262
GERHARD KRAUSE AND KLAUS SANDER
stage is lacking as yet. Defects during embryogenesis may lead not only
to phenocopies (Gloor, 1947; Maas, 1948), but also to genetical mosaics
which demonstrate interaction between a tissue-specific prepattern and
mutants of the genome (Stern, 1956). The constitution and modification
of nuclei during development are of the utmost importance for embryogenesis as was shown earlier by Boveri. The caryotype originating
during fusion of pronuclei is differentiated sexually in most insects. By
way of 'nature's experiments', insects especially offer for analysis
numerous cases of abnormal maturation and fertilization, parthenogenesis, inter-sexuality, gynandry, and elimination of Keimbahn
chromosomes (Wiese, 1960; Stefani, 1959; Matuszewski, 1960; GeyerDuszynska, 1961). These are being amplified by artificially produced
abnormities, chimaeras or mosaics (Astaurov et ah, 1957; von Borstel,
1957; Hannah, 1955; S. Seidel, 1960; Seiler et ah, 1958-1960). Changes in
ploidy of cells, which so commonly occur during postembryonic development (Henke, 1953; Risler, 1954, 1959) are observed less frequently
during embryogenesis, polyteny being absent altogether in early stages.
Better understanding of the caryoplasmic determination of developmental processes may be expected from recent studies concerning
somatic mutation (Becker, 1957; Löbbecke and Oltmanns, 1961), the
importance of nucleoli for the formation and storage of RNA influencing
embryonic growth (Beermann, 1960), and organ specific chromosome
modifications (Beermann, 1952).
For the assessment of physiologically active substances in the insect
egg, different genotypes may be utilized (Egelhaaf, 1956) but generally
other methods are employed (e.g. v.d. Crone-Gloor, 1959); as yet it is
almost impossible to assess the connections with the developmental
processes observed. Histochemical methods have been applied successfully to oogenesis (Bonhag, 1958, 1959; v. Kraft, 1960a, b ; Nath et ah,
1959; Sirlin and Jacob, 1960), whereas embryonic development has been
investigated in a few cases only, and hardly even with a view to observing changes in important regions (Bier, 1953; Brächet, 1960; Jura, 1959;
Jura et ah, 1958, 1959; Tawfik, 1957; Yao, 1950). Studies, by means of
the electron microscope, of cell organelles that may be acting as internal
factors for development, are rare (King, 1960; Okada and Waddington,
1959). The role of intracellular symbionts as internal factors of development is made clear in the numerous descriptions given by Büchner and
his pupils (Büchner, 1953).
III. Preformed Prerequisites in the Ooplasm
The ooplasmic architecture of insect eggs involves several visible
components. Yolk globules and other deutoplasmic particles are distri-
GERHARD KRAUSE AND KLAUS SANDER
stage is lacking as yet. Defects during embryogenesis may lead not only
to phenocopies (Gloor, 1947; Maas, 1948), but also to genetical mosaics
which demonstrate interaction between a tissue-specific prepattern and
mutants of the genome (Stern, 1956). The constitution and modification
of nuclei during development are of the utmost importance for embryogenesis as was shown earlier by Boveri. The caryotype originating
during fusion of pronuclei is differentiated sexually in most insects. By
way of 'nature's experiments', insects especially offer for analysis
numerous cases of abnormal maturation and fertilization, parthenogenesis, inter-sexuality, gynandry, and elimination of Keimbahn
chromosomes (Wiese, 1960; Stefani, 1959; Matuszewski, 1960; GeyerDuszynska, 1961). These are being amplified by artificially produced
abnormities, chimaeras or mosaics (Astaurov et ah, 1957; von Borstel,
1957; Hannah, 1955; S. Seidel, 1960; Seiler et ah, 1958-1960). Changes in
ploidy of cells, which so commonly occur during postembryonic development (Henke, 1953; Risler, 1954, 1959) are observed less frequently
during embryogenesis, polyteny being absent altogether in early stages.
Better understanding of the caryoplasmic determination of developmental processes may be expected from recent studies concerning
somatic mutation (Becker, 1957; Löbbecke and Oltmanns, 1961), the
importance of nucleoli for the formation and storage of RNA influencing
embryonic growth (Beermann, 1960), and organ specific chromosome
modifications (Beermann, 1952).
For the assessment of physiologically active substances in the insect
egg, different genotypes may be utilized (Egelhaaf, 1956) but generally
other methods are employed (e.g. v.d. Crone-Gloor, 1959); as yet it is
almost impossible to assess the connections with the developmental
processes observed. Histochemical methods have been applied successfully to oogenesis (Bonhag, 1958, 1959; v. Kraft, 1960a, b ; Nath et ah,
1959; Sirlin and Jacob, 1960), whereas embryonic development has been
investigated in a few cases only, and hardly even with a view to observing changes in important regions (Bier, 1953; Brächet, 1960; Jura, 1959;
Jura et ah, 1958, 1959; Tawfik, 1957; Yao, 1950). Studies, by means of
the electron microscope, of cell organelles that may be acting as internal
factors for development, are rare (King, 1960; Okada and Waddington,
1959). The role of intracellular symbionts as internal factors of development is made clear in the numerous descriptions given by Büchner and
his pupils (Büchner, 1953).
III. Preformed Prerequisites in the Ooplasm
The ooplasmic architecture of insect eggs involves several visible
components. Yolk globules and other deutoplasmic particles are distri-