148 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 



Applying these generalisations to the simpler members of the 

 series, it would appear probable, then, that given a primordium 

 subtending a considerable angle, the cliances of variation between 

 successive whorls of members would be correspondingly decreased. 

 The difference between three members in a whorl and four, for 



Fig. 56. — Descending symmetrical phyllotaxis : geometrical representation of the apex 

 of a shoot of Mqiiiseium Telmateia, showing irregular parastichies. 



example,- being considerable, it would be expected that^ individual 

 or specific variations to tetramery, or from pentamery to hexamery, 

 should, when they occur, affect all the whorls of the shoot, and this 

 in fact is the general case. The occurrence of such a condition as 

 that observed in a starved plant of Cucurbita Pepo, which is normally 



