4
JANE Μ. OPPENHEIMER
measured in years is not the only factor involved in the acquisition of
historical perspective.
The choice of Pander and Haeckel for examples has not been haphazard. These investigators are appropriate as illustrations since they
can be said, in a qualified simplification, to have represented in a way
the beginning and the end of the development of the germ layer theory
that dominated the embryology of the 19th century: Pander the beginning, since he first put on a sound observational basis what Wolff had
extracted from natural philosophy; Haeckel the end, since he stretched
what had been observed by his time into a theoretical framework so taut
that whatever tenuous relations might otherwise have been maintained
between the germ layer concept and biological reality were severed as a
result of its artificial overextension.
If maintaining an attitude of reverence for the germ layers seems to
us from our vantage point to represent a prevailing intellectual habit of
a majority of 19th century embryologists, what often appears to us to
exemplify the equivalent frame of mind at the turn of the century is the
outlook which characterized the investigators who followed soon after
Haeckel—Roux, Driesch, Herbst, Boveri, O. Hertwig, Spemann, and
Harrison; and we often say glibly of these, that they modernized embryology by making it experimental. The implication is thus very frequently drawn that the embryology characteristic of the 19th century was
static, as contrasted with the more dynamic developmental physiology
of the 20th. There is a strong fallacy in this argument which ignores
the very evident facts that Pander and von Baer were just as profoundly
concerned with change as we are today, and that those later 19th century
investigators who patiently developed the germ layer theory had themselves a broad general background and a consequent wide variety of
embryological interests. The customary and frequent opposition of 19th
century embryology as morphological to that of the 20th century as experimental is further misleading in that it accentuates the use of the
experimental method as an end in itself rather than as an adjunct to the
descriptive method which deals with the more obvious embryonic
features. It confuses the content of what was studied with the manner
of its studying, and quite obscures what may well prove to be a much
more incisive distinction between the exertions of this science as carried
out before and after the turn of the century.
First to concentrate briefly on method, it might to some persons seem
a closer approximation to accuracy to generalize that the methods of the
19th century were descriptive, while those of the 20th are analytical, and
that a difference between the 19th century and the 20th may be that the
JANE Μ. OPPENHEIMER
measured in years is not the only factor involved in the acquisition of
historical perspective.
The choice of Pander and Haeckel for examples has not been haphazard. These investigators are appropriate as illustrations since they
can be said, in a qualified simplification, to have represented in a way
the beginning and the end of the development of the germ layer theory
that dominated the embryology of the 19th century: Pander the beginning, since he first put on a sound observational basis what Wolff had
extracted from natural philosophy; Haeckel the end, since he stretched
what had been observed by his time into a theoretical framework so taut
that whatever tenuous relations might otherwise have been maintained
between the germ layer concept and biological reality were severed as a
result of its artificial overextension.
If maintaining an attitude of reverence for the germ layers seems to
us from our vantage point to represent a prevailing intellectual habit of
a majority of 19th century embryologists, what often appears to us to
exemplify the equivalent frame of mind at the turn of the century is the
outlook which characterized the investigators who followed soon after
Haeckel—Roux, Driesch, Herbst, Boveri, O. Hertwig, Spemann, and
Harrison; and we often say glibly of these, that they modernized embryology by making it experimental. The implication is thus very frequently drawn that the embryology characteristic of the 19th century was
static, as contrasted with the more dynamic developmental physiology
of the 20th. There is a strong fallacy in this argument which ignores
the very evident facts that Pander and von Baer were just as profoundly
concerned with change as we are today, and that those later 19th century
investigators who patiently developed the germ layer theory had themselves a broad general background and a consequent wide variety of
embryological interests. The customary and frequent opposition of 19th
century embryology as morphological to that of the 20th century as experimental is further misleading in that it accentuates the use of the
experimental method as an end in itself rather than as an adjunct to the
descriptive method which deals with the more obvious embryonic
features. It confuses the content of what was studied with the manner
of its studying, and quite obscures what may well prove to be a much
more incisive distinction between the exertions of this science as carried
out before and after the turn of the century.
First to concentrate briefly on method, it might to some persons seem
a closer approximation to accuracy to generalize that the methods of the
19th century were descriptive, while those of the 20th are analytical, and
that a difference between the 19th century and the 20th may be that the