162 



OBSERVATIONS UFON MULING AMONG PLANTS. 



but these had smaller leaves, a more vigorous growth, and 

 stronger but more finely divided branches. It is possible that 

 the main crop was due to the presence of stamens in the 

 Lychnis, which is not always strictly dicecious, the two ab- 

 normal forms being due to the hybrid fecundation. The experi- 

 ment was repeated, but did not succeed. Mr. Herbert has occa- 

 sionally observed, in the case of multilocular capsules, hybrid 

 and natural seeds in the same plant. Such cases are, however, 

 of extreme rarity. 



The mode of experiment may be varied by dusting the stigma 

 at different intervals with the different kinds of pollen. It is 

 clear, however, that the strange pollen must be applied first, to 

 have in general any effect on the result. If impregnation has 

 taken place, which in different genera requires very different 

 periods, as in Nicotiana two hours, in Malva and Hibiscus 

 three, in Dianthus five or six, &c, the application of the native 

 pollen has no effect. The fruit is not more perfect, the seeds 

 more numerous or different in their nature, nor is any superfeta- 

 tion effected, but the small number of seeds are precisely such 

 as would have been generated by the simple hybrid fecundation. 

 Two kinds of seeds were, however, produced in Nicotiana 

 rustica impregnated with N paniculata, by dusting half of the 

 stigma with the strange pollen before the expansion of the 

 corolla, and the remainder after a lapse of twenty hours ; and 

 the conditions of the experiment were varied till the pure type 

 vanished entirely, and merely the usual bastard type made its 

 appearance. The account of the experiments is very interesting, 

 but too long for extraction. 



A mixture of pure and hybrid seeds can only take place when 

 the strange pollen is applied first, and the native pollen before 

 the intrusive has affected the whole of the ovary, either by im- 

 pregnating the ovules or destroying their vitality, or before 

 the surface of the stigma has undergone such a change as to 

 make impregnation impossible; or in the case where the native 

 pollen is first applied, where the quantity is extremely small, 

 and the intrusive pollen after a very short interval. 



The occurrence, however, as said above, of the pure and bas- 

 tard type from the seed of the same plant is extremely rare, 

 and can only happen under very peculiar circumstances ; but 

 even a threefold produce is not absolutely without example, the 

 successive impregnation of Nicotiana paniculata with N. qua- 

 drivalvis and iV". Langsdorfii having given rise to three types ; 

 three plants proving the pure species, four the hybrid panicu- 

 lato- Langsdorfii, and a single individual paniculato-quadrival- 

 vis. A repetition of the experiment produced merely the latter 

 hybrid form. 



