LUTHER BURBANK 



So now, when he attempts to restore fixity to 

 something that he has purposely made unstable, 

 he is at once confronted with the danger of 

 undoing much that he has accomplished. The 

 measure of success that he can hope to attain 

 will depend very largely upon the particular kind 

 of unit characters that he has combined in the 

 product that he now wishes to make stable. 



We have seen that, as between the opposing 

 members of any pair of unit characters, it is 

 usually discovered that one has prepotency or 

 dominancy over the other. When blackberries 

 of normal color, for example, are crossed with 

 the white blackberry, the progeny are all black, 

 because this color is the dominant member, and 

 white the recessive or negative member of the pair 

 of unit characters. But we saw also that the 

 recessive trait will reappear in the succeeding 

 generation, and that when it does reappear, it will, 

 within certain limits, thereafter breed true. 



So, when in the second generation we again 

 produce a white blackberry, we have a type which 

 is fixed as regards the particular character of 

 whiteness. In other words, our white blackberry, 

 even though both its parents, and one grandparent, 

 were black, may be considered a berry of pure 

 white strain. From the moment of its appearance 

 it is a fixed type as to color. 



[240] 



