PLANT HYBRIDIZATION BEFORE MENDEL 55 



more rapid growth, the accelerated, earlier, and prolonged time 



of flowering, the development of young shoots in autumn from 



the roots, as well as from the stem, and a longer duration of the 



plant, are to be reckoned among the general characteristics of 



hybrids, (p. 193.) 



"it is very difficult," he says, "to assume a valid reason for the en- 

 hanced vegetative vigor before flowering. The continuation of the 

 same after flowering, on the other hand, might be explained from the 

 fact that these plants cannot, like the natural ones, be exhausted and 

 impoverished through the development of the seed." (p. 194.) 



With respect to the matter of increased rate of growth in hy- 

 brids, Kolreuter makes the following interesting and rather sur- 

 prising remark : 



"l would wish that I or another were so fortunate as to obtain a 

 hybrid of trees, which, in respect to the utilization of their wood, might 

 have a great economic influence. Perhaps such trees among other good 

 characteristics would also have these, that, if the natural ones required 

 for their full growth, for example, a hundred years, they would reach 

 it in half this time. At least I do not see why they should behave 

 differently in this respect from other hybrid plants." (p. 194.) 



Ten further crosses of Nicofiana are reported in the third 

 "Fortsetzung," but inasmuch as all but two are compound crosses, 

 they furnish no data of importance. The two remaining are ( A''. 

 paniculata X rustica) X rustica and (N. rustica X pciniculata) 

 X rustica^ i.e., back-crosses upon an F^, as they would now be 

 designated, or, in Kolreuter's terminology, hybrids in the descend- 

 ing degree, i.e., hybrids on the way toward a return to one of 

 the parents. However, no data are given of present genetic value. 



Of the remaining crosses described, 29 are Dianthus crosses, 

 the species used being barhatus^ chinensis, brabetisis, carthusia- 

 norum^ superbus^ deltoides, armeria, plumarius, glaucus and vari- 

 ous forms of the garden pink, presumably also plumarius, but 

 referred to here as "'hortensis.'" The Dianthus crosses are distrib- 

 uted as follows : 



Species and variety-crosses 12 F^ back crosses 5 



Compound crosses 10 Fj selfs 2 



Kolreuter remarks as to the cross Dianthus barbatus X chinen- 

 sis that, between the eighteen plants from this cross and those 

 from the reverse cross ("Fortsetz. der Vorlauf. Nachr.," p. 44), 

 there was to be found no noticeable difference. Reference to the 

 page in question, however, gives the cross there reported as Dian- 



