14 



Lewis Knudson 



It was noted also that in the presence of certain concentrations of glucose, 

 starch was produced in the root, although normally starch is not produced 

 in radish roots. The following figures, taken from Molliard's paper, show 

 the influence of concentration on growi;h under the conditions of the 

 experiment : 



Influence of Glucose on Radish. Duration of Experiment, Three Months 



Knop's solution + 



Dry 



weight 

 (miliigrams) 



Ratio of 



dry- 

 weight 

 to fresh 

 weight 



No glucose 



2 per cent glucose 



5 per cent glucose 



10 per cent glucose 



15 per cent glucose 



0.056 

 0.089 

 0.110 

 0.132 

 0.167 



As a result of certain other experiments Molliard concluded that there 

 exists an antagonism between absorption of sugar and assimilation of 

 carbon dioxide. This will be considered later. 



Lubimenko (1906 b) has noted the assimilation of various sugars by 

 plantlets of Pinus Pinea, and as a result of his experiments he comes 

 to the conclusion that the assimilation of sugar is dependent on a photo- 

 chemical reaction. 



Bokorm^ (1911) found that Spirogyra and Cladophora not only could 

 absorb methyl alcohol, but could produce starch from it. His results 

 indicate further than the scarlet runner bean and the pea can also utilize 

 methyl alcohol, but not ethyl alcohol nor the higher alcohols. His experi- 

 ments were not made under sterile conditions. 



In a recent paper Ravin (1913) has presented the results of his very 

 comprehensive investigation of the influence of certain organic acids and 

 their acid and neutral salts on the growth of radish as well as on certain 

 algae and fungi. He has presented an excellent resume of the literature 

 relative to the use of organic acids, so that no further treatment is here 

 necessary. The common garden radish (Raphanus sativus) was employed, 

 and the plants were grown under sterile conditions in large culture tubes 



