24
JANE Μ. OPPENHEIMER
weight of the dead hand of the past. It is still true, as Harrison is not
the only one to have pointed out, that the cell remains a natural unit
for the embryo. To continue with one of the examples utilized in the
previous section, Vogt, to repeat what has been said of him above, interpreted morphogenetic movements in terms of groups of cells. Holtfreter has enabled separate cells to reveal their independence and individuality of movement; in fact, it is only in the light of the considerable autonomy of the individual cells that the role of the surface coat in organizing their activities becomes so dramatic. The significance of the cell for
20th century embryology is that, while it maintains all the dignity as the
structural unit which the 19th century bestowed upon it (and indeed,
paradoxically enough, in the mid-20th century this is being enhanced
rather than otherwise as a result of the application of phase and especially electron microscopy to embryological material; see for instance
Porter, 1954), it has also acquired fresh merit as a functional unit, functioning as a unit rather than as the sum of its various inclusions.
Investigation of its activities at this functional level is one of the popular fashions of the midcentury, of which the work of Holtfreter represents only a single aspect. That of Niu (1956), which purports to
analyze induction as a cell-to-cell rather than a layer-to-layer relationship, is another; and all of the studies which exploit disaggregation as an
embryological tool (Moscona and Moscona, 1952; Weiss and Andres,
1952; Grobstein, 1954, 1955) offer tacit admission of the supremacy of the
cell over the simple cell aggregate as a primary unit of developmental
function, insofar as aggregation is accomplished by the selective migration of individual cells.
However, even these studies are not an exclusive product of the middle
of the 20th century. The very flask cells whose activity Holtfreter
(1943b) has demonstrated as so vital in the transformations of the amphibian gastrula were the subject of a great monograph published over
25 years ago (Ruffini, 1925), and indeed were most vividly described in
action for the gastrulating frog's egg in 1900 by Η. V. Wilson (who was
also, by the way, the first to study systematically the selective recongregation of disaggregated cells in the modern sense, see p. 26). Notions
of cellular autonomy date back at least as far as to Virchow (see J. W.
Wilson, 1947b), whose influence on later recognition of the cell as a
dynamic independent entity is usually most unjustly underestimated by
biologists of whatever stamp. The studies on cell lineage so popular
around the turn of the century implied an interest in cellular autonomy,
though in the minds of the wise, such as Ε. B. Wilson (1892, 1899) and
Conklin (1897, 1905), the whole was never forgotten for the part. And
JANE Μ. OPPENHEIMER
weight of the dead hand of the past. It is still true, as Harrison is not
the only one to have pointed out, that the cell remains a natural unit
for the embryo. To continue with one of the examples utilized in the
previous section, Vogt, to repeat what has been said of him above, interpreted morphogenetic movements in terms of groups of cells. Holtfreter has enabled separate cells to reveal their independence and individuality of movement; in fact, it is only in the light of the considerable autonomy of the individual cells that the role of the surface coat in organizing their activities becomes so dramatic. The significance of the cell for
20th century embryology is that, while it maintains all the dignity as the
structural unit which the 19th century bestowed upon it (and indeed,
paradoxically enough, in the mid-20th century this is being enhanced
rather than otherwise as a result of the application of phase and especially electron microscopy to embryological material; see for instance
Porter, 1954), it has also acquired fresh merit as a functional unit, functioning as a unit rather than as the sum of its various inclusions.
Investigation of its activities at this functional level is one of the popular fashions of the midcentury, of which the work of Holtfreter represents only a single aspect. That of Niu (1956), which purports to
analyze induction as a cell-to-cell rather than a layer-to-layer relationship, is another; and all of the studies which exploit disaggregation as an
embryological tool (Moscona and Moscona, 1952; Weiss and Andres,
1952; Grobstein, 1954, 1955) offer tacit admission of the supremacy of the
cell over the simple cell aggregate as a primary unit of developmental
function, insofar as aggregation is accomplished by the selective migration of individual cells.
However, even these studies are not an exclusive product of the middle
of the 20th century. The very flask cells whose activity Holtfreter
(1943b) has demonstrated as so vital in the transformations of the amphibian gastrula were the subject of a great monograph published over
25 years ago (Ruffini, 1925), and indeed were most vividly described in
action for the gastrulating frog's egg in 1900 by Η. V. Wilson (who was
also, by the way, the first to study systematically the selective recongregation of disaggregated cells in the modern sense, see p. 26). Notions
of cellular autonomy date back at least as far as to Virchow (see J. W.
Wilson, 1947b), whose influence on later recognition of the cell as a
dynamic independent entity is usually most unjustly underestimated by
biologists of whatever stamp. The studies on cell lineage so popular
around the turn of the century implied an interest in cellular autonomy,
though in the minds of the wise, such as Ε. B. Wilson (1892, 1899) and
Conklin (1897, 1905), the whole was never forgotten for the part. And