REJUVENESCENCE IN NATURE. 319 



flowers of C. Laburnum : 2, C. Adami mixed with flowers 

 of C. purpureus ; 3, C, Adami mixed with flowers of both 

 parent-species. Hitherto I have only observed the first 

 of these three cases, to which also belong the mixed 

 racemes described at Henon, the isolated yellow flowers 

 (belongingtoC.Za52<r?22<»2) being displayed among the ordi- 

 nary rose-red flowers of C. Adami.* These mixed racemes, 

 at the same time, exhibit the peculiarity that the yellow 

 flowers set fruit, while the rose-red fall ofi" immediately 

 after the flowering, so that in the recurrence of C. Adami 

 to one or other parent-species, the fertility lost in the 

 hybrid reappears. But the strangest thing that happens 

 in the recurrence of C. Adami to C. Laburnum, is the 

 phenomenon of mixed flowers, which belong, both in the 

 calyx and the corolla, partly to C. Adami, partly to 

 C. Laburnum, in which even single segments of the calyx 

 and single petals are halved, the former appearing 

 half reddish-brown and smooth (C. Adami), half grey- 

 green and villous, the latter half red (C. Adami) and 

 half yellow (C. Laburnum). A raceme in which this 

 occurredf exhibited, carefully counted up, among the 

 33 flowers it bore, 21 unaltered flowers of C. Adami, 

 3 pure flowers of C. Laburnum, and 8 mixed flowers, the 

 7 of which, compared in the subjoined table, % exhibited 

 the following conditions of intermixture in calyx and 

 corolla. § 



* In reference to the hybrid nature of C. Adami it is not unimportant to 

 remark that the reverse phenomenon, namely, racemes of C. Laburnmn 

 intermixed with single flowers of C. Adami, has not been observed either by 

 others or by myself. If these mixed racemes depend on a partial recurrence 

 of the hybrid to the parent-species, this case cannot occur at all. 



+ In the Carlsruhe Botanic Garden, May IS^S. 



J Compare here the outlines in plate v and the accompanying explana- 

 tions. The eighth mixed flower was not in perfect preservation. 



§ I neglected to examine accurately the condition of the stamens and 

 ovaries of these flowers. 



