LUTHER BURBANK 
cions of this second generation that we now graft 
into membership in the aristocratic cherry colony. 
And when, after another interval of two years, 
these cions come into flower and are mutually 
cross-pollenized, the seeds they bear, being the off- 
spring of mixed dominants (Bb x Bb), will pro- 
duce a generation of seedlings precisely repeating, 
as regards the quality under consideration, the 
formula of their parent generation. In a given 
lot of four thousand, let us say, one thousand will 
be BB, two thousand will be Bb, and one thousand 
will be bb. 
And precisely the same difficulty in selection 
confronts the experimenter that confronted him 
before. 
If he could only know which are the pure domi- 
nants and which the mixed one, all would be well. 
But not only is it impossible for him to know 
this, but he may not be able even to determine 
with certainty, from examination of the foliage of 
the seedlings, which ones belong to the group of 
three thousand that bear the dominant factor 
(either BB or Bb), and which to the group of one 
thousand that bear only recessive factors (bb). 
It must be borne in mind that the experimenter 
is really considering a large number of qualities, 
and it must be understood also that there may 
not be any clearly established point of correlation 
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