356 THE STRUCTURE OF EVOLUTIONARY THEORY
the early 19th century formalist oracle of Naturphilosophie, who had proceeded
him at Tubingen, and had taught Agassiz, among others. Thus, Eimer doubted
Darwinian functionalism from both sides of 19th century German biology—the
romanticism of early 19th century formalist morphology, and the mechanism of
late 19th century experimentalism.
All sources agree that Eimer's treatise (1890 translation) became the major
English language source for the theory of orthogenesis. Contemporaries either set
their own discussion in its light (see Whitman, 1919—a posthumous publication of
work done before 1910), or recommended its primary study to those unfamiliar
with, or hostile to, orthogenesis (Kellogg, 1907, p. 322). Modern historians of
sciences (Bowler, 1979, 1983) continue to view Eimer as "the major popularizer"
of orthogenesis (Bowler, 1983, p. 141, in his book on non-Darwinian evolutionists
of the late 19th century). I shall therefore treat Eimer's views first.
Eimer's mechanist side led him to reject any vitalist or "teleological" tinge to
orthogenesis. "I repudiate any special internal force of evolution. According to my
view, everything in evolution is due to perfectly natural processes, to material,
physical causes" (1890, p. 64). In fact, Eimer's philosophical defense of
orthogenesis relies largely on its putative superiority over Darwinism as an
evolutionary mechanics in the determinist tradition; for a discovery of law like
order and direction in the key domain that Darwin had surrendered to chance—the
origin of variation—would represent a notable triumph for a physicalist worldview.
Eimer's opening words (1890, p. 1) set his entire argument in this context: "It
seemed to me long ago of the greatest importance to undertake an investigation of
the question whether the modification (variation) of the species of animals is not
governed by definite laws." Eimer, of course, concluded in the affirmative (1890,
p. 1): "If the principles of Darwinism are true because they can be shown to follow
from natural laws, then it was to be expected that obedience to laws would also be
discovered in that province which Darwin had surrendered to chance. But if
variation were shown to follow certain laws, the same demonstration would apply
to the origins of species."
If the directions of variation are strongly channeled and law like, then
evolutionary history may one day achieve the predictability of physical science (in
its late 19th century deterministic version): "The evolution—the growth— of
species one from another proceeds onwards as though following a plan drawn out
beforehand" (1890, p. 29). This leaning towards predictability flows from the
particular theory of channeling adopted by all leading orthogeneticists—phyletic
cooptation of the ontogenetic pathway. By virtually synonymizing "evolution" and
"growth" in the statement cited above, Eimer expressed the common Haeckelian
belief that if ontogeny and phylogeny cannot be exactly equated, both processes
proceed under a common nexus of causes ("phylogeny is the mechanical cause of
ontogeny," to cite a familiar Haeckelian maxim—see Gould, 1977b).
Since the predictable character of ontogeny cannot be denied, this comparison
establishes a prima facie case for orthogenetically channeled evolutionary