TWENTIETH CENTURY EMBRYOLOGICAL CONCEPTS
33
concept for coordination of all embryological explanation: the Unity of
Biochemistry of the 20th century supplants the Unity of Descent of the
19th century and the Unity of Type of the 18th as a synthesizing scheme.
It purports to explain in different terms than these that unity in diversity
which is the primary distinguishing feature of the developing embryo,
a unity no longer now being accounted for by an Urbild in the mind of
nature, or merely by common ancestry, but rather by the ubiquity of
action of ATP or DNA. The century which began its efforts by diversification has reached its turning point by attempting again to construct
a centralizing doctrine, this time on a chemical basis.
This is a synthesizing scheme insofar as it is single and emphasizes
singleness, in a manner which would have appealed to an 18th century
Naturphilosoph
or a 19th century Haeckelian. Whether if it is not false,
it is truly synthetic, or simply analytic after all; whether it explains, or
merely describes, only what is made of it during the final half of the 20th
century will reveal. If actually it remains but analytical, which is a
patent possibility, at least it describes more quantitatively and in richer
precision than before some of the mechanisms whereby progressive differentiation manifests itself, bringing this principle closer to the point
where truly synthetic investigations can begin.
V. SOME CONCLUDING FANCIES
There are no conclusions in the accepted sense to be drawn from the
foregoing. Only a few arbitrarily chosen aspects of embryological investigation have been selected for comment, those which have happened
to appeal subjectively to a most subjective critic either for their apparent
relationships to the past, or their seeming potentialities for the future.
Such is the waywardness of the course of that will-of-the-wisp, scientific
progress, that its future path is unpredictable,
"Und wenn ein Irrlicht Euch die Wege weisen soll,
So müsst Ihr's so genau nicht nehmen."
But if there is to be no formal epilogue, a few random and fragmentary
concluding notes may be appended.
An article preliminary to this one (Oppenheimer, 1955a) rather
labored the possibility that the development of embryological concepts
up into the 19th century could be characterized by a gradual
transition from metaphysical towards physical interpretations. The
question then arises, has the threshold of the metaphysical in embryology
continued to recede during the present century? This is not so easy to
answer as it might seem. When Lillie, for instance, at the beginning of
33
concept for coordination of all embryological explanation: the Unity of
Biochemistry of the 20th century supplants the Unity of Descent of the
19th century and the Unity of Type of the 18th as a synthesizing scheme.
It purports to explain in different terms than these that unity in diversity
which is the primary distinguishing feature of the developing embryo,
a unity no longer now being accounted for by an Urbild in the mind of
nature, or merely by common ancestry, but rather by the ubiquity of
action of ATP or DNA. The century which began its efforts by diversification has reached its turning point by attempting again to construct
a centralizing doctrine, this time on a chemical basis.
This is a synthesizing scheme insofar as it is single and emphasizes
singleness, in a manner which would have appealed to an 18th century
Naturphilosoph
or a 19th century Haeckelian. Whether if it is not false,
it is truly synthetic, or simply analytic after all; whether it explains, or
merely describes, only what is made of it during the final half of the 20th
century will reveal. If actually it remains but analytical, which is a
patent possibility, at least it describes more quantitatively and in richer
precision than before some of the mechanisms whereby progressive differentiation manifests itself, bringing this principle closer to the point
where truly synthetic investigations can begin.
V. SOME CONCLUDING FANCIES
There are no conclusions in the accepted sense to be drawn from the
foregoing. Only a few arbitrarily chosen aspects of embryological investigation have been selected for comment, those which have happened
to appeal subjectively to a most subjective critic either for their apparent
relationships to the past, or their seeming potentialities for the future.
Such is the waywardness of the course of that will-of-the-wisp, scientific
progress, that its future path is unpredictable,
"Und wenn ein Irrlicht Euch die Wege weisen soll,
So müsst Ihr's so genau nicht nehmen."
But if there is to be no formal epilogue, a few random and fragmentary
concluding notes may be appended.
An article preliminary to this one (Oppenheimer, 1955a) rather
labored the possibility that the development of embryological concepts
up into the 19th century could be characterized by a gradual
transition from metaphysical towards physical interpretations. The
question then arises, has the threshold of the metaphysical in embryology
continued to recede during the present century? This is not so easy to
answer as it might seem. When Lillie, for instance, at the beginning of