574 

 ■med. w 



)rt tiiiK" will dissolve 



centres (Fig. 125 //) lia\e Ween f( 

 the less resistant tissue. 



In older circumxallatioii on a maple hranch, which was not at all lux- 

 uriant, a spliitin(j of the annual rina was noticed, since the region of the 

 autumn wood on one side of the branch was divided into two parts by a 

 considerably thicker zone of spring wood, rich in duels, and then rcuniti-d 

 with the zones tirsl formed so that one more annual ring could be counted 

 on one side of the twig than on the other. 



When such excrescences are remarked for the first time in trunks 

 which, up to that time, had been healthy (this is the case in the early summer 

 months) it will be advisable to strongly scarify the tree. The knife could 

 be inserted above the excrescence and several long cuts be made through 

 the l)lister into the healthy undcrlving tissue. Hv the wound stimulus thus 



[•'ii;. i:.'<j. Tile .same wound as in Ki 



A latcial -section. 



brought to bear on the healthy tissue near the blister, it is incited to an 

 increased circunn allation acli\it}-. and the pressurt- of the diseased excres- 

 cent tissue on the plastic untlerlying niaterial is reduced. 



Frost W'kimklk.s. 



While the raising of the whole bark bod}' from the wood cylinder 

 found in places in frost blisters could be proved to have been their cause, 

 in frost wrinkles a loosening of the outer, coarser bark layers from the 

 tender, inner bark is concerned. The phenomenon has been obser\ed as 

 yet only on the new growth of cherry branches in June. The branches 

 were conspicuous because of the coarse wrinkles on one side of the other- 

 wise smooth bark. The cambium was not disturbed, the i)ith was some- 

 what browned. 



;\s has been pro\ed. a penetrating frost produces great ditiferences in 

 tension in the trunk. The frost, without necessarily forming frost crystals 



i 



