Cork and Sarh 153 



When spring returns, a number of new cork 

 cells form, just beneath the sealed-up lenticel. 

 These are a light, loose mass, and by their strong 

 growth they split the seal above them and open 

 the little vent once more. 



Cork can serve the living trees as surgical 

 plaster. It is often used by vegetation to cover 

 small raw spots and heal slight wounds. Every 

 little scar left on the bough by a fallen leaf is a 

 patch of cork. 



Before the hottest August days have passed, a 

 very thin layer of cork begins to form in many 

 trees just at the place where the leaf-stalk joins 

 the bough. 



At first this is not an unbroken sheet of cells, 

 but a very thin plate, incomplete and full of 

 gaps and holes. It lies across the softer part 

 of the leaf-stalks, but does not sever the woody 

 threads which tie the leaf to the branch. 



At about the same time, or a little later, another 

 change takes place in the leaf-stem. 



Just outside the forming cork plate there is now 

 a narrow band of rounded cells, lying together, 

 and with many empty spaces among them. This 

 is the " absciss " or " cuttlng-off " layer. One can 

 see it in some plants, when autumn is here, as a 

 pale band in the leaf-stalk. It is most noticeable 

 on the blackberry vines, where it appears as a 

 yellowish-green girdle just above the place where 

 the purple leaf-stalk joins the branch. The most 



