134
LUISE STANGE
cells of the leaf is also reported for Polytrichum attenuatum (Bopp, 1961).
Heitz (1925 ; cf. also Correns, 1899) has pointed out that in many mosses
initials for protonema regeneration are present. They can be recognized
by their smaller chloroplasts and larger nucleus and especially nucleolus.
Heitz termed these cells 'enlarged embryonic cells'. In such cases we are
dealing with reactivation of quiescent embryonic cells.
In the cases of Funaria (Bopp, 1955), Splachnum (von Maltzahn and
MacNutt, 1958) and Atrichum (Gemell, 1953) it could be shown that
isolation of the distal, middle and proximal regions of the leaf from each
other led to the appearance or augmentation of protonematal regenerates
in those parts of the leaf which participated less intensely or not at all in
regeneration in the whole leaf (e.g. Table IV). From these results it can
TABLE IV
Funaria hygrometrica. Distribution of regenerates over the leaf area in whole
and subdivided isolated leaves
Conditions
Area in leaf
Distal
Middle
Proximal
Whole
third
third
third
area
Whole leaf
47
13
0
40
Leaf subdivided into thirds
100
100
94
Percentage of leaves bearing regenerates in the respective area is shown (from
Bopp, 1955).
be concluded that within the whole leaf correlations between cells are
present which inhibit regeneration in cells in special parts of the leaf.
Isolation of parts of the leaf brings about removal of inhibitory influences. Similar inhibitory correlations exist between leaf and stem
cells. When in Splachnum the leaf was still attached to a segment of a
stem, no regeneration from the leaf cells occurred but only from the
stem cells (Table V).
TABLE V
Splachnum ampullaceum. Number of protonemata from isolated stem segments
and leaves under different correlative conditions
Treatment
Stem segment and detached leaf
Stem segment plus one leaf attached
Basal half of leaf isolated
Basal half of leaf attached to plant
No.
from stem
17-5
260
of protonemata
from leaf
420
1-4
37
0
Each datum represents the average of at least 30-40 leaves (from MacQuarrie
and von Maltzahn, 1959).
LUISE STANGE
cells of the leaf is also reported for Polytrichum attenuatum (Bopp, 1961).
Heitz (1925 ; cf. also Correns, 1899) has pointed out that in many mosses
initials for protonema regeneration are present. They can be recognized
by their smaller chloroplasts and larger nucleus and especially nucleolus.
Heitz termed these cells 'enlarged embryonic cells'. In such cases we are
dealing with reactivation of quiescent embryonic cells.
In the cases of Funaria (Bopp, 1955), Splachnum (von Maltzahn and
MacNutt, 1958) and Atrichum (Gemell, 1953) it could be shown that
isolation of the distal, middle and proximal regions of the leaf from each
other led to the appearance or augmentation of protonematal regenerates
in those parts of the leaf which participated less intensely or not at all in
regeneration in the whole leaf (e.g. Table IV). From these results it can
TABLE IV
Funaria hygrometrica. Distribution of regenerates over the leaf area in whole
and subdivided isolated leaves
Conditions
Area in leaf
Distal
Middle
Proximal
Whole
third
third
third
area
Whole leaf
47
13
0
40
Leaf subdivided into thirds
100
100
94
Percentage of leaves bearing regenerates in the respective area is shown (from
Bopp, 1955).
be concluded that within the whole leaf correlations between cells are
present which inhibit regeneration in cells in special parts of the leaf.
Isolation of parts of the leaf brings about removal of inhibitory influences. Similar inhibitory correlations exist between leaf and stem
cells. When in Splachnum the leaf was still attached to a segment of a
stem, no regeneration from the leaf cells occurred but only from the
stem cells (Table V).
TABLE V
Splachnum ampullaceum. Number of protonemata from isolated stem segments
and leaves under different correlative conditions
Treatment
Stem segment and detached leaf
Stem segment plus one leaf attached
Basal half of leaf isolated
Basal half of leaf attached to plant
No.
from stem
17-5
260
of protonemata
from leaf
420
1-4
37
0
Each datum represents the average of at least 30-40 leaves (from MacQuarrie
and von Maltzahn, 1959).