STRUCTURE OF FLOWERS. 113 



absolute number of organs of the same name is usually 

 determined by the number of similar verticils which are 

 developed. Thus, when there are two rows of stamens, 

 their number is double that of the petals ; when three 

 rows, triple ; and so on. A second cause of variation in 

 the relative number, which I have already mentioned 

 elsewhere, is, that sometimes, in the place which it 

 would seem ought to have been occupied by only one 

 stamen, a bundle of them is developed ; but even in this 

 case, the number is a multiple of the petals or sepals. 

 Lastly, plants frequently present a more remarkable, and, 

 if I may so say, a more intimate kind of numerical 

 aberration. It is not rare to find upon the same plant of 

 the Rue, flowers with four sepals, four petals, eight 

 stamens, and four united carpels ; whilst others have five 

 sepals, five petals, ten stamens, and ten carpels. We 

 remark in this case, and in all analogous ones, that the 

 flowers of the centre of cymes, which are developed 

 first, are five-parted, and the following four-parted, and 

 Linnaeus has established as a rule in his system, founded 

 upon the number of parts, that it is always by the first 

 developed flowers that the number ought to be fixed. 

 The examples of this kind of aberration, which affects at 

 the same time all the verticils without deranging the 

 symmetry, are repeated so frequently, that Linnaeus used 

 to express them by this phrase, " Quinta seu quartapars 

 fructificationis interdum additur." We find facts of this 

 kind in the Syringas, which have their flowers sometimes 

 on a quaternary plan, sometimes on a quinary one ; in 

 Asperula, the flowers are sometimes three-parted, some- 

 times four-parted, &c. This phenomenon is entirely 

 analogous to that which we have observed when speaking 

 of the verticils of leaves, which are so liable to vary in 

 number ; we should say that a branch, whether furnished 

 with verticillate leaves, or with verticillate floral parts, 



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