LUTHER BURBANK 
hereditary “complexes” that we speak of as unit 
characters is the most powerful individual factor. 
But, inasmuch as the great body of antecedent 
factors are using their influence in unison in 
another direction, it is inconceivable that the in- 
fluence of the single new factor should greatly 
change the aggregate result. 
In this view, what we term a species is a com- 
pany of organisms in the germ plasm of which the 
groups of factors for each main characteristic have 
become purely and unqualifiedly recessive, so that 
they act as a unit in producing a given character. 
They thus determine the chief characteristics of 
heredity in the Darwinian sense, which finds its 
popular expression in the phrase “like produces 
like.” 
Meantime, there are always minor groups of 
newer characters that are fighting for recognition, 
and while these are relatively insignificant because 
of their newness and small number as compared 
with the whole, yet they are conspicuous and im- 
portant in the eyes of the plant developer because 
they represent precisely those modifications of 
form and constitution and color that mark what we 
speak of as variations from type; and because they 
are so matched against one another in heredity— 
in the manner that we call Mendelian—as to make 
it possible for the plant developer to segregate and 
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