250 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 



the more it develops, the more it tends to close over the apex, and 

 hence exerts all the greater pressure on the enclosed primordia, the 

 normal curve-systems for which should be (5 + 8) in small shoots. 

 Longitudinal sections of such a bud (December) show the well-marked 

 crater, the external surface and rim clothed with protective scale- 



Fig. 84. — Gedrus Idbani. Transverse section of winter bud, system (5 + 8), 

 showing effect of pressure of orateriform axis. 



leaves, the base of the inner surface producing the young foliage-leaves 

 of the next season, and a conical growing-point rising from the base 

 (fig. 85). 

 A transverse section just above the apical cone, passing through the crater 

 wall, will show sections of leaf-primordia about three cycles deep 

 (fig. 84). The nature of the packing is obvious, irregular hexagonal 

 figures being produced, as in the packing of parenchymatous tissue ; 



