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RALPH S. LILLIE. 



form larvse with exposures varying in length from 4 to 6 minutes. 

 The optima seem to be less sharply defined when the eggs are 

 in the best of condition, probably because then the power of 

 regulatory adjustment to environmental variations is at its 

 maximum, and slight deviations from the optima are auto- 

 matically corrected. 



Table VI. 

 33°. 



At 34° the majority of eggs form membranes with one minute's 

 exposure, and 30 seconds is sufficient for a minority. A few eggs 

 form larvae after 2 minutes' exposure; the optimum is 3 to 4 

 minutes; longer exposure is injurious. Table VII. summarizes 



Table VII. 



34^ 



