The San Francisco call., 1906-03-25

a
I'VE may therefore state that arti-
hcial' partheHogenesfs can only. be pro-
duced by shypertonfc sea water when
the latter. acts in the presence of free
oxygen. This eliminates the idea that
the hypertonic sea water might act
through preventing oxidations. II
eliminates likewise the idea that its
effect upon artificial parthenogenesis is
due 70 a coagulation caused by the
withdrawal of water from the egg. If
this were the case, the absence or pres
ence of oxygen should make no diff
ference
We can. however, easily understand
this role of oxygen in the action of the
hypertonic sea water If we consider
the facts published in our previous
papers. I think we may consider it an
established fact (Which 1 have, by the
way, verified a large number of times
during this recent series of expert
ments) that the process of segmenta-
ton and development is primarily an
oxidative process and that IT comes to
a sudden standstill If the free oxygen
is taken from the egg This process
Of oxidation is obviously intimately
connected with the synthesis of
nuclein material from constituents of
the protoplasm, since this process ceases
when the egg is deprived of oxygen /.
I'm the unfertilized egg of the sea
urchin this synthesis cannot occur (or
only so slowly that it is not noticeable)
But the direct observations mentioned in
previous papers show that this process
can be produced If we cause an artificial
membrane formation. But If nothing else
is done to the egg it dies in the presence
Of oxygen, possibly because the oxida-
tons occur in a wrong direction and lead
to the formation of toxic products
PREVENTS TOXIC SUBSTANCES.
1.-The loss Of water on the part of the
egg caused by the hypertonic sea water
leads in the presence of free oxygen to
the formation Of certain compounds which
turn the oxidative processes in the egg
into the right direction and prevent the
formation of the toxic substances and the
disintegration Of the egg caused thereby.
Such compounds may possibly be
formed in the egg when the oxidative
processes are prevented for q long period
of time, while other catalytic processes
are allowed to go on This might explain
the observations made by Lyon and my
self, mentioned in the preceding paper.
81 think the results Of this paper ex-
plain also a fact which ] found last year
and which appeared riddle at that time
When the membrane formation is pro-
duced first in an egg it needs to be ex-
posed to the hypertonic sea water only
about forty-five to fifty minutes at Is
degrees in order to develop. If. however;
the egg is exposed to the hypertonic sea
water first and the membrane formation
is caused afterward the exposure to the
hvpertonic sea water must be at least
about ninety minutes at the same tenn
perature.
ssWhy should the reaction time for the
hvpertonic sea water be so different in
both cases. The fact that the hypertonic
sea water acts only in the presence of
oxygen seems to explain this difference.
The main difference between the sea-
urchin egg with and without artificial
membrane formation lies in lie fact that
In the former oxidatiye processes are
started Tor immensely accelerated), which
In the latter are lacking, or extremely
slow. We are tempted to assume that
In the egg after the membrane forma-
ton is caused oxidases become active.
while these oxidases do not exist or act
very slowly in the resting egg in which
he process of membrane formation is not
caused.
PROCESS NOW CLEAR.
wherever We produce the development
II the egg Of the sea-urchin by two diff
ierent agencies the membrane formation
lnd the hypertonic sea water, the role
II both seems now tolerably clear. Pro-
,esses of oxidation are started by the |
membrane formation. Certain products !
# oxidation are formed through the ac- |
ion Of the hypertonic sea water, which '