32 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



are the independent variable, and that the oxidations are deter- 

 mined or regulated by the hydroiytic processes. Our investi- 

 gations do not contradict such a view. Since we are not able 

 to measure the hydroiytic processes in the egg directly, we tried 

 to solve our problem with the aid of the temperature coefficient. 

 We determined the temperature coefficient for the velocity of 

 segmentation in the egg of Arbacia by measuring the time 

 which elapses from the moment of fertilization to the moment 

 of the division of the egg into two cells for various temperatures. 

 Then we measured the influence of the same variation of tem- 

 perature upon the rate of oxidations in the cell. If the oxida- 

 tions were the independent variable for the development of the 

 egg the temperature coefficients for both processes should be 

 identical or run parallel. This is, however, not the case. The 

 experiments were made on the eggs of Arbacia at Woods Hole. 

 The time which elapsed between fertilization and the first 

 segmentation was as follows : 



TABLE II 



* Where the times are given in the form of a sum the eggs were put into the 

 thermostat as many minutes after fertilization as the first figure indicates. 



The temperature coefficients for segmentation are the 

 greater the lower the temperature. For the interval 7-17 

 the coefficient is more than three times as large as for the interval 

 17.5-27.5 (Table III). 



