The Fruitful Facets of Gabon's Polyhedron 431
Darwinian escape from this paradox lay in a claim that fluctuating variation would
be reconstituted symmetrically about a newly established mean— and that
continual, directional selection to great cumulative effect could therefore be
achieved. De Vries, following the classic argument about a "rigid sphere" of
variation, as famously formulated by Fleeming Jenkin (1867), simply denied that
such reconstitution could occur. Again, using Wallace as Darwin's surrogate, de
Vries stated (1909a, volume 1, p. 42): "I admit that with this assumption [of
limitless and reconstitutable variation] it would be very easy and simple to account
for the phenomenon of adaptation ... If [Wallace's] assumption is once granted
everything follows. But it is, as a matter of fact, fallacious."
De Vries summarized his views on the inefficacy of fluctuating variation
(which, he suspected, did not have a particulate Mendelian basis and arose by
influences that we would now call ecophenotypic). How could substantial and
permanent evolutionary change originate from a style of variation that (1) always
regressed toward the mean; (2) arose in strictly limited extent, with preponderance
near the mean, and only rarely at a useful phenotypic difference (the normal
curve); (3) enjoined a strictly linear set of effects, only producing more or less of a
feature, while "creative" evolution required the development of true novelty:
"Individual variability, when tested by sowing, reverts to its original mean, the
forms of its variants are connected together, are coherent and not discontinuous. It
is centripetal in as much as the variations are grouped most densely around a mean.
Finally—and this is very important—it is linear; because the deviations occur in
only two directions— less or more."
By default therefore, but not at all as a negative argument, evolutionary
novelty must arise by a phenomenologically and causally distinct style of variation
that de Vries called "mutational"—i.e., sudden, fortuitous (and therefore
nonadaptive), true breeding and nonreverting saltations. De Vries called these
saltational variants "species," but we must understand (as he did) that such units
cannot be equated with traditional Linnaean taxa of the same name. With his
mutation theory, de Vries entered (and largely shaped, though he did not originate)
a major debate in systematics.
Obviously, a de Vriesian saltation does not, in se, make a new species in our
usual sense of the term—for the single mutant plant is only an individual with a
discontinuous phenotype, however true breeding in self-fertilization. In what sense,
then, could de Vries insist that he had discovered the mechanism for the origin of
new species?
In large part, de Vries based his claim upon an attempted redefinition. He
argued that the traditional Linnaean species encompasses an imprecise, compound
aggregation including varying numbers of phenotypically distinct, true-breeding
entities (and a fair amount of continuous variability as well, based on the
fluctuating style). The true-breeding subtypes represent nature's genuine units and
should be so designated. They arise by discontinuous saltation, without
intermediates, and should be called "elementary species." As a