206 MASS. EXPERIMENT STATION BULLETIN 170. 



Winterkilling of Cork Camhium. 

 As alread)^ stated, the effects of low temperature on a tree may be en- 

 tirely local; i.e., it ma.y affect some particular organ or some one portion 



% 

 % 



_i 



75 



70 

 65 



40-6096 



30- 

 20° 

 10- 



LJ L... 



30.5..., 



300 L.r 



29.5 



29.0 m 



55 

 30 

 25 

 20 

 15 

 10 

 5 



— T I 



-MEAN REL HUMIDITY 

 -i-IEAN TEMP 

 -BAROMETER 

 -FROST CRACK 



^MAR.. 



Fig. 79, — Showing curve of opening and closing of frost cracks in elm trees. Tiie 

 lower curve represents the variations in the opening and closing the others 

 represent the mean rehttive luimidity, mean temperature and barometer in 

 the order named. 



of the tree only. Following one of our extremely severe winters a few 

 years ago, elms and some sycamores were found suddenly discarding 

 their outer bark, — a rather unusual phenomenon. This loss of the outer 



