Vl] DEVELOPMENT OF FORM 73 



rhomboidal figure, the shape of the base depending a 

 good deal on the persistence of the angles of the lower 

 branches, the degree of curvature they make as they 

 become heavier with age, and the number and lengths of 

 the branches they give off below (Figs. 18, 19). 



Fig. 21. Fourth stage in development of the Lime- Willow type. 



Such a tree may very easily give rise to a dome- 

 shaped crown, such as that described above, if the lower 

 branches spread widely, or give off other branches which 

 do so, as the leader ceases to grow, and the upper laterals 

 gradually fill up the interspaces by their further branches 



