32
JANE Μ. OPPENHEIMER
Child's studies on the axial gradients; the Scandinavian studies on polar
gradients in echinoderm eggs; Warburg's respiratory studies on sea
urchin eggs; Harrison's investigations on symmetry; the discovery of abnormal inductors. Considerable additional work which has not been
specifically cited here has similarly been of inestimable influence in this
direction: not least, the publication of Needham's large treatise (1931).
If, however, all of these investigations and others unnamed helped to
move embryology towards its present position, they were able to do so
not only as a result of prior progress in chemistry and biochemistry, but
also—and let it not be forgotten—because the position had been prepared by others who had been strictly embryological in their inclinations.
Roux, while he despaired in some of his moods, mechanist though he
was, of explaining embryological phenomena in molecular terms, at least
recognized this possibility. Herbst first demonstrated the transformability of the germ layers in 1892 by the use of the lithium ion. One of
the subsections of Driesch's (1894) book on development was entitled
Contact Induction (Berührungsinduktion); the section following it was
entitled, Chemical Inductors, with two subsections called, respectively,
Chemical Induction as Growth Regulator and Chemical Induction of
Oriented Movements. Driesch, furthermore, was almost obsessed by the
importance of enzymes, with an interest which once more he may have
acquired from Sachs (Driesch, 1894, p. 44). The first attempt at a
complete chemical and biochemical description of the egg (in this case
that of Ascaris) was made as early as 1913, by Fauré-Fremiet, himself
a microbiologist as well as an embryologist.
In other words, though chemical embryology has certainly of late
fallen under the influence of the discoveries of fundamental mechanisms worked out on nonembryonic material, it has had an illustrious
past all of its own. It might even prove an interesting gambit to explore
to what degree investigation of some of these fundamental biochemical
mechanisms may have been encouraged by the asking of opportune
questions by some of the more progressive embryologists.
What is of course characteristic of the chemical and biochemical
studies is that at the present time, as in fact during all previous periods
when they were utilized at all, molecular explanations have been applied to embryological considerations at every level. Molecular orientation is called upon as explanatory of such fundamental properties of the
whole organism as polarity and symmetry; specificity of organs, of tissues,
of layers, and of cells has been analyzed on a molecular basis, as have
the functions of cell inclusions of all varieties and magnitudes. As a
result, a new concept has arisen during this century as a synthesizing
JANE Μ. OPPENHEIMER
Child's studies on the axial gradients; the Scandinavian studies on polar
gradients in echinoderm eggs; Warburg's respiratory studies on sea
urchin eggs; Harrison's investigations on symmetry; the discovery of abnormal inductors. Considerable additional work which has not been
specifically cited here has similarly been of inestimable influence in this
direction: not least, the publication of Needham's large treatise (1931).
If, however, all of these investigations and others unnamed helped to
move embryology towards its present position, they were able to do so
not only as a result of prior progress in chemistry and biochemistry, but
also—and let it not be forgotten—because the position had been prepared by others who had been strictly embryological in their inclinations.
Roux, while he despaired in some of his moods, mechanist though he
was, of explaining embryological phenomena in molecular terms, at least
recognized this possibility. Herbst first demonstrated the transformability of the germ layers in 1892 by the use of the lithium ion. One of
the subsections of Driesch's (1894) book on development was entitled
Contact Induction (Berührungsinduktion); the section following it was
entitled, Chemical Inductors, with two subsections called, respectively,
Chemical Induction as Growth Regulator and Chemical Induction of
Oriented Movements. Driesch, furthermore, was almost obsessed by the
importance of enzymes, with an interest which once more he may have
acquired from Sachs (Driesch, 1894, p. 44). The first attempt at a
complete chemical and biochemical description of the egg (in this case
that of Ascaris) was made as early as 1913, by Fauré-Fremiet, himself
a microbiologist as well as an embryologist.
In other words, though chemical embryology has certainly of late
fallen under the influence of the discoveries of fundamental mechanisms worked out on nonembryonic material, it has had an illustrious
past all of its own. It might even prove an interesting gambit to explore
to what degree investigation of some of these fundamental biochemical
mechanisms may have been encouraged by the asking of opportune
questions by some of the more progressive embryologists.
What is of course characteristic of the chemical and biochemical
studies is that at the present time, as in fact during all previous periods
when they were utilized at all, molecular explanations have been applied to embryological considerations at every level. Molecular orientation is called upon as explanatory of such fundamental properties of the
whole organism as polarity and symmetry; specificity of organs, of tissues,
of layers, and of cells has been analyzed on a molecular basis, as have
the functions of cell inclusions of all varieties and magnitudes. As a
result, a new concept has arisen during this century as a synthesizing