THE PROBLEM OF ACTIVATION 



249 



quent development (see the first table above). (3) In 

 each experiment the percentage of reacting eggs in- 

 creases with time of exposure to an optimum and then 

 decreases. (4) The optimum time for production of 

 larvae at 31° is 14 to 15 minutes; at 32°, from 6 to 8 

 minutes; that is, the rate of the activation reaction is 

 approximately doubled by a rise of 1° in temperature. 

 At 33° the optimum exposure is about 4§ to 5I minutes; 

 at 34°, 3 to 4 minutes; at 35°, ij to 2 minutes; and at 

 36°, I to ij minutes. 



The range of effective temperatures is from about 

 29° to 38°. The following table shows the time varia- 

 tions for various effects within this range: 



APPROXIMATE TIMES OF EXPOSURE REQUIRED TO PRO- 

 DUCE THE FOLLOWING EFFECTS AT DIFFERENT 



TEMPERATURES 



Tempera- 

 ture 



29° 

 30° 

 31° 

 32° 

 33° 

 34° 

 35° 

 36° 

 37° 

 38° 



Formation of 

 Membranes 



Ca.12-14 m. 

 8-10 m. 

 Ca. 4 m. 

 Ca. 2 m. 

 Ca. I m. 



Ca. 

 Ca. 



^ to I m. 

 ^ m. 

 15 sec. 



Minimum for 

 Larvae 



20-25 rn. 

 Ca. 18 m. 

 Ca. 8 m. 

 4-5 m. 



2^-3 m. 

 Ca. 2 m. 

 i-ij m. 

 30-45 sec. 



Optimum for 

 Larvae 



30-40 m. 

 Ca. 28 m. 

 Ca. 15 m. 

 7- 8 m. 

 4I-52 m. 

 3-3h ni. 

 1^-2^ m. 

 1-15 m. 

 30-35 sec. 

 Ca. 20 sec. 



Maximum for 

 Larvae 



?> 30 m. 



21-25 m. 



10-12 m. 



8-10 m. 



Ca. 5 m. 



Ca. 3 m. 



Ca. 2 m. 



Commenting upon the process underlying the time 

 variation at the different temperatures, R. S. LiUie says: 



In endeavoring to form some consistent conception of the 

 nature of this process, the following facts have to be consid- 

 ered. It exhibits a high temperature coefhcient: from fifteen 

 to twenty times the duration of exposure is required to induce 



