THE WHITE BLACKBERRY 345 



velopment of the white blackberry. His expla- 

 nation would run something like this: 



When the Lawton blackberry is crossed with 

 the whitish berry, all the offspring of the first 

 fihal generation are black because blackness and 

 whiteness are a pair of "unit characters," both 

 elements or factors of which cannot be mani- 

 fested in the same individual; and blackness is 

 the "dominant" character of the two, whiteness 

 being "recessive." 



But the hereditary factors or "determiners" 

 that make for whiteness, though momentarily 

 subordinated, are not eliminated, and half the 

 germ cells produced by the hybrid generation in 

 which blackness is dominant, will contain the 

 factor of whiteness, whereas the other half con- 

 tain the factor of blackness. And when in a suc- 

 cessive generation a germ cell containing the 

 factor of whiteness unites with the germ cell of 

 another plant similarly containing the factor of 

 whiteness, the offspring of that union will be 

 white, their organisms inheriting no factor of 

 blackness whatever. 



It may chance, however, that for many succes- 

 sive generations a germ cell containing only the 

 factor of whitness fails to mate with another 

 similar germ cell and so no white-fruited pro- 

 geny is produced. In such a case for generation 



