Increase in Permeability to Electrolytes. 3 
in the sea water would be free to move around the egg. Hober 1 
has shown that the plasma membrane of the erythrocyte is less 
permeable than the interior, to ions, and this is also probably 
true of the egg. 
In sugar solution unfertilized eggs showed anodal disintegration 
with less current than did fertilized eggs, indicating that the latter 
were more permeable to anions, or that the electrolytes had 
already diffused out, in either case showing an increased perme- 
ability to electrolytes. 
In a molecular solution of dextrose (approximately isomotic 
with sea water) fertilized eggs were plasmolysed more rapidly than 
unfertilized eggs, indicating that the latter were less permeable 
to the salts exerting the internal osmotic pressure. 
To sum up, the increased electric conductivity and liability 
to plasmolysis with molecular sugar solution and the decreased 
liability to anodal disintegration, of the fertilized egg, indicate 
that it is more permeable than the unfertilized egg, to electrolytes. 
How could this increase in permeability to electrolytes be related 
to the development of the egg? 
Loeb has shown that oxygen and hydroxyl ions in the medium 
are necessary for development. But eggs will not develop in 
sea water (which contains oxygen and OH ions) unless some change 
is induced. Probably this change allows oxygen and hydroxyl 
ions to reach such a concentration within the egg that rapid oxi- 
dation may take place. The accumulation of carbon dioxide 
within the unfertilized egg lowers the concentration of hydroxyl 
ions. Increased permeability to electrolytes, including carbonic 
acid, would allow the escape of the latter and the rise in concen- 
tration of hydroxyl ions. 
The increase in permeability probably causes the increased 
elimination of carbon dioxide and catalase, and the increased 
absorption of oxygen, which have been observed by Lyon, War- 
burg, Loeb and others. 
x Arch. f. d. ges. Physiol., cxxx, 237. 
