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 CQH in the sea-water 

 is raised. This statement is corroborated by the fact referred 

 to above that the addition of some NaHC0 3 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 4 OH. Since he was able to show 

 that NH 4 OH diffuses into the cell while NaOH does not, he 

 concludes from this and a similar observation 1 "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, 1CT 8 N, 10~ 6 N, and 10~ 3 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 COH io~ (> N. Of the two others the one 

 was too acid, the other too alkaline. NH 4 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. 



