THE WHITE BLACKBERRY 



nor yellow factors appeared, the offspring of this 

 union being of course the pure white blackberry. 



The presence of the yellow factor accounts 

 for the further fact, to which reference sliould 

 be made, that there were various intermediate 

 types of berries, neither black nor white, which 

 appeared in successive generations but which are 

 eliminated by selection as they did not fall in with 

 our plan of development of a white race. 



The explanation just given makes it clear that, 

 once a union of germ-cell factors having only the 

 white element was effected, the black and the 

 yellow factors being entirely eliminated from that 

 particular individual, the germ cells arising from 

 that individual would necessarily contain only the 

 factor of whiteness; hence that all the progeny of 

 that individual would "breed true" and produce 

 white berries. 



Such is indeed the observed fact with my devel- 

 oped strains of white blackberries. Grown from 

 the seeds, these breed far truer to their parentage 

 than is the case with most cultivated fruits. As 

 to certain other qualities they may vary, but all 

 are white. 



The Mendelian explanation obviously cannot 

 add any force to this observed and long ago 

 recorded fact. 



But it does serve to explain the observed fixity 



[69] 



