OBSERVATIONS UPOM MUUNG AMONG PLANTS, ] 1 



the acoe?s of the pollen of some nearly related species ; but this 

 contradicts the laws which have been established as to elective 

 affinity. 



In very fruitful hybrids no such deviations or different types 

 have been observed ; it should seem therefore that the integrity 

 and force of the organs of fruciification prevent the occurrence 

 of such deviations. It appears, too, that the paternal element is 

 of greater power to produce variations of form than the maternal. 



When hybi'ids are impregnated a third or fourth time with 

 the pollen of the original male parent, they gradually approxi- 

 mate more and more to the male type, and at last are not dis- 

 tingLushable from it, except perhaps in a less degree of fertility, 

 though this negative sign vanishes sooner or later. There is no 

 certainty as to the number of successive impregnations neces- 

 sary to produce this complete change. Different species exhil)it 

 in this respect very different results. Nicotiana rustico-pani- 

 culata, even in the fifth degree, is occasionally completely sterile 

 either as to the stigma or anthers, but CuSpecially as regards the 

 latter. 



Mules, however, may be also impregnated with the pollen of 

 the mother plant. The maternal type is of course prevalent in 

 such mules, which may account for the greater fertility of ma= 

 ternal than paternal hybrids. A greater number also of different 

 types is formed than in the second generation of simple hybrids, 

 and the second degree of paternal bastards, where they are at 

 most two or three, insomuch that if the colour of the blossoms 

 be taken into the account, they amount in Dianthus chinensi- 

 harhatus 9 chinensis ^ to fifteen. All bear a greater or less 

 resemblance to the maternal type. In the next generation, 

 whether fertilized with their own or with the pollen of the 

 original mother, most of the plants have completely reverted to 

 tiie mother type. 



Thus by the means of hybridization one species is changed 

 gradually into another, though the hybrids themselves through 

 the whole period of their existence preserve their proper type. 

 The simple hybrid reverts to the mother type by repeated im- 

 pregnation with the maternal pollen, or when the paternal pollen 

 is applied, goes forward to the type of the father; the conver- 

 sion of the mother into the father is, however, seldom synchro- 

 nous with the contrary change. * Nicotiana rustica was clianged 

 in this manner by Kolreuter into N. paniculata, and similar 

 changes have been effected by others. The experiments require 

 much care and time, and great caution to avoid error ; but there 

 is not the least reason to doubt the truth of the fact, as has 

 been done by some impugners of the sexual theory. It is ob- 

 vious that to ensure success, species must be chosen which are 

 pre-eminently disposed to hybridize, and whose mules are fertile, 



