82 



NATURE OF CORK TISSUE 



since they are not capable of dividing they are pulled apart, 

 forming the characteristic furrows in the bark. It will often 

 be noticed that the bark of some trees, see the cone-bearing 

 trees, sycamore, etc., cleaves ofif in shell-like scales. This is 



Fig. 48. Fig. 49. 



Fig. 48. Cross-section of cells of bottle cork showing the delicate character 

 of cork cells. 



Fig. 49. Scale bark of pitch pine. The crescent-like lines in the bark 

 show the successive positions of the cork cambium. 



due to the formation of a new cambium that joins on to the old 

 cambium in the form of crescents (Fig. 49). Consequently as 

 this bark is pushed out it breaks along these successive crescent 

 shaped cambiums and finally cleaves off in scales. In some 



Fig. 50. Cross-section of the outer part of a stem showing the early 

 development of a lenticel. Note the irregular character and loose arrange- 

 ment of the cells below the stoma and the cork cambium, c, extending out on 

 either side of the lenticel. 



trees the cork cells break off about as fast as they are formed, so 

 that a comparatively thin layer of cork cells remains attached to 

 the trunk. Such trees have a smooth bark, as in the beech. 

 In other cases the cork cells are formed in great abundance, 



