138
LUISE STANGE
sion in other cells and can eventually divert them to special development and function (rhizoids). The differences between the cells of an
isolated tissue may vary in size in respect to the prerequisites for
division. The extreme case would be the presence of quiescent embryonic
cells, like the already mentioned case of protonema-initials in some
mosses (cf. Bopp, 1955).
C. The Nature of Correlations in Differentiation
I t has been known since the early investigations of Vöchting (1885),
Goebel (1902), Linsbauer (1926) and others that regeneration of
permanent cells becomes possible when these cells are separated in
some way from the meristematic centre(s) of the plant. In the intact
plant the cellular continuity between meristematic and permanent cells
inhibits the embryonic functions in the latter cells.
There is general agreement that, in experiments with lower plants,
wounding without interruption of the correlations between the apical
meristem and mature cells does not cause regeneration (e.g. IsaburoNagai, 1914; Heitz, 1925; Linsbauer, 1926; Albaum, 1938b). Meyer
(1953) cut fern prothallia lengthwise into three parts of equal size, the
central one bearing the apical cell. This part, although bearing two
wound surfaces, continued its apical growth without any sign of regeneration. Only the two lateral pieces produced several new apical
cells. Bopp (1955) divided leaves of Funaria into halves both parallel
and at right angles to the longitudinal axis. While the right and the left
halves together formed as many regenerates as whole isolated leaves,
the distal and proximal halves together produced about 50% more
regenerates. This increase could not have been caused by the wound
but must have been due to interruption of correlations between the cells
within the leaf. Similarly, in experiments with Splachnum (Table V)
leaves were cut into halves at right angles to the longitudinal axis and
then isolated from or left attached to the plant (MacQuarrie and von
Maltzahn, 1959). The half leaves attached to the plant did not form
regenerates in spite of their large wound surface. In Riella it is possible,
as shown in Fig. 7, to incise the wing without inducing regeneration, if
the cut follows a distinct angle to the rib and does not interrupt directional relations between the cells (Stange, 1957). In all these cases,
regeneration is caused by interruption of correlations between growing
and non-growing parts of the plants.
Different opinions exist about the nature of these correlations between growing and non-growing parts. In general two possibilities are
recognized. (1) In the continuity of the whole plant the permanent cells
have to carry out special functions for the growing parts, probably the
production of substances required by the growing cells. After isolation
LUISE STANGE
sion in other cells and can eventually divert them to special development and function (rhizoids). The differences between the cells of an
isolated tissue may vary in size in respect to the prerequisites for
division. The extreme case would be the presence of quiescent embryonic
cells, like the already mentioned case of protonema-initials in some
mosses (cf. Bopp, 1955).
C. The Nature of Correlations in Differentiation
I t has been known since the early investigations of Vöchting (1885),
Goebel (1902), Linsbauer (1926) and others that regeneration of
permanent cells becomes possible when these cells are separated in
some way from the meristematic centre(s) of the plant. In the intact
plant the cellular continuity between meristematic and permanent cells
inhibits the embryonic functions in the latter cells.
There is general agreement that, in experiments with lower plants,
wounding without interruption of the correlations between the apical
meristem and mature cells does not cause regeneration (e.g. IsaburoNagai, 1914; Heitz, 1925; Linsbauer, 1926; Albaum, 1938b). Meyer
(1953) cut fern prothallia lengthwise into three parts of equal size, the
central one bearing the apical cell. This part, although bearing two
wound surfaces, continued its apical growth without any sign of regeneration. Only the two lateral pieces produced several new apical
cells. Bopp (1955) divided leaves of Funaria into halves both parallel
and at right angles to the longitudinal axis. While the right and the left
halves together formed as many regenerates as whole isolated leaves,
the distal and proximal halves together produced about 50% more
regenerates. This increase could not have been caused by the wound
but must have been due to interruption of correlations between the cells
within the leaf. Similarly, in experiments with Splachnum (Table V)
leaves were cut into halves at right angles to the longitudinal axis and
then isolated from or left attached to the plant (MacQuarrie and von
Maltzahn, 1959). The half leaves attached to the plant did not form
regenerates in spite of their large wound surface. In Riella it is possible,
as shown in Fig. 7, to incise the wing without inducing regeneration, if
the cut follows a distinct angle to the rib and does not interrupt directional relations between the cells (Stange, 1957). In all these cases,
regeneration is caused by interruption of correlations between growing
and non-growing parts of the plants.
Different opinions exist about the nature of these correlations between growing and non-growing parts. In general two possibilities are
recognized. (1) In the continuity of the whole plant the permanent cells
have to carry out special functions for the growing parts, probably the
production of substances required by the growing cells. After isolation