LUTHER BURBANK 
esting aspect of heredity to which we referred at 
the beginning of this chapter—the phase com- 
monly spoken of as Mendelism. The essential 
characteristic of this aspect of heredity, as we have 
pointed out over and over, is that heritable charac- 
teristics are transmitted in a sense independently 
one of another, in such a way that they may be 
segregated and put together again in new com- 
binations in successive generations. 
The detail within this scheme of transmission, 
with which Mendel himself was chiefly concerned, 
and which absorbed the attention of his followers 
until it was found that there was need of taking a 
wider view, was involved in the phenomena of 
dominance and recessiveness. Mendel found, for 
instance, as we are aware, that when a tall pea 
vine was crossed with a short one the hybrids of 
the first generation were all tall, because, as he 
said, tallness was dominant and shortness reces- 
sive. And in the second generation one-fourth of 
the vines were short because the factors for short- 
ness were segregated, according to the theory of 
chances, and one-fourth of the vines were pure 
recessives. 
The fact of such dominance and recessiveness 
between pairs of heritable characters is too ob- 
vious to escape attention of any careful practical 
experimenter, now that attention has been called 
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