
like those of the preceding experiment. The nutrient solution was slightly 
modified by the substitution of ferrous chloride for ferric chloride, and the 
sucrose used was Merck's highest purity. The nutrient solution at the 
outset had a hydrogen-ion concentration of P[H] 6.80. 
Two plants were used in the experiment: corn, variety Weber's Dent, 
and Canada field pea. Unfortunately most of the cultures of Canada field 
pea became contaminated, and data were obtained from only one sucrose 
culture. 
An examination of table 2 reveals the fact that as usual a better growth 
is obtained with sugar than without. An exception is culture number 6, 
which was maintained in diffused light in the laboratory for ten days pre- 
ceding the conclusion of the experiment. 
In cultures 6 to 10 inclusive there was noted an increase in reducing 
sugars, but none was found in cultures 11 to 15 inclusive. The amount of 
reducing sugar in the sucrose cultures, while appreciable, is again relatively 
small compared to the total sugar present. In culture number 8 the un- 
usually large amount of reducing sugar was undoubtedly due in part to 
contamination by a species of Penicillium which made its appearance during 
the last week of growth. The average hydrogen-ion concentration was 
at the conclusion of the experiment P[H] 7.35. 
In order to determine whether or not the enzyme invertase is present 
in the culture solution, 500 cc. portions of the solutions were incubated for 
14 days at a temperature of 32° C. As an antiseptic agent, 2 percent of 
