I 



Influence of Certain Carbohydrates on Green Plants 37 



grown in the presence of saccharose traces of reducing sugars were detected 

 by the use of Benedict's (1908-09) solution. The agar in the immediate 

 region of the traversing roots showed traces of reducing sugars, which were 

 made more evident by the use of Benedict's solution. The agar from the 

 center of the mass through which the roots had not penetrated gave no in- 

 dication of reducing sugars. The agar was also tested for hexose sugar by 

 means of osazone tests. None was noted except in the saccharose culture. 

 A number of the cultures of this series were examined on March 7, 

 and the results as regards green weight determinations at that time are 

 given in table 14. The results are concordant with the data obtained 

 from the cultures examined on March 16 (table 13). Unfortunately the 

 saccharose culture examined on March 7 showed contamination by a 

 yeast, and its increased growth may have been due in part to an increased 

 supply of carbon dioxide produced as a result of this contamination. 



TABLE 14. Influence of Various Sugars on Vetch Grown in the Greenhouse 



(Duration, fifty-four days) 



Culture solution 



Length 

 of tops 

 (centi- 

 meters) 



Length 

 of roots 

 (centi- 

 meters) 



Total 



green 



weight 



(grams) 



Green 



weight 



per plant 



(grams) 



Check (no sugar) .... 

 Maltose, 2 per cent . . 

 Lactose, 2 per cent . . . 

 Saccharose, 2 per cent 



34.0 

 37.0 

 27.5 

 47.0 



17.1 

 15.0 

 21.0 

 26.0 



1.629 

 3.720 

 2.386 

 6.428 



0.407 

 0.930 

 0.596 

 1.607 



* This culture was contaminated by a yeast. 



INFLUENCE OF VARIOUS SUGARS ON VETCH GROWN IN WATER CULTURES 



In all the preceding experiments agar media were employed. The 

 roots of plants do not readily penetrate the agar, and furthermore the 

 adsorptive properties of the agar probably interfere somewhat with the 

 absorption of the dissolved substances, as well as lessen the action of any 

 enzymes that might be secreted by the roots. For these reasons, and also 

 when it is desired to measure quantitatively the amount of sugar absorbed 

 by the plants in the various cultures, the use of water cultures is 

 advantageous. 



