T H E E A R L Y E M B R Y O G E N E S I S OF I N S E C T S
299
during their spread. Such an explanation would also account for the
regulation after belt irradiation destroying the surface of the entire DC
region containing the pattern shown in Fig. 6c, but leaving anterior and
posterior embryonic blastoderm regions intact (Seidel, 1934). The experimental results do not yet warrant any uniform picture of ooplasmic
prerequisites for metameric organization in the insect egg, but we have
tried to point out ways and means to reconcile apparently conflicting
results obtained by different methods and by different investigators.
As for irradiation by U.V. or X-rays, the results so far gained by this
valuable method are frequently marred by lack of knowledge concerning
the action of these rays on insect eggs. Apart from operations in which
no nucleus was present in the target area (e.g., Goldman and Setlow,
1956; Geyer-Duszynska, 1961), it is even difficult to tell whether it is the
nuclei or the plasm which is the primary site of reaction leading to the
defect observed, and this despite numerous investigations (see Ulrich,
1957). From the results of work on Habrobracon, von Borstel and Wolff
(1955) suggest that photoreactivation after U.V. treatment, believed by
these authors to be possible only in case of nuclear damage, is a method
for distinguishing between nuclear and plasmic influences in embryogenesis. Irradiation effects (2600 Ä) can be diminished by subsequent
application of visible light (3600 Ä) in case of irradiation of the ventral
.side containing the nucleus, but not in the case of dorsal irradiation. Yet
there remains a chance that these findings are due to uneven distribution of periplasmic prerequisites in the Habrobracon egg, as indicated by
some facts already mentioned in this paper, and especially by the observation of a dorsal maximum of basophilia in the egg of the honey-bee
(Schnetter, 1934a). More precisely located irradiation, description of
damage resulting to the ooplasm, and observation of abnormal development instead of, or in addition to, records of hatching percentage and
imaginal malformations would render such experiments still more valuable for analysis of development. It is hoped that the present report
will stimulate more intensive observations in this direction, and promote
the study, descriptive as well as analytical, of insect embryogenesis in
general.
Acknowledgements
We wish to thank Dr. K. Bier for permission to quote his unpublished
results.
References
Ando, H. (1960). Sei. Rep. Tokyo Kyoiku Daigaku Sect. B, 9, 227.
Astaurov, B. L. and Ostriakova-Varshaver, V. P. (1957). J. Embryol. 5, 449.
299
during their spread. Such an explanation would also account for the
regulation after belt irradiation destroying the surface of the entire DC
region containing the pattern shown in Fig. 6c, but leaving anterior and
posterior embryonic blastoderm regions intact (Seidel, 1934). The experimental results do not yet warrant any uniform picture of ooplasmic
prerequisites for metameric organization in the insect egg, but we have
tried to point out ways and means to reconcile apparently conflicting
results obtained by different methods and by different investigators.
As for irradiation by U.V. or X-rays, the results so far gained by this
valuable method are frequently marred by lack of knowledge concerning
the action of these rays on insect eggs. Apart from operations in which
no nucleus was present in the target area (e.g., Goldman and Setlow,
1956; Geyer-Duszynska, 1961), it is even difficult to tell whether it is the
nuclei or the plasm which is the primary site of reaction leading to the
defect observed, and this despite numerous investigations (see Ulrich,
1957). From the results of work on Habrobracon, von Borstel and Wolff
(1955) suggest that photoreactivation after U.V. treatment, believed by
these authors to be possible only in case of nuclear damage, is a method
for distinguishing between nuclear and plasmic influences in embryogenesis. Irradiation effects (2600 Ä) can be diminished by subsequent
application of visible light (3600 Ä) in case of irradiation of the ventral
.side containing the nucleus, but not in the case of dorsal irradiation. Yet
there remains a chance that these findings are due to uneven distribution of periplasmic prerequisites in the Habrobracon egg, as indicated by
some facts already mentioned in this paper, and especially by the observation of a dorsal maximum of basophilia in the egg of the honey-bee
(Schnetter, 1934a). More precisely located irradiation, description of
damage resulting to the ooplasm, and observation of abnormal development instead of, or in addition to, records of hatching percentage and
imaginal malformations would render such experiments still more valuable for analysis of development. It is hoped that the present report
will stimulate more intensive observations in this direction, and promote
the study, descriptive as well as analytical, of insect embryogenesis in
general.
Acknowledgements
We wish to thank Dr. K. Bier for permission to quote his unpublished
results.
References
Ando, H. (1960). Sei. Rep. Tokyo Kyoiku Daigaku Sect. B, 9, 227.
Astaurov, B. L. and Ostriakova-Varshaver, V. P. (1957). J. Embryol. 5, 449.