146 RELATION OF PHYLLOTAXIS TO MECHANICAL LAWS. 

 The following table expresses these results : — 



Inspectiou of the bulk-ratio column, which may be assumed to 

 be fairly accurate when the angle subtended is 60 degrees or less, 

 is sufficient to show that the rise from pentamery to hexamery, 

 for example, would represent a comparatively small variation as 

 expressed in the formation of a larger and better nourished axis 

 which tended to produce members of a constant type. 



The diagrams also illustrate the fact that whorled tetramery has 

 almost identically the same bulk-ratio as the (3 -j- 5) asymmetrical 

 system from which a spiral pentamerous flower is phylogeneticaUy 

 derived ; while whorled hexamery almost equally approximates the 

 bulk-ratio .3 : 1 of the asymmetrical (5 + 8) system. 



It is easy to adduce facts which fall into line with such generalisa- 

 tions, although they do not necessarily add any proof of the theory ; 

 for example, the latter case is of interest in connection with the 

 readiness with which terminal flowers of Campanula media vary 

 to symmetrical hexamery when the vegetative main shoot presents 

 the (5-f 8) asymmetry. 



As an example of the perfect irregularity of the symmetrical 

 expanding construction, and its absolute independence of the 

 Fibonacci series, the vegetative shoots of Eguisetum TelmMeia 

 afford conspicuous illustration. 



For example : a weak foliage shoot of 32 nodes, the continuation 

 of a rhizome bearing leaves in whorls of 10-11, showed a rapid 



