VITELLINE MEMBRANE AND CORTICAL PARTICLES 269
of the openings, the stomata, of the cortical particles. On the other hand,
it seems evident that the lipoproteins in the deeper cortical cytoplasm
also undergo a change with the progress of the impulse (see further
Section II,D).
The changes in the peripheral cortical layer soon influence the underlying cytoplasm, as may be inferred from observations with dark-field
illumination. The ground cytoplasm appears darker (i.e., more homogeneous) than in the unfertilized egg. What this change represents from
a biochemical point of view will be discussed later (Section ΙΙ,Ε and F).
Rothschild and Swann (1949) recorded photographically the rate of
the change in light scattering in the surface that, as shown above, follows upon effective attachment of a spermatozoon. The species examined
was Psammechinus
miliaris. The photographic records of Rothschild
and Swann have been reexamined by Kaczer (1955). The analysis of the
primary material shows that after a varying time of latency (5-10 sec)
the rate of change in light scattering increases rather steeply. The rate
of change decreases after half-completion of the change that occurs 1520 sec after fertilization. From this point the rate is almost constant, but
it increases again during the last phase of change covering the region
which is most distal from the initial region (Kaczer, loc. cit., Fig. 2).
Rothschild and Swann (1949) interpreted the form of the rate curve
as due to the formation of a diffusible substance at the site of effective
sperm attachment. The pathway of diffusion may be through the interior cytoplasm or through a narrow cortical layer. According to Kaczer
(1955) it is not possible to decide between these two possibilities on the
basis of the present curves. Kaczer's model studies point to the conclusion that an autocatalytic process is decisive for the rate changes in light
scattering.
Runnström and Kriszat (1952) observed fertilization in eggs of Psammechinus miliaris that were attached to a glass plate. The jelly coat had
been removed by acid treatment, and by a slight overexposure to acid
the eggs had become sticky to the glass. On fertilization, a normal fertilization membrane was formed from the free surface, but the attached
region of the eggs failed to be activated (Fig. 23A). After removal of
the eggs from the glass plate, the attached region formed a bulge that,
according to all criteria (coarser cytoplasmic structure, wrinkling in
hypertonic medium) appeared unfertilized. The bulge underwent monospermic fertilization with elevation of a fertilization membrane. No restraint of the diffusion of a substance from the site of effective sperm
attachment was introduced in this experiment. If such diffusion was the
factor propagating the impulse, the glass-attached region should have
been included in the activation. It was inferred, therefore, that the
of the openings, the stomata, of the cortical particles. On the other hand,
it seems evident that the lipoproteins in the deeper cortical cytoplasm
also undergo a change with the progress of the impulse (see further
Section II,D).
The changes in the peripheral cortical layer soon influence the underlying cytoplasm, as may be inferred from observations with dark-field
illumination. The ground cytoplasm appears darker (i.e., more homogeneous) than in the unfertilized egg. What this change represents from
a biochemical point of view will be discussed later (Section ΙΙ,Ε and F).
Rothschild and Swann (1949) recorded photographically the rate of
the change in light scattering in the surface that, as shown above, follows upon effective attachment of a spermatozoon. The species examined
was Psammechinus
miliaris. The photographic records of Rothschild
and Swann have been reexamined by Kaczer (1955). The analysis of the
primary material shows that after a varying time of latency (5-10 sec)
the rate of change in light scattering increases rather steeply. The rate
of change decreases after half-completion of the change that occurs 1520 sec after fertilization. From this point the rate is almost constant, but
it increases again during the last phase of change covering the region
which is most distal from the initial region (Kaczer, loc. cit., Fig. 2).
Rothschild and Swann (1949) interpreted the form of the rate curve
as due to the formation of a diffusible substance at the site of effective
sperm attachment. The pathway of diffusion may be through the interior cytoplasm or through a narrow cortical layer. According to Kaczer
(1955) it is not possible to decide between these two possibilities on the
basis of the present curves. Kaczer's model studies point to the conclusion that an autocatalytic process is decisive for the rate changes in light
scattering.
Runnström and Kriszat (1952) observed fertilization in eggs of Psammechinus miliaris that were attached to a glass plate. The jelly coat had
been removed by acid treatment, and by a slight overexposure to acid
the eggs had become sticky to the glass. On fertilization, a normal fertilization membrane was formed from the free surface, but the attached
region of the eggs failed to be activated (Fig. 23A). After removal of
the eggs from the glass plate, the attached region formed a bulge that,
according to all criteria (coarser cytoplasmic structure, wrinkling in
hypertonic medium) appeared unfertilized. The bulge underwent monospermic fertilization with elevation of a fertilization membrane. No restraint of the diffusion of a substance from the site of effective sperm
attachment was introduced in this experiment. If such diffusion was the
factor propagating the impulse, the glass-attached region should have
been included in the activation. It was inferred, therefore, that the