400 THE STRUCTURE OF EVOLUTIONARY THEORY
Bateson notes the fascination of his colleagues for the causes of variation as
expressed in the nature of heredity, but holds that the absence of any hard evidence
has mired the subject in fanciful and speculative hypotheses, from Darwin's
pangenesis to Haeckel's perigenesis. The quest should be postponed for now
(though Bateson wouldn't have long to wait, as the Mendelian revival lay just
around the corner of the coming century). Meanwhile, an empirical approach might
yield great benefits, at least by providing an inductive entry to the difficult subject
of causes. Why not, in short, simply gather the facts of variation: "It is especially
strange that while few take much heed of the modes of variation or of the visible
facts of descent, everyone is interested in the causes of variation and the nature of
'heredity,' a subject of extreme and peculiar difficulty. In the absence of special
knowledge, these things are discussed with enthusiasm, even by the public at large.
But if we are to make way with this problem, special knowledge is the first need.
We must know what special evidence each group of animals and plants can give,
and this specialists alone can tell us" (1894, p. ix).
Bateson chose to express this strategy of empirical compilation in the title of
his book: "To collect and codify the facts of variation is, I submit, the first duty of
the naturalist" (1894, p. vi). Brave words, to be sure, but Bateson recognized that
such a complex and multifarious subject could not be resolved simply by toting the
relative frequencies of an empirical list. He also understood that the very idea of a
totally unbiased listing could only operate as a self-serving fiction to bolster a myth
of perfect scientific objectivity. Bateson recognized a pervasive bias in traditional
accounts of variation—strong preferences for continuity and gradualism, as
expressed in the old Leibnizian and Linnaean aphorism, natura non facit saltum:
"First there is in the minds of some persons an inherent conviction that all natural
processes are continuous... Secondly, variation has been supposed to be always
continuous and to proceed by minute steps because changes of this kind are so
common in variation" (1894, p. 16). Bateson's list, therefore, would be a purposive
account of a particular sort of variation: "If facts of the old kind will not help, let us
seek facts of a new kind" (1894, p. vi).
Since Bateson sought the causes of evolution in variation itself, and since he
viewed discontinuity as the primary fact of natural history, discontinuous variation
among organisms within populations became his favored source of evolutionary
change. Materials for the Study of Variation is not an unbiased compendium of all
organic mutability, but rather an explicit attempt to catalog discontinuous variation
as a source of insight into internally driven causes of evolution. The subtitle of the
book explicitly refutes any claim to balance or comprehensiveness among styles:
"Treated with Especial Regard to Discontinuity in the Origin of Species."
Bateson divided variation into meristic (for serially and symmetrically
repeated, countable and discontinuous structures) and substantive (for ordinary
continuous variability). As an obvious ploy to promote his preference for locating
the causes of evolution in discontinuity of variation, the meristic