254 Raphael Falk
at once shifted his research program to the studygenetics— a term he introduced
in 1905 — and aggressively promoted Mendel’s conception of the rules of heredity
and the methodology of hybridization. It would be no exaggeration to assert that
he very much acted as Mendel’s Bulldog, just as Huxley was Darwin’s [Cock, 1973;
Coleman, 1970; Darden, 1977; Falk, 1995b; Olby, 1987].
De Vries’s confounding Mendel’s methodology and his own ideology harassed
the study of genetics at least during the first decade of the twentieth century, and
arguably it still does today. Mendel did not employ in his explanations invisible
particulate determinants, nor did he conceive of the difference between the poten-
tial for a trait and the trait proper. Instead, he studiously paid much attention to
the pea varieties that would be adequate for his experimental design, noting that,
Selection of the plant group for experiments of this kind must be made
with the greatest possible care if one does not want to jeopardize all
possibilities of success from the very outset.
The experimental plants must necessarily- Possess constant differing traits.
- Their hybrids must be protected from the influence of foreign
pollen... - There should be no marked disturbances in the fertility of the
hybrids and their offspring in successive generations....[Mendel,
1866/1966, 3].
Of the 34 varieties of peas that he examined for two years he selected only
twenty-two that “yielded quite similar and constant offspring” [Mendel, 1866/1966,
4]. Among these he picked out seven traits, each of which turned up regularly in
one of two distinct alternative forms. In retrospect, for Mendel this procedure
made the distinction between genotype and phenotype redundant [Falk, 1991].
De Vries’ notion of the organism as a patchwork mosaic of discrete factors
that keep their identity from one generation to the next, and segregate from each
other in the gametes of hybrids [de Vries, 1900/1966] was enthusiastically adopted
by Bateson. Like de Vries he contended the stepwise discontinuous evolutionary
progress. According to Bateson’s “Theory of Repetition of Parts” organisms are
constructed as discontinuous repeats with variations of the same theme. Different
organisms are systemic variations of such repeats [Bateson, 1894]. Together with
his coworkers he examined the validity of the Mendelian principles of independent
segregation of unit-characters for many traits in various plant and animal species
as well as in humans. Unit-characters were defined as such by morphological
considerations. He suggested that the two alternatives of unit character (which he
called allelomorphs, later shortened to alleles) represented the respective presence
and absence of the unit character [Schwartz, 2002]. However, upon encountering
cases in which the structural or physiological unit characters did not correspond to
the unit character of inheritance Bateson and coworkers resorted toad hochelping