Cork and Bark 147 



The stem of a very young seedling tree is cov- 

 ered with a delicate skin of leaf-like texture. This 

 is but insufficient protection against parching. The 

 water which starts from the root-hairs to reach the 

 leaves must not be dried away and wasted while 

 it is on its upward journey. As the young stem 

 lengthens, something waterproof is needed to take 

 the place of the tender first-skin, and this new want 

 of the baby tree is supplied by a well-fitting suit 

 of cork. 



A like covering is given to new twigs and sprays. 

 It appears as a very fine, transparent, brownish 

 skin. 



This skin of cork, like all other parts of the 

 tree, is made of many cells; but instead of lying 

 somewhat loosely together, as plant-cells often 

 do, with a chink here and a space there, these are 

 arranged in rows, and they look as if they had 

 been fitted together and joined at the sides and 

 corners, as pigeon-holes are in a desk, or bricks in 

 a chimney. 



There is some brown coloring matter in the 

 walls of cork cells, but inside they are generally 

 empty of everything except air, and perhaps a 

 few brown crystals of tannin. 



So when there are several layers of cork cells, 

 one behind another, they act as the air space in a 

 double-walled house. The cork skin is a barrier 

 to summer heat and also to winter cold. 



But also it is often a barrier between life and 



