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Ex ovo omnia. Detail
of the frontispiece, probably drawn and etched by Richard Gaywood,
from William Harvey, Exercitationes de generatione animalium:
Quibus accedunt quaedam de partu: de membranis ac humoribus
uteri& de conceptione, London: Octavian Pulleyn, 1651.
21 x 16 cm.
By permission of the Syndics of Cambridge University Library.
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Everything from the egg. For the Aristotelian
William Harvey, the egg was not the structure we know today but a product
of conception. The frontispiece of his treatise on generation shows Zeus
opening a bisected egg labelled Ex ovo omnia: ‘Everything from
the egg’. This releases humans, other animals and plants and so drew on
earlier representations of Pandora’s mythical box, from which all good and
evil had flown out into the world. Several decades later, the Dutch anatomist
Regnier de Graaf postulated that mammals always develop from a female egg.
Yet by modern standards what he saw under the microscope was not the egg
itself but a cluster of cells around it, the ‘Graafian follicle’. The human
egg remained elusive for centuries to come.
Debates over generation
Mechanical philosophers in the 1600s built on
Aristotelian epigenesis to explain generation entirely in terms of moving
particles and attractive forces, but because this risked charges of atheism
for dispensing with God, a new theory of pre-existence soon became dominant.
The theory of pre-existence had it that all adult structures were
already present in the egg, only much smaller. God had generated every
germ at the Creation, one within the other like a Russian doll. The related
doctrine of preformationism argued that the body of the new being was complete
in the parent seed so that during gestation the embryo only increased in
size. ‘Ovists’ placed the germ in the egg,
‘animalculists’ in the sperm.
During the 1700s epigenesists and preformationists wielded the microscope
to support their claims, but could not agree on what they saw or how to
interpret it. The controversy represented deeper conflicts: materialism
versus orthodox Christianity and empiricism against rationalism. Epigenesis
seemingly triumphed, but in fact the rules of the game changed. Embryologists
no longer sought to explain the source of organization; they took organization
as given and dissected animals to establish its laws.
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A preformationist ‘origin of man’. The preformationist
take on generation is vividly shown in this famous woodcut,
first published in ‘A ground-plan of the origin of man’
(Anthropogeniae ichnographia) by the Dutch
anatomist Thomas Kerckring in 1671. Here it is reprinted
in a two-part discussion of the macrocosm and microcosm
by the alchemist and physician Franciscs Mercurius Van
Helmont. Embryos supposedly just a few weeks old are
as fully-formed as children. Figure I shows ‘two humane
eggs of different bigness’, figure II ‘an Embryo of
three, or at the most four days after Conception’, and
figure III ‘the Hepar uterynum [placenta] with the Veins
and Arteries … dispersed through the substance of it’.
Figure IV ‘represents to the eye a gristly Scheleton
of an embryo of three weeks’, figure V ‘an Embryo of
one month’, and figure VI, to the modern eye the diminutive
skeleton of a child, ‘an Embryo of six weeks’.
From The pardoxal (sic) discourse of F. M. Van
Helmont, part 2, London: printed by J.C. and Freeman
Collins for Robert Kettlewel, at the Hand and Scepter
near St Dunstan’s Church in Fleetstreet, 1685, f. 22.
19 x 11.5 cm.
Wellcome Library, London.
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‘A child in the egg’, 1685
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Le petit animal. This human figure in
the head of a spermatozoon, published in a book by the
Dutch physicist and microscopist Nicolas Hartsoeker,
has been reproduced countless times. Captions usually
state that it represents the homunculus Hartsoeker saw,
or thought he saw, inside the sperm, under the microscope.
Yet Hartsoeker said only that ‘perhaps’ we would see
this—were it possible to see through the ‘skin’ that
surrounded the sperm head, and if we had the tools.
And he never used the term ‘homunculus’, which had dangerous
alchemical connotations, but wrote of le petit animal
and l’enfant.
From Nicolaas Hartsoeker, Essay de dioptrique,
Paris: Jean Anisson, 1694, p. 230. 24.5 x 18.5 cm.
By permission of the Syndics of Cambridge University
Library.
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‘The homunculus in the sperm’, 1694
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