FIXING GOOD TRAITS 



But, unfortunately, it is not sufficient that the 

 white blackberry should breed true as regards the 

 quality of whiteness alone. There are other quali- 

 ties of size and flavor that are equally essential. 

 And these, it would appear, include sundry other 

 pairs of unit characters — sweetness versus sour- 

 ness, large size versus small size, profuse bearing 

 versus scant bearing, and the like — that are repre- 

 sented in our berry by mixed factors. 



In the Mendelian view, it will be recalled, there 

 are always two factors representing any pair of 

 unit characters. 



In the case of our white blackberry, in the 

 Mendelian view, both factors for the unit char- 

 acter blackness-versus-whiteness are of the white 

 order; or in the technical phrase, the berry is 

 "homozygous" for that pair of factors. 



But as regards, let us say, the factor for the 

 unit character bigness-versus-smallness the case is 

 different; for this character may chance to be 

 represented by one factor of each type. In other 

 words, resorting again to the technical language, 

 the berry may be "heterozygous" as regards that 

 character. 



In this particular generation, the quality of 

 bigness prevails, because bigness is dominant to 

 smallness. But the factor for smallness must have 

 a hearing in the next generation. 



[241] 



