III. GENETICS
It was an ancient question whether the male or the
female contributes the
seed which grows into the em-
bryo; the answer to
it partly determined a society's
view of blood-kinship and legal
inheritance. In classical
Greece the father was thought to be the primary
con-
tributor, but they disputed whether
the mother pro-
vides merely nutrition (as in
the dramatic decision in
Aeschylus' Oresteia) or a
second seed which unites with
the father's. Aristotle's analysis of current
theories in
his Generation of Animals shows that
discussions were
particularly lively in this field, where much
evidence
was quoted, some seriously misleading—for example,
that fishes swallow the milt, or that wound-scars have
been inherited (G.A. I. 17-18, III. 5, IV. 1). He himself
opposed
the concept of female seed, but it was ac-
cepted by Galen, Avicenna, and the Renaissance scien-
tists, until finally it was superseded by Von
Baer's
demonstration of the mammalian ovum. Among many
diverse
theories held by the atomists, “pangenesis”
was
important: that seed is drawn from every part of
both parents' bodies, to
account for resemblances. An-
other was
“preformationism”: that every part of the
embryo must
preexist in the seed (“for how could hair
grow from
non-hair?” said Anaxagoras). Some argued
that males must develop
from the father's seed and
females from the mother's; others attributed
sex-
differentiation to
differences of heat or position in the
uterus. Multiple births, monstrous
growths, superfeta-
tion, sterility, were
regularly quoted in evidence: to
some they suggested disproportion between
two seeds,
to others they suggested excess or deficiency of heat.
A Persian tradition connecting the semen with the
brain and spinal marrow
was followed by those who
held the brain to be the center of psychic
activity.
Those who held the heart to be the center argued that
semen
must come from the blood. A Greek tradition
associated it with foam (aphros, as in Aphrodite). Aris-
totle rationalized this idea in terms of pneuma, which
emulsifies the semen, being present in
it as the vehicle
of soul.
Aristotle gathered together these trains of thought
in a formulation based
on his own theory of matter
and form. The male seed transmits soul, which
is form
and movement; but its somatic part is sloughed away.
The
female contributes only the material (the cata-
menia). Among his arguments, he points out that fishes'
eggs do not
develop unless sprinkled with the milt,
yet this does not change them
quantitatively; and that
certain insects (as he thought) can receive the
male
impulse without a transmission of seed. Using his con-
cept of “mastery” he argues that
family likeness de-
pends upon the extent to
which the male impulse
controls the female material. Malformations, redun-
dancies, sterility, are due to disproportion of materials.
After Aristotle, the concept of female seed was re-
vived by the Alexandrian anatomists, who demon-
strated the genital connections of the ovaries and con-
cluded that these are channels for seeds
coming from
the blood. Later Galen demonstrated the oviduct in
sheep;
but instead of moving to a concept of mam-
malian ovum, he tried to reconcile this new datum with
Aristotle's
view, arguing that the female seed contrib-
utes only nutrition and the allantois, while the male
seed forms the
other embryonic membranes (chorion,
amnion) and bodily parts.
It was a universal belief (until Pasteur) that many
insects and plants grow
out of rotting materials without
seed. The early cosmologists used this to
argue that
life must have begun in that way. A typical account
occurs
in the History of Diodorus Siculus in the first
century B.C. In the primeval mud (that is, cold dry
earth
mixed with wet rain and the sun's heat) there appear
membranes containing embryo
animals of every kind,
which grow up and then reproduce themselves sexu-
ally. There was no ancient theory of
evolution out of
simpler forms, and therefore one problem was to ex-
plain how young animals, having appeared sponta-
neously, could survive in the mud
long enough to
become mature.
Those like Aristotle, who held that the universe had
no beginning, still had
to account for spontaneity. He
argued that pneuma
containing vital warmth is some-
times present
in water and earth mixed; a foamy bubble
is then formed, out of which may
arise eels and certain
of the fishes, testaceans and insects. He would
not
however allow that rottenness is a cause, for rottenness
is
disintegration whereas only concoction by heat can
generate new life.
