Biology Reference
In-Depth Information
course, essential for an understanding of the adaptation mechanisms
of the rod and cone outer segment channels.
The long developmental history described here is obviously
at odds with the common conception that the duplicity theory is a
static, well-defined theory formulated by Schultze (
1866
). Instead, it
shows that profound changes in the basic presumptions have been
made and that the duplicity theory still is rapidly developing 140
years after Schultze's publication. Actually, we are short of a satisfac-
tory understanding of how rods and cones are involved in
any
of
the major visual functions. This clearly reveals the developmental
potential of the theory: since all visual processes are triggered by
phototransduction in rods and cones, there will be no end to the
developmental history of the duplicity theory until we know, with
regard to all major visual functions, the differences and similarities
between the rod and cone processing, and also when and how the rod
and cone systems interact.
