18
V A N C E T A R T A R
bands in the patches and by the fact that the mass continues to contract
on stimulation and to swim in random fashion, showing that cilia and
contractile elements remain intact. Very promptly an adhesive tail pole
emerges from a patch whose tapering pigmented bands identify it as a
portion from the original posterior end. The projecting holdfast may
be surrounded by other patches in complete disarrangement. But the
patches then gradually reorient themselves with their stripes running
parallel and homopolar, and as they realign the stripes join together in
continuous runs, provided that the spacing or pigment bands are of
about the same width. Eventually a sufficiently large area of fine
striping will thus be formed, adjacent to organized or still disorganized
wide-striping. Conditions for primordium induction are thereby obtained and an anläge appears in the fine stripes (Fig. lOd). Further
reconstitution consists only in the development of the oral primordium
and the progressive realignment and rejoining of stripe patches. Any
parts which fail to fit into the normal pattern are eventually resorbed
(Tartar, 1960b).
This is a rather astonishing performance and we naturally wonder
what may be the nature of the guidance by which it is accomplished. It
seems surprising that the minced Stentor does not dedifferentiate its
structure and start afresh. It is quite capable of resorbing ectoplasmic
structures, as we have seen. It may be that a mincerate retains its
striping, however jumbled, because this is the sole basis of reconstitution. Although the patches heal together quite securely, they do shift
and reorient with respect to each other. Retaining their intrinsic polarity, this orientation becomes parallel and homopolar, after which the
stripes of adjacent patches achieve intimate reconnection and form continuous lines. There is no evidence of an imposed axis which reorientates
all the patches like a magnet, and the action of an external field is ruled
out by the continuous rotation of the specimen. Rather, the impression
is of a gradual resolution of the problem by the patches themselves
which in their reorientation gradually come to settle upon a single polar
axis. I t is noteworthy that pedal and oral regeneration occur promptly
and within the normal time, long before any general harmony of stripe
pattern is achieved, requiring only the local conditions appropriate
thereto, namely, posterior stripe ends in the case of the holdfast and a
locus of stripe width contrast for the oral primordium.
V I I I . Nucleocytoplasmic Interaction
A. Cytoplasmic Differentiation without Nuclear Differentiation
The Stentor macronucleus may be briefly referred to as the nucleus,
for the reason already given. Like the nuclei of dipterous salivary gland
V A N C E T A R T A R
bands in the patches and by the fact that the mass continues to contract
on stimulation and to swim in random fashion, showing that cilia and
contractile elements remain intact. Very promptly an adhesive tail pole
emerges from a patch whose tapering pigmented bands identify it as a
portion from the original posterior end. The projecting holdfast may
be surrounded by other patches in complete disarrangement. But the
patches then gradually reorient themselves with their stripes running
parallel and homopolar, and as they realign the stripes join together in
continuous runs, provided that the spacing or pigment bands are of
about the same width. Eventually a sufficiently large area of fine
striping will thus be formed, adjacent to organized or still disorganized
wide-striping. Conditions for primordium induction are thereby obtained and an anläge appears in the fine stripes (Fig. lOd). Further
reconstitution consists only in the development of the oral primordium
and the progressive realignment and rejoining of stripe patches. Any
parts which fail to fit into the normal pattern are eventually resorbed
(Tartar, 1960b).
This is a rather astonishing performance and we naturally wonder
what may be the nature of the guidance by which it is accomplished. It
seems surprising that the minced Stentor does not dedifferentiate its
structure and start afresh. It is quite capable of resorbing ectoplasmic
structures, as we have seen. It may be that a mincerate retains its
striping, however jumbled, because this is the sole basis of reconstitution. Although the patches heal together quite securely, they do shift
and reorient with respect to each other. Retaining their intrinsic polarity, this orientation becomes parallel and homopolar, after which the
stripes of adjacent patches achieve intimate reconnection and form continuous lines. There is no evidence of an imposed axis which reorientates
all the patches like a magnet, and the action of an external field is ruled
out by the continuous rotation of the specimen. Rather, the impression
is of a gradual resolution of the problem by the patches themselves
which in their reorientation gradually come to settle upon a single polar
axis. I t is noteworthy that pedal and oral regeneration occur promptly
and within the normal time, long before any general harmony of stripe
pattern is achieved, requiring only the local conditions appropriate
thereto, namely, posterior stripe ends in the case of the holdfast and a
locus of stripe width contrast for the oral primordium.
V I I I . Nucleocytoplasmic Interaction
A. Cytoplasmic Differentiation without Nuclear Differentiation
The Stentor macronucleus may be briefly referred to as the nucleus,
for the reason already given. Like the nuclei of dipterous salivary gland