6
JANE Μ. OPPENHEIMER
they differed little from their predecessors of the 19th century or of all
the centuries since Aristotle. The great difference became that their
questions were more eclectic and thus provided a strong revitalizing
impulse towards the production of new ideas, for the solution of which
they invented transitory not permanent technical approaches. What
does a blastomere do in the absence of its sisters? How does an embryo
develop when you cut off its tail? What happens when you shake an
egg to pieces? or if you cut away some of its protoplasm? or if you
whirl it around or turn it upside down? or if you put it into a solution
as improbable of developmental significance as lithium? It was a hallmark of the work of the turn of the century that when the new experimental method was turned toward devising a crucial experiment, the
question to be answered was one that had been framed earlier by older
and other methods (e.g. Harrison's introduction in 1907 of the tissue
culture technique to verify a former hypothesis that the neuroblast is the
source of the outgrowing axone); otherwise the inquiries were at the
start to a considerable degree undirected.
Roux himself, to be sure, might not have concurred with this interpretation, and it is not to be denied that he and others of his time were
men of ideas. Great volumes of theoretical discussion poured from his
own pen and from that of Driesch, and Roux as well as Driesch eventually abandoned actual experimentation in favor of theorizing. But
while the Roux-Weismann theory, for instance, stimulated considerable
attention to the possibilities of its experimental confirmation or invalidation, this theory never matched the intellectual dominance attained by
the germ layer theory before it, and it remained a proclivity of a majority
of the early experimentalists that they were men of many ideas and not
just a single one. And even when the contemporaries and immediate
followers of Roux and Driesch started their experiments out of theoretical considerations, it is quite possible that they often forgot their ideas
in their joy at being able at last to play with the embryo as they would.
No one who has ever operated on a living embryo can ever believe but
that when the early experimentalists carried out their manipulations they
did so in large part because of their sheer pleasure in doing so. Whatever their motivation, it can hardly have worked to the detriment of
embryology that they diversified their interests instead of concentrating
them, since thereby they opened the many new avenues of investigation
whose divergence characterizes the entrance to the modern scene.
The fact remains, however, that the generalization of the early experimental results on a profound theoretical level had to await the passage
of approximately a third of the 20th century. Spemann's (1936, 1938)
JANE Μ. OPPENHEIMER
they differed little from their predecessors of the 19th century or of all
the centuries since Aristotle. The great difference became that their
questions were more eclectic and thus provided a strong revitalizing
impulse towards the production of new ideas, for the solution of which
they invented transitory not permanent technical approaches. What
does a blastomere do in the absence of its sisters? How does an embryo
develop when you cut off its tail? What happens when you shake an
egg to pieces? or if you cut away some of its protoplasm? or if you
whirl it around or turn it upside down? or if you put it into a solution
as improbable of developmental significance as lithium? It was a hallmark of the work of the turn of the century that when the new experimental method was turned toward devising a crucial experiment, the
question to be answered was one that had been framed earlier by older
and other methods (e.g. Harrison's introduction in 1907 of the tissue
culture technique to verify a former hypothesis that the neuroblast is the
source of the outgrowing axone); otherwise the inquiries were at the
start to a considerable degree undirected.
Roux himself, to be sure, might not have concurred with this interpretation, and it is not to be denied that he and others of his time were
men of ideas. Great volumes of theoretical discussion poured from his
own pen and from that of Driesch, and Roux as well as Driesch eventually abandoned actual experimentation in favor of theorizing. But
while the Roux-Weismann theory, for instance, stimulated considerable
attention to the possibilities of its experimental confirmation or invalidation, this theory never matched the intellectual dominance attained by
the germ layer theory before it, and it remained a proclivity of a majority
of the early experimentalists that they were men of many ideas and not
just a single one. And even when the contemporaries and immediate
followers of Roux and Driesch started their experiments out of theoretical considerations, it is quite possible that they often forgot their ideas
in their joy at being able at last to play with the embryo as they would.
No one who has ever operated on a living embryo can ever believe but
that when the early experimentalists carried out their manipulations they
did so in large part because of their sheer pleasure in doing so. Whatever their motivation, it can hardly have worked to the detriment of
embryology that they diversified their interests instead of concentrating
them, since thereby they opened the many new avenues of investigation
whose divergence characterizes the entrance to the modern scene.
The fact remains, however, that the generalization of the early experimental results on a profound theoretical level had to await the passage
of approximately a third of the 20th century. Spemann's (1936, 1938)