14
VANCE TARTAR
other Metazoa (Rose, 1957; Tardent, 1960). As Weisz (1956) remarked,
in division, when an oral primordium is formed in spite of the presence
of intact feeding organelles (and the same would be true of reorganizers),
the cell would in some way have to escape the inhibitive influence normally exerted by the feeding organelles.
Conversely, activation of Stentor to primordium formation may bear
a significant resemblance to activation of the egg to development by
fertilization. In both cases there is a pervasive change of state of a cell
resulting in epigenetic elaborations. The analogy becomes more than
specious if we compare Stentor with a remarkable case of the egg developing without cleavage. In 1906 Lillie (see also Pasteels, 1934) reported
that if eggs of the marine worm Chaetopterus are briefly treated with
KC1 many can develop into 'larvae' similar to the normal even though
neither normal mitosis nor cytosomal division occurs; an elaboration of
cilia is an important part of this development (Fig. 11).
V I . Upper and Lower Limits to Size of Organizational Mass
A. Lower Limits
One of the most obvious features of morphogenesis is that the form
of an organism is largely independent of absolute size. From Protozoa
to man, dwarf and giant types can be produced by a variety of means,
embryological, nutritional, genetic and hormonal. Apart from striking
cases of allometric growth, normal growth does not markedly alter the
form, and in any case the basic 'Bauplan' remains unaltered. That the
same form can be expressed in a wide range of sizes, often far exceeding
the normal range of the species, doubtless has an important implication
which will some day be revealed. For a beginning, Woodger (1929) suggested that if the organizing relationships between the parts of an organism are geometric, these relationships could remain the same over a
wide size range just as one can have similar triangles of any size. The
well-known principle of embryology, that the fate of apart depends upon
its position with reference to the whole, is presumptive evidence that the
organizing relationships are geometric. However that may be, the typical
form of Stentor is also manifested in a wide range of sizes.
Long ago Lillie (1896) obtained complete regeneration in fragments of
S. coeruleus only ^ the
s i
z e °f large, normal animals and no smaller.
Thinking this to be of considerable theoretical importance he postulated
that there is a 'minimal organization mass', of absolute value for any
given species, below which the form of the organism cannot be realized.
However, Morgan (1901) soon obtained Stentor regenerants from pieces
no larger than ^ the size of the largest normal animals and he supposed
that the reason smaller fragments do not regenerate a perfect form is
VANCE TARTAR
other Metazoa (Rose, 1957; Tardent, 1960). As Weisz (1956) remarked,
in division, when an oral primordium is formed in spite of the presence
of intact feeding organelles (and the same would be true of reorganizers),
the cell would in some way have to escape the inhibitive influence normally exerted by the feeding organelles.
Conversely, activation of Stentor to primordium formation may bear
a significant resemblance to activation of the egg to development by
fertilization. In both cases there is a pervasive change of state of a cell
resulting in epigenetic elaborations. The analogy becomes more than
specious if we compare Stentor with a remarkable case of the egg developing without cleavage. In 1906 Lillie (see also Pasteels, 1934) reported
that if eggs of the marine worm Chaetopterus are briefly treated with
KC1 many can develop into 'larvae' similar to the normal even though
neither normal mitosis nor cytosomal division occurs; an elaboration of
cilia is an important part of this development (Fig. 11).
V I . Upper and Lower Limits to Size of Organizational Mass
A. Lower Limits
One of the most obvious features of morphogenesis is that the form
of an organism is largely independent of absolute size. From Protozoa
to man, dwarf and giant types can be produced by a variety of means,
embryological, nutritional, genetic and hormonal. Apart from striking
cases of allometric growth, normal growth does not markedly alter the
form, and in any case the basic 'Bauplan' remains unaltered. That the
same form can be expressed in a wide range of sizes, often far exceeding
the normal range of the species, doubtless has an important implication
which will some day be revealed. For a beginning, Woodger (1929) suggested that if the organizing relationships between the parts of an organism are geometric, these relationships could remain the same over a
wide size range just as one can have similar triangles of any size. The
well-known principle of embryology, that the fate of apart depends upon
its position with reference to the whole, is presumptive evidence that the
organizing relationships are geometric. However that may be, the typical
form of Stentor is also manifested in a wide range of sizes.
Long ago Lillie (1896) obtained complete regeneration in fragments of
S. coeruleus only ^ the
s i
z e °f large, normal animals and no smaller.
Thinking this to be of considerable theoretical importance he postulated
that there is a 'minimal organization mass', of absolute value for any
given species, below which the form of the organism cannot be realized.
However, Morgan (1901) soon obtained Stentor regenerants from pieces
no larger than ^ the size of the largest normal animals and he supposed
that the reason smaller fragments do not regenerate a perfect form is