A Critique of Pure (Genetic) Information

30 Chapter 1
compromising ante-act, H 2O is always H 2O, and reacts always in the same
manner, whatsoever may be the “history” of its formation or the earlier state
of its elements. I suggest that it is useful to emphasize this “radical” ahistoric
genotype-conception of heredity in its strict antagonism to the transmission-or
phenotype-view (Johannsen 1911).
Having distinguished between development and inheritance Johanssen
had no need to interpret the gene in a reductivist-preformationist fashion.
He recommended that the genotype be understood along the lines of
the German term Reaktionsnormen used by Woltereck to refer to the full
range of an organism’s potential (1911). The phenotype of an organism
for Johannsen is the product of the whole genotype reacting to the environmental
conditions of its development. Phenotypes can be seen to vary
along a continuum because the Reakionnormen of the genotype are
capable of plastically adapting to variant conditions. Genotypes vary discretely,
but the consequences on phenotype are realized at the level of
the Reaktionnormen as a whole:
Hence the talk of the “genes for any particular character” ought to be omitted,
even in cases where no danger of confusion seems to exist. So, as to the classical
cases of peas, it is not correct to speak of the gene—or genes—for “yellow”
in the cotyledons or for their “wrinkles,”—yellow color and wrinkled shape
being only reactions of factors that may have many other effects in the pea-plants
(Johannsen 1911).
From Cytoplasmic Anlagen to Morgan’s Conversion
Johannsen clarified the conceptual basis for an independent science of
genetics, but it was T. H. Morgan who turned it into an actual research
program. Morgan, unlike the founders of modern Mendelism, was not
a plant breeder or evolutionary naturalist but rather an embryologist.
He was steeped in the controversies introduced in previous sections
(“Chopping up the Anlagen” and “A Bifurcation in Embryology”) pertaining
to how the potential of the organism is distributed between
nucleus and cytoplasm and between egg cell and progeny cells. The fact
that the course of this history does not lead in a logically compelled or
conclusive way to the gene-centered paradigm is what makes it interesting
and important. Embryology did not culminate in genetics—rather,
Morgan converted to the practice of the new discipline, leaving the unre-