LUTHER BURBANK 



But these big words, while it is convenient to 

 know their meaning, need not greatly concern us. 

 It suffices to recall the convenient terms "domi- 

 nant" and "recessive"; to recognize that a good 

 many antagonistic traits may be classed as unit 

 characters; and to welcome the conception of the 

 division of the factors or determiners of such a 

 pair of unit characters in the germ cell, as enab- 

 ling us to form a tangible picture of the modus 

 operandi through which the observed phenomena 

 of heredity may be brought about. 



Mixed Heritage of the Blackberries 



It remains to be said that the case of our black- 

 berries is a little more complex than the case of 

 the guinea pigs just referred to, because there is a 

 second pigment involved. The "Crystal White" 

 berry, it will be recalled, was not white but brown- 

 ish in color. There were thus transmissible two 

 pairs of unit characters involved as regards the 

 matter of color, namely (1) black versus white, 

 and (2) yellow or brown versus white. 



The black factor or determiner dominated 

 absolutely in the first generation; but in the second 

 generation a certain number of germ cells were 

 paired in such a way as to eliminate the black but 

 retain the yellow factor. 



It required a third mixture of the germ-cell 

 factors to produce a union in which neither black 



[68] 



