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GEORGE SZÉKELY
were again superseded by the sweeping generalizations of a new overall
concept: that of the establishment of connections by neurons on the basis
of a refined system of biochemical specificities. The first observations
leading to such views were initially made by Weiss (1924), but were
not immediately brought into relation with the question of the establishment of interneuronal connections. The observation that supernumerary
limb transplanted into the shoulder region would act in timing and
movement pattern exactly as the normal forelimb was originally described as a function of "resonance." This term probably had a more
descriptive meaning to indicate that impulse patterns "addressed" to a
muscle would reach it in spite of gross disarrangement of its connections.
The fundamental observations of Sperry (1944) on the regeneration
of the optic nerve, and the development of reversed visual fields in case
of reversed eye, brought the question of establishment of neuronal connections during development and regeneration into focus again. It would
be difficult to explain this result other than by assuming that certain
specific local properties of retinal neurons establish functionally effective
connections only with tectal neurons of corresponding local specificities.
It was almost a logical necessity—once the phenomenon was established
—to generalize the concept first to the further connections between the
optic lobe and lower motor centers (Sperry, 1948) and then into an
overall principle governing the selection of interneuronal connections at
large (Sperry, 1951, 1955, 1963). The observation that such local specificities of neurons are established during embryonic development, much
earlier than the growth of nerve fibers peripherally begins (Stone, 1948;
Székely, 1954), was only welcome additional proof of specific characters
already imprinted on the early neuroblast by its location. The concept
has developed further in consequence of an impressive body of evidence
collected mainly by Sperry (1951, 1955) and various collaborators
(Sperry and Miner, 1949; Miner, 1951; Arora and Sperry, 1962; Attardi
and Sperry, 1963), as well as by other authors (Weiss, 1941, 1942;
Weiss and Ruch, 1936; Kollros, 1943; Guth and Bernstein, 1961), on the
importance of the specific locus of termination of primary sensory
neurons for the kinds and modes of synaptic articulations they establish
in the centers. However, the concept attained its final degree of sophistication by incorporation of the original observation of Weiss (1924) on
the so-called "myotypic responses" into the framework of the specificity
hypothesis. Assuming that nerve sprouts from the shoulder girdle nerves
would grow into the implanted supernumerary limb at random, one had
only to suppose that any motor fiber that has by chance reached a
muscle would be imprinted by some specific and presumably biochemical
character of this muscle. Thus, the specific character of this motoneuron
GEORGE SZÉKELY
were again superseded by the sweeping generalizations of a new overall
concept: that of the establishment of connections by neurons on the basis
of a refined system of biochemical specificities. The first observations
leading to such views were initially made by Weiss (1924), but were
not immediately brought into relation with the question of the establishment of interneuronal connections. The observation that supernumerary
limb transplanted into the shoulder region would act in timing and
movement pattern exactly as the normal forelimb was originally described as a function of "resonance." This term probably had a more
descriptive meaning to indicate that impulse patterns "addressed" to a
muscle would reach it in spite of gross disarrangement of its connections.
The fundamental observations of Sperry (1944) on the regeneration
of the optic nerve, and the development of reversed visual fields in case
of reversed eye, brought the question of establishment of neuronal connections during development and regeneration into focus again. It would
be difficult to explain this result other than by assuming that certain
specific local properties of retinal neurons establish functionally effective
connections only with tectal neurons of corresponding local specificities.
It was almost a logical necessity—once the phenomenon was established
—to generalize the concept first to the further connections between the
optic lobe and lower motor centers (Sperry, 1948) and then into an
overall principle governing the selection of interneuronal connections at
large (Sperry, 1951, 1955, 1963). The observation that such local specificities of neurons are established during embryonic development, much
earlier than the growth of nerve fibers peripherally begins (Stone, 1948;
Székely, 1954), was only welcome additional proof of specific characters
already imprinted on the early neuroblast by its location. The concept
has developed further in consequence of an impressive body of evidence
collected mainly by Sperry (1951, 1955) and various collaborators
(Sperry and Miner, 1949; Miner, 1951; Arora and Sperry, 1962; Attardi
and Sperry, 1963), as well as by other authors (Weiss, 1941, 1942;
Weiss and Ruch, 1936; Kollros, 1943; Guth and Bernstein, 1961), on the
importance of the specific locus of termination of primary sensory
neurons for the kinds and modes of synaptic articulations they establish
in the centers. However, the concept attained its final degree of sophistication by incorporation of the original observation of Weiss (1924) on
the so-called "myotypic responses" into the framework of the specificity
hypothesis. Assuming that nerve sprouts from the shoulder girdle nerves
would grow into the implanted supernumerary limb at random, one had
only to suppose that any motor fiber that has by chance reached a
muscle would be imprinted by some specific and presumably biochemical
character of this muscle. Thus, the specific character of this motoneuron