VITELLINE MEMBRANE AND CORTICAL PARTICLES 243
what deviating configuration of the lamella. It consisted of a densely
coiled material, whereas the normal structure is that of a perforated
plate. The coiled lamella may have arisen by an elongation and fusion
of the vacuoles present in more spherical form in the platelike configuration. This case is also an exception representing a less probable configuration.
The genetical basis of the cortical particles in
Strongylocentrotus
droebachiensis
and those of Strongylocentrotus
purpuratus must be similar in certain respects, but different in others. The resemblance between
these species is not as close as the resemblance found between Echinus
esculentus and Echinus acutus. Hemicentrotus
pulcherrimus
is more removed from the other two species. Even regarding the lamella, the similarity with S. droebachiensis
is not complete. The contrast between H.
pulcherrimus
and the two other species is particularly great if several
extralamellar bodies are present instead of the larger single one seen
in Fig. 14. The genetical basis must then be rather different from that
in the two other species. The difference in configurations of the cortical
particles add, then, some weight to the transfer of S. pulcherrimus
to a
different genus,
Hemicentrotus.
2. The Differentiation
of the Cortical Particles in the Oocytes
Runnström and Monné (1945) showed that the cortical particles are
present in the interior cytoplasm but not in the cortex of the oocytes of
Psammechinus
miliaris. In connection with the maturation of the egg,
the scattered granules are transported into the cortex where they form a
single uniform layer and are spaced in a very regular way, relative to
each other. This result was further elaborated by Monné and Hârde
(1951) using Paracentrotus
lividus and Arbacia lixula as material. Moreover, the results were confirmed by electron-microscopic studies of McCulloch (1952) on Arbacia punctulata and of Afzelius (1956) on Echinus
esculentus, Psammechinus
miliaris, and Spatangus
purpureus.
Lönning
(1963) has recently presented electron micrographs of the cortical particles in the oocytes and mature eggs of Brissopsis lyrifera, where the
same differences with respect to their location are found as in the previously mentioned species. In quite young oocytes Lönning found no cortical particles.
This writer (unpublished material, 1963-1964) has made an attempt
to trace the early development of the cortical particles in oocytes of
Brissopsis lyrifera, Psammechinus
miliaris, and Paracentrotus
lividus.
The following report and the views expressed are in many respects preliminary in nature.
In Brissopsis oocytes, numerous germs of cortical particles are found
what deviating configuration of the lamella. It consisted of a densely
coiled material, whereas the normal structure is that of a perforated
plate. The coiled lamella may have arisen by an elongation and fusion
of the vacuoles present in more spherical form in the platelike configuration. This case is also an exception representing a less probable configuration.
The genetical basis of the cortical particles in
Strongylocentrotus
droebachiensis
and those of Strongylocentrotus
purpuratus must be similar in certain respects, but different in others. The resemblance between
these species is not as close as the resemblance found between Echinus
esculentus and Echinus acutus. Hemicentrotus
pulcherrimus
is more removed from the other two species. Even regarding the lamella, the similarity with S. droebachiensis
is not complete. The contrast between H.
pulcherrimus
and the two other species is particularly great if several
extralamellar bodies are present instead of the larger single one seen
in Fig. 14. The genetical basis must then be rather different from that
in the two other species. The difference in configurations of the cortical
particles add, then, some weight to the transfer of S. pulcherrimus
to a
different genus,
Hemicentrotus.
2. The Differentiation
of the Cortical Particles in the Oocytes
Runnström and Monné (1945) showed that the cortical particles are
present in the interior cytoplasm but not in the cortex of the oocytes of
Psammechinus
miliaris. In connection with the maturation of the egg,
the scattered granules are transported into the cortex where they form a
single uniform layer and are spaced in a very regular way, relative to
each other. This result was further elaborated by Monné and Hârde
(1951) using Paracentrotus
lividus and Arbacia lixula as material. Moreover, the results were confirmed by electron-microscopic studies of McCulloch (1952) on Arbacia punctulata and of Afzelius (1956) on Echinus
esculentus, Psammechinus
miliaris, and Spatangus
purpureus.
Lönning
(1963) has recently presented electron micrographs of the cortical particles in the oocytes and mature eggs of Brissopsis lyrifera, where the
same differences with respect to their location are found as in the previously mentioned species. In quite young oocytes Lönning found no cortical particles.
This writer (unpublished material, 1963-1964) has made an attempt
to trace the early development of the cortical particles in oocytes of
Brissopsis lyrifera, Psammechinus
miliaris, and Paracentrotus
lividus.
The following report and the views expressed are in many respects preliminary in nature.
In Brissopsis oocytes, numerous germs of cortical particles are found