96 THE TREE BOOK 



taken in, and so the food supply, "the grist" 

 for the mill, is daily growing scarcer. The 

 sleep of the trees is, then, a necessity, caused 

 by the cutting off of the food supply. So, like 

 the bear and the woodchuck, they don their 

 warmest coats and settle down contentedly to 

 wait for spring. 



As the cold increases, most of the water 

 within the cells of the living layer of the tree 

 filters through the cell walls and forms, into 

 little ice crystals in the surrounding spaces. 

 There is room here for the expansion caused 

 by freezing and the delicate cell walls are thus 

 saved from injury. Often the cold becomes se- 

 vere enough to stiffen the gummy substances 

 still left in the cells. But the tree is safe. It 

 is now in a death-like trance, and may even 

 freeze solid without injury. The pines, hem- 

 locks, and water-side maples are often frozen 

 throughout, their roots, thrust sidewise into the 

 surface soil, "as frost-'bound below as their 

 creaking boughs above." But the deeply- 

 rooted trees, like the ashes and oaks, have their 

 long tap roots driven below the frost-line into 

 the region of perpetual spring. 



We call the woods bare in winter, but it is 

 then that the trees best display their majestic 

 grandeur, their strength and sturdiness. Some 



