Influence of Certain Carbohydrates on Green Plants 35 



TABLE 12. Influence of Various Sugars on Growth of Vetch in the Dark 

 (Duration, fifty-four days. Dry weight of seed, 30 miUigrams) 







Length 

 of roots 

 (centi- 

 meters) 



Total 



Dry 



Loss in 



Culture solution 



Length 



of tops 



(centimeters) 



dry 

 weight 

 (miUi- 

 grams) 



weight 

 per plant 

 (milli- 

 grams) 



weight 



per plant 



(milH- 



grams) 







f 12.5] 



' 21 











1 



1 3[2-7 



67 



16.7 



13.3 



Check (no sugar) 





[ 20. OJ 

 13.0 



I 3J 



f '^1 











2 



13.0 [17. 7 

 [ 27. oJ 

 f 36.0 



1 tr 



f ^1 



50 



16.7 



13.3 





1 



16.0 28.7 



4 7.0 



57 



19.0 



11.0 



Lactose, 2 per cent ^ 





[ 34. OJ 



25.0 

 \ 25.0^26.3 



f 9] 











2 



8 7.3 



60 



20.0 



10.0 







[ 29. OJ 



[ 5j 











f 26.01 



r 91 ■ 









Maltose, 2 per cent 



28.0 25.0 

 I 21. Oj 



u 



^a.7 



65 



21.7 



8.3 









r 40.01 





flOl 













35.0 





10 











Saccharose, 2 per cent 



16.0 

 22.0 

 35.0 



29.6 



7 



7 

 7 



•8.2 



118 



23.6 



6.4 



The check cultures grown in the dark lost nearly one-half of the original 

 dry weight. The saccharose, on the other hand, permitted considerable 

 growth involving a large expenditure of energy but at only a very small 

 loss of the original weight. In every case better growth occurred in the 

 presence of a sugar, the saccharose being better than the maltose, and the 

 maltose better than the lactose, in the nutrition of the plant. In this 

 connection it was noted that the agar medium containing saccharose 

 showed reducing sugars in the immediate region of the roots, but none was 

 detected in the central part of the agar mass. As stated previously, the 

 nutrient solution is without effect on saccharose, and consequently^ the 

 presence of reducing sugars must be ascribed to the secretion of the enzyme 

 invertase or to the excretion from the roots of the reducing sugar. 



The results obtained with cultures grown in the greenhouse are given in 

 table 13: 



