320 Vnivcrsitij of California Fuhlicaiions in Botany [Vol. 5 



.V. paniculata X -V. vincaeflora may be produced only with great 

 difficulty (p. 146). It is decidedly like the male parent (p. 256), so 

 much so that the only influence of paniculata is to be seen in slight 

 changes in the form and color of flowers and a slight broadening of 

 the leaves. On page 286 this hybrid is reported to be the most striking 

 example of hybrids resembling the male parent. It is sterile. The 

 reciprocal cross, vincaeflora X paniculata, is listed among those in- 

 fertile hybrids which resemble the maternal parent. 



Gartner appears to have been particularly impressed with the 

 varying degree of influence of one or the other parent in the develop- 

 ment of the hybrid, and presents the following general discussion of 

 this problem (p. 255) : 



The extent and degree of deviation of the hybrid type from the habit of 

 the parents and their individual cdiaraoters is very different with different 

 species of a given genus. With respect to this matter Kolreuter makes the 

 following assertion: "The greater the differences between two species, the 

 greater must be the change which occurs iu the hybrid produced by crossing 

 them; and the less the difference between the two natural species the smaller 

 and less noticeable will be the change which occurs when they are hybridized." 

 These two propositions do obtain in many cases, particularly the second; but 

 in many cases thej- do not, particularly in certain types where iu crossing 

 the type displays entirely different relations toward the oue or the other 

 parent form, and the characters are distributed to different parts of the 

 hybrid in diverse degrees. Very notable in this respect is the behavior of 

 the hybrids Nicotiana suaveolens and vincaeflora ; for they in their combinations 

 with N. Langsdorfii retain their own type so completely that they present 

 differences only in the separation of the filaments from the corolla tube, the 

 bluish color of the anthers, the greenish coloration of the corolla, and the 

 curving of the corolla tube; in the hybrid suaveolenti-macropliylla, on the other 

 hand, suaveolens cannot be detected and macropliylla predominates by far. One 

 of the most noteworthy examples of such influence is the hybrid Nicotiana 

 paniculato-vincacflora ; because N. paniculata is so entirely converted into the 

 type of vincaeflora that only in the smaller greenish blossoms, the rounded, sig- 

 nificantly smaller, white limb, the partial separation of the filaments from 

 the tube, which is not crooked, in the somewdiat broader leaves and in the 

 more delicate branching is a slight difference to be noted from vincaeflora; 

 for neither in the whole growth and habit of the plant nor in the general form 

 of the leaves and their wn-inkled surfaces does any notable deviation occur; 

 whereas, on the other hand, in a combination of this species with N. quaclri- 

 valvis $ the influence of the latter in the hybrid (N. cpiadrivalvi-viiicaeflora) can- 

 not be mistaken. 



Less striking cases of this kind are furnished by Nicotiana rustico-quadri- 

 valvis, glutinoso-quadrivalvis, in which the male type predominates, by N. 

 grandifloro-glutinoso, Altliaea cannabino-officinalis, in which, on the other hand, 

 the female predominates. In most of the hybrids compounded from mixed 

 relationships, as in Nicotiana rustico-paniculato-angnMifolia, rustico-paniculato- 

 glutinosa, and others, the paternal type is so exclusively predominant that these 

 hybrids might be taken as mere varieties of the jjaternal parents. 



