314 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 



the quincuncial calyx as a § series this proceeding required the 

 assistance of " prosenthesis." Similarly, the fundamental type of a 

 trimerous Monocotyledonous type is a (2 + 3) system, giving a 

 cycle of three members in lateral contact ; so that, when expressed 



Fig. 109.— Geometrical construction for contact-cycles, (3 + 5) system, in terms of 

 Archimedean spirals of the third intersection. 



in the adult condition by spirals of Archimedes, it would give a § 

 divergence formula rather than the J of systematists. 



The extent, however, to which reliance can be placed on such 

 contact-phenomena in bud-sections remains to be further con- 

 sidered from the standpoint of varying growth-phenomena observed 

 in primordia which do not necessarily retain their primary 

 contact-relations. 



