University of Virginia Library

INHERITANCE THROUGH
PANGENESIS

Pangenesis is a theory of a process of hereditary trans-
mission according to which all parts of the organism
contribute to the formation of the entire organism.
First propounded in ancient Greece, the hypothesis has
continually reappeared (often in different and increas-
ingly more sophisticated terms and occasionally under
different names) in both popular and scientific litera-
ture up to recent times.

The main inducement leading to the original formu-
lation of the idea of pangenesis was the ancients' rec-
ognition that many single characters of the organism
can vary quite independently of the rest and can be
separately transmitted to offspring. Thus it was that
instances of point-to-point resemblance between par-
ent and offspring seemed to them to necessitate a
theory of transmission based on intermediary particles
possessing a parallel point-to-point correspondence.

The origins of the idea can be found in the fragments
of the Pre-Socratics, e.g., Anaxagoras and the atomists.
However, a fairly detailed picture of the process as
envisioned in sexual reproduction appears in the
Hippocratic corpus (fifth century B.C.).

(Hippocrates, VII, 471-75).

Quite understandably, the ancients focussed their
attention on the adult form. The alternating generation
represented in the germinal link was seen as but a slight
interruption in the somatic continuum of the genera-
tions constituting the human race. Under such a view,
the pangenetical process was their conceptualization
of how all the heritable human traits could be funnelled
from one generation into the next through the vehicle
of the germ (see Diagram, p. 625).

In their original considerations, two choices had lain
open to the ancient speculators. First, that the consti-
tution of the germ linking the two generations could
involve only a quantitative change; that is, differen-
tiated in miniature on a point-to-point correspondence
with its differentiated parent. Second, that the germ
represented an actual qualitative change wherein the
fully-differentiated constitution of the parent form had
somehow been translated or distilled into an undiffer-
entiated “essence” or “anima” which nonetheless con-
tained the potential for future differentiation.

The first upholders of pangenesis—the atomists and
those whose biological speculations were based on
rather strict parallels with the physico-mechanical
world—could accept only quantitative change. The
first opposition to pangenesis came from Aristotle, the
man whose empirical studies of generation helped to
liberate biology from the physical world view. Espous-
ing epigenesis and a teleological vitalism, he insisted
on qualitative change.

Aristotle's attempt to refute the pangenetical hy-
pothesis, however, was by no means successful. His
counter to the central theme requiring unit-character
transmission via corresponding particles was disap-
pointingly tangential. He could only respond weakly
by asking “how could there be such particles for ab-
stract characters as voice or temperament, or from such
nongenerating sources as nails or hair?”

Even more significant to the Greeks, for whom “first
principles” dictated so much to observation, Aristotle
was left in the apparently untenable position of having
to contradict the very basic maxim that “nothing can
come from nothing” (that is, that true multiplicity
cannot arise from an undifferentiated unity). Where
then, was the basis for the great differentiation that
must follow? Certainly, his critics felt, not in the
singularly undifferentiated matter which Aristotle had
seen in the egg.

Besides this purely rational argument, there were
two other equally important reasons why Aristotle did
not prevail against pangenesis. First, the idealized
nature of contemporary theories rendered them im-
pervious to either proof or disproof by the limited
observations of their time. Second, and relatedly, the
Attic philosophy which envisioned no manipulation of
nature precluded a program of controlled experi-
mentation that might have yielded an understanding
of the roles of nature and nurture upon the construction
of living things. Such was to remain the case until the
scientific revolution of the seventeenth century.

The revival of pangenesis was one of the biological
manifestations of the physico-mechanico-reductionism
which characterized seventeenth-century science. Yet
again it was the object of contemporary criticism.
Mechanists such as Kenelm Digby saw insurmountable
difficulties surrounding the assemblage and segregation
of the gemmules purported to take place in the gonads.
Vitalists such as William Harvey could not accept the
theory's stress on heterogeneity and its seemingly pre-
formationist implications. Pangenesis found its sup-
porters chiefly among those such as Antoine Le Grand
who, fervent believers in the inheritance of acquired
characters, saw it as the only rational mechanical
process which could account for such.

Despite the rapid inroads made by biological
microscopy from the last quarter of the seventeenth
century, scientists had failed to identify unequivocally
the actual physical sites of germ production. Conse-
quently, the first half of the eighteenth century was
rife with speculation substituting for observation.
Pangenesis would have been obscured in the great
debate that followed between epigenesis preformation
had it not been for Maupertius and Buffon in the
second half of the century. Accepting pangenesis as
a mode of germ formation, they stressed its distinction
from theories of individual development. Thus, the idea
remained current, though generally ignored during the
general preoccupation with the processes of ontogeny
which characterized contemporary research.

In 1809 there did appear an account of inheritance
based on the modification of the germ via changes
impressed on the parent form. It formed the basis of
the evolutionary mechanism put forward by the French
biologist Jean Lamarck. The finer details of process or
mechanism, however, were generally omitted by him
(save for occasional references to the action of bodily
fluids). On the other hand, the controversy which fol-
lowed upon the promulgation of Lamarck's theory does
serve to underline the important twofold nature of the
subject of acquired modifications. Notwithstanding the
question of the heritability of such changes (assumed
by Lamarck), there remained in his view, two distinct
modes of acquisition. First, he recognized a purely
passive or unconscious form of modification. Environ-
mental conditions brought about changes without any
activity or awareness on the part of the organism. Such
changes are impressed strictly from without. Second
(and often in addition to the first), where sentient and
thinking beings are involved, Lamarck saw the envi-

ronment as producing heritable change through a
stimulus-response interaction—with the organism itself
taking on the role of active agent in effecting change.
The source of such organic response for Lamarck was
the sentiment intérieur possessed by all sentient beings.
The response of this faculty to environmental stimuli
was manifested by changes in behavior, or habit, or
the use of organic parts. The consequent alteration of
structure was thus achieved in a quite different manner
from that acquired passively. Taken together with
Lamarck's often ludicrous examples, the involvement
of a conscious mind or will was thus only too apparent
to his readers. It was rejected with a vitriolic
vehemence shocking even in its time. Due in no small
part to Lamarck, theories of both evolution and hered-
itary transmission were scientific anathema for nearly
half a century.

It must be seen that the objections over Lamarck's
invoking of the will as a factor in the acquisition of
change were not directed towards his assumptions as
to the mode of transmission. In fact, a belief in the
inheritance of acquired characters was almost uni-
versally held throughout most of the nineteenth cen-
tury. It was Darwin who, in his Variation of Plants
and Animals under Domestication (1868), picked up
this aspect of the subject and thereby resurrected
pangenesis. It was the first detailed discussion in nearly
a century. The Variation was Darwin's conscious at-
tempt to realize two aims that had remained unfulfilled
in his Origin of Species (1859). First, he supplied the
mass of documentation supporting domestic variation
which had occupied the first chapter of the Origin.
Second (and occupying the entire second volume of
the work), he directed himself to discussing the phe-
nomena of inheritance and the causes of variation—on
both of which his evolutionary theory so evidently
depended. It was in the last major chapter of this
volume that he put forward what he called his “Provi-
sional Hypothesis of Pangenesis.” (Darwin gave no
indication whatever that he was aware of any prede-
cessors.)

A comparison of Darwin with Hippocrates will show
how little the central theme had changed in over two
thousand years. Said Darwin:

(Darwin, II,
357).

(II,
383).

Darwin goes on to give his reasons for his hypothesis,
citing the state of genetical knowledge of his time: the
abundance of many sets of conflicting and seemingly
contradictory observations and the lack of any syn-
thesis in the form of a theory or set of laws con-
sistently applicable to the known facts. “I have been
led, or rather forced, to form a view which to a cer-
tain extent connects these facts by a tangible method”
(II, 357).

The method was simply to address himself, in the
Baconian style he espoused, to all the known classes
of genetic phenomena, and from there to extract the
one mechanism which could account for all. The recent
historiography of science has too readily dismissed this
instance of Darwin's theorizing as too patently ad hoc
to merit serious attention. But the strength of such
criticism is undermined by closer examination. It must
be seen that it was Darwin's firm conviction that no
general theory of inheritance was acceptable unless it
equally explained important, exceptional phenomena.
These he initially listed as: instances of noninheritance;
dominance simultaneous with blending; exact duplica-
tion of parent through both sexual and asexual repro-
duction; inheritance of the effects of use, disuse, and
habit; atavism; and saltations. In other words, for
Darwin the rule must be proved by way of a valid
explanatory incorporation of its exceptions. That his
resultant hypothesis was not as ad hoc as modern his-
torians have suggested is further shown by its anticipa-
tion (within, of course, the limitations of an admittedly
poly-particulate theory) of many of the results of the
machinations of the present bi-particulate theory of
inheritance. Most noteworthy of these is his anticipa-
tion of panmixis, crossing over, and position effects (II,
396-400).

It was left to a German biologist, August Weismann,
working during this same period, to put an end to the
long scientific vitality of the pangenetical hypothesis.
Working not only from his own observations but the
accumulation of observation on the physical origins of
the generative elements by others, Weismann is gener-
ally credited with the hypothesis that has since re-
placed pangenesis in the modern view of sexual gener-
ation. Weismann's “theory of the germplasm” (1885,
published 1893) was based on the first clear distinction
between two fundamental types of cell, and the two
distinct forms of cell division which characterize their
reproduction. These were seen as the cells constituting
the general bodily structure or somatoplasm, and those
cells comprising the reproductive or generative tissues
(containing the genetic constitution) or germplasm.
Where the great mass of ordinary body cells reproduce
through mitosis or common, fully-duplicating cell di-
vision, the germinal elements are produced through
meiosis, or reduction-division. The latter elements fuse

at the inception of the new generation and upon its
sexual maturity proceed to produce future germinal
elements in the same way. Weismann thus demon-
strated that the somatoplasm is in no way causally
linked to the production of the germplasm. In such
a view, ultimate biological continuity is achieved
through a direct cellular continuity involving germ
cells only (see Diagram).

As is so often the case in the history of ideas—
particularly those emanating from scientific theories—
their wider significance tends to extend well beyond
the strictly literal context from which they originated.
The extrapolations of interpretation have often out-
lived or at least outweighed their sources. This has been
true whether the science upon which they are based
was good or bad, the reasoning sound or fallacious,
or whether the interpretations have so exceeded their
bases as to bear little resemblance to the original. This
has been much the case in the history of pangenesis.
Thus it is necessary to discuss the major implications
that have followed from it and to give some indication
of the trends of thought they have produced. These
implications are: (1) The genetic constitution of organic
beings can be modified from without, via changes
impressed on the bodily constitution. (2) Modifications
in the individual characters of one generation can be
transmitted and translated into modifications in the
same characters in the following generation. (3) Similar
individuals exposed to similar conditions will be simi-
larly and simultaneously modified. (4) As environmental
conditions impress structural change so, in the case of
sentient or thinking beings, can they effect changes
through permanent alterations in habit, behavior,
or—in the case of man—the direction of the mind or
will. (5) As man can control his environment, so can
he therefore control his genetic constitution and thus
change need no longer be left to chance, but to the
conscious manipulation of man. (6) As the bodily con-
stitution of the organism lies causally prior to the
genetic constitution, so it must be the principal subject
for the impression of change.

It is clear that the history of the implications of

pangenesis is a longer and far more complicated one
than of the concept itself. Consequently, only the two
main areas of this history will be discussed here—the
social and the scientific.

From the ancient Greeks through Darwin there was
a general awareness and agreement upon the first three
points. Darwin went part way towards accepting the
fourth point but, giving primacy to structure, he ex-
cepted (or, in some cases, simply avoided discussing)
the action of mind or will in effecting heritable change.
(A reservation certainly not found in Lamarck!) Indeed,
in the post-Origin years from 1868, he came more and
more to rely upon these points as, first ancillary, then
supporting, and finally cooperative processes of evolu-
tionary modification of natural selection. It remained
increasingly an article of faith with him that natural
selection was the most important source of such
change. Despite Weismann's refutation of pangenesis
—and the inheritance of acquired characters for which
it was the vehicle—anti-Darwinian critics chose to
anchor natural selection to its mistaken assumptions
regarding hereditary transmission. Thus, it was not to
be until the second decade of the present century—
when Weissmann's view was linked with Mendel's laws
into a fully comprehensive picture of hereditary trans-
mission—that Darwinian evolution reached truly
widespread acceptance.

During this same latter third of the nineteenth cen-
tury, however, a number of social thinkers (Spencer,
Marx, and their followers) were just beginning to ab-
sorb the implications of the pangenetical hypothesis
in its evolutionary context. Coupled with their inter-
pretation of Darwinian evolution, it seemed to provide
the very key—the ultimate biological justification—for
radical change. It was their extrapolations, based on
the last three of the above-mentioned implications, that
provided for them the basis for a de novo establishment
of revolutionary change.

Nothing runs more counter to a revolutionary phi-
losophy than a sense of commitment to the past. The
genetic constitution that identifies every living being
in the world is the biological legacy from the past.
It dictates the direction of our development and thus
represents a commitment to a relatively fixed pattern
of the future as an ineluctable continuation of the past.
As such, it involves the characteristics that distinguish
races and species and, from the point of view of these
social thinkers, the social constructs of man based upon
them. Yet in pangenesis—a doctrine as old as rational
thought itself and supported by reputable scientists
through to (then) recent times—lay a hope of breaking,
or at least radically altering, the precedent of the past.

That Karl Marx, the first of a now-century-old line
of such interpreters, should have written Darwin asking
his permission to dedicate Das Kapital to him is at
least understandable, albeit a bit ludicrous. (Darwin
graciously refused on the grounds of being unable to
see any connection between their subjects.)

Despite the continued scientific verification of the
Weismann-Mendel theory of inheritance, and the
contingent repudiation of pangenesis, Marxians and the
Soviet interpreters of Marx (i.e., Lysenko, Michurin,
et al.) refused to relinquish the theory which had pro-
vided the support for their dogma. Stalinist biology
continued to fight against the current of accepted
science in an effort to revalidate the fallen theory. In
the present era, however, it is almost safe to say that
with the repudiation of both Stalin and Lysenko
Marxian biology enjoys no more serious support in the
Soviet Union than does anti-Darwinism in America.
It remains that a life-span of two and a half millennia
is a record one for the history of an idea.

BIBLIOGRAPHY

C. Darwin, The Variation of Plants and Animals under
Domestication (London, 1868). Hippocrates, “On Genera-
tion,” in Oeuvres complètes d'Hippocrate, ed. É. Littré
(Amsterdam, 1962), Vol. VII; excerpt trans. by P. Vorzimmer.

The remaining primary sources for over 2000 years of
pangenetical thought are too numerous to cite here: full
citations can be found below in the two best secondary
sources on theories of inheritance. Both E. S. Russell, The
Interpretation of Development and Heredity (Oxford, 1930),
and F. J. Cole, Early Theories of Sexual Generation (Oxford,
1930) are excellent and as useful today as they have always
been. For both a valuable history of the idea of the inherit-
ance of acquired characters and for the subsequent Marxian
interpretations down to recent times, see Conway Zirkle's
eminently readable Evolution, Marxian Biology, and the
Social Scene (Philadelphia, 1959).

PETER VORZIMMER

[See also Biological Conceptions in Antiquity; Evolutionism;
Genetic Continuity; Inheritance of Acquired Charac-
teristics; Recapitulation.]