162 BLASTOGENIC VARIATIONS. 



be a strict mean in all parts; (2) the paternal or mater- 

 nal characters may predominate; (3) the paternal char- 

 acters may predominate in some parts of the hybrid, 

 and the maternal in others. The first-mentioned con- 

 dition is by far the most frequent. For instance, Kol- 

 reuter states that the hybrid between Nicotiana rustica 

 9 and N. paniculata 5 (two species of tobacco plant) 

 is exactly intermediate between the parent forms. On 

 the other hand, the hybrid between N. paniculata 9 

 and N. vincoeflora $ bears so close a resemblance to 

 the second of these species that the characters of N. 

 paniculata can hardly be recognised at all. An in- 

 stance of the third class is occasionally found in the 

 cross between N. rustica 9 and N. paniculata $ , the 

 blossoms resembling one parent species, and the leaves 

 the other. Again, Milardet * has obtained a series of 

 non-separating crosses by the union of Fragaria, Rubus, 

 etc. They resembled either the male or the female 

 parent. De Yries f has obtained a similar result with 

 (Enothera muricata 9 X biennis, which displayed the 

 paternal character. Crosses between CEnothera La- 

 marckiana 9 and 0. nanella $ gave progeny which 

 always displayed two types, the maternal and paternal, 

 but these occurred in very varying ratios. Crosses of 

 0. lata 9 and 0. Lamarckiana $ also yielded progeny 

 of both parental types. 



Plant hybrids are of considerably more frequent oc- 

 currence in nature than animal hybrids, and, by virtue 

 of the fertility which they often possess are of dis- 



*Mem. Soc. Sc. Phys. et. Nat. Bordeaux, vol. iv. p. 1, 1894. 

 fBer. d. deutscli. Bot. Ges., xviii. p. 435, 1900. Translation in 

 J. Roy. Hort. Soc., xxv. p. 249, 1901. 



