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xviii
Hereditary Genius
must be an average “regression” in passing from the parental to the filial
centre.
It is impossible briefly to give a full idea, in this place, either of the
necessity or of the proof of regression; they have been thoroughly
discussed in the work in question, Suffice it to say, that the result gives
precision to the idea of a typical centre from which individual variations
occur in accordance with the law of frequency, often to a small amount,
more rarely to a larger one, very rarely indeed to one that is much larger,
and practically never to one that is larger still. The filial centre falls back
further towards mediocrity in a constant proportion to the distance to which
the parental centre has deviated from it, whether the direction of the
deviation be in excess or in deficiency. All true variations are (as I
maintain) of this kind, and it is in consequence impossible that the natural
qualities of a race may be permanently changed through the action of
selection upon mere variations. The selection of the most serviceable
variations cannot even produce any great degree of artificial and
temporary improvement, because an equilibrium between deviation and
regression will soon be reached, whereby the best of the offspring will
cease to be better than their own sires and dams.
The case is quite different in respect to what are technically known as
“sports.” In these, a new character suddenly makes its appearance in a
particular individual, causing him to differ distinctly from his parents and
from others of his race. Such new characters are also found to be
transmitted to descendants. Here there has been a change of typical centre,
a new point of departure has somehow come into existence, towards which
regression has henceforth to be measured, and consequently a real
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