REGENERATION IN LOWER PLANTS
123
of the behaviour of cellular organelles in isolated leaves by means of
electron microscopy (von Maltzahn and Mühlethaler, 1962a). Small
round 'buds' are formed at the periphery of the chloroplasts. These
structures are delimited by a double membrane which is at first continuous with that of the main body of the chloroplast. The 'buds' do not
contain any inside lamellae but only relatively dense stroma. After its
separation from the chloroplast these plastid initials represent an
independent organelle with the potentiality to grow and to form
stroma and grana lamellae. The authors assume that these plastid
initials have the potentiality of further multipUcation by means of
fission giving rise to more structures of the same kind.
In the course of these electron microscopical investigations of the
behaviour of cellular organelles in leaf cells of Splachnum during
embryonization a similar process of 'budding fission' was described also
for mitochondria (von Maltzahn and Mühlethaler, 1962b). Twenty-six
hours after isolation of the leaf from the gametophore almost spherical
bodies surrounded by a double membrane can be seen attached to the
periphery of mitochondria. It is assumed that the chamber of these
bodies is initially continuous with that of the mitochondrion from which
the 'bud' arises. After separation from the mitochondrion the mitochondrial initial enlarges and differential growth of the two membranes
leads to cristae formation. The authors state that mitochondrial initials
and plastid initials are morphologically similar immediately after their
formation. While in mature cells of attached leaves the variation in size
of mitochondria is small, in later stages of embryonization the mitochondrial population in cells of detached leaves is composed of mitochondrial initials, promitochondria and small and large mitochondria.
In investigations on regeneration of various species of Cladophoraceae essentially similar changes in single isolated cells were described
(Schoser, 1956). The cells of these green algae are multinuclear. About
1-2 days after isolation, depending on the species, an accumulation of
cytoplasm at the basal pole of the cell is observed. At the same time the
stainability of the nuclei intensifies and the size of nuclei and in particular of nucleoli increases. The quotient of nucleus volume to nucleolus
volume decreases considerably. Mitosis which ceases immediately after
isolation starts again in the basal part of the cell. The cell grows out at
the basal pole and after 4r-l0 days, depending on the species, a new
rhizoidal cell is formed by separating off the basal part by a new cell
wall. Regeneration at the apical cell pole then follows in a similar way.
If two cells are isolated together, the apical cell grows out at its apical
pole at the same time as the basal cell produces at its base a new
rhizoidal cell. Several cytochemical reactions were carried out with this
material. The results after staining with phenylfluoron suggest that
123
of the behaviour of cellular organelles in isolated leaves by means of
electron microscopy (von Maltzahn and Mühlethaler, 1962a). Small
round 'buds' are formed at the periphery of the chloroplasts. These
structures are delimited by a double membrane which is at first continuous with that of the main body of the chloroplast. The 'buds' do not
contain any inside lamellae but only relatively dense stroma. After its
separation from the chloroplast these plastid initials represent an
independent organelle with the potentiality to grow and to form
stroma and grana lamellae. The authors assume that these plastid
initials have the potentiality of further multipUcation by means of
fission giving rise to more structures of the same kind.
In the course of these electron microscopical investigations of the
behaviour of cellular organelles in leaf cells of Splachnum during
embryonization a similar process of 'budding fission' was described also
for mitochondria (von Maltzahn and Mühlethaler, 1962b). Twenty-six
hours after isolation of the leaf from the gametophore almost spherical
bodies surrounded by a double membrane can be seen attached to the
periphery of mitochondria. It is assumed that the chamber of these
bodies is initially continuous with that of the mitochondrion from which
the 'bud' arises. After separation from the mitochondrion the mitochondrial initial enlarges and differential growth of the two membranes
leads to cristae formation. The authors state that mitochondrial initials
and plastid initials are morphologically similar immediately after their
formation. While in mature cells of attached leaves the variation in size
of mitochondria is small, in later stages of embryonization the mitochondrial population in cells of detached leaves is composed of mitochondrial initials, promitochondria and small and large mitochondria.
In investigations on regeneration of various species of Cladophoraceae essentially similar changes in single isolated cells were described
(Schoser, 1956). The cells of these green algae are multinuclear. About
1-2 days after isolation, depending on the species, an accumulation of
cytoplasm at the basal pole of the cell is observed. At the same time the
stainability of the nuclei intensifies and the size of nuclei and in particular of nucleoli increases. The quotient of nucleus volume to nucleolus
volume decreases considerably. Mitosis which ceases immediately after
isolation starts again in the basal part of the cell. The cell grows out at
the basal pole and after 4r-l0 days, depending on the species, a new
rhizoidal cell is formed by separating off the basal part by a new cell
wall. Regeneration at the apical cell pole then follows in a similar way.
If two cells are isolated together, the apical cell grows out at its apical
pole at the same time as the basal cell produces at its base a new
rhizoidal cell. Several cytochemical reactions were carried out with this
material. The results after staining with phenylfluoron suggest that