Biology Reference
In-Depth Information
of the cell theory which he tried to integrate into his conception of
heredity, but from a functional point of view, the gemmules are still
analogous to Hippocrates' foam.
While being relatively marginal in Darwin's work, the
Hippocratic conception of heredity is nevertheless not fortuitous. It
would have been difficult for Darwin to uphold an Aristotelian the-
ory: as Jean Gayon (1992A, 1992B) saw it, to be able to conceive
of its transformation, he had abandoned the idea that the species
corresponded to a structure or form shared by a population of indi-
viduals. He had even completely refuted this concept. In his opin-
ion, all the individuals of a species differ from each other and it
is these individual differences which provide the ground on which
natural selection acts.
“
…we have many slight differences which may be called individual
differences, such as are known frequently to appear in the offspring
from the same parents, or which may be presumed to have thus
arisen, from being frequently observed in the individuals of the
same species inhabiting the same confined locality.
No one sup-
poses that all the individuals of the same species are cast
in the very same mould.
47
These individual differences are
highly important for us, as they afford materials for natural selec-
tion to accumulate, in the same manner as man can accumulate in
any given direction individual differences in his domesticated pro-
ductions”
(OS pp. 101-102).
It is therefore difficult for Darwin's theory to adapt to the
Aristotelian conception. The latter supposes that individuals of
a given species are born due to transmission of a form which by
definition does not vary. If this were the case, how could they
evolve and give rise to a new species? For this reason, Darwin
demonstrates moreover that all the characteristics of an organism,
including those which are considered to be important from a
47
Original text not in bold.
