36 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
sea-water. This leads him to believe that these eggs develop 
best in a solution in which the concentration of hydroxylions 
equals that of the sea-water; and that while it is possible to 
delay their development by a lowering of this concentration, 
no acceleration can be produced if the Con in the sea-water 
is raised. This statement is corroborated by the fact referred 
to above that the addition of some NaHCO, is more favor- 
able for the development of the larvae than the addition of 
NaOH. 
7. Warburg states that it is possible to raise the rate of 
oxidations in the fertilized egg through the addition of NaOH, 
but not by the addition of NH,OH. Since he was able to show 
that NH,OH diffuses into the cell while NaOH does not, he 
concludes from this and a similar observation! “that all the 
substances which increase the oxidations in the fertilized eggs 
belong to that class which according to Overton cannot enter 
into the living cell” (p. 328). “‘The influence of an increase 
of the concentration of the HO ions upon respiration is neither 
determined by the entrance of ions into the eggs, nor by their 
reacting with the membrane of the cytoplasm, but merely 
by their presence in the solution surrounding the egg”’ (p. 314). 
Warburg quotes determinations of the oxygen consumption of 
newly fertilized eggs of Strongylocentrotus at Naples for three 
different concentrations of NaOH, 10° N, 10° N, and 10° N. 
The ratio of these oxidations in three solutions was 1.4:3.9:8.1. 
Only in one of these three solutions did the eggs develop, namely, 
in the one with the Con 10° N. Of the two others the one 
was too acid, the other too alkaline. NH,OH did not raise 
the rate of oxidations perceptibly. 
1 Warburg, ‘‘Ueber die Oxydationen in lebenden Zellen nach Versuchen am 
Seeigelei,’”’ Zeitschr. f. physiol. Chem., LXVI, 305, 1910. The other observation 
not discussed in the text refers to an increase of oxidations in the fertilized egg 
under the influence of hypertonic solution. "Wasteneys and I were not able to 
confirm this statement of Warburg; we found that the oxidations in the fertilized 
egg of Strongylocentrotus purpuratus are not increased if the eggs are put into a 
hypertonic solution. 
