REJUVENESCENCE IN NATURE. 79 



within the formation of the corolla. Thus in most cases 

 of double or multiple corollas we see the inner circles 

 formed of shorter and smaller petals. In Fumaria the 

 inner two petals are only inconsiderably, but in Hype- 

 coum considerably shorter than the outer two. Jacquinia 

 and Achras exhibit the same thing in pentamerous and 

 hexamerous circles. Asimina triloba has a trimerous 

 calyx, the sepals of which are four lines long. This is 

 followed by three trimerous circles of petals : those of the 

 first circle are 7 8 lines long, those of the second about 

 5 lines, and those of the third scarcely more than 2 

 lines long. The stamens are 1 line long ; the three-lobed 

 fruit (formed of three carpels) attains a length of 4 5 

 inches when ripe ! The decrease of length of the inner 

 petals is further shown in all flowers with very numerous 

 petals, whether they stand in a complex cyclic or in an 

 acyclic arrangement, as, for instance, in Illicium, Nym- 

 phtea* and Mescmbryanthemum.^ Finally, the graduated 

 decrease in length in successive petals is very beautifully 

 exhibited by all " double" flowers, as they are called, and 

 most distinctly of all, in those where the doubling arises 

 merely from formation of petals in the place of stamens (and 

 often of carpels also), without the superaddition of axil- 

 lary sprouts. | The best examples of this kind are found 

 in the Ranunculaceae, especially in Ranunculus, Clematis, 



* Nymphaa alba has about twenty-four petals, the inmost and shortest of 

 which exhibit a gradual transition into the staminal formation. 



t Many species have more than one hundred petals. 



% In the majority of double flowers the " doubling" is complicated by the 

 formation of sprouts in the axils of the petals. The sprouts thus appearing 

 are again imperfect flowers, with undeveloped axes, and mostly formed of 

 few petals and occasionally several stamens. Hence arises an apparently 

 irregular accumulation of large and small petals, interposed in various direc- 

 tions, and often intermixed, with isolated stamens, of which it cannot be 

 accurately determined which organs belong to the parent flower and which 

 to the progeny. This occurs frequently, for instance, in double May 

 flowers, Pinks, 'Cruciferse, Mallows, and Roses. However, doubling some- 

 times occurs with and without axillary increase in the same plant. Some- 

 times the axillary products of double flowers acquire greater completeness, 

 as is shown most beautifully in the case not unfrequently occurring in 

 gardens of Althcea rosea, first observed by G. Engelmann. Vide Engelmann, 

 ' De Antholysi,' t. i, fig. 6. 



