man, physical as well as intellectual and moral qualities; it must hold
true for the plant kingdom as well as for the animal kingdom; in short, it
must include the whole living world.

Quetelet's law may be most easily studied in those cases where the
variability relates to measure, number and weight, and a vast number of
facts have since confirmed its exactness and its validity for all kinds of
organisms, organs and qualities. But if we examine it more closely, we
find that it includes just those minute variations, which, as Darwin
repeatedly pointed out, have often no significance for the origin of
species. In the phenomena, described by Quetelet's law nothing "happens to
arise"; all is governed by the common law, which states that small
deviations from the mean type are frequent, but that larger aberrations are
rare, the rarer as they are larger. Any degree of variation will be found
to occur, if only the number of individuals studied is large enough: it is
even possible to calculate before hand, how many specimens must be compared
in order to find a previously fixed degree of deviation.

The variations, which from time to time happen to appear, are evidently not
governed by this law. They cannot, as yet, be produced at will: no
sowings of thousands or even of millions of plants will induce them,
although by such means the chance of their occurring will obviously be
increased. But they are known to occur, and to occur suddenly and
abruptly. They have been observed especially in horticulture, where they
are ranged in the large and ill-defined group called sports. Korschinsky
has collected all the evidence which horticultural literature affords on
this point. (S. Korschinsky, "Heterogenesis und Evolution", "Flora", Vol.
LXXXIX. pages 240-363, 1901.) Several cases of the first appearance of a
horticultural novelty have been recorded: this has always happened in the
same way; it appeared suddenly and unexpectedly without any definite