FERTILIZATION AND OXIDATION 27 
pustulosa, at Naples, by Winkler’s method, and found that after 
fertilization the egg consumes from six to seven times as much 
oxygen as before fertilization.’ 7 Wasteneys and I determined 
the consumption of oxygen in unfertilized eggs of Arbacia 
at Woods Hole. We found that immediately after fertili- 
zation the egg consumes almost four times as much oxygen 
as before fertilization.2 In experiments on Strongylocentrotus 
purpuratus in Pacific Grove we found that immediately after 
fertilization the egg consumed five to seven times as much 
oxygen as before fertilization.* 
This difference in the rate of oxidations in the unfertilized 
and fertilized eggs of the sea-urchin is probably due to the fact 
that the unfertilized egg of the sea-urchin is usually in the 
resting stage, i.e., no nuclear divisions are going on in it, 
when it is taken out of the ovary and it generally remains in 
this state if no spermatozoon enters. 
2. The conditions are, however, entirely different in the 
starfish egg. This egg is, as a rule, immature when taken out 
of the ovary, but as soon as it gets into the sea-water, it 
may become mature; i.e., two nuclear divisions take place in 
succession and the polar bodies are thrown out. I have shown 
in a former paper that this process requires the presence of free 
oxygen in the same way as the developing sea-urchin egg. Lack 
of oxygen or presence of KCN prevents these nuclear maturation 
divisions in the starfish egg with the same certainty as it does 
the nuclear divisions in the fertilized sea-urchin egg.* And, 
moreover, I was able to show that a slightly alkaline reaction 
of the surrounding solution is as favorable to the process of 
maturation of the starfish egg as it is to the segmentation of 
the fertilized egg of Strongylocentrotus purpuratus. 
10. Warburg, Zeitschr. f. physiol. Chem., LVII, 6, 1908. 
2 Loeb and Wasteneys, Biochem. Zeitschr., XXXVI, 351, 1911. 
3 Loeb and Wasteneys, Jour. Biol. Chem., XIV, 469, 1913. 
4Loeb, ‘‘ Maturation, Natural Death and the Prolongation of the Life of 
Unfertilized Starfish Eggs,’’ Biol. Buli., III, 295, 1902. 
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