FRUIT-BUD FORMATION 65 



often observed when a tree is suddenly injured by freezing, 

 fire, disease (canker), mice, or similar agency. 



The supposition in all these cases has been that there was 

 an accumulation of reserves throughout the tissues above 

 the wound and this was favorable to the differentiation of 

 flowering parts. Since experiments have recently indicated 

 that a major part of the nitrates may be transported up 

 through the cortical .tissues as well as that carbohydrates 

 are carried down through them, it would seem that a sudden 

 transfer from Class I or II to that of Class III may take place, 

 owing to the interruption in the supply of available nitrates, 

 and consequent accumulation of carbohydrates. Usually 

 the leaves of ringed trees soon turn yellowish and are checked 

 in their growth, which indicates a lack of nitrogen. If 

 this is true, then an important factor is introduced in connec- 

 tion with any accumulation of reserves which may take 

 place, to bring about a condition for flowering. 



Drinkard's results in ringing dwarf trees indicate that, 

 for the conditions with which he worked, the greatest flower- 

 ing was secured when the ringing was done on May 31st, 

 to a less degree on June 23d, and no results were obtained 

 when it was performed April 23d. On the other hand, the 

 author obtained a 100 per cent bloom when mature trees 

 were ringed on April 30 (in New Hampshire), as compared 

 with a 35 per cent bloom on adjacent untreated trees. The 

 trees were seriously impaired, however, as a result and bridge- 

 grafting was resorted to. This difference was obviously 

 due either to a dissimilar condition of the reserves in the tops 

 of the trees or to an unlike soil condition, as well as to the 

 age and variety of the trees. 



Howe 1 ringed a block of five-year-old trees in New York 

 State with marked results in flowering, but the general 

 effect on the trees was devitalizing and it was concluded that 



1 N. Y. [Geneva] Agr. Exp. Sta. Bull. 391. 1914. 



