102 THE METHOD OF DARWIN. 



interbreeding, I raised, close together, two 

 large beds of self -fertilized and crossed seed- 

 lings from the same plant of Linaria vulgaris 

 (common Toad Flax). To my surprise, the 

 crossed plants, when fully grown, were plainly 

 taller and more vigorous than the self-fertilized 

 ones. 



"Bees incessantly visit the flowers of this 

 Linaria, and carry pollen from one to the 

 other; and if the insects are excluded the 

 flowers produce extremely few seeds, so that 

 the wild plants from which my seedlings were 

 raised must have been intercrossed during all 

 previous generations. It seems therefore quite 

 incredible that the difference between the two 

 beds of seedlings could have been due to a 

 single act of self-fertilization; and I attributed 

 the result to the self-fertilized seeds not hav- 

 ing been well ripened, improbable as it was 

 that all should have been in this state, or to 

 some other accidental and inexplicable cause." 

 During the next season he raised two beds of 

 carnations (Dianthus caryophyllus) in the same 

 way and for the same purpose; the preceding 

 generations in this case also must have been 

 continuously cross-fertilized; again "the self- 

 fertilized seedlings were plainly inferior in 

 height and vigor to the crossed." 



