46 THE STRUCTUEE OF FLOWERS. 



rule, most intimately connected witli the union of tlieir fibro- 

 vascular cords with those of the perianth ; and as parts of 

 flowers are often multiplied, as the petals of Camellia, 

 perianth-leaves of Daffodils, etc., such has given rise to the 

 idea of chorisis or dedouhlement of French authors ; as if 

 one organ had split into two or more. That vascular cords 

 can become repeatedly bifurcated is abundantly observable, 

 whether radially, as in the case of the carpels of the Holly- 

 hock, or tangentially, as in producing the stamens of the 

 same flower. The more correct way, therefore, of regarding 

 the process would seem to be, first, to recognize the phjUo- 

 tactical origin of the perianth as the basis to start from, and 

 then to regard each fibro-vascular cord as an instrument 

 for furnishing any number of appendages, whether they be 

 additional petals, stamens, or carpels, by the process of 

 chorisis, not of the complete organ, as generally meant, bat 

 of the cord belonging to it. 



To summarize these remarks — we find that the cause of the 

 alternation of the whorls of the perianth, or of the calyx and 

 corolla, is due to their being made up of cycles of spiral 

 arrangements, which are projected on to the same plane, and 

 so form verticils. Their positions are then shifted so that 

 the parts of each whorl bisect the angles between the parts 

 of the whorl succeeding or preceding it. 



Secondly, having laid this foundation, the stamens and 

 carpels follow in superposition to one or other or both of 

 the preceding whorls in consequence of the branching 

 of the fibro-vascular cords. And this accounts for super- 

 position. 



It may be still further inquired why in some cases the 

 sepaline, and why in others it is the petaline cords which 

 give rise to a whorl of stamens or carpels, as the case niay 

 be. The reply at present must be speculative, for there may 



