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 . 24 mg. 

 . 1st hour after fertilization . 94 mg, 

 2d hour after f ertiUzation . 80 mg. 

 3d hour after f ertiUzation . 87 mg. 

 4th hour after fertilization 0.91 mg. 

 5th hour after fertilization 1 . 06 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 IJ hours in fertiUzed egg — 



first 1| hours . 67 mg. 



second IJ hours 0.74 mg. 



third H hours . 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 

 sXirrounding 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 Erdmarm and Conklin.^ 



1 Conklln, "Cell Size and Nuclear Size," Jour. Exper. Zool, XII, 1, 1912. 



