26
JANE Μ. OPPENHEIMER
related to the whole sequence of allied concepts in chemistry from the
time of the alchemists to that of Berzelius and of those responsible for
contemporary resonance theories. They have however also a rich background in the biological concepts of the late 19th and early 20th century. HaeckeFs motive in dividing siphonophore larvae (1869) was to
verify his hypothesis that amoebae, ontogenetically as well as phylogenetically, aggregate to form these organisms. The tropism theories,
already pointed out as so significant in the development of concepts of
induction by Herbst and Roux and Driesch and Harrison and Spemann,
were essentially mechanistic explanations of selective affinity, whether of
the sunflower for the sun or of the moth for the flame. Born (1897) already in the first communication describing the union of embryonic parts
in the amphibian placed heavy emphasis on the junction of like to
like. Η. V. Wilson, in the first decade of the new century (1907, 1911),
dissociated the cells first of sponges, then of hydroids, by squeezing them
through bolting cloth, and described with consummate accuracy their
selective reaggregation to form new organisms.
The significance of the current studies of affinity however runs far
deeper than that they represent a transition between the past and
present. They also form a new bridge between studies at the supracellular level at one side, and at the subcellular on the other, and thus
also between the present and the future. On the supracellular level they
have led, again through the insight of Holtfreter (Townes and Holtfreter, 1955), to new concepts of the mechanisms responsible for folding
and cavitation, thus relating cells to layers in a new sense of the 20th
rather than the old of the 19th; and on the subcellular, attempts to explain affinities in terms of subcellular constituents are already beginning
to lead towards the explanation of gross morphogenetic phenomena in
terms of demonstrable protein activity [see for instance Spiegel, 1955,
who relates cell-to-cell adhesion to the presence of demonstrated surface
antigens; immunological studies on fertilization (Tyler, 1955); and
various genetic studies of development].
2.
CELLULAR COMPONENTS: MICROSCOPIC AND SUBMICROSCOPIC
Cellular affinity, no matter how analyzed or described, implies either
cellular or subcellular specificity, and it remains to discuss the development of latter day concepts of specificity in development. Specificity
is of course no purely developmental phenomenon, it can fairly be
designated as the key characteristic not only of all embryological but of
all biological systems, as is self-evident from the application of the name
species to the organism as the fundamental biological unit. In one way,
JANE Μ. OPPENHEIMER
related to the whole sequence of allied concepts in chemistry from the
time of the alchemists to that of Berzelius and of those responsible for
contemporary resonance theories. They have however also a rich background in the biological concepts of the late 19th and early 20th century. HaeckeFs motive in dividing siphonophore larvae (1869) was to
verify his hypothesis that amoebae, ontogenetically as well as phylogenetically, aggregate to form these organisms. The tropism theories,
already pointed out as so significant in the development of concepts of
induction by Herbst and Roux and Driesch and Harrison and Spemann,
were essentially mechanistic explanations of selective affinity, whether of
the sunflower for the sun or of the moth for the flame. Born (1897) already in the first communication describing the union of embryonic parts
in the amphibian placed heavy emphasis on the junction of like to
like. Η. V. Wilson, in the first decade of the new century (1907, 1911),
dissociated the cells first of sponges, then of hydroids, by squeezing them
through bolting cloth, and described with consummate accuracy their
selective reaggregation to form new organisms.
The significance of the current studies of affinity however runs far
deeper than that they represent a transition between the past and
present. They also form a new bridge between studies at the supracellular level at one side, and at the subcellular on the other, and thus
also between the present and the future. On the supracellular level they
have led, again through the insight of Holtfreter (Townes and Holtfreter, 1955), to new concepts of the mechanisms responsible for folding
and cavitation, thus relating cells to layers in a new sense of the 20th
rather than the old of the 19th; and on the subcellular, attempts to explain affinities in terms of subcellular constituents are already beginning
to lead towards the explanation of gross morphogenetic phenomena in
terms of demonstrable protein activity [see for instance Spiegel, 1955,
who relates cell-to-cell adhesion to the presence of demonstrated surface
antigens; immunological studies on fertilization (Tyler, 1955); and
various genetic studies of development].
2.
CELLULAR COMPONENTS: MICROSCOPIC AND SUBMICROSCOPIC
Cellular affinity, no matter how analyzed or described, implies either
cellular or subcellular specificity, and it remains to discuss the development of latter day concepts of specificity in development. Specificity
is of course no purely developmental phenomenon, it can fairly be
designated as the key characteristic not only of all embryological but of
all biological systems, as is self-evident from the application of the name
species to the organism as the fundamental biological unit. In one way,