INJURIES DUE TO FROST AND HAIL 31 



of water, and it is the freezing of this water that is the cause 

 of injury under certain conditions. What happens is briefly 

 as follows. During a late spring frost water is abstracted 

 from the cells into the intercellular spaces, and more especially 

 under the epidermis of leaves and shoots, where it freezes 



n 



FIG. 3. A ' stag-headed oak ' growing in Epping Forest. 

 (A. Clarke.) 



into parallel prismatic crystals. This withdrawal of water 

 from the cells of a leaf causes it to droop and exhibit the well- 

 known symptoms of the effect of frost. If thawing takes 

 place slowly, so that the water can be again absorbed by the 

 cells, the leaf gradually becomes erect, and no lasting injury 



