NOTATION. 219 



commonly utilised agree with the rule. The second case is that 

 of the multijugate system, while the most special third case is the 

 familiar one of whorled arrangement in which successive whorls 

 alternate. 



All these phenomena, again, are more simply and correctly de- 

 scribed in terms of the curve systems. It has been noted that 

 only in the first case is there a single spiral which can be isolated 

 as an ontogenetic spiral; and the fact that such a spiral can be 

 isolated, and is consequently seen when the whole system under- 

 goes a very general, though entirely secondary, elongation, is a 

 geometrical accident of the construction, however useful such 

 secondary elongation may be in the plant economy. The recog- 

 nition of this spiral on adult plant-forms by Bonnet is thus 

 necessarily responsible for the peculiar inverted manner of re- 

 garding phyllotaxis phenomena, and although the inverted mode 

 of expression is common to many branches of plant-morphology, 

 there is no justification for the continuation of such lines of 

 thought at the present day. 



