370 LUTHER BURBANK 



nomena of dominance and recessiveness. Men- 

 del found, for instance, as we are aware, that 

 when a tall pea vine was crossed with a short one 

 the hybrids of the first generation were all tall, 

 because, as he said, tallness was dominant and 

 shortness recessive. And in the second genera- 

 tion one-fourth of the vines were short because 

 the factors for shortness were segregated, ac- 

 cording to the theory of chances, and one-fourth 

 of the vines were pure recessives. 



The fact of such dominance and recessiveness 

 between pairs of heritable characters is too ob- 

 vious to escape attention of any careful practi- 

 cal experimenter, now that attention has been 

 called to it. But it is equally obvious that there 

 are vast numbers of other heritable characters 

 regarding which no such clear matching as to 

 dominance and recessiveness is observed to take 

 place. 



And so the early enthusiasts were led finally 

 to see that Mendelian dominance and recessive- 

 ness apply only to a certain small number of 

 hereditary factors in the case of any individual 

 plant or animal. 



They came presently, after much heated argu- 

 ment, to admit that dominance and recessive- 

 ness constitute after all only a minor aspect of 

 Mendelian heredity. 



