42 



Lewis Knudson 



maltose, and saccharose were emploj^ed. While with the carbon-equivalent 

 solutions glucose is probably at an advantage because of increased osmotic 

 pressure, with equimolecular solutions glucose suffers by comparison 

 because of less available carbon. For everj- molecule of saccharose 

 entering the plant there is made available one molecule of glucose and 

 one of fructose, by virtue of the action of the enzynie invertase. Thus 

 it is evident that glucose would have to penetrate twice as rapidly as 

 saccharose in order to produce the same effect. 



In this experiment the glucose, maltose, and saccharose used were 

 of 0.05 gram molecular concentration in Pfeffei;'s solution at one-half 

 its normal strength. Large cylinders were used, containing 200 cubic 

 centimeters of the nutrient solution plus 0.5 per cent of agar. In each 

 cylinder two seeds, each weighing 32 milligrams, were sown, after being 

 sterilized in the usual way. The cultures were made in quadruplicate, 

 but again, as in the preceding experiment, a number of the cultures had 

 to be discarded because of delayed germination and other conditions. 

 The sugar determination was made gravimetrically by the Fehling method. 

 The nutrient medium was made up to 1000 cubic centimeters, and the 

 sample taken for analysis was freed of agar by precipitation with lead 

 subacetate; the lead being removed by treatment with anhydrous sodium 

 sulfate. The results obtained are given in table 17: 



TABLE 17. Influence of Equimoleculae Sugar Solutions on Vetch 

 (Duration, thirty-three days) 



















Sugar 



Sugar 





Cultvire 

 solution 





Number 



of 



plants 



Green 

 weight 

 (grams) 



Dry 

 weight 



roots 

 (grams) 



Dry 



weight 



of 



tops 



(grams) 



Total 



dry 



weight 



(grams) 



Gain 



in 

 weight 

 (grams) 



begin- 

 ning, 

 of 



experi- 

 ment 



(grams) 



at 

 end 

 of 

 experi- 

 ment 



Sugar 



sorbed 

 (grams) 



















(grams) 





Check (no 



-II 



2 



1.82 



0.036 



0.133 



0.169 



0.105 











2 



1.52 



0.028 



0.128 



0.156 



0.092 









Glucose 



n 



2 



1.90 



0.040 



0.153 



0.193 



0.129 



1.759 



1.675 



0.084 



•12 



2 



2.30 



0.043 



0.213 



0.256 



0.192 



1.759 



1.660 



0.099 



Maltose 



•{I 



1 



1..32 



0.027 



0.113 



0.140 



0.108 



3.577 



3.545 



0.032 



2 



2.02 



0.054 



0.150 



0.204 



0.140 



3.577 



3.480 



0.097 



Saccharose. . . 



f *i 



2 



2.55 



0.080 



0.190 



0.270 



0.206 



3.666 



3.544 



• 0.122 



lt2 



2 



2.40 



0.073 



0.190 



0.263 



0.199 



3.666 



3.550 



0.116 



* 0.302 gram of reducing sugar present. 

 t 0.342 gram of reducing sugar present. 



