Cork and Bark 149 



the birches. The beautiful white robe of the 

 canoe-birch is just a sheet of cork. It is as thin 

 and strong as parchment, and is the outermost 

 covering of trunk and boughs. 



But most trees wear their cork as an under- 

 vest, beneath their cracking, weather-stained outer 

 bark. And most trees remove the cork-making 

 business after a while from the outermost surface 

 of the trunk and boughs. In some trees curved 

 plates of cork form down beneath the surface, and 

 as all the wood outside these dies and dries, masses 

 of bark are gouged out of the living tree. 



But if the curving cork plates stand upright in 

 the wood of the tree, they cut off scale-like slices, 

 such as we see on the trunks of larches, plane 

 trees, and old pines. The scales on the pitch pines 

 are irregular in shape, like the pieces of a puzzle, 

 and they dovetail and cling together, making what 

 is known as scale bark. 



The outside cork-layers, made in bygone 

 springs, have quite lost their elasticity. When 

 they are stretched and strained by growing trunks 

 and swelling limbs they split in many places, while 

 the old dead substance outside the cork is deeply 

 cracked or split through and through. 



This dead outside of the tree may contain cells 

 of many sorts, which in their lifetime served many 

 uses. Now we speak of them all together as the 

 " outer bark." 



The rents in it go through everything till they 



