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Hereditary Genius
371
an average are perfectly clear. It would represent the results,
supposing the competing “gemmules” to be equally fertile, and also
supposing the proportion of the gemmules affected by individual
variation, to be constant in all the cases.
The immediate consequence of the theory of Pangenesis is
somewhat startling. It appears to show that a man is wholly built up
of his own and ancestral peculiarities, and only in an infinitesimal
degree of characteristics handed down in an unchanged form, from
extremely ancient times. It would follow that under a prolonged term
of constant conditions, it would matter little or nothing what were the
characteristics of the early progenitors of a race, the type being
supposed constant, for the progeny would invariably be moulded by
those of its more recent ancestry.
The reason for what I have just stated is easily to be comprehended
if easy though improbable figures be employed in illustration.
Suppose, for the sake merely of a very simple numerical example,
that a child acquired one-tenth of his nature from individual variation,
and inherited the remaining nine-tenths from his parents. It follows,
that his two parents would have handed down only nine-tenths of
nine-tenths, or 0.81 from his grandparents, 0.729 from his great-
grandparents, and so on; the numerator of the fraction increasing in
each successive step, less rapidly than the denominator, until we
arrive at a vanishing value of the fraction.¹
The part inherited by this child in an unchanged form, from all his
ancestors above the fiftieth degree, would be only one five-
thousandth of his whole nature.
I do not see why any serious difficulty should stand
1
The formula is as follows:—
G = the total number of gemmules; of which those
derived unchanged through parentage = Gr; the remainder, = G (1 — r), being changed
through individual variation. Then—
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