146
LUISE STANGE
and/or energy by photosynthesis. After treatment of the leaves with a
solution of sodium fluoride, the number of buds decreased proportionally
to the duration of treatment. In summary, the dependence of progression
of differentiation of regenerative development on the type of isolated
part can be attributed to differences in the size of the photosynthesizing
area of the isolated part. That the progression of differentiation is dependent on a supply of some substances produced in photosynthesizing
cells, was shown also in regeneration experiments with isolated filaments
of caulonema, which is the second stage in protonema development
preceding the formation of buds under normal conditions. After
isolation, the cells of the caulonema filament divided and the number of
their chloroplasts increased (Bopp, 1954). In this way a typical chloronema, the first stage in normal protonematal development, was formed.
But if a filtrate of a culture medium, in which protonema has grown for
some time, was added to the caulonema cells, they did not form chloronema but produced buds (Ernst, 1958; Bopp, 1959). The only information available on the substance(s) responsible for this effect is that they
are destroyed by heating.
B. Determination Preserved in Regeneration
It has been learned from many regeneration experiments that the
quality of the regenerate is independent of the original properties of the
cell from which it arises. In the process of regeneration through embryonization, the cell usually does not only take over the functions of
growth and division but proves its totipotency by the development of a
complete new plant. For instance in mosses, after isolation of parts as
dissimilar as protonema cells, leaves of the gametophyte, or segments of
the seta of the sporophyte, protonema, the lowest stage of differentiation, is the first regeneration product. (The protonema is diploid in the
case of sporophyte regeneration.) However, quite different behaviour of
regenerating cells has been reported in recent years.
In his very interesting investigations on regeneration of the sporophyte of Physcomitrium piriforme and the hybrid sporogonium resulting
from cross-fertilization between Physcomitrium piriforme and Funaria
hygrometrica (PiHy and HyPi), Bauer (1957, 1959a, b, 1961a, b, 1963)
showed that the age of the sporogonium used for regeneration is of
special significance for the quality of the regenerates (Fig. 8). When the
sporogonium has reached a developmental stage in which the seta tip
has begun to thicken, only protonema filaments are regenerated no
matter from what region of the sporogonium the section is isolated.
Completely different results are obtained when very young sporogonia,
the tips of which are still largely embryonic, are used for the regeneration
experiments. In a young sporogonium one can distinguish several
LUISE STANGE
and/or energy by photosynthesis. After treatment of the leaves with a
solution of sodium fluoride, the number of buds decreased proportionally
to the duration of treatment. In summary, the dependence of progression
of differentiation of regenerative development on the type of isolated
part can be attributed to differences in the size of the photosynthesizing
area of the isolated part. That the progression of differentiation is dependent on a supply of some substances produced in photosynthesizing
cells, was shown also in regeneration experiments with isolated filaments
of caulonema, which is the second stage in protonema development
preceding the formation of buds under normal conditions. After
isolation, the cells of the caulonema filament divided and the number of
their chloroplasts increased (Bopp, 1954). In this way a typical chloronema, the first stage in normal protonematal development, was formed.
But if a filtrate of a culture medium, in which protonema has grown for
some time, was added to the caulonema cells, they did not form chloronema but produced buds (Ernst, 1958; Bopp, 1959). The only information available on the substance(s) responsible for this effect is that they
are destroyed by heating.
B. Determination Preserved in Regeneration
It has been learned from many regeneration experiments that the
quality of the regenerate is independent of the original properties of the
cell from which it arises. In the process of regeneration through embryonization, the cell usually does not only take over the functions of
growth and division but proves its totipotency by the development of a
complete new plant. For instance in mosses, after isolation of parts as
dissimilar as protonema cells, leaves of the gametophyte, or segments of
the seta of the sporophyte, protonema, the lowest stage of differentiation, is the first regeneration product. (The protonema is diploid in the
case of sporophyte regeneration.) However, quite different behaviour of
regenerating cells has been reported in recent years.
In his very interesting investigations on regeneration of the sporophyte of Physcomitrium piriforme and the hybrid sporogonium resulting
from cross-fertilization between Physcomitrium piriforme and Funaria
hygrometrica (PiHy and HyPi), Bauer (1957, 1959a, b, 1961a, b, 1963)
showed that the age of the sporogonium used for regeneration is of
special significance for the quality of the regenerates (Fig. 8). When the
sporogonium has reached a developmental stage in which the seta tip
has begun to thicken, only protonema filaments are regenerated no
matter from what region of the sporogonium the section is isolated.
Completely different results are obtained when very young sporogonia,
the tips of which are still largely embryonic, are used for the regeneration
experiments. In a young sporogonium one can distinguish several