128 VEGETABLE ORGANOGRAPHY. 



the petals may be united to the sepals and stamens ; the 

 stamens are frequently so to the petals, but very rarely 

 to the carpels. The sepals and carpels may be united 

 by the interposition of the torus, which is the common 

 base of the petals and stamens, which organs then are 

 adherent to the calyx, and appear to arise from near its 

 summit, or from the point where it begins to be free. 



The parts of each verticil are capable of being changed 

 into true leaves, like those of the plant. This pheno- 

 menon is most frequent in the parts already more folia- 

 ceous, as the sepals and petals. 



The parts of each verticil are capable of taking a 

 petaloid appearance ; this phenomenon is constant in the 

 petal, frequent in the stamens, and more seldom found 

 in the carpels (except in the stylary prolongation), sepals, 

 and bracts. 



The parts of each row or verticil are capable of 

 changing to the nature of the row which immediately 

 touches it. Thus, we find the sepals changed to a petal- 

 oid nature (Primula calycanthema), petals changed to 

 stamens (Capsella Bursa pastoris), stamens to carpels 

 {Magnolia fuscata) ; or quite the reverse, viz. — carpels 

 changed to stamens [Euphorbia palustris), stamens to 

 petals (all double flowers), or petals changed to the nature 

 of the calyx {Ranunculus abortivus). Goethe has very 

 happily designated the first of these series of transfor- 

 mations, by the name of Ascending or Direct Meta- 

 morphosis, and the second by that of Descending or 

 Inverse Metamorphosis. 



All the floral verticils then are of a very analogous 

 nature as regards their tissue, but they differ much in 

 their physiological state. Those which are foliaceous, 

 as the bracts and calyx, serve for the nutrition, the 

 others for the sexual reproduction. In several verticils 

 we may distinguish the parts of the leaves which com- 



