394 THE SELF-FERTILIZATION OF PLANTS. 



still another consideration, which obtains, in connec- 

 tion with this subject. A plant may be very degener- 

 ate in structure; possess very many organs in a rudi- 

 mentary condition ; may not have crossed with another 

 variety of the same species; and yet such plant may 

 be, at least for one generation, very fertile and vigor- 

 ous. Such conditions would well consist with a state 

 of facts, where the plant had been crossed by an indi- 

 vidual of a distinct, but allied species. It is frequently 

 possible, as Darwin shows, for an individual which is 

 wholly self-impotent, to cross with a distinct species, 

 and be very prolific. 



On page 297, Origin of Species, Darwin says, that 

 he is led: 



" To refer to a most singular fact, namely, that there 

 are individual plants, of a certain species of Lobelia, 

 and of some other genera, which can be far more easily 

 fertilized by the pollen of another, and distinct species, 

 than by their own pollen. * * For these species 

 (Lobelia and Hippeastrum) have been found to yield 

 seed to the pollen of a distinct species, though quite 

 sterile with their own pollen, notwithstanding that their 

 own pollen was found to be perfectly good, for it fer- 1 

 tilized distinct species." 



It may be asked : is the fertility and vigor acquired, 

 for one generation, by a cross with a distinct species, 

 due to a return to the perfect type ? In a measure, or, 

 sub modo, it is. It is not, however, a perfect type com- 

 mon to both species. The reason, why fertilization 

 may be effected, for one generation, by the pollen of a 

 distinct species, is because, in the reproductive element 

 of the foreign, but allied species, the given individual 



