vi] INFLUENCING THE FORMATION OF ANTHOCYANINS 103 



plants to produce normally coloured flowers and fruits in the dark is 

 due to a plentiful supply of reserve material (flowers of Tulipa). 



(2) If there is more than a plentiful supply of chromogen owing 

 to the flowering parts being removed or to a large supply of carbo- 

 hydrates,, a certain amount of abnormal reddening may take place, 

 ex., leaves of plants deprived of the inflorescence, adventitious shoots 

 from tree trunks ; possibly this may explain reddening in sugar cultures. 



(3) A still further increase of carbohydrates and chromogen such 

 as is caused by blocking the translocation current leads to still more 

 abnormal reddening, ex. injured leaves, decorticated stems, etc. 



(4) In autumnal and winter leaves, there may be an accumulation 

 of sugar and chromogen owing to the slowing down of the translocation 

 current, and the lack of starch formation at low temperatures. The 

 effect of low temperature may also retard growth in general and the 

 using up of synthetic products. 



(5) In young leaves it is possible that the mechanism for trans- 

 location is not developed so early as the powers of synthesis of sugar 

 and chromogen. Hence again there is accumulation of these products. 



direction, or amount, of certain chemical reactions which are, in any case, part of the 

 essential metabolism of the plant. If we are to believe the evidence of Gaston Bonnier 

 and others, it is just these variations which may occur. 



