316 TIJK PHENOMENON OF 



of three kinds, red, yellow, and white, in the fourth 

 case. 



Analogous cases of heterogeneous composition of the 

 vegetable stock occur in hybrids of Phanerogamous plants, 

 through return to the parent form on the hybrid stock 

 itself, whereby it may happen that two specifically dif- 

 ferent species may present themselves united, together 

 with the hybrid, upon the same stock. This, however, 

 is a far rarer phenomenon than the occurrence of several 

 varieties on the stock, for hybrids, as the celebrated 

 experiments of Kolreuter* showed, ordinarily return by 

 way of reproduction, to one or other parent species, after 

 having been impregnated by this for several generations. 

 The only certainly known instance of the recurrence of a 

 hybrid plant to the parent species on the stock itself, has 

 been found recently in the generally diffused garden 

 intermediate species, between Cytisus Laburnum and 

 C. purpureus (C. Laburno -purpureus, Walpers,f C. Adami, 

 Poiret), j the hybrid nature of which, in spite of the con- 

 trary assertions of Loudon$ and ReissekJ cannot well be 



* See his preliminary reports ('Vorlaufige Nachrichten) of experiments 

 relating to the sexes of plants, particularly the third series, (1766,) p. 51, 

 where is described the " complete conversion of one natural species of plant 

 into another," namely Nicotiana rustica into N. paniculata. The first 

 impregnation of N. rustica with N. paniculata produced a hybrid, which 

 assumed completely the character of the parent plant in the " fourth 

 ascending step," '. <?., after three transitional generations produced by 

 repeated impregnation with N. paniculata. 

 NICOTIANA RUSTICA $ > 



paniculata $ ) Q 1 



paniculata $ i 9 



paniculata * if O 



*'?U "-a. 



t ' Repertorium,' i, 634, (1842,) where two figures of it are cited. (The 

 ' Botanist,' i, t. 7. ' Bot. Register,' t. 1965.) 



\ The authorship of the name C, Adami is thus stated everywhere; 

 where Poiret has given a notice or description of Adam's new plant, I do not 

 know. 



According to Loudon, (as appears from a note in the ' Bot. Zeitung,' 

 1843, p. 133,) Adam obtained his new Cytisus by grafting a bud of C. 

 purpureus on C. alpinus (?). I cannot consult the source of the statement 

 here cited, (' Gard. Mag.,' xii, 225, and xv, 122.) 



|| According to Reissek, (Haidinger, 'Berichte iiber die Mittheil. von 



