78 DEVELOPMENT OF PINE-TREE [CH. 



described will gradually alter the shape of the crown more 

 and more until a state of affairs something like that shown 

 in the diagrammatic Fig. 25 is attained. All further- 

 growth in height has here ceased, and the clearing of the 

 bole of older branches has gone on until only the principal 

 laterals of the topmost whorls are left, and these have 

 begun to clear themselves of their older branches. The 



Fig. 25. Diagram of an old Pine-tree of umbrella like form, 

 result is a more or less rounded or flattened crown, like 

 an umbrella on its stick, or a mushroom on its stalk, 

 and although this condition has been reached by the 

 repeated production of buds in regular sequence, so many 

 incidents of competition for light and air, breakage by 

 wind and snow, injuries by birds and insects, and so forth 

 have occurred that the symmetry of the branching is now 

 practically lost. 



