Biology Reference
In-Depth Information
3
The Schultze tradition
3.1 The duplicity theory of Max Schultze
The first section of Helmholtz's classical 'Handbuch der Physiolo-
gischen Optik' was published in 1856, the second (containing the
Young-Helmholtz trichromatic colour theory) in 1860, the third
partly at the beginning and partly towards the close of 1866, while the
complete work was published in 1867. The Young-Helmholtz colour
theory was, therefore, known to Max Schultze (professor in anatomy
and the director of the Anatomic Institute in Bonn, Germany) when he
published his important work in 1866. Indeed, he accepted its major
assumption that three different cone fibres conveyed independent,
qualitatively different colour-related processes.
Yet, in addition to the cone receptors and their functions,
he introduced the much more numerous rod receptors presuming
that they were responsible for night vision, and that they mediated
achromatic sensation only. This theory of Schultze may be seen
as
the third major paradigm shift in vision research
. It entailed
a profound new insight into visual processing and generated basic
questions about differences and similarities as well as about possible
interactions between the information processing of the two different
receptor systems.
3.2 Evidence in favour of the theory
Schultze's hypothesis that the retina contained two basically different
kinds of receptor was based on extensive, comparative histological
studies. Although he was aware of the fact that the structure of a
receptor type in different species, and even in the same retina, may differ
markedly, he found rods and cones
in general
to differ both with respect
