114 VEGETABLE ORGANOGRAPHY. 



is, as it were, composed of several fragments united lon- 

 gitudinally, and that symmetry always exists even when 

 one of these fragments is wanting. A monstrosity of 

 Iris Chinenis seems to support this theory ; we know 

 that the flower of this plant is formed upon the ternary 

 plan, i.e. that it is composed, 1st, of two verticils of 

 three leaves, transformed into lobes of the perigone, and 

 united at their base with the ovary ; 2d, of a verticil of 

 three stamens ; 3d, of a verticil of three carpels, united 

 together, and also to the perigone. But in the example 

 to which I allude, the flower is only composed of two- 

 thirds of these organs, the perigone is in two rows of 

 two leaves, and it has but two stamens and two carpels ; 

 but the other third, thus to speak, remains behind, half 

 developed, and we find the rudiments of it very visible 

 below the flower. 



Does not this, which we have clearly seen in this case, 

 because of the abortion not being complete, evidently 

 exist in the cases where the abortion is more complete 

 and regular ; as, for example, when the flowers arranged 

 in a quinary manner in the Rue, Syringa, &c, pass to the 

 quaternary plan ? Is it not also to the same cause that 

 we must refer the cases where flowers, belonging by 

 their analogies to a certain class, have a less number of 

 organs than they ought to ? Thus, for example, all the 

 Asparagi are upon the ternary plan ; and if Mayanthemum 

 appears organized upon a binary one, it is probable that 

 a third of its organs are constantly abortive, as we have 

 seen to take place accidentally in the Iris. If several 

 Myrtaceae, Rubiaceae, &c, present a quaternary plan, 

 whilst others have a quinary one, is it not that a fifth of 

 their organs is abortive ? 



We may consider that the two great classes of plants 

 have their floral verticils composed of a determined 

 number of pieces — Monocotyledons three, Dicotyledons 



