98 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
All these observations point to the conclusion that the 
processes determining or underlying nuclear division depend 
upon oxidations. 
The eggs of the starfish must be fertilized at the time the 
second polar body is given off or immediately afterward, since 
otherwise they disintegrate and cannot be fertilized at all. 
When we compare the rate of oxidations in starfish eggs imme- 
diately before and after fertilization, we find no difference, as 
Table I shows. It should be remarked that while as a rule 100 
per cent of the sea-urchin eggs can be fertilized by sperm, in the 
case of starfish eggs a much smaller percentage is usually ferti- 
lized since in most cases not all the eggs become mature 
simultaneously. 
TABLE [! 
Consumption of | Consumption of 
Number of Experiment Oxygen of the Oxygen of the 
|Unfertilized Eggs) Fertilized Eggs 
Percentage of 
Fertilized Eggs 
Les erste Sine fielaleceee ere 0.67 mg 0.51 mg. 11 
WS ores ccsteets cate eee 0.64 0.52 20 
III 0.78 0.85 25 
LIM (ie Ocoee ctepctcioettcr 0.34 0.31 7 
i Eee meen Seer crore osc 0.26 0.33 52 
It is obvious that no noticeable increase in the rate of the 
oxidation is caused in this egg through the entrance of the 
spermatozoon. This is intelligible from the fact that those 
oxidations which lead to nuclear division were already going on. 
in the eggs at the time the spermatozoon entered. 
3. Warburg? compared the rates of oxidations in the eight- 
cell stage and the thirty-two-cell stage. Their ratio was as 
4-2 to 6-8; a slight increase. Wasteneys and I* measured 
the change in the rate of oxidations each hour for five consecu- 
tive hours after fertilization in the eggs of Arbacia at Woods 
1 Loeb and Wasteneys, Archiv f. Entwicklungsmechanik, XXXV, 556, 1912. 
2 Warburg, Zeitschr. f. physiol. Chem., LVII, 1, 1908. 
’ Loeb and Wasteneys, Biochem. Zeitschr., XXXVI, 351, 1911. 
