Influence of Certain Carbohydrates on Green Plants 17 



in height and in number and size of leaves. Check plants grown under 

 conditions similar but with the elimination of amino acids from the soil 

 failed to make any marked growth, and some died of starvation. In one 

 experiment with Lepidium sativum twenty seedlings were grown under 

 a bell jar in the absence of carbon dioxide but with the amino-acids mix- 

 ture present. In ten days the increase in weight was from 44 to 120 

 milligrams. The check culture, in the absence of the amino acids, showed 

 a gain of only 4 milligrams. In a similar experiment with Ocimum, 

 the gain of the seedlings supplied with the amino acids was from 100 

 to 350 milligrams, while the check plants showed a gain of only 20 milli- 

 grams. Jost (1913) has suggested that the amino acids may be absorbed 

 and broken down in the plant, yielding carbon dioxide, which is utilized 

 by the* plant in photosynthesis. 



Grafe (1909) conducted somewhat similar experiments, employing 

 Phaseolus vulgaris. He used the same mixture of amino acids as was used 

 by Lefevre, but grew his plants in water cultures. He obtained, in general, 

 toxic effects on the roots of the culture plants grown in the presence of the 

 amino acids. His results do not, however, disprove the conclusions of 

 Lefevre, since in the experiments of the latter the soil employed 

 undoubtedly inhibited the toxicity of the amino-acids mixture. 



From a cons deration of the above-mentioned investigations it becomes 

 evident that a considerable number of organic substances can be utilized 

 by green plants and that these substances are of a wide range of character. 

 The investigation here reported is confined to the influence of certain 

 of the carbohydrates on green plants. The experiments are not in all 

 cases so clear-cut and decisive in their results as was hoped for, but the 

 difficulties of experimentation and the limited supply of culture vessels 

 made ideal results almost impossible of attainment. However, the results 

 are in general conclusive. 



METHOD OF INVESTIGATION 



culture vessels 

 Throughout the investigation the plants were grown in culture vessels 

 plugged with cotton and maintained under sterile conditions. In certain 

 experiments the culture vessels were large test tubes, 30 by 4 centimeters 

 in size; in other experiments large glass cylinders were employed, 63 by 

 10 centimeters in size; while in still other experiments the culture vessels 



