62 Lewis Knudson 



by roots, found a very weak secretion by the root hairs of corn, though in 

 the other cases diastase secretion was effected by the disconnected root 

 cap cells and by the dead root hairs. Czapek (1913) states that the 

 evidence so far presented does not indicate any active ability on the 

 part of the root to secrete enzymes. 



The secretion of enzymes by plant roots is not within the scope of 

 this paper. Investigations on this subject are now in progress and will be 

 reported at a later date. - Certain observations were made, however, tend- 

 ing to show that the enzyme invertase is secreted by roots of plants. 

 The observations made are summarized separately in this place for the 

 sake of convenience. 



In a number of the experiments with vetch it was noted that in the 

 saccharose cultures reducing sugars were found in the media at the con- 

 clusion of the experiment. In the water-culture experiments with vetch 

 (page 39) the total amount of sugar remaining in two cultures at the end 

 of the experiment was 0.422 gram and 0.413 gram, respectively. Of the 

 former, 0.151 gram was reducing sugar and of the latter 0.125 gram was 

 reducing sugar. In another experiment, with agar cultures (page 42), 

 the total sugar remaining in each of two cultures was 3.544 grams, but in 

 one the reducing sugar was 0.302 gram and in the other 0.342 gram. 

 The culture media in all cases was in its reaction alkaline to methyl orange 

 and acid to phenolphthalein. Somewhat similar results were obtained 

 with radish and sunflower. There was very marked inversion of sac- 

 charose in the culture medium in which Canada field pea was grown, and 

 some evidence was obtained on the excretion of raffinase (Knudson, 1915). 



It has not yet been definitely proved that the inversion of saccharose 

 is due to the invertase secreted into the culture medium. It is possible 

 that the saccharose is inverted in the roots and the reducing sugars are 

 secreted, but this is less probable. It is possible also that the enzyme 

 m_ay be released as a result of the death of root hairs or other cells of the 

 roots, and that it is not secreted from living cells. 



INFLUENCE OF SUGAR ON COLOR PRODUCTION 



The work of Ewart, Overton, Wheldale, and others (Wheldale, 1911) 

 indicates a close relationship between the sugar content of the plant 

 and pigment production. It would naturally be expected, then, that 

 the sugar supplied to plants would show production of anthocyan pigment. 



