Rejuvenescence 43 



during the last three hundred years of its life that 

 near the circumference 100 rings were traceable 

 within one inch.' Yew-trees are apt to become more 

 or less unequal on opposite sides, owing to a variety 

 of causes, such as greater exposure on one side to 

 frost or cold, winds or snowstorms, causing fracture, 

 or difference of soil. In this way many trees not 

 only show an eccentric arrangement of their annual 

 rings,^ and a difference between the two sides, but 

 they may also differ on the same horizontal level 

 on the same side. Bowman's observations on the 

 Darley Dale Yew show a variation of thirty-three 

 to sixty-six rings in an inch of radius. A tree 

 may have died on one side, or may have ceased 

 growing, while the other side is growing vigorously. 

 There may be a period during which the tree grows 

 scarcely at all, but after the top is broken, rejuven- 

 escence takes place, and rapid growth ensues. 



It is not only the young shoots that are welded 

 by the spread of the bark. The wounds left by 

 large branches having been cut off or broken, and 

 even exposed surfaces of dead wood which has lost 

 its bark, may become sealed over by a polyp-like 

 growth, and further decay prevented by their be- 

 coming hermetically closed. The old tree at 

 Crowhurst, Surrey, shows very strikingly how this 

 kind of action has conduced to its preservation. 



^ One mentioned by Sir R. Christison had its centre twice as distant from 

 one side as from the other. This tree was only 24 inches in girth. 



