FERTILIZATION AND OXIDATION 29 
Hole. The same eggs served as material for these determi- 
nations. Temperature, 23° C. 
Consumption of oxygen per hour before fertilization 0.24 mg. 
lst hour after fertilization 0.94 mg. 
2d hour after fertilization 0.80 mg. 
3d hour after fertilization 0.87 mg. 
4th hour after fertilization 0.91 mg. 
5th hour after fertilization 1.05 mg. 
The value for the hour following fertilization is probably 
a little too high on account of the presence of sperm, which was 
washed away after the first determination. That this assump- 
tion is correct is shown by a repetition of the experiment. 
Consumption of oxygen per i} hours in fertilized egg— 
first 13 hours 0.67 mg. 
second 13 hours 0.74 mg. 
third 13 hours 0.83 mg. 
The consumption of oxygen increased about 24 per cent in 
4% hours. During this same time the eggs developed from the 
one-cell stage to the thirty-two-cell stage or beyond. 
The question arises, What causes this increase? The ques- 
tion cannot be answered definitely. During the division the 
total surface of the egg increases. But it must be remembered 
that the blastomeres are in close contact with each other and 
that hence only a fraction of their surface is exposed to the 
surrounding medium. If the intensity of oxidations increases 
with the total free surface of the eggs, the slight increase of the 
rate of oxidations with the process of segmentation might be 
intelligible. 
But this is not the only possibility. It had been stated by 
Boveri that in each cell division the mass of the nucleus doubled, 
so that in the eight-cell stage the total nuclear mass would be 
eight times as great as in the one-cell stage. But this has been 
denied by more recent workers like Miss Erdmann and Conklin.! 
1 Conklin, ‘‘ Cell Size and Nuclear Size,” Jour. Exper. Zool., XII, 1, 1912. 
