"[28]
[Footnote 28: _Scientific American_ Sup., January 3, 1914.]
Heredity we now see is a method of analysis, and the facts brought to
light by Mendelism help us very much toward an understanding of living
matter. Especially does it help us to understand the complexity
underlying the facts of heredity, which until now have seemed so strange
and capricious. As Professor Punnett of Cambridge remarks:
"Constitutional differences of a radical nature may be concealed beneath
an apparent identity of external form. Purple sweet peas from the same
pod, indistinguishable in appearance and of identical ancestry, may yet
be fundamentally different in their constitution. From one may come
purples, reds, and whites; from another only purples and reds; from
another purples and whites alone; whilst a fourth will breed true to
purple. Any method of investigation which fails to take account of the
radical differences of constitution which may underlie external
similarity, must necessarily be doomed to failure. Conversely, we
realize to-day that individuals identical in constitution may yet have
an entirely different ancestral history. From the cross between two
fowls with rose and pea combs, each of irreproachable pedigree for
generations, come single combs in the second generation, _and these
singles are precisely similar in their behavior to singles bred from
strains of unblemished ancestry_.
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