458 REPRODUCTION. 



1182. Focke has shown that hybrids between remotely related 

 species are generally delicate and difficult of cultivation, but that 

 those which result from nearly related species are remarkable for 

 the vigor of their vegetative organs. Nageli has also pointed 

 out that the latter have a somewhat longer lease of life than the 

 parents ; thus annuals can become biennials or even perennials. 



1183. Hybrids between closely related species usually have 

 larger or more showy flowers than either of the parents, but their 

 reproductive organs are much weaker. This diminution of fer- 

 tility may be complete, but it is usually only partial. The pollen- 

 grains are generally fewer and often less developed, the ovules 

 are less likely to afford sound germs. As a rule, the stamens 

 are more affected than the pistils. 



1184. Derivative hybrids are the offspring resulting from a 

 union of a hybrid with one of the parent forms, or with another 

 hybrid from a different source. In the former case there is fre- 

 quently observed a marked tendency towards reversion, which 

 may be heightened by repeated experiments in the same direc- 

 tion, until at last it is complete. l 



1185. Hybrids and their offspring exhibit a marked tendency 

 to vary. This fact is utilized by horticulturists in the production 

 of new varieties. Varieties thus produced must, however, be 

 perpetuated by other means than by seed. 8 



influence of the alien pollen was shown, as before noticed, in the markings of 

 the stem, and also in a diminished power of seed-bearing ; but this was all. 



" In the next year, wishing to see if the male parent would not make his 

 influence appear more distinctly in the second generation, I fertilized several 

 of these fifty hybrids with the pollen of L. auratum, precisely as their fe- 

 male parent had been fertilized. The crop of seed was extremely scanty ; but 

 there was enough to produce eight or ten young bulbs. Of these, when 

 they bloomed, one bore a flower combining the features of both parents ; 

 but, though large, it was far inferior to L. Parkmanni in form and color. 

 The remaining flowers were not distinguishable from those of the pure 

 L. speciosum" (Bulletin of the Bussey Institution, ii., 1878, p. 161). 



1 For a full treatment of this subject, the student should examine Nageli's 

 treatise in Sitzungsberichte der Kbnigl.-bayer.-Akad. der Wissenschaften zu 

 Miinchen, 1865, ii. ; and that by Focke, Pflanzen-misclUinge, 1881. 



2 For a full account of the variation of hybrids, the student should see 

 Naudin, Ann. des Sc. nat., ser. 4, 1863, tome xix. 



For a study of the influence of foreign pollen on the form of .the fruit, see 

 a paper by Maximowicz : St. Petersb. Acad. Sci. Bull, xvii., 1872, col. 275. 



